# Global language geography and language history: challenges and opportunities

Matthias Urban

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Matthias Urban. Global language geography and language history: challenges and opportunities. Open Research Europe, 2024, 4, pp.213. 10.12688/openreseurope.18421.3. hal-05458818

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**REVISED** Global language geography and language history:
challenges and opportunities

[version 3; peer review: 3 approved, 2 approved with reservations]

Matthias Urban<fnref n="1" />,<fnref n="2" />

**v3** First published: 07 Oct 2024, **4**:213
https://doi.org/10.12688/openreseurope.18421.1

Second version: 20 Jan 2025, **4**:213
https://doi.org/10.12688/openreseurope.18421.2

Latest published: 17 Nov 2025, **4**:213
https://doi.org/10.12688/openreseurope.18421.3

**Abstract**

While it has almost become a truism of comparative linguistics that linguistic diversity is unevenly distributed across the globe, the underlying processes are poorly understood up to the present day. Linguists are thus in the embarassing situation that they do not understand significant regularities in the way the objects of their study -languages- pattern. In this essay, I explore three interrelated strands of thought to create a perspective on the question that is different from those explored so far: first, I suggest that instead of looking at present-day levels of diversity statically, we should take an approach that looks into how these distributions were generated. Related to this point and in contradistinction to extant work, second, I advocate an inductive approach which includes qualitative case studies that inform theory-building and allow empirical judgments on the propensity of certain environments to foster the emergence of certain linguistic landscapes. Third, I ponder that, in contrast to the traditional focus of historical linguistics on language diversification and expansion, understanding how the ranges of languages are reduced might be the key missing piece of evidence in a global theory of linguistic diversity and its genesis. This new perspective is also able to address the striking correlation between linguistic and biological diversity, which suggests that the processes that created and maintain both are, on some level, qualitatively similar.

**Plain language summary**

This essay reflects on the distribution of linguistic diversity across the globe, which at present cannot be explained satisfactorily. I suggest that to understand this distribution we need to look at actual, concrete processes that have generated the ranges of individual languages, and that we can extrapolate from these to understand

**Open Peer Review**

Approval Status

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1. **Stan Brunn**, University of Kentucky,
Lexington, USA

2. **Guglielmo Inglese** ID, Universita degli Studi
di Torino, Turin, Italy

3. **Alexandre François** ID, Centre National de
la Recherche Scientifique, Paris, France
Ecole Normale Superieure, Paris, France
Australian National University School of
Culture History and Language, Canberra,
Australia

4. **Tuomas Väisänen** ID, University of Helsinki,
Helsinki, Finland
University of Helsinki, Helsinki, Finland
University of Helsinki, Helsinki, Finland

<footnote n="1">¹Dynamique Du Langage, Centre Nacional de la Recherche Scientifique, Lyon, France</footnote>

<footnote n="2">²Université de Lyon, Lyon, France</footnote>
patterns in linguistic diversity at large.

**Keywords**

Language geography, language dispersal, linguistic diversity, typology, historical linguistics

5. Hedvig Skirgård ID, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

Any reports and responses or comments on the article can be found at the end of the article.

HE

This article is included in the Horizon Europe gateway.

erc

This article is included in the European Research Council (ERC) gateway.

a

This article is included in the Linguistic Diversity collection.

**Corresponding author:** Matthias Urban (matthias.urban@cnrs.fr)

**Author roles:** Urban M: Conceptualization, Funding Acquisition, Investigation, Methodology, Project Administration, Writing - Original Draft Preparation, Writing - Review & Editing

**Competing interests:** No competing interests were disclosed.

**Grant information:** This project has received funding from the European Research Council (ERC) under the European Union (LANGUAGE REDUX) Grant agreement No. 101124345.

*The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.*

**Copyright:** © 2025 Urban M. This is an open access article distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**How to cite this article:** Urban M. Global language geography and language history: challenges and opportunities [version 3; peer review: 3 approved, 2 approved with reservations] Open Research Europe 2025, 4:213 https://doi.org/10.12688/openreseurope.18421.3

**First published:** 07 Oct 2024, 4:213 https://doi.org/10.12688/openreseurope.18421.1
**REVISED** Amendments from Version 2

This version reflects further substantial rewriting and refocusing of content vis-a-vis the previous version. In particular, the focus of the discussion is now more clearly on language richness (as opposed to other measures of linguistic diversity), and there is a better balance between the review of the current state of the art and suggestions for further advance. While maintaining a conceptual (rather than practical) stance, a newly added subsection titled "From empirical case studies of range reduction to generalizations on linguistic diversity" contains entirely new text and describes concrete ways to approach linguistic diversity based on the dynamics of language expansion and range reduction.

Any further responses from the reviewers can be found at the end of the article

**Introduction: The puzzle of linguistic diversity**

During the 19th and 20th century, our knowledge concerning the diversity of human languages has increased massively. We know now that there are many more distinct languages spoken around the world than what has generally been thought possible some centuries ago, namely around 7000. We also know now that the way these languages function is massively more diverse than has been thought possible as well (Evans & Levinson, 2009).

"Linguistic diversity" can mean several related things that must be distinguished carefully. First, the term can refer to the sheer number of languages relative to the size of a study area, e.g. a country (this is sometimes called "language richness"). Second, linguistic diversity" can reference the number of different language families relative to the size of a study area (this is sometimes referred to as "phylogenetic diversity"). These two parameters (which can be derived either by sheer counting or the computation of diversity indexes adapted from ecology, Peukert, 2017) correlate often, but not always. In Africa, for instance, the sub-Saharan belt hosts hundreds of clearly distinct languages, but many belong to the so-called Bantu branch of the Niger-Congo family that began to diversify several thousand years ago. Orthogonally to these two dimensions, finally, the languages in a given study area may also be very similar or very diverse in how they sound and how their grammars work (this parameter is sometimes also called "structural diversity", Nettle, 1998).

The three parameters–language richness, phylogenetic diversity, typological diversity–define very distinct linguistic landscapes in different parts of the world.

In Vanuatu, for example, the approximately 9,400 inhabitants of the 50 villages on Banks and Torres Islands recognize 17 distinct languages. This is very high language richness relative

<table><tr><td>Hiw</td><td>sɪsə</td><td>tati</td><td>jejməəLen</td><td>wuəLɔŋ</td><td>kʷe</td><td>i</td><td>nə</td><td>məŋa</td><td>ta</td></tr><tr><td>Lo-Toga</td><td>nɪhə</td><td>tat</td><td>lolmərɛn</td><td>u</td><td>kʷɛ</td><td>e</td><td>nə</td><td>βəŋəβaŋə</td><td>mətə</td></tr><tr><td>Lehali</td><td>kɛj</td><td>tɛtnɛ</td><td>ɣalal</td><td>ɣalsɛ</td><td>kʷo</td><td></td><td>n-</td><td>βap</td><td>muŋγɛn</td></tr><tr><td>Löyöp</td><td>kɪɛj</td><td>tɛ</td><td>ɣilal</td><td>ṭʃoŋmat</td><td>ṭʃɛkpʷɛ</td><td></td><td>n-</td><td>βaβap</td><td>ŋmʷɔŋiɛn</td></tr><tr><td>Volow</td><td>ŋgij</td><td>ɛt</td><td>ɪŋalal</td><td>ɣalsi</td><td>tɛŋġbʷɛ</td><td></td><td>n-</td><td>ɣatγat</td><td>njɔŋŋiŋ</td></tr><tr><td>Mwotlap</td><td>kij</td><td>ɛt</td><td>ɪŋalal</td><td>ɣalsi</td><td>kpʷɛtɛ</td><td></td><td>nɔ-</td><td>hɔhɔlɛ</td><td>nɔŋɔŋŋiŋ</td></tr><tr><td>Lemerig</td><td>tær</td><td>I</td><td>γo|ol|</td><td>ʔo|rmaʔ</td><td>ʔæ.kiʔis</td><td></td><td>n-</td><td>tɛktɛk</td><td>mɔγɔt</td></tr><tr><td>Vera'a</td><td>n dir</td><td>I?</td><td>lamai</td><td>ɛntɛγ</td><td>ʔiŋ</td><td></td><td>in</td><td>tıktık</td><td>mu'nı</td></tr><tr><td>Vurës</td><td>nır</td><td>ɣıtı-</td><td>γilal</td><td>warɛγ</td><td>tɛn</td><td></td><td>ɔ</td><td>kpʷakpʷ</td><td>naməγγını</td></tr><tr><td>Mwesen</td><td>nır</td><td>ɛtɛ</td><td>lılı</td><td>maŋtɛ</td><td>βɪs</td><td></td><td>ɔ</td><td>γatlɛ</td><td>mɔγɔnın</td></tr><tr><td>Mota</td><td>nira</td><td>ɣate</td><td>γlala</td><td>mantay</td><td>tkpʷe</td><td></td><td>o</td><td>βaβæ</td><td>naŋmʷunina</td></tr><tr><td>Nume</td><td>nir</td><td>βitis</td><td>ɣil</td><td>liŋliŋi</td><td>mi</td><td></td><td>u</td><td>luwluw</td><td>namγın</td></tr><tr><td>Dorig</td><td>nır</td><td>sɔwɛ</td><td>βriγıl</td><td>taβul</td><td>tɛ</td><td></td><td>na</td><td>lŋa-</td><td>γın</td></tr><tr><td>Koro</td><td>nır</td><td>tı</td><td>rɔŋ</td><td>taβul</td><td>wɔs.mɛlɛ</td><td></td><td>ɔ</td><td>βalβalaw</td><td>namıγın</td></tr><tr><td>Olrat</td><td>nij</td><td>tı</td><td>rɔŋ</td><td>βılı:</td><td>wɔs.mɛlɛ</td><td></td><td></td><td>ususra:</td><td>mɔtʃ</td></tr><tr><td>Lakon</td><td>ɣi:</td><td>atı</td><td>rɔŋ</td><td>kɛrɛ</td><td>aβuḥ.malɛ</td><td></td><td></td><td>ɛlŋa-</td><td>nγıtʃ</td></tr><tr><td>Mwerlap</td><td>kɛr</td><td>ti</td><td>βalyɛar</td><td>mınmın</td><td>tıkpʷitɛ</td><td></td><td>nə-</td><td>liŋi-</td><td>γɛan</td></tr><tr><td>3PL</td><td>NOT.YET<sub>1</sub></td><td>know</td><td>properly</td><td>NOT.YET<sub>2</sub></td><td></td><td>[OBL]</td><td>ART</td><td>speech</td><td>POSS: 1INCL.PL</td></tr></table>
to the number of inhabitants and surface area. However, these
form part of the Oceanic subgroup of the vast Austronesian
language family, and within that group, are more or less closely
related to one another.

Above is the sentence *They don't know our language very well yet* in each of these 17 languages, collected by Alexandre François (2011). In spite of lexical differences, the structure of the sentence in each of the 17 languages is remarkably similar, so that one can sometimes translate word by word from either one of the Banks and Torres Islands languages to any other because their grammars work in similar ways. In sum, with 17 languages, language richness is very high on these islands; phylogenetic diversity is very low as they are all related to one another; and structural diversity likewise is low.

Northern Eurasian languages score relatively low on all three counts: there are relatively few different languages; these belong to a small number of distinct language families; and most, in particular those resulting from recent language spreads, are quite similar in how they sound and how their grammars work.

These are some examples of the myriad different ways in
which the three parameters of diversity can combine.

In this essay, I will mainly be using the term “linguistic diversity”
in the sense of “language richness”. However, the research
program I sketch makes reference also to different levels of
typological diversity in different parts of the world in ways that
follow from the same general underlying reasoning.

Visualizing linguistic diversity in an accessible way is not easy
and requires a number of decisions and qualifications. While

there are parts of the world where relatively clear language
boundaries exist, this is not the case everywhere. Languages may
overlap in geographical space in complex ways, either because
speakers of more than one language live next to each other in
the same communities, or because languages “live” next to
each other in the minds of bi- or multilingual speakers (societal
vs. individual bi- or multilingualism, Appel & Muysken,
2005), or both. Any representation of language on maps is
inadequate to capture these distributions in their full complexity
(Luebbering, 2013; Urcioli, 1995), and for most of the world’s
languages, such detailed information is simply unavailable
anyhow.

Figure 1 nevertheless attempts to show globally uneven levels of language richness. It represents languages as dots in the absence of widely available polygon data that could represent the ranges in which languages are spoken more realistically, let alone more detailed information on the distribution of languages in social space.<fnref n="1" /> Coordinates come from Glottolog (Hammarström et al., 2024), the leading catalogue of the

<figure><img src="image_5.png" /><figcaption>**Figure 1.** Global linguistic diversity (language richness). Created using the R package glottospace (Norder et al., 2022).</figcaption></figure>

<footnote n="1">¹ More technically, the dots represent “languoids” – a neologism introduced in Cysouw & Good (2013) for linguistic entities that may correspond to language families, languages, or dialects in traditional parlance. Boundaries between these widely familiar categories are not sharply defined – for instance, a set of dialects that are so divergent that speakers have difficulties understanding each other is not very different from a small family of closely related languages. The notion languoid allows reference to linguistic entities recognized in the literature without enforcing permanent decisions on their position on the dialect–language–language family continuum, and Glottolog allows for flexible “upgrading” or “downgrading” of the classification level as more information becomes available. The dots show linguistic entities with identifiers that are currently considered “language-level” in Glottolog (Forkel & Hammarström, 2022), based on the absence of mutual intellegibility with any other language (Hammarström et al., 2024).</footnote>
world's languages via the glottospace R package (Norder et al., 2022). In the case of small-scale languages, dots typically represent the center of the area where the language is spoken; in other cases, historical or demographic information inform decisions (as when Russian is plotted at the coordinates of Moscow).

Asymmetric levels of language richness are not only observed within continent or island-sized areas such as those I have just mentioned, but scale down to variation *within* such areas: In New Guinea, it is the coastal areas in the north that host disproportionately much of the island's language richness, while the New Guinea highlands, which traverse the island longitudinally, are lower in diversity both measured in terms of individual languages and in terms of different families.¹ Figure 2 gives an impression of this.

As can be observed in Figure 3, in South America, diversity levels are high throughout greater Amazonia, but particularly pronounced on the eastern margins. In the Andes themselves, and as one moves southward to Patagonia and Tierra del Fuego, language richness and phylogenetic diversity becomes notably lower. In North America, it is only California that boasted a hyperdiverse mosaic of languages or language families, whereas to the east of the Rockies, diversity is measurably lower.

It is such observations of nested diversity clines that suggest that it is no mere coincidence of history that New Guinea, Amazonia, and California are hyperdiverse, whereas Greenland, Patagonia, and eastern north America are not to the same extent. However, up to the present day, the reasons for regionally uneven diversity levels are not understood.

As the differential patterning of linguistic diversity has come to the attention of linguists and scholars in other disciplines in the early 21st century, a striking congruence with biological diversity was observed (Gorenflo et al., 2012; Maffi, 2005; Moore et al., 2002). Also this relationship is not only observed globally, but on intra-continental scales, too (though at some levels of resolution, it breaks down: Manne, 2002). For instance, in South America, the Amazonian fringe and the cloud forest ecotone at the intersection of Andes and eastern lowlands are not only hotspots of linguistic, but also biological diversity.

Languages are cultural products, shaped by the communicative behaviour of their speakers (Du Bois, 1987) and the social ecologies they are embedded in (Pakendorf et al., 2021; see more extended discussion in the following sections). They are *not* species. Drawing an analogy between biological evolution and “cultural evolution” is as tempting as potentially dangerous and simplifying, especially as we have a lot of qualitative knowledge on the maintenance of linguistic diversity and their social ecologies that are specifically human (again, more extended discussion is in the following sections). Still, undes- niably, languages cover geographical space in ways that are strikingly similar to the ways in which biological species do.

Like Hua et al. (2019), I tend to view this association as epiphenomenal (linguistic and biological diversity co-vary with climate and/or environment, which shapes the distribution of both) rather than causal (humans diversify culturally in areas with high biodiversity more readily because of the richness of available resources).

The latter scenario would be consistent with a prominent hypothesis that has been suggested to explain the uneven

<figure><img src="image_6.png" /><figcaption>**Figure 2.** Linguistic diversity (language richness) in Indonesia and Papua New Guinea. Created using the R package glottospace (Norder et al., 2022).</figcaption></figure>
<figure><img src="image_7.png" /><figcaption>**Figure 3. Linguistic diversity (language richness) in South America.** Created using the R package glottospace (Norder et al., 2022).</figcaption></figure>

linguistic diversity of the world. In the next section, I turn to
current perspectives on linguistic diversity, including this
hypothesis of “ecological risk” (Nettle, 1999). I also discuss
some of the issues I see with extant work, and questions that
still remain open, either because studies so far have yielded
contradictory answers or because they have not been a focus
of attention.

**Current perspectives (and their problems)**

Explaining global linguistic diversity: Emergence and
maturation of a research field

There are minimally three dimensions to the problem of explain-
ing global linguistic diversity: first, there is the question which

types of environments (if any are identifiable) are conducive
to high linguistic diversity and which mitigate its develop-
ment; second, there is the question if the congruence between
cultural and biological diversity is a coincidence, and, if not,
how it should be explained; and third, especially because
languages are not species, there is the question how such fac-
tors, if they could be identified, link up with actual human
linguistic and non-linguistic behavior.

In the last 25 years or so, a number of studies have appeared
that address the question of linguistic diversity and its drivers.
However, they have mainly focussed on the first dimension,
while the actual behaviour of people that, in the long term,
could lead to these distributions has received much less attention. I will return to this point later.

Early studies (Cashdan, 2001; Collard & Foley, 2002; Hillebrand, 2004; Mace & Pagel, 1995) mainly noted a latitudinal gradient to global levels of linguistic diversity (see also Gavin & Stepp, 2014).

Nettle (1996; 1998) was an influential pioneer in singling out a possible explanation, and his “ecological risk” hypothesis is still viable today: Nettle argued that linguistic diversity in the sense of language richness correlates not just with latitude, but more directly with the length of the Mean Growing Season, i.e. the number of months per year that allow, given local conditions like temperature, rainfall, etc., vegetation to grow. The length of the Mean Growing Season, in turn, is taken by Nettle as a proxy for “ecological risk”: Where it is long, ecological risk is low, and societies are hypothesized to be self-sufficient: the environment allows enough resources for most parts of the year to ensure reliable subsistence. Such conditions are said to foster the development of many small, self-reliant speech communities that do not need to maintain outside ties to safeguard against supply shortages. Where climatic conditions are less stable, or where resources are scarcer due to a shorter Mean Growing Season, people must increasingly derisk their subsistence base. This involves the exploitation of resources on larger tracts of land, and/or the maintenance of stronger inter-community ties and larger networks – hence, so the hypothesis, fewer speech communities spread out over wider ranges<fnref n="2" />.

In the meantime, the size of the data analyzed, the number of possible environmental variables considered, and the methodological sophistication of relevant work has grown enormously. Spatial autocorrelation, a typical phenomenon in spatially structured data, has been shown to confound results in research on the environmental and social conditioning factors of linguistic diversity (Cardillo et al., 2015). It has also been noted that the effect of surveyed climatic variables may be non-stationary and interact in locally specific ways in generating linguistic diversity or inhibiting it (Pacheco Coelho et al., 2019). As a whole, research on the drivers of linguistic diversity, reassuringly, shows the typical signs of maturation of a field of scientific investigation.

At the same time, however, the results of relevant studies that have appeared after Nettle differ widely. We have now a whole series of articles, often in high-standing journals and using sophisticated methodology, that share the general concern of identifying ecological drivers of linguistic diversity, and that assess a wider range of environmental parameters

rather than just Mean Growing Season as a proxy for ecological risk. Axelsen and Manrubia (2014) identify the presence of rivers and terrain roughness (technically, “rugosity”) as factors that are conducive to the rise of linguistically diverse landscapes – but earlier Currie and Mace (2009) only found a weak effect of rugosity (which they measured differently, however). While Sutherland (2003) found no evidence for Nettle’s ecological risk hypothesis, Hua et al. (2019) found the effect of geology-related variables like rugosity to be relatively negligible compared to climate and year round productivity, consistent with an account like that of Nettle. Derungs et al.’s (2018) results are likewise consistent with the “ecological risk” hypothesis, but they conclude that climate –latitude, precipitation, and temperature – is more relevant for linguistic diversity of food-producing (agriculturalist) societies than for hunter-gatherers, which would mean that “ecological risk” should affect different types of people in different ways.

## Language ideologies, diversification trajectories, and macro-distributions of linguistic diversity

While the question which environmental or climatic conditions foster linguistic diversity thus remains open for the time being, a broader question is how *any* climatic and environmental factors could lead to actual linguistic and non-linguistic behavior of people that, in turn, sets into motion processes that would generate observed patterns of diversity. As sketched above, an answer to this question is encapsulated in the “ecological risk” hypothesis. However, as far as I am aware, that ecological risk actualizes linguistic behavior with repercussions on language richness, or even phylogenetic and structural diversity, has so far never been shown through detailed qualitative case studies, but only stipulated by hypothesis.

Where case studies on the ecology of linguistic diversity in the tradition of the ethnography of communication (Hymes, 1964) exist, it often turns out that it is language ideologies of one kind or another that sustain diversity in arrangements of so-called small scale multilingualism (Pakendorf et al., 2021).

One well-described case again comes from Vanuatu (François (2012): forms of speech, whether linguists would classify them as dialects or languages, are considered to be locally anchored to communities in individual villages, as are other cultural activities such as ways of preparing food, singing etc. This link between place and language is valued and actively maintained and fosters the development of locally specific speech forms, including details of pronunciation and vocabulary that come to be viewed as typical of different places – and these are precisely those highly salient features of speech that people are likely to note and associate with different languages. At the same time, there is “egalitarian multilingualism” (Haudricourt, 1961; Vaughan & Singer, 2018): no language is considered per se more valuable than any other (even though, in practice, some languages are particularly important because they have disproportionally high speaker numbers). People do not mind learning the languages of others, also because marriages are typically exogamous

<footnote n="2">² This should in principle be relevant both for agrictulturalist and more “traditional” lifestyles involving hunting and gathering, as ultimately plants form the basis for subsistence in both cases.</footnote>
so that multilingual households are common. Such kinship
ties are complemented by commercial ones, and together they
lead to dense networks of social and commercial interaction.
This, of course, is fertile ground for convergence effects such
as the ones reflected in the parallellism in grammar between
Vanuatu languages. In sum, the particular linguistic ecology of
Northern Vanuatu fosters both differentiation and fragmenta-
tion with high language richness and low structural diversity:
that is, exactly the configuration of linguistic diversity that
can be observed.

On the other hand, other qualitative, “thick” (Geertz, 1973)
descriptions of language ecologies suggest that notions like
“group boundary formation” (Gavin et al., 2013), i.e. the essen-
tializing use of a form of speech to identify one’s “ethnic
group”, set it off against other such groups, and thus yield
“ethnolinguistic groups”, are far from universal. Nettle him-
self, who relies on the “ethnolinguistic group” as a unit of anal-
ysis, quotes Brooks (1993: 27) to the effect that in West Africa,
“individuals and families change their language and modify their
social and cultural practices in ways that are often perplexing to
outsiders.” In other words, language is not always firmly
linked to particular individuals that together would make up an
“ethnolinguistic group”, but language use may be depend-
ent on social context, roles, and local language ideologies. An
influential analysis of such configurations in the Balkans is in
Irvine and Gal (2000); for the ancient and present-day
Central Andes in Babel (2018) and Urban (2018; To appear); and
for Upland Southeast Asia and the Himalayas in Scott (2009)
and Shneiderman (2010). As Evans (2018: 13) aptly puts it, “the
focus on languages diversity as something manifested by dis-
crete, internally coherent entities can remove the very types of
evidence we need to tackle the diversification problem.”

In sum, the qualitative literature suggests that the recruit-
ment of languages as markers of local identity and groups,
while existing also in some “traditional” contexts, is far from
universal. General, one-size-fits-all explanations for the genesis of
linguistic diversity are thus problematic.

More specifically, in direct contradiction to the idea that eco-
logical risk fosters a smaller number of languages with wider
ranges, in traditional settings, it is precisely linguistic diversity
which, sustained in multilingual landscapes, can be observed
as a strategy “that maximizes alliances and protective networks
through different languages” (Lüpke, 2016: 53).

At present, thus, research on global linguistic diversity is in a
remarkably open situation. The questions are on the table, but
I think it is fair to say that answers that are robust to different
analytic approaches and datasets and that are consistent with
actually observed linguistic and non-linguistic behaviour have
not crystallized yet. The impasse pertains most pressingly
to the first two dimensions of linguistic diversity that I have
sketched in the introduction. Astonishingly, linguists do not
understand the ways in which their objects of study –languages–
are distributed on the largest scales, and especially why they
are distributed this way. This is in contrast to the micro-
levels of variation. Dialectologists, since the 19th century, have
developed methods to describe and (at least to some extent)

explain how features of pronunciation, grammar, and words
change in geographical space, and the entire discipline of vari-
ationist sociolinguistics explores how language varies in social
space. It is also in contrast to what we, as linguists, know on
the distribution of features across whole languages and large
regions (a field of study often called “areal typology”, in
which clines and very large skewings, not dissimilar to those
concerning linguistic diversity, have been observed up to con-
tinental scales – Bickel, 2020; Dryer, 1989; Güldemann &
Hammarström, 2020; Nichols, 1992; Urban et al., 2019), and
what we are beginning to learn on how the social ecologies in
which languages are learned and spoken influence their struc-
ture and complexity (e.g. Lupyan & Dale, 2010; Trudgill,
2011). The situation is also relevant to the human sciences
at large as the processes by which human societies produce
those key cultural products which they have used to define
themselves since antiquity –languages— remains in the dark.

Dynamizing linguistic diversity

A research program

As the main contribution of this essay, in this section I explore
lines of reasoning that might lead to perspectives on linguis-
tic diversity and its origins that is able to bring together the
abovementioned perspectives more satisfactorily. Since this
is an essay, my discussion is mainly programmatic; whether
the picture I will try to get into focus has merit is an open
question.

I want to make three interrelated points: first, I suggest that
instead of attempting to find parameters of variation (climatic,
environmental, political, etc.) between regions with differential
levels of linguistic diversity, a process-based approach that
looks into how these distributions were generated can fur-
nish perspectives that would be otherwise missed. In this vein, I
suggest a way to dynamize the question of linguistic diver-
sity and its drivers in a way that references the observed con-
gruence between linguistic and biological diversity.<fnref n="3" /> Second,
I ponder that, in contrast to the traditional focus of historical
linguistics on language diversification and expansion, under-
standing how the ranges of languages contract might be the
key missing piece of evidence in a global theory of linguis-
tic diversity and its genesis. Related to this point and in con-
tradistinction to extant work, third, I advocate an inductive
approach that departs from qualitative case studies which both
inform theory-building and allow empirical judgments on the
propensity of certain environments to foster the emerge of
certain linguistic landscapes.

Spread zones, residual zones, and the dynamics of
linguistic diversity

The starting point for developing my argument is the
well-known distinction between spread and accretion (or resid-
ual) zones. Nichols (1992; 1997) distinguishes these as pro-
totypical and contrasting types of language distributions in

<footnote n="3">³ This parallels how language typology has been dynamized by not looking at static synchronic features of languages, but at the historical processes of language change that shape how languages function at present (e.g. Cristofaro, 2019; Greenberg, 1978).</footnote>
geographical space, and sketches their underlying dynamics. The dichotomy references the uneven distribution of linguistic diversity and at the same time contains elements of a theory to account for these dynamically.

As far as language geography is concerned, spread zones are dominated by relatively few language families (i.e. have low phylogenetic diversity), and at times even just contain few individual languages (i.e. have low language richness). These distributions are shaped by frequent and long-distance language expansions, which tend to completely or almost completely obliterate preexisting languages. These may include the languages that spread via earlier episodes of such expansions ("spread-over-spread" dynamics). As is expected in situations of rapid and long-range language spreads, the spreading languages are quite similar to one another as a result of the little time available for diversification through language change (i.e. low typological diversity). Thus, in spread zones, which languages and language families dominate the linguistic landscape can change drastically and quickly, but net linguistic diversity does not: it remains low on all three counts.

Accretion zones, in the definition of Nichols (1992: 14–15), have the following characteristics: they contain old families (i.e. ones that are deeply diversified internally – this does not necessarily mean that these families must contain many individual languages, but that the languages belonging to its different branches are not closely related, which indicates a long time of internal differentiation). “Old families” in the relevant sense should be taken to include language isolates, which are the sole representative of lineages that are so old that relatives cannot be detected anymore. No major language expansions originate from accretion zones, but they may attract instrusive languages and thus serve as a linguistic “refugium of sorts” in Nichols’s words. The arrival of these languages, however, does not lead to significant levelling of preexisting linguistic diversity in the accretion zone; rather, in addition to processes of diversification through language change that take place relatively undisturbedly, they contribute further to a accretion zone’s linguistic diversity.

Nichols (1992) also characterizes typical characteristics of spread and accretion zones in terms of climate and environment, and explicitly mentions economic autonomy as a key condition for the genesis of accretion zones. This is a clear and important point of articulation with the research on linguistic diversity that I have sketched above, in particular Nettle's theory of ecological risk and economic autonomy or the lack thereof, but at the same time opening an access point to a dynamic, process-based understanding of linguistic diversity.

Spread and accretion zones can thus be thought of as prototypes of very different linguistic landscapes that form against the backdrop of different economic and subsistence affordances for human societies. The crucial (prescient) contribution of these prototypes is that they are explicitly connected to different diachronic dynamics of language geography.

A key relevant process is language expansion and diversification, the traditional forte of historical linguistics since the inception of the field. But what is of particular interest when it comes to explaining linguistic diversity, complementarily to the dynamics of spread zones, is the dynamics of accretion zones – those parts of the world that major language spreads do not reach, or where they at least do not have an impact that would reduce linguistic diversity significantly. Indeed, “often a residual zone will be located at the periphery of a spread zone” (Nichols, 1992: 21) – consistent with the idea that the culmination point of language expansions is typically reached before these areas are affected. This is in line with the now robust observation that language spread trajectories respond to the environment (Bentz et al., 2018). For instance, the thrust of the Bantu expansion reflects "a measureable preference for ... familiar savannah habitats" (Grollemund et al., 2015: 13299) of the people driving it.

## How language ranges contract

In Urban (2021), I provide a perspective on such dynamics through qualitative case studies on language isolates and how the ranges in which these languages are spoken have contracted in the course of attested history. Basque is a textbook example. Once spoken far into the Pyrenees and into the Ebro valley of Northern Spain (in fact, Ebro goes back etymologically to a Basque word for ‘valley’), the domain of the language has gradually shrunk, starting in antiquity and continuing up to the present. Figure 4, from Urban (2021), illustrates the process. Why is Basque spoken today in exactly that part of its former range in which we find it rather than in another? Trask (1997) explains that "the mountainous Basque terrain, with little agricultural land, no cities, few obvious resources, and harbours that faced uselessly (from the Roman point of view) onto the Atlantic, was simply too insignificant to be worth the trouble of colonization. And the same lack of Roman interest is very largely what guaranteed the unique survival of the Basque language". Needless to say, this also means that the expansion of Latin came to a halt, or was mitigated, before reaching the Basque country.<fnref n="4" /> Basque is just one example of a broader patterns in neolithic Europe, where languages that likely predate the Indo-European spread are conspicuously found in peripheral regions like Basque, or on islands, in other words, at the geographical margins of Europe.

One can hypothesize similar dynamics to explain linguistic distributions and the emergence of accretion zones for which we cannot rely on historical evidence. In western Mexico and Mesoamerica, language isolates and small language families are found at the edges of major agricultural spreads, suggesting a dynamics in which former, pre-spread language distributions were reduced to geographically and economically marginal regions. Similar processes are not restricted to the deep past. They can be observed about 1500 years later in the context

<footnote n="4">⁴ In Urban (2021), I also discuss the historical language geography of Burushaski, which is largely parallel to that of Basque, but adds a vertical dimension to the relevant geographical processes (see also Nichols, 2013).</footnote>
<figure><img src="image_8.png" /><figcaption>Figure 4. Historical changes in the geographical extent of the Basque language, from Urban (2021).</figcaption></figure>

of colonial regimes. For instance, on the Pacific coast and in the Andean highlands of South America, Spanish colonial administrators removed Indigenous people from the agriculturally most productive lands and resettled them to less fertile regions and into mission towns. They also show themselves in the context of government-backed settler colonialism of the kind that drove the US westward expansion. Neither are such processes restricted to demographic changes introduced by agriculturalist, state-level imperial societies. Evans and McConvell (1998) provide a model for explaining a significant language spread in hunter-gatherer contexts, informed by deep-rooted Australian cultural practices.

The advantage of this process-based, range reduction oriented approach to studying linguistic diversity is that its net results are compatible with, and in certain cases predicted by, qualitative local language dynamics and ecologies. Vanuatu as described by François (2012) is one such example. Another concerns the Caucasus as a prototypical accretion zone. Nichols (2013) describes the traditional language dynamics of the Caucasus as one of asymmetric and gendered multilingualism which is embedded in and dynamized by the traditional subsistence patterns in this mountain area. Languages in the highland villages are typically community-based and the vehicles of communication for inward-facing “societies of intimates” (Thurston, 1989). They are not or only very rarely learned by outsiders. The men of these communities, however, spend time in the lowlands to visit markets, and often stay the whole

winter months in the lowlands, where herds would still find pasture. As such they are under pressure to learn languages of the lowlands, but lowlanders are under no pressure to learn highland languages. Thus, the general language dynamics of the Caucasus is one in which languages would constantly encroach the territory in an uphill direction, building up additional diversity without ousting that which already exists. As a result, the oldest layers of the diverse linguistic landscape of the Caucasus would be found at the highest altitudes, according to this model. Over the *longue durée* the Caucasus should accrete linguistic diversity both on the levels of language richness and phylogenetic diversity.

## A new view on the relationship between linguistic and biological diversity

Finally, there is the question of the curious congruence between linguistic and biological diversity. The model also has advantages here. While comparisons between linguistic diversity and species diversity have frequently been made, this has, to the best of my knowledge, only concerned the static situation at present, just like investigations of linguistic diversity have mainly been static (though see Gavin *et al.*, 2013; Gavin *et al.*, 2017; Pacheco Coelho *et al.*, 2019). However, there is a point of articulation between both when conceived of in dynamic terms. This point of articulation is the specific way how the geographical ranges of species and languages shrink and contract as they are pushed out of their former ranges. This may happen by invasive species or anthropogenic
factors in the case of species, and in the case of languages by the expansion of a language or a language family that comes to be spoken in regions that previously had had other languages (as we have seen for Basque).

Traditionally, biologists have thought that when the geographical range of a species contracts, this would likely begin in the peripheries of the region, which typically offer only less-than-optimal habitats and where the density of populations is less even and dense. Hence, in peripheral regions individuals would be more vulnerable to disruptive factors, while core populations would be less so and therefore persist longer. However, Channell and Lomolino (2000) have shown that the locales where species survive the longest typically are situated exactly at the periphery of the larger, original range. For instance, the Tasmanian tiger (*Thylacinus cynocephalus*) originally occurred throughout New Guinea and Australia, and received its name from its last refugium, the island of Tasmania at the southeasternmost periphery of the original range. The characteristics of these refugia as described by Channell and Lomolino (2000) are "those along the edge of the range, on an isolated and undisturbed island, or at high elevations", a type of location that we have encountered before - in language dynamics.

## From empirical case studies of range reduction to generalizations on linguistic diversity

In those regions of the world with long-standing Indigenous traditions of writing, we are in some cases lucky enough that we can trace changes in the distribution of languages in space through time over millenia. Basque is an example of such a fortunate case. In many parts of the world, however, the time depths for which we can trace language history is heavily limited by the inavailability of written sources from which we could infer older stages of languages and their distribution in space. In such regions, language distributions can be known only from the point of European colonization onward, and more detailed descriptions are in many cases only available significantly after that. Nevertheless, ancillary sources like the distributions of toponyms with characteristic elements that can be attributed to a certain language or language group, in some cases can give time-depth to language distributions in space also in the absence of direct historical documentation.

In most parts of the world, Indigenous languages are under pressure, and are increasingly replaced by the official languages of modern national states whose use promises possibilities of upward social mobility and economic opportunities. The result is that many minority languages are not used anymore across the whole range in which they are known to have once been spoken, but are increasingly restricted to certain parts of that original distribution, or have, as the end result, become dormant

While a major issue for the language sciences and the cultures that once sustained it, the pressure under which Indigenous languages find themselves affords a “geography-strong” (Di Carlo & Pizziolo, 2012) historical linguistics the possibility to empirically compare distributions of languages in space

at different points of time, like we can for Basque. And once these differences are studied across a number of individual cases, it becomes possible to ask broader questions: how does the landscape and climate of the places in which languages survive longest (or have survived longest before perhaps eventually becoming dormant) differ from the places in which they were once spoken? Is the terrain more rugose (hence less accessible), is it less productive for human subsistence, or, to make the link with extant theorizing, does it perhaps differ in measurable ways in Mean Growing Season because of differences in temperature or rainfall? These differences can be quantified precisely (in the simplest possible form by comparing summary statistics of polygons representing original and reduced distributions across languages), and in turn they allow us to characterize different types of environments in terms of their potential for preservation of languages and linguistic distributions that have been ousted elsewhere – very much like Nicholsian accretion zones, but derived in a radically empirical way.

And once this crucial extrapolation from known cases of language range contraction to generalized geographical-climatic profiles is made, a suite of questions relating to linguistic diversity can be asked and answered empirically: we can compare levels of language richness and phylogenetic diversity in areas like those to which, in known instances, languages have tended to get restricted to when coming under pressure from one or more expanding languages. We can also compare whether the typological profiles we find in them differ from surrounding areas, dovetailing with the idea that certain types of environments host typological profiles that may have once been more common generally but replaced in areas with more spread-potential by later language spread (Efrat-Kowalsky et al., 2023). In general, we can formulate a spatially explicit, process-based account of linguistic diversity, informed and dynamized by spatial processes of language expansion and retraction.

## Conclusion

Here, I have presented an overview on the puzzle of global linguistic diversity. Highly unevenly distributed across different regions of the world, linguistic diversity is integrated with and sustained by societies and their respective views on language, linguistic diversity, and what role it should play. I have presented a model for understanding linguistic diversity that, in contrast to most extant work, is based on qualitative case studies of how the range of languages contract in the wake of language expansion. This model makes references to environmental variables that promote or inhibit the social, cultural, political, and economic dynamics that are associated with language spread and thus leaves room for human agency. Furthermore, the model takes serious the fact that languages are cultural, not biological products, and does not require a deterministic view on cultural and linguistic diversity. At the same time, it still opens a perspective on the dynamics of linguistic diversity that can be related meaningfully to the patently similar dynamics of biological diversity.

I acknowledge that there is a lot that is not yet understood, and that loose threads remain. One point that I wish to
highlight here is the general applicability. I have suggested that high-diversity zones arise because large-scale language expansion processes culminate before they are reached, and that they do so because of less favorable environments for speakers of spreading languages. However, accretion zones are also found in California, with a climate that provides suitable conditions for a reliable food and subsistence base year round – this is consistent with Nettle's ecological risk hypothesis, but not necessarily the range reduction-based dynamic model that I have sketched here. Eventually, it may be the case that we must reckon with non-stationary effects of different environments on linguistic diversity levels (Pacheco Coelho et al., 2019) and the way they shape ideologies that sustain highly diverse linguistic landscapes. In other words, we might have to distinguish several types of accretion zones (as

is now done for spread zones: Nichols, 2015), created by different diachronic cultural and linguistic dynamics. This would also be consistent with the “non-stationary” nature of language ideologies, which express different attitudes towards multilingualism and which involve different roles of language, language variation, and linguistic differences in constituting ethnic or social identities.

## Ethics and consent

Ethical approval and consent were not required.

## Data availability statement

No data are associated with this article.

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# Open Peer Review

Current Peer Review Status: ✓ ✓ ✓ ? ?

Version 3

Reviewer Report 29 December 2025

https://doi.org/10.21956/openreseurope.21868.r64282

© 2025 Väisänen T. This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

?

Tuomas Väisänen

<figure><img src="image_9.png" /></figure>

Statement

The manuscript has improved nicely since the latest revisions, and I have only one moderate/minor concern and several very minor concerns left. The moderate concern relates to the remaining ambiguity to what the proposed process-based and range-reduction-oriented approach actually is. To remedy this, I suggest adding an informative figure that would illustrate the approach and visually juxtapose it with previous approaches, to make it crystal-clear. Alternatively, I suggest adding a paragraph where this is clearly defined.

The minor concerns relate to textual clarity. First, there are several one sentence paragraphs here and there, which I find hard to find the reason for, as they would easily fit into paragraphs above or below them. They break up the flow of the MS and do not seem to have a consistent theme or a stylistic purpose. Second there are also several instances of wordy language, such as "the ways in which" which could just be said as "how", and some sentences have numerous subordinated clauses that make it difficult to follow the author's train of thought. Similarly, some of the sentences are quite long and the MS would benefit from splitting them into separate sentences. Third, there are occasions in the MS where the author is referring to another part in the MS, but in a vague manner, such as "I will come back to this point later", I suggest adding clear references to sections to such occasions. Related to this, the author often uses words like "this", "those", and "these" to reference something stated earlier, instead of writing out what the author is actually talking about, which makes understanding some statements rather difficult. Finally, and as mentioned in my previous review, there also are a few instances of the author referring to a theory or a statement made by a central author (like Nettle or Nichols), without providing a reference to go with it.

Thus, I recommend minor revisions. I have provided detailed comments to highlight most of these concerns I mentioned above, but ask the author to check the MS throughout. However, I look

<footnote n="1">¹ Department of Geosciences and Geography, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>

<footnote n="2">² Helsinki Institute of Sustainability Science, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>

<footnote n="3">³ Helsinki Institute of Urban Regional Studies, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>
forward to seeing the revised MS, which I believe will be in a very acceptable condition by next round.

## Detailed comments

### Puzzle of linguistic diversity

* Can you integrate the sentence "These are some examples of the myriad different ways in which the three parameters of diversity can combine." into the text above it, as it now stands alone as a one sentence paragraph?

* Figures 1-3: Could you add colors to the dots based on language or language family to further illustrate the high diversity of languages?

* The first time you mention "ecological risk" you are referring to it as if the reader knows it already. Please revise.

### Current perspectives

* The first paragraph is quite unclear. You state there is one question per each dimension, but then all of the singular questions actually consist of two questions. The questions can be formulated into singular questions and the subordinated clauses of "if they could be identified" can be revised as a statement after the questions.

* I suggest revising these three dimensions into a table, as they are a central part of the MS, and this would make them pop out and easier to reference throughout the MS.

* "I will return to this point later". Unclear. Please indicate in which section you address this

* "Such conditions are said to.." said by whom?

### Language ideologies, diversification trajectories

* "Nettle himself". Just Nettle will do, no need to specify it further.

* "..the qualitative literature suggests..." which literature? The ones summarized in the paragraph above this one, or something else? Please clarify, and if you are talking about something else, provide references to the literature.

* The sentence starting with "More specifically, in direct...." is very complex and difficult to follow. Not to mention, a one-sentence paragraph. Can you please break it down into smaller sentences and clarify the statement you are making here?

* "The questions are on the table..." Which questions? The ones you mentioned in the beginning of Current Perspectives section? Presumably so, given what follows, but please be clear when you're referring to something explicitly stated in the MS.

* The sentence starting with "It is also in contrast to what we...." is very long. Please break it down to increase clarity.

### Dynamizing linguistic diversity

* The first sentence of the section is unclear. Origins of what? Which abovementioned perspectives?

* Make the three interrelated points into an actual list to help with clarity. Also avoid complicated sentences when making central statements like the ones you make here.

* Related to the second point: "how the ranges of languages contract", what do you mean here? Geographical ranges? Geographical contraction? I suggest qualifying the word with geographical or spatial if you are talking about geographical distributions
and their changing sizes.

## Spread zones

* Generally, for this section, why have "residual zone" in the title if you use "accretion zone" in the text instead? Choose the term you use and use throughout.

* "Well-known distinction between spread and accretion zones"? Consider the journal you are writing for, a generalist journal with a wide audience. Even if these concepts are well-known in linguistics, they are not outside of it, and I suggest you open them up for the reader with one-two sentences. To myself, accretion zones are related to tectonic geology, so this sentence is quite confusing to me. Are these concepts used by Nichols (1992; 1997) you reference in the following sentence?

* "The dichotomy references the uneven distribution..." which dichotomy? An expanding and contracting language distribution? If so, then the concepts need to be opened in a more intuitive manner, because "spread zones" imply the geographical ranges of language are expanding. Accretion zones are also implying this (e.g. "quiet accretion of wealth"), but is this just a more slowly growing expansion? If both are expanding, but at different rates, where does the dichotomy come from?

* The paragraph starting with "As far as language geography..." makes several rather strong statements, but has no references to prior work to substantiate the claims. If these are the author's own speculation, it should be stated more clearly. If they are from the work of Nichols (or somebody else), then referring to them appropriately is required.

## How language ranges contract

* "They also show themselves" is already quite far away to reference the dynamics describing how previously widely spread languages are pushed to the margins. Please revise

* If you are not elaborating on the Vanuatu example by Francois (2012), then I suggest either dropping it or moving it after the Caucasus example. Now it is a bit counter-intuitive to have this as the first example, but no elaboration is provided, while the second example takes up most of the paragraph.

## A new view

* I agree with the argument made here, but I wish to point out something, that would be good to mention/clarify here, is that languages can not spread without humans, and how humans "spread" is a bit different to species of animals that might have specific requirements for their ecological niche. Throughout the globe, humans have common tendencies in their selection for their habitat and thus, it is fairly logical for the language contraction to start from the most densely populated areas as they have the natural, social and cultural resources to support a larger population. Also, taking the Basque speaker and Roman conquest example: It is also far more logical from an imperial/military perspective to start taking over the towns rather than isolated regions, because these places are more habitable and have more resources than the remote regions. By capturing such places, the invading force takes control of the most important hubs and resources from the defending force, complicating their efforts, and thus causing the original populations having to evacuate to more remote regions with less resources to sustain a larger population. Similar to humans, some animals are generalists and can thrive in a wide variety of environments (seagulls, pigeons, mice, dogs etc) and thus can also retreat to more remote regions as they can survive there as well (likely the Tasmanian tiger was more of a generalist as well). Conversely, other species are highly specialized to specific environmental conditions, and if
their habitat is destroyed or another invading species outcompetes them in their ecological
niche, they usually die out.

**From empirical case studies**

* The paragraph starting with "While a major issue for the language sciences...".

* The starting sentence is quite wordy, can you simplify it?

* The latter half of this paragraph has described very clearly what the authors is going for with the MS, and I think it should be also stated in a succinct manner in the abstract and introduction as well.

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** Geography, linguistic landscapes, regional sciences

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Version 2

Reviewer Report 08 April 2025

https://doi.org/10.21956/openreseurope.20844.r49965

© 2025 **François A.** This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Alexandre François

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This paper is a useful synthesis of various issues raised by the uneven distribution of languages in the geographical space; it brings about an insightful discussion of major concepts discussed in the literature.

The article covers a broad territory, in all senses of the word, but does so in a generally clear enough manner, that the author's stream of thought can be followed. This could have been a challenge with such an ambitious paper, considering the array of notions under discussion – such as “language richness”, “phylogenetic diversity”, “structural diversity”, key concepts introduced by Nettle (“ecological risk”, Mean Growing Season), as well as those presented by Nichols, and numerous other authors cited. But the author manages to draw a thread between all these notions, and to make them resonate with each other in a meaningful way.

<footnote n="1">¹ LaTTiCe, Centre National de la Recherche Scientifique, Paris, France</footnote>

<footnote n="2">² Ecole Normale Superieure, Paris, Île-de-France, France</footnote>

<footnote n="3">³ Linguistics, Australian National University School of Culture History and Language, Canberra, Australian Capital Territory, Australia</footnote>
Isn't "language richness" also often labelled "language density" (indeed one of the subtypes "language diversity")? or are these supposed to be two separate concepts?

Compared to the earlier version, I believe that the second edition of this paper has gained in clarity – partly due to a neat presentation of concrete examples right from the start. These do help the reader figure out quickly what kind of linguistic diversity is exactly at stake in the paper. The Vanuatu example provides a welcome opportunity to contrast language density (or "richness") with structural diversity, which are respectively high and low here (as rightfully explained p.4). The reader can't help wonder what other combinations of parameters would be attested around the world. Thus, perhaps an example of a zone with high structural diversity would have been welcome – but I understand this might have made the article too long.

I also appreciated the discussion comparing linguistic diversity and biodiversity.

I will only end with a few notes on harmless errors that can easily be fixed through careful proofreading, in case the author can still edit the text:

p. 1 *unevently* → *unevenly*

p. 1 *embarrassing* → *embarrassing*

p. 3 *a slightly situation* → (?)

p. 4 *yilal* or *yilal* → (?)

p. 4 *jəjməg̈Len* or *jəjməg̈Len* → (?)

p. 4 *addresse* → *addressee*

p. 5 *ecotone* → *ecozone*

p. 7 *hence, so the hypothesis, fewer* → (unclear)

p. 7 *agriculturalist* → *agriculturalist*

p. 7 *quantitative* → *quantitative*

p. 9 *instrusive* → *intrusive*

p. 9 *characterizes typical characteristics* → (?)

p. 11 *qualitative* → *qualitative*

Overall, this is an instructive and inspiring paper.

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** historical linguistics; linguistic typology; social ecology and language ideologies

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.
© 2025 Skirgård H. This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Hedvig Skirgård ID

Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

This manuscript presents an overview of several studies pertaining to the unevenness of linguistic diversity and the possible causes thereof, and then presents the author's preferred approach to the field of study. It's overall well-written and well situated in the literature and the proposed approach is sound.

I do however think that in its current form it is not best serving what I take to be the main aim: presenting a new approach which is process-based, range-focussed and with theoretical foundations in existing qualitative research. There are two main issues as I see it.

1) Zero in on language richness

While it's definitely worthwhile to mention other dimensions of language diversity such as phylogenetic diversity and structural diversity, I fear that the space currently given to these in the manuscript distracts from the main message - which seems to me to be the new approach which is primarily (but not only) related to language richness. To streamline the paper, I propose to the author to consider removing some of the content related to other metrics and instead give more space to specifics of the new approach at the end. Alternatively, if the other dimensions of linguistic diversity are kept, there should be more done in the last section to consistently refer back to the implications of the proposed approach on all three mentioned metrics.

2) Flesh out the preferred model more

Currently I am unfortunately not entirely clear on the specifics of the author's recommended approach. For example, are Agent-Based Models something that would fit? More details on the kind of research that the author calls for would be welcome, especially large-scale studies.

I have also listed other medium and minor points. I am sorry if the review is too long, I am very excited by the topic matter and enjoyed the paper. Please focus on the two main points above, and take only from the rest what you want.

Medium points:

I find the authors characterisation of the question of what predicts language richness as "poorly understood" to be too strong. The body of literature that the author cites paints a picture of several relevant predictors, such as certain environmental conditions, political complexity etc. We may not completely understand the distribution of language diversity across the world, but that is not the same as it being "poorly understood". At a simple level, we can for example observe that where there are more people there are more languages. This is why the question of language richness is often linked to general questions about what drives population distributions (e.g. environmental factors like carrying capacity etc). We can see this relationship by taking the number of languages (according to Glottolog 3.0) per country and the population in 1950 per country (according to the UN). A simple Pearson correlation tests gives a moderate significant correlation (R= 0.47, p<0.001); if you log10-transform both variables to account for outliers, the
correlation is stronger (R = 0.76, p<0.001). Naturally, this isn't enough analysis by far (countries are not good units, we'd want older population data, more sophisticated statistical models, correlation is not causation etc), but I think it illustrates that population size is probably one of several relevant parameters and that we can look more broadly at literature that studies the uneven distribution of people over the world.

On a related note, the link between number of languages and number of people becomes trickier when we consider that cultures with high political complexity and agriculture tend to have larger populations and spread over larger areas (c.f. Currie & Mace 2009) and hence reduce the language richness of their region. I'd appreciate the author's insights into how to approach the effect of population size on language richness in relation to spread and accretion zones. Is it the case that there's a minimal population that is needed for language diversity, but that once that limit is reached other factors are more important?

Regarding accretion zones, the author may be interested to read Graff et al (2024, pre-print) where they study the interaction between genetic and language diversity, finding that regions with high linguistic diversity feature low genetic diversity which suggests more relative isolation.

Page 3: "sub-saharan Africa" is a huge region which contains many families besides Bantu (and even in addition to the larger family of Atlantic-Congo to which the Bantu languages belong). There's Khoisan, Mande, Khoe-Kwadi, Afro-Asiatic; not to mention language isolates and other families. For an example of a place with high language richness and uncontroversially low phylogenetic diversity, I'd suggest sticking with Vanuatu where the field agrees that all indigenous pre-contact languages are Oceanic.

Page 4, footnote 1: as the author has chosen to only plot languoids which are of the level "language" in Glottolog, I think the discussion of the term "languoids" is superfluous.

I second Dr Inglese that a working definition of a language is warranted. Instead of discussing languoids, I propose that the author refers to Glottolog's definition of "language" (Hammarström et al 2020), Gooskens & Schneider's work (i.a. 2016) and Ethnologue's description of their process (Eberhard et al 2019).

Page 11: I appreciate the author's use of the work by Pacheco Coelho et al (2019). One of the possible concerns with non-stationary effects is the potential for over-fitting models. Pacheco Coelho et al (2019) guard against this by for example spatial smoothing, not allowing estimates to fluctuate too much between adjacent regions. Does the author have any comments on how their overall approach would be sensitive to overfitting and if so, how this could be mitigated?

Page 11: the reference to a "brute evolutionary view" came a bit out of left field for me and felt needlessly harsh. I'm not sure I understand what is being referred to here. I found this characterisation a bit too strong and would recommend a more specific description instead.

Minor points:

Page 3 "a slightly situation" -> "a somewhat similar situation" or other phrase

Page 5: language richness and language density are used essentially interchangeably. To make it
easier on the reader, please consider using "language richness" only.

Page 7: if possible, I'd recommend avoiding the term "Melanesia" as it is not always particularly helpful for an academic historical perspective. "Melanesia" encompasses a very wide diversity of communities and is not scholarly defined. I believe that Sankoff (1980) mainly discusses parts of Papua New Guinea specifically. Laycock (1982) does discuss Melanesia more broadly, but mainly exemplifies with Papua New Guinea and New Caledonia. If there is such a thing as a specific cultural ideology that is truly well-spread over the entire region and emblematic of it such that it is not found elsewhere, I am not convinced the current citations are enough. For the argument in this paper, I believe the Melanesian framing can be dropped and the author can go straight to the example and specifically cite work on Vanuatu (and/or Australia).

Page 7: reference addition suggestions, the earliest paper I know for "egalitarian bi/multilingualism" is Haudricourt (1961) and one of the more recent overviews is Vaughan & Singer (2018). Evans (2018:21) discusses more places in which egalitarian multilingualism has been documented. Haudricourt (1961) also discuses Caucasus, so if the author wants to reference the earliest source that could be done in sections relation to Caucasus.

Page 7: The author refers to Thurston (1989), Trudgill (2011) etc. If the author wants to delve further into the literature on social ecology of languages, I've included at the end a list of terms and citations that I personally keep on hand in order to distinguish different related concepts in the literature. In particular, I believe it could be advantageous to discuss linguistic epidemiology/propagation in relation to esotereogny/hyperdialectism and the situation described by Nichols (2013) in the Caucasus. However, I'm also sensitive to the length of the essay already so this can also be ignored in favour of brevity.

Page 9: accretion and residual zone are used interchangeably, please do mention both the first time but after that just use one (I prefer accretion).

Terminology list mentioned earlier

* *metatypy*

[a] change in morphosyntactic type and grammatical organisation [and also semantic patterns] which a language undergoes as a result of its speakers' bilingualism in another language. This change is driven by grammatical calquing, i.e. the copying of constructional meanings from the modified language and the innovation of new structures using inherited material to express them.
Ross (1999); Gumperz & Wilson (1971); Kulkarni-Joshi (2016)

* *calquing*

the borrowing of structural content from another language which increases inter-translatability (one-to-one mappings)

* *esoterogeny*

The process of making a language more esoteric and thus more difficult for non-speakers to understand
Thurston (1987)
* schismogenesis

a process of differentiation in the norms of individual behaviour resulting from cumulative
interaction between individuals

Bateson (1936)

* neighbour- opposition

when one finds forms in a language variety which are not predictable historically from

Neogrammarian sound laws and which function to make the distance from a neighbouring variety greater than would otherwise have been the case [...]The linguistic feature in question is often seen by the speakers as a salient and even, in some cases, symbolic or shibboleth feature of that variety.

Larsen (1886); Jahr (2017)

* hyperdialectism

when dialect speakers overgeneralise differences [...] in order to symbolise their separate identities

Trudgill (2003)

* linguistic epidemiology / propagation

strong convergence within groups which has the by-effect of divergence between groups

Enfield (2003, 2008); Toulmin (2009)

* doppel-avoidance

bilinguals avoiding potential false-friends by choosing diverging lexical items

Ellison & Miceli (2017)

References:

1. Bateson, G. (1936) [Ref 1]

2. Currie TE, et al., 2009 [Ref 2]

3. Eberhard, D. M., Simons, G. F., & Fennig, C. D. (2019). The problem of language identification. In D. M. Eberhard, G. F. Simons, & C. D. Fennig (Eds.), Ethnologue: Languages of the World (22nd ed.). Dallas, Texas: SIL International. https://www.ethnologue.com/about/problem-language-identification.

4. Ellison, T. M. et al., 2017 [Ref 3]

5. Enfield, N. 2013 [Ref 4]

6. Enfield, N. 2008 [Ref 5]

7. Evans, N. (2018). The dynamics of language diversity. In R. Mesthrie & D. Bradley (Eds.), The dynamics of language: Plenary and focus lectures from the 20th International Congress of Linguists (pp. 12–35). Claremont: UCT Press. https://ciplnet.com/wp-content/uploads/2024/02/ICI20_Plenary-and-focus-lectures.pdf

8. Gooskens, C., & Schneider, C. (2016). Testing mutual intelligibility between closely related languages in an oral society. https://hdl.handle.net/10125/24696

9. Graff, A., et al., 2024 [Ref 6]

10. Gumperz, J. J., & Wilson, R. (1971). Convergence and creolization. Pidginization and Creolization of Languages, 151, 167. https://search.worldcat.org/title/1311039317
11. Hammarström, H., et al., 2019 [Ref 7]

12. Haudricourt, A. 1961 [Ref 8]

13. Jahr, E. H. 2017 [Ref 9]

14. Kulkarni-Joshi, S. 2016 [Ref 10]

15. Larsen, A. B. (1886). Oversigt over de trondhjemske dialekters slægtskabsforhold [Overview of the relationships between the dialects of Trøndelag]. In Det Kongelige Norske Videnskabers Selskabs Skrifter 1885 (pp. 37–117). Trondheim, Norway: Interessentsskabets Bogtrykkeri. https://search.worldcat.org/title/10348260381

16. Laycock, D. C. (1982). Melanesian linguistic diversity: A Melanesian choice? In R. J. May & H. Nelson (Eds.), Melanesia: Beyond diversity. https://openresearch-repository.anu.edu.au/bitstream/1885/133344/1/RSPAS_Melanesia_Beyond_Diversity.pdf

17. Maclaurin, J, et al., 2008 [Ref 11]

18. Pacheco Coelho, et al., 2019 (Ref 12)

19. Ross, M. (1999). Exploring metatypy: How does contact-induced typological change come about? Keynote talk given at the Australian Linguistic Society's annual meeting, Perth. https://www.academia.edu/3404466/Exploring_metatypy_how_doesContact-induced Typological change

20. Thurston, W. R. (1987). Processes of change in the languages of North-Western New Britain. Canberra: Pacific Linguistics. https://openresearch-repository.anu.edu.au/bitstream/1885/145417/1/PL-B99.pdf

21. Vaughan, J, et al., 2018 [Ref 13]

References

1. Bateson G: Naven. 1958. Publisher Full Text

2. Currie TE, Mace R: Political complexity predicts the spread of ethnolinguistic groups. Proc Natl Acad Sci U S A. 2009; **106** (18): 7339-44 PubMed Abstract | Publisher Full Text

3. Ellison T, Miceli L: Language monitoring in bilinguals as a mechanism for rapid lexical divergence. Language. 2017; **93** (2): 255-287 Publisher Full Text

4. Enfield N: Linguistic Epidemiology. 2013. Publisher Full Text

5. Enfield N: Transmission Biases in Linguistic Epidemiology. Journal of Language Contact. 2008; **2** (1): 299-310 Publisher Full Text

6. Graff A, Ringen E, Zakharko T, Stoneking M, et al.: An inverse correlation between linguistic and genetic diversity. bioRxiv. 2024. Publisher Full Text

7. H, Hammarström R, Forkel M, Haspelmath: glottolog/glottolog: Glottolog database 4.0. https://zenodo.org/records/3260726. 2019. Publisher Full Text

8. Haudricourt A: Richesse en phonèmes et richesse en locuteurs. L'Homme. 1961; **1** (1): 5-10 Publisher Full Text

9. Jahr E: A pioneering sociolinguistic concept: Amund B. Larsen and his discovery in the 1880s of neighbour opposition as a socio-psychological mechanism in linguistic change – and its rediscovery in the 1980s as hyperdialectism. European Journal of Scandinavian Studies. 2017; **47** (2). Publisher Full Text

10. Kulkarni-Joshi S: Forty years of language contact and change in Kupwar: A critical assessment of the intertranslatability model. Journal of South Asian Languages and Linguistics. 2016; **3** (2): 147-174 Publisher Full Text

11. Maclaurin J, Sterelny K: What Is Biodiversity?. 2008. Publisher Full Text

12. Pacheco Coelho MT, Pereira EB, Haynie HJ, Rangel TF, et al.: Drivers of geographical patterns of
North American language diversity. *Proc Biol Sci.* 2019; **286** (1899): 20190242 PubMed Abstract | Publisher Full Text

13. Vaughan J, Singer R: Indigenous multilingualisms past and present. *Language & Communication* . 2018; **62**: 83-90 Publisher Full Text

**Is the topic of the essay discussed accurately in the context of the current literature?**

Yes

**Is the work clearly and cogently presented?**

Partly

**Is the argument persuasive and supported by appropriate evidence?**

Yes

**Does the essay contribute to the cultural, historical, social understanding of the field?**

Yes

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** linguistic typology, cultural evolution, historical linguistics

**I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.**

Author Response 13 Apr 2025

**Matthias Urban**

Thank you very much for your careful read and detailed comments!

In response to the main points, I've revised the manuscript as follows: to address the imbalance between more review-oriented text with all three dimensions of diversity in scope on the one hand and relative brevity of the different kind of approach I have in mind, I've basically shortened the former and focused more (though not exclusively) on language richness, and expanded discussion of the latter.

In particular, the section titled "Dynamizing linguistic diversity" now contains subsections (as requested by reviewer #4). These include a subsection titled "From empirical case studies of range reduction to generalizations on linguistic diversity" that contains entirely new text and describes ways to approach linguistic diversity based on the dynamics of language expansion and range reduction. I've also added text on the comparison of typological distributions this will enable to "do something" with that parameter later on in the text as well. I've deliberately kept the discussion conceptual and non-technical (though I mention summary statistics on polygons as a way to quantify environment) ... I'm thinking of this as a conceptual essay and operationalization etc. would be a matter for subsequent papers.
Thank you also for the helpful "meso" and "minor" comments. I've made good use of most, though not all. For example, since this is really a programmatic essay, I would like to keep it non-technical and not go into modeling issues like overfitting when allong nonstationary effects or factoring in population size, and I think I'd like to keep the "languoid" in - it's only in a footnote, and it does justice to the difficulty with languages as reified notions.

**Competing Interests:** No competing interests were disclosed.

Reviewer Report 22 January 2025

https://doi.org/10.21956/openreseurope.20844.r49963

© 2025 **Inglese G.** This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Guglielmo Inglese

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Università degli Studi di Torino, Turin, Piedmont, Italy

I am pleased with the revised version of the paper and have no further comments to make.

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** historical linguistics and linguistic typology

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Version 1

Reviewer Report 30 December 2024

https://doi.org/10.21956/openreseurope.19907.r46601

© 2024 **Väisänen T.** This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Tuomas Väisänen

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<footnote n="1">¹ Department of Geosciences and Geography, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>

<footnote n="2">² Helsinki Institute of Sustainability Science, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>

<footnote n="3">³ Helsinki Institute of Urban Regional Studies, University of Helsinki, Helsinki, Uusimaa, Finland</footnote>
I welcome and enjoy any manuscript, such as this one, that bridges the gap between geography and linguistics. The article describes how linguistic diversity and its geographical distribution have been studied in the field of linguistics over the past few decades, and proposes combining several theories (climatic, environmental, economic, language ideological) that attempt to explain why the diversity of languages varies geographically across the globe. The author manages to make a convincing case for his proposal, while pointing out remaining areas which still need to be worked on. In summary, I quite like the manuscript and find it makes a valuable contribution.

However, I have two minor conceptual issues and one minor structural issue. The remaining comments are even more minor technical stuff regarding typographical mistakes and textual clarity. First, I find it a bit confusing the author uses both "linguistic diversity" and "language diversity" while ostensibly referring to the same phenomena. However, if they are different, the distinction between these two concepts should be explained to the reader clearly. Now, it is not mentioned in the manuscript. Second, the author does not state which type of "linguistic diversity" he means, which is puzzling as the introduction lays out the different meanings the concept has (number of languages, number of language families, structural diversity). This is crucial information as it is the central concept, and it is operationalized throughout the manuscript. My take after reading the manuscript is that the author is mostly talking about the number of different languages, unless explicitly mentioning language families, but this should be explicitly stated. Third, the "Current perspectives" and "Dynamizing linguistic diversity" sections would benefit from sub-sectioning (and potentially some minor restructuring) as they are long and the reader has forgotten the three main perspectives or points by the end of the section.

Overall, the article is already in rather good shape, and my recommendation is a minor revision for the above-mentioned reasons. Although, I must confess that I am a geographer first and foremost, so I am leaning on the other reviewers' remarks on the author's grasp on the theoretical literature on historical linguistics.

Below are my detailed comments:

**Introduction**

o I have a comment on (or perhaps a slight issue with) the author's delineation of three types of understanding "language diversity". I argue there is a fourth type of language diversity, that draws on methods commonly used in ecology to quantify the diversity of species (see work of Peukert, 2013 [Ref 1]; Hiippala T, et al., 2019 [Ref 2]; Hiippala T, et al., 2020[Ref 3]). In fact, I think this fourth type could be integrated with the first or second examples provided (the "language richness" and "language family richness" examples), as it is related to quantification of linguistic diversity (that is, the diversity of languages). However, this additional understanding of language diversity goes a bit further than just the sheer number of languages in a given study area, and is focused on several perspectives simultaneously: richness, dominance, evenness, and diversity.

o These perspectives can be quantified (or estimated) by a wide selection of metrics, each with their own benefits and drawbacks. In this context, richness is in its simplest form the number of languages, as the author states, but not only that. Dominance describes whether the given sample is dominated by one or more languages. Evenness describes the between-class similarity of the distribution of languages, that is, if all languages are spoken by as many individuals. Diversity tries to incorporate both richness and evenness into one metric.
* Some unclear sentences and unnecessary self-referential language in the paragraph discussing Figure 3 (starting p3)

* Last paragraph of Introduction on page 5. Please provide a reference to this "particular interpretation of a prominent hypothesis". Furthermore, I don't see how the starting sentence of this paragraph is connected to the rest of the sentences in the paragraph.

**Current perspectives**

* General comment: I suggest some slight restructuring and adding subsections that correspond to the three dimensions (or are they perspectives, as the section title leads the reader to believe?) laid out here. This would help the reader follow the arguments made better.

* In the starting paragraph: what is/are "lowbeds linguistic landscapes"?

* Can there be one sentence paragraphs in an ORE article? I am referring to the paragraph starting with "Early studies (Cashdan, 2001....". If not, I would integrate this somewhere else or flesh it out.

* The sentence "As a whole, research, reassuringly, shows the typical signs of maturation of a field of scientific investigation". Please rephrase this sentence. I take it, you mean this specific subfield of research has matured, but now you're referring to research in general. A similar thing happens in the last paragraph of the "Current perspectives" section in the beginning of the paragraph.

* The use of "largest imaginable scale" is a bit vague and over the top here. I presume you mean "globally", please clarify.

* Please rephrase the last sentence of this paragraph, it is very long and difficult to understand.

**Dynamizing linguistic diversity**

* General comment on this section: I think this section would improve if you could divide it into subsections that relate to the three interrelated points you want to make, especially as it is the section containing the main contribution by the author's own words. Now, it is a bit hard to follow how you address these points.

* Last sentence of the first paragraph. Please elaborate how your approach departs from the case studies.

* Paragraph starting with "Nichols also characterizes..." on page 8 requires a reference to the work(s) of Nichols being referred to here.

* On page 9, there is a partially missing subordinate clause in the sentence starting with "As a result, the oldest layers of the diverse linguistic landscape..."

**Conclusion**

* The first sentence is very long. Please consider dividing it into two or more sentences.

* Another paragraph of only one sentence here. Please flesh it out, or integrate somewhere else.

* The last sentence has a missing space between words.

**References**

1. Peukert H: Measuring language diversity in urban ecosystems. 2: 75-96 Publisher Full Text

2. Hiippala T, Hausmann A, Tenkanen H, Toivonen T: Exploring the linguistic landscape of geotagged social media content in urban environments. Digital Scholarship in the Humanities. 2019; 34 (2): 290-309 Publisher Full Text

3. Hiippala T, Väisänen T, Toivonen T, Järv O: Mapping the languages of Twitter in Finland.
Neuphilologische Mitteilungen. 2020; **121** (1): 12-44 Publisher Full Text

**Is the topic of the essay discussed accurately in the context of the current literature?**

Yes

**Is the work clearly and cogently presented?**

Partly

**Is the argument persuasive and supported by appropriate evidence?**

Yes

**Does the essay contribute to the cultural, historical, social understanding of the field?**

Yes

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** Urban geography, linguistic diversity, geoinformatics, regional science

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Author Response 13 Apr 2025

**Matthias Urban**

Thank you very much for your comments, and apologies for the long time it has taken me to respond. Your comments were received almost exactly at the point I had prepared a revision based on the previously received three reports so I thought it wiser to wait with a further round of revision until all reports are in.

I've revised the text taking into account both your main points of criticism as well as the minor ones. Concerning the former, I've replaced "language diversity" with "linguistic diversity" except in one direct quote - no difference is implied by the terms. I have made clear that indeed language richness is the main variable I look at in the introduction, though in response to one of the main points of reviewer

#5 I've included some more discussion of typological diversity to the section "Dynamizing linguistic diversity". At any rate, it should be clearer now what I am talking about in each particular instance. I've also added subsections to the main sections to guide the reader better. Finally, I've taken care of the further comments you made on individual sections (some were superseded already in the first revision).

**Competing Interests:** No competing interests were disclosed.

Reviewer Report 02 December 2024

https://doi.org/10.21956/openreseurope.19907.r45031
© 2024 **François A.** This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

<figure><img src="image_17.png" /></figure>

Alexandre François

<figure><img src="image_18.png" /></figure>

¹ LaTTiCe, Centre National de la Recherche Scientifique, Paris, France

² Ecole Normale Superieure, Paris, Île-de-France, France

³ Linguistics, Australian National University School of Culture History and Language, Canberra, Australian Capital Territory, Australia

The paper "Global language geography and language history: challenges and opportunities" raises the question of linguistic diversity and of the uneven distribution of languages around the world. It discusses what different factors can account for it – including geographical, ecological, economical, ideological factors. This text is rather rich in references, taken from different disciplines relevant to this discussion. Its argument is sound and convincing.

The section on geographical and ecological factors – around the notion of “ecological risk” – is insufficiently clear about its subject. We understand that access to food and resources is an important key, but key to what exactly? to increasing human density in general (regardless of how many languages are spoken)? to favouring more numerous, smaller-size communities? Do these economic factors favour linguistic *density* (number of languages per capita)? or do they go as far as fostering linguistic *diversity* strictly speaking – i.e. the structural distance between neighbouring languages? I wish the author brought more clarity to the discussion, so the reader can see exactly what would be direct causes vs. indirect factors explaining language diversity.

The discussion about language ideologies would gain from incorporating the notion of "egalitarian multilingualism": this attitude among neighbouring groups has been described in the literature (e.g. on Vanuatu, and Melanesia more generally) as an important factor in the maintenance or even the increase of linguistic diversity. In many parts of the world, language is taken as emblematic of place, an attitude which has been shown to intensify the divergence of languages over time. This results in a social ecology where smaller language communities are favoured, bringing about a tightly fragmented linguistic landscape (cf. studies on Vanuatu, or on Australia).

The passage on spread vs. residual zones is an excellent synthesis of J. Nichols's reflection on different language ecologies.

On the formal side, the current version of the text still has many typos, as well as some stylistic imperfections (excessive hypotaxis; repetitions; some unclear passages), and minor errors (e.g. "ephemeral" instead of "epiphenomenal"; "southwesternmost" for "southeasternmost"...) Yet this could be easily corrected by the author.

Overall, this paper is a solid synthesis of the last decades of reflection on an important topic, namely the factors underlying the distribution of languages around the planet. While it says little about the languages themselves (e.g. which aspects tend to change vs. which tend to be stable over time?), it does bring together the viewpoints of various disciplines, to construct an inspired reflection that bridges linguistics and human geography.
**Is the topic of the essay discussed accurately in the context of the current literature?**

Yes

**Is the work clearly and cogently presented?**

Partly

**Is the argument persuasive and supported by appropriate evidence?**

Yes

**Does the essay contribute to the cultural, historical, social understanding of the field?**

Yes

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** historical linguistics; linguistic typology; social ecology and language ideologies

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Author Response 22 Dec 2024

Matthias Urban

Thank you for reading the article and for your extensive and thoughtful comments! I have taken them into account in revising the manuscript. I have clarified that indeed language density is what is thought to depend on "ecological risk", this indeed wasn't fully clear. You will note that I make quite extensive reference to Vanuatu with reference to your work in the revised version. This serves multiple purposes: on the one hand, it provides an opportunity for actual linguistic exemplification requested by reviewer #1; it provides an opportunity to give an example of a local language ecology and its linguistic outcomes; and it provides an opportunity to introduce "egalitarian multilingualism", as you request. Finally, I have rewritten the text relatively extensively to make it less prolix and easier to follow the line of thought, and I have emended the wrong choices of words you noted (thank you for your close reading!).

**Competing Interests:** No competing interests were disclosed.

Reviewer Report 28 November 2024

https://doi.org/10.21956/openreseurope.19907.r45382
© 2024 **Inglese G.** This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

<figure><img src="image_19.png" /></figure>

**Guglielmo Inglese**

<figure><img src="image_20.png" /></figure>

Università degli Studi di Torino, Turin, Piedmont, Italy

The paper offers a fresh and stimulating overview current approaches to explaining linguistic diversity and the distribution of languages worldwide. It explores a number of shortcomings in existing research that links linguistic diversity to environmental factors and proposes, as an alternative, a focus on the historical process of language spread and recess that result in synchronic language diversity patterns. The paper is overall well written and provides an exhaustive and informed survey of the topic, while also laying a clear ground for future research. Its argumentation is nicely supported by a number of specific examples (e.g. the situation of Basque and that of the languages of the Caucasus). I have a few suggestions on points that deserve further improvement. First, a definition of what counts as a language is missing: this is both an empirical issue (in the sense that is not clear on which data figures 1 to 3 are based) as well as a more theoretical one. Even a working definition, such as that provided by Gil 2016 (but other definitions may be good as well, this is just one example), could make the point clearer. Second, it might be worth stressing that a shift in focus to processes in explaining linguistic diversity finds a parallel in current trends in source-oriented typology (I'm thinking of a number of papers by Sonia Cristofaro, e.g. Cristofaro 2019 (Ref 3) among others). These represent different ways in which historical thinking may reshape our understanding of linguistic diversity. Finally, the brief mention of the connection between the study of worldwide linguistic diversity with dialectology/variationist sociolinguistics might be expanded upon (see the classic Trudgill 2011 and the discussion in Inglese & Ballarè 2023).

**References**

1. Inglese G, Ballarè S: 1 Analyzing language variation: Where sociolinguistics and linguistic typology meet. 2023. 1-28 Publisher Full Text

2. Gil D: Describing languoids: When incommensurability meets the language-dialect continuum. *Linguistic Typology*. 2016; **20** (2): 439-462 Publisher Full Text

3. S, Cristofaro: Taking diachronic evidence seriously: Result-oriented vs. source-oriented explanations of typological universals. https://zenodo.org/records/2583806. 2019. Publisher Full Text

**Is the topic of the essay discussed accurately in the context of the current literature?**

Yes

**Is the work clearly and cogently presented?**

Yes

**Is the argument persuasive and supported by appropriate evidence?**

Yes

**Does the essay contribute to the cultural, historical, social understanding of the field?**

Yes
**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** historical linguistics and linguistic typology

I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.

Author Response 22 Dec 2024

Matthias Urban

Thank you for reading and commenting on the article! I have added relatively extensive discussion of where the data come from (viz. Glottolog) and the policies for assignment of coordinates. Extended discussion of the notion of "languoid" that is relevant here as well is in note [1]. A reference to "sociolinguistic typology" à la Trudgill is added to the main text, and a reference to dynamic diachronic approaches to typology in note [3].

**Competing Interests:** No competing interests were disclosed.

Reviewer Report 05 November 2024

https://doi.org/10.21956/openreseurope.19907.r45380

© 2024 Brunn S. This is an open access peer review report distributed under the terms of the [Creative Commons Attribution License](https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

<figure><img src="image_21.png" /></figure>

Stan Brunn

University of Kentucky, Lexington, Kentucky, USA

An original, insightful and well referenced and written statement exploring linguistic diversity in new contexts: environmental and climate variable AS WELL as different continental and regional settings. I would ask the author to address mapping the location of some groups to show the difficulties in mapping the "degrees" of diversity in some historical and contemporary contexts. This focus would again address the problems of not only mapping "where a language is spoken" but also how "slippery" it is to map locations across a linguistic space, but also over time. Second, the paper could/would be stronger IF some examples of words or phrases were used by certain groups over time or in a place. A most thought-provoking contribution.

**Is the topic of the essay discussed accurately in the context of the current literature?**

Yes

**Is the work clearly and cogently presented?**

No
**Is the argument persuasive and supported by appropriate evidence?**

Yes

**Does the essay contribute to the cultural, historical, social understanding of the field?**

Yes

**Competing Interests:** No competing interests were disclosed.

**Reviewer Expertise:** the intersections of social, cultural, political and environmental geographies.

**I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.**

Author Response 22 Dec 2024

**Matthias Urban**

Thank you for reading and commenting on this article. I have included the additional information you requested in the revised version, including sample linguistic data from Vanuatu that illustrate different aspects of linguistic diversity

**Competing Interests:** No competing interests were disclosed.