日 本 人 類 学 会 進 化 人 類 分 科 会 	 	 ニ ュ ー ス レ タ ー 	
 

目次
次回案内
	
  第 29 回シンポジウム「資源をめぐる葛藤とその解決法の進化史」

2

平成 24 年度	  開催シンポジウム	  第 28 回シンポジウム「大型類人猿の生活史戦略と人類進化」	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
 

3

	
 
山極壽一（京都大学大学院理学研究科）
	  「Life history strategies of the great apes」
	
 

	
 

4

Jay KELLY（アリゾナ州立大学）

	  	
  「Life history inference in the early hominins Australopithecus and Paranthropus」	
  	
  	
  	
  11

1

次回案内

	
  	
  第29回シンポジウム「資源をめぐる葛藤とその解決法の進化史」

	
  	
 

オーガナイザー：山極壽一(京都大学大学院理学研究科)
	
  	
  	
  ディスカッサント：	
  竹ノ下祐二（中部学院大学）、河合香吏（東京外国語大学 AA 研）
	
  	
  	
  日時：	
  2012年 11月 2日（金）17時20分から19時20分まで
場所：	
  慶應義塾大学日吉キャンパス	
  C 会場
	
  	
  	
  	
  山極壽一（京都大学大学院理学研究科）
	
  	
  	
  「資源をめぐる葛藤の進化史的背景」
	
  	
  	
  	
 
	
  	
  	
  	
  藤田志歩（鹿児島大学）
	
  	
  	
  	
  	
  「ストレスホルモンの解析と霊長類の葛藤」
	
  	
  	
  	
 
	
  	
  	
  	
  中務真人（京都大学大学院理学研究科）
	
  	
  	
  	
  	
  「化石霊長類群集における競争とニッチ分割」
	
  	
  	
  	
 
	
  	
  	
  	
  木村大治（京都大学大学院アジア・アフリカ地域研究研究科）
	
  	
  	
  	
  	
  「アフリカの狩猟採集民と農耕民の森林資源をめぐる葛藤と解決」
	
  	
  	
  	
  討論
	
  	
  	
  	
  総会

2

日本人類学会進化人類学分科会第 28 回シンポジウム「大型類人猿の生活史戦略と人類進化」

7 月 6 日(金) ウインク愛知	  1004 会議室
オーガナイザー：山極壽一(京都大学大学院理学研究科)
	
  	
  	
  	
  	
  	
  	
  	
  古市 剛史(京都大学霊長類研究所)
	
  	
  	
  	
  	
  	
  	
  	
  中務真人(京都大学大学院理学研究科)

山極壽一（京都大学大学院理学研究科）
	  「Life history strategies of the great apes」」
Jay KELLY（アリゾナ州立大学）
	  「Life history inference in the early hominins Australopithecus and Paranthropus」

3Life history strategies of the great apes
山極壽一
京都大学大学院理学研究科	
 	
 Primates show slow life history traits, suchmonkeys may respond to limited access to food re-as small litter size, long gestation, long lactation,

sources by delaying reproduction (Cheney et al.,and long life span, in spite of striking contrasts in1988). Female Japanese macaques and savanna ba-

habitats, diet, mobility and range size between themboons with high ranks tend to mature earlier than(Harvey et al., 1987; Read & Harvey, 1989; Ross,

females with low ranks (Altmann et al., 1988;

1998). Recent arguments have proposed determi-

Gouzoules et al., 1982; Takahata et al., 1999). The-

nant factors of slow life history in primates, such as

se observations may suggest that life history traits

large brain size (Allman et al., 1993; Martin, 1996),

of primates may have evolved as a species-specifichigh risk of juvenile mortality (Janson & vanstrategy as well as the immediate responses to en-

Schaik, 1993) and arboreal life style (Eisenberg,

vironment changes.

1981; Martin, 1995), but no single factor seem toSocial structure and social behavior are also

fully explain it (Harvey & Purvis, 1999; van Schaik

important for life history traits. Among mammals,& Deaner, 2002).

primates have a unique social feature in that the two

Ecological factors may influence the life his-sexes live together even outside the breeding season.

tory traits of primates in various ways (Kappeler etThis may result in diversity of social structure andal., 2003). The low growth rate of primates may be

may characterize the fast-slow continuum in rela-caused by a negative association between mortality

tion to social systems. Female gregariousness, so-rates and growth rates, and the juveniles’ vulner-cial relationships, or alloparental care of dependent

ability to food shortage and predation may shape

infants may also affect life history traits such as

their life history traits (Janson & van Schaik, 1993).

postnatal growth rate, weaning age and inter-birthPrimates may be adapted to the low mortality rates

interval (Fairbanks, 1990; Stanford, 1992). Maleprevalent in their ancestral habitat (tropical forests),

reproductive strategies may constitute a strong se-since other arboreal mammals such as bats (Jones &lective force on life history traits. Infanticide by

MacLarnon, 2001) also have low mortality rates.

males promotes prolonged male-female association

Primates living in the more unpredictable habitats(van Schaik, 2000), complex male-infant relation-

have higher birth rates and earlier age at first re-ships (Paul et al., 2000), patterns of female move-production (Ross, 1998). The apes that are strictly

ments

distributed in and around the tropical forests have

Yamagiwa & Kahekwa, 2001), and female repro-

slow life history traits, while old world monkeys

ductive biology (Watts, 2000; van Noordwijk &living in variable habitats have relatively rapid life

van Schaik, 2000). Recent findings show large

history traits. Large intra-specific variations are alsovariations in social structure and behavior between

found in some life history traits. Female vervet

species and within species (Barton et al., 1996;

betweengroups(Steenbeck,

2000;

4

Henzi & Barrett, 2003; Doran et al., 2002;
Yamagiwa et al., 2003). Life history traits are alsoeasy to change, relatively independently, via selection (Kappeler et al., 2003). However, it is still unclear how such social variation is linked with life
history variation.
The social structures of the great apes arehighly differentiated. Both male and female

Table 1. Comparison of female reproductive
features among great apes

orangutans usually live alone and overlap theirhome range partially with neighboring individuals

Both species of orangutans (Pongo abelii and P.

of the same sex (Galdikas, 1984; Delgado & van

pygmaeus) show the highest age at first reproduc-

Schaik, 2000; van Schaik, 1999). A male’s large

tion (15.4 and 15.7 years on average, respectively)

range includes multiple small ranges of females,

and the longest inter-birth interval (9.3 and 7.7

although “unflanged male,” mature but with unde-years on average, respectively) among the apes.

veloped external adult features, occasionally roam

Gorillas (Gorilla beringei beringei and G.b. grau-

widely (van Schaik et al., 2004). Gorillas form aeri) show the lowest age at first reproduction (10.1

cohesive group consisting of a mature male andand 10.6 years, respectively) and the shortest in-several females with their offspring (Schaller, 1963;

ter-birth interval (3.9 and 4.6 years, respectively).

Jones & Sabater Pi, 1971; Fossey, 1983; Yamagiwa,

Both species of chimpanzees are intermediate be-1983). They do not show territoriality, and their

tween orangutans and gorillas. The previous studies

home ranges extensively overlap with those ofargued that ecological factors, such as frugivorous

neighboring groups (Schaller, 1963; Yamagiwa et

diet and arboreal lifestyle, promoted slow life his-al., 1996; Parnell, 2002). Chimpanzees form a large

tory among extant apes (Doran et al., 2002; vangroup including multiple males and females, but

Schaik & Deaner, 2002; Wich et al., 2004). How-

they frequently change partners to associate with

ever, recent studies reported frugivorous diet andand range in small parties (Goodall, 1968; Nishida,arboreal foraging of western gorillas (Remis, 1997;

1968; Boesch & Boesch-Achermann, 2000). In-

Rogers et al., 2004). Although the more frugivorous

ter-group relationships are antagonistic and areorangutans (Pongo abelii) at Ketambe show slower

sometimes characterized by overt aggression, evenlife history than the less frugivorous orangutans

including killing individuals of neighboring groups(Pongo pygmaeus) at Tanjung Putting, the moreduring encounters (Goodall et al., 1979; Nishida etfrugivorous bonobos (Pan paniscus) show rela-al., 1985; Watts et al., 2006).

tively faster life history than the less frugivorous

Despite such sharp differences in social

chimpanzees (Pan troglodytes).

structure, females of the great apes have the com-

Social factors, rather than ecological factors,

mon feature of starting reproduction after leaving

may influence the life history parameters of female

their natal groups. A comparison of life history

apes. Among them, their solitary nature and maleparameters in female great apes indicates that or-

reproductive tactics may have great influences on

angutans have the slowest life history.

the fast-slow continuum in the life history of female5apes. Female orangutans, who usually spend a soli-

Boesch & Boesch-Achermann, 2000). Immigranttary life, show the slowest life history. Maturing

female bonobos first establish affiliative relation-

females need to establish their own home range andships with resident females through socio-sexual

relationships with reproductive mates after separa-

behavior (Idani, 1991; Kano, 1992; Furuichi, 1997;

tion from their mothers. They need a longer time to

Hohmann et al., 1999). Although group life may

attain these tasks than female chimpanzees and go-

facilitate female chimpanzees in starting or resum-

rillas, who transfer into other groups immediately

ing reproduction earlier than do female orangutans,

after emigration. Solitary travel for weeks ormore complex social relationships within a groupmonths by female chimpanzees or gorillas has

and unassisted caretaking may prevent them fromrarely been seen (Wrangham, 1979; Nishida, 1979;

having a fast life history.

Goodall, 1986; Boesch & Boesch-Achermann,
2000; Watts, 2003; Stokes et al., 2003; Yamagiwa
et al., 2003). Female chimpanzees and gorillas may
easily find mates for reproduction in the group theyjoin and thus may not need to establish their own
ranging areas. Instead, they need to establish social
relationships with unrelated conspecifics within the
new group. Immigrant females usually get harassedby resident females in both chimpanzees and gorillas (Goodall, 1986; Idani, 1991; Furuichi, 1997;

Figure 1. Costs of female transfer and fast-slow

Watts, 1991, 1994; Harcourt & Stewart, 2007). Fe-

continuum of life history

male gorillas get support from the leading males,
who frequently intervene in conflicts among fe-

In summary, male mating tactics may influence themales (Watts, 1997; Harcourt & Stewart, 2007).

life history of the great apes in different ways. Fe-

The leading male monopolizes most of the copula-male dispersal and independent reproduction fromtions with fertile females and takes intensive care of

related conspecifics may enable them to form vari-

the offspring before and after weaning (Fossey,ous social structures and flexible life history traits

1979; Fletcher, 2001; Stewart, 2001). These social

according to male mating strategies. Ecologicalfeatures may facilitate weaning at the earlier age,

factors basically shape the gregariousness of fe-

shorter inter-birth interval, and female reproduction

males in female-dispersal species, but they canat an earlier age for gorillas than for chimpanzees.

choose from a wide variety of feeding strategies,

By contrast, female chimpanzees and bonobos

from individual dispersal to moving in cohesive

copulate with multiple males and take care of in-groups. Males also take various mating tactics ac-

fants by themselves (Tutin, 1979; Goodall, 1986;

cording to female movement and association pat-Kano, 1992). Female chimpanzees tend to associateterns, which in turn also vary with male associa-

or interact with other adults less frequently thantions and mating strategies. Although the influences

males, and mothers with dependent infants rarelyof these ecological and social factors on life history

join males (Wrangham, 1979; Nishida, 1979;of great apes are different between genera, between
6species, and between populations, the solitary

Heesy CP (2002) Multivariate and phylo-

nature may urge females to choose a slower life

genetic approaches to understanding chim-

history, while stable associations between males

panzee and bonobo behavioral diversity. In:

and females may promote a faster life history. Fru-

Boesch C, Hohmann G, Marchant LF (eds),

givorous orangutans and chimpanzees may suffer

Behavioural Diversity in Chimpanzees andmore costs of female dispersal through decreased

Bonobos, Cambridge, Cambridge Univer-foraging efficiency than folivorous gorillas, andsity Press, pp.14-34.

chimpanzees with fission-fusion grouping may suf-

Eisenberg JF (1981) The mammalian radiations: An

fer more social stress than gorillas in highly cohe-analysis of trends in evolution, adaptation,

sive groups. Such differences may generally shapeand behavior. Chicago University Press,

the fast-slow continuum of life history in fe-

Chicago.

male-dispersal primate species.

Fairbanks LA (1990) Reciprocal benefits of allomothering for female vervet monkeys. Anim

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10

Life-history inference In the early hominins Australopithecus and Paranthropus
Jay Kelley
Institute of Human Origins, Arizona State University
For primates as a whole, age at M1 emergence has

Estimated ages at M1 emergence were calcu-

been demonstrated to be a reliable proxy for thelated for four species of the early hominin genera

general pace of life history. New ages at M1 emer-

Australopithecus and Paranthropus using data ongence for several wild great ape individuals

adult average cranial capacity, as well as previously(~3.7-4.6 years) show a particularly close corre-

estimated ages at death in several infant

spondence to key life-history attributes related tonile individuals that died during or soon after M1

lifetime reproductive output, more so than body

eruption (Bromage & Dean, 1985; Dean, 1987;

mass or adult cranial capacity. If these new ages

Dean et al., 1993; Lacruz et al., 1995). The latterapproximate the respective species means, then age

were based partly on the preserved growth records

at M1 emergence would appear to be a highly reli-in the teeth of these individuals combined with data

able predictor of life history within Hominidae, in-on tooth formation in extant apes.

and juve-

cluding fossil members of the clade.
Estimated
SpeciesSpecimen

M1 eruption stage

age
at death (yrs)

Australopithecus
afarensis
Australopithecus
africanus
Australopithecus
africanus
Paranthropus
robustus
Paranthropus
robustus
Paranthropus
boiseia

LH 2

Sts 24

Taung 1

SK 62

SK 63

KNM-ER 1820

Recently into occlusion
Recently into occlusion with slightwear
Recently into occlusion with veryslight wear
Cusp tips just below alveolar margin
In occlusion with wear facets
Mesial cusp tips above level ofdP4 cervix

Estimated age at M1
emergence (yrs)a

3.25

2.9

3.30

2.9

3.73-3.93

3.3-3.5

3.35-3.48

3.8-3.9

3.4-3.7

2.8-3.1

2.5-3.1

2.7-3.3

Based on age at death estimates, adjusted for stage of eruption.

Table 1. Estimated ages at death and M1 emergence in six early hominin individuals

The two methods generally produced different

ing either an all-anthropoid or gorilla model, or

results. Predicted M1 emergence ages based on cra-

4.3-4.4 years using a chimpanzee model. Those

nial capacity were in the range of 3.7-3.8 years us-

based on ages at death in the early hominin indi11

viduals had an overall range (lowest minimum toto those of gorillas. Finally, it is possible that thehighest maximum estimates for all individuals) ofages at death in most or all of the early hominin

2.7-3.9 years, with a range of species means of ap-

juveniles have been systematically underestimated,

proximately 3.0-3.4 years (Table 1).

with consequent underestimation of ages at M1

Four of the six individuals, however, had mean

emergence. An examination of molar crown andestimates of only about 3.0 years. Most interesting,root formation in early hominins, extant great apes

unless early hominins are modeled as chimpanzees

and humans suggests that this may indeed be thein the age at M1 emergence/cranial capacity regres-case unless root growth in the early hominins was

sion, the ranges from both methods are below, or

more rapid even than in Gorilla, which, perhaps

barely overlap, the range of M1 emergence ages ofalong with Pongo, has the fastest root growth

the free-living great ape individuals (3.7-4.6 years).

among extant great apes and humans. Estimates ofWhat stands out in these results is that most of
the estimates of age at M1 emergence derived fromages at death in the early hominin individuals are somuch earlier than the expected ages based on cranial capacity, and, for the most part, also so muchearlier than those determined for the extant great
ape individuals. However, in extant great apes andhumans, cranial capacity is neither a particularly
precise nor accurate predictor of age at M1 emergence, nor is it strongly concordant with the timingof key life-history attributes.

Equally important isthat age of M1 emergence does appear to be a very
reliable predictor of life history in extant hominids.
The critical issue, therefore, is the accuracy of
the age at death estimates in the fossil hominins,which largely determines the accuracy of the estimates of age at M1 emergence. If they are reasonably accurate, then the life histories of Australopithecus and Paranthropus species would likely havebeen considerably faster than in any of the extant
great apes. Alternatively, there could have been selection for accelerated dental development andtherefore early M1 emergence, as in indriids forexample compared to other lemurs, perhaps associated with relatively early weaning. Again as in indriids, other life history parameters might have been
relatively slower and more or less commensuratewith cranial capacities, which were nearly identical

M1 crown formation times in Australopithecus andParanthropus mostly fall in the range of about
2.4-2.7 years. Even with root extension rates as fast
as in Gorilla, M1 emergence any earlier than about
3.5-3.7 years of age would therefore be highly unlikely. If the ages at death in the early hominin individuals have in fact been underestimated, then
their life histories would likely have been slower
than presently appears to be the case and probably
more in line with those of the extant great apes, assuggested by their cranial capacities.
Until recently, none of the above alternatives
could be dismissed and each could be argued withreference to growth and ecology in extant primates.
Means now exist, however, to determine – without
recourse to the partially destructive methods otherwise needed to reveal all the dental growth information required to calculate reliable and precise
ages at death – if the ages at death in the early
hominins examined here have been underestimated.
Together, confocal microscopy and X-ray synchrotron microtomography can faithfully render manyof the details of dental incremental growth that previously had to be estimated for specimens that
could not be sectioned. A project has now been initiated by researchers in France and the U.S. to reexamine ages at death in a number of fossil
hominins using these techniques.
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Dean,

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Re-evaluation of the age at death of immature
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Dean, M. C, Beynon, A. D, Thackeray, J. F. &Macho, G. A. (1993). Histological reconstruction of dental development and age at death of ajuvenile Paranthropus robustus specimen, SK
63, from Swartkrans, South Africa.

Am. J.

Phys. Anthropol. 91, 401–419.
Dean, M. C. (1987). Growth layers and incremental
markings in hard tissues: A review of the literature and some preliminary observations
about enamel structure in Paranthropus boisei.
J. Hum. Evol. 16, 157–172.
Lacruz, R. S., Ramirez Rozzi, F. & Bromage, T. G.
(2005). Dental enamel hypoplasia, age at death,and weaning in the Taung child.

S. Afr. J. Sci.

101, 567–569.

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