Aquatic ape hypothesis

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[[File:AAT Confer 3.jpg|thumb|right|165px|Delegates of the Aquatic Ape Symposium 1987]]
{{pseudoscience}}
The '''aquatic ape hypothesis''' (or a common misnomer: '''aquatic ape ''theory''''') is the proposal that wading, swimming, and diving for food had a large [[evolutionary]] effect on the ancestors of [[human]]s and is in part responsible for the split between the common ancestors of humans and other great [[ape]]s.

The hypothesis is in contradiction to the more established [[hypothesis]] that the environment of evolutionary adaptiveness for hominids was the [[Savanna hypothesis|savannas]] of the {{wpl|East African Rift|Rift Valley}} and the more recent hypotheses that the environment was forests or even that it rapidly fluctuated. The hypothesis is largely considered to be [[pseudoscience]].

==History== 
The hypothesis that the morphological divergence of hominids was dictated by an aquatic environment was first formulated in 1923 by the [[Germany|German]] physician {{wpl|Max Westenhöfer}}<ref>[http://cerbi.ldi5.com/imprimersans.php3?id_article=33.com About an Aquatic Stage in Man's Evolution with references to Max Westenhöfer and initial bipedalism]</ref><ref>[http://web.archive.org/web/20140816190653/http://www.riverapes.com/AAH/Westnfr/WestnHfr.htm Title page, excerpts from "Der Eigenweg des Menschen", 1942]</ref> and [[United Kingdom|British]] marine biologist Sir {{wpl|Alister Hardy||.}}<ref>[https://doi.org/10.1017/S0016672300030184 ''Cambridge University Press'': The Aquatic Ape: Fact or Fiction?]</ref> Hardy was inspired after returning from an [[Antarctica|Antarctic]] expedition where he noticed the subcutaneous blubber fat layers of whales and seals and saw parallels to humans.<ref>PDF: [http://kimberlymoynahan.com/wp-content/uploads/2012/04/Hardy1960.pdf ''The New Scientist'': Was Man More Aquatic in the Past? by Hardy, 1960]</ref> He was also impressed by the human "exceptional ability" to swim. Fearing it would jeopardize his scientific career, Hardy did not publish his ideas until 1960.

Elaine Morgan {{lived|1920|2013}} was a [[Wales|Welsh]] [[Author|writer]] and the chief proponent of the aquatic ape hypothesis. Morgan took up the fight in 1972 when she discussed the aquatic ape hypothesis in her book ''The Descent of Woman.''<ref>Elaine Morgan, ''The Descent of Woman: The Classic Study of Evolution''. Souvenir Press; Fourth Edition, 1 February 2001, [[Special:Booksources/0285627007|ISBN 0285627007]].</ref> Morgan was the primary proponent of the hypothesis, and culminated her argument in 1997 with the publication of ''The Aquatic Ape Hypothesis.''<ref name=aquatic>Elaine Morgan, ''The Aquatic Ape Hypothesis''. Souvenir Press; Second Edition, 1 June 2017. [[Special:Booksources/0285643614|ISBN 0285643614]].</ref><ref>Vaneechoutte, M. 2000. 'Report of the Symposium ‘Water and Human Evolution’. Human Evolution 15(3) 243-251.</ref> Her critics accused her of having used "sloppy and unscientific writing techniques" and maintain that she was guilty of [[quote mining]].<ref>[http://www.aquaticape.org/quotes.html Critique] of Morgan</ref> She was described as being more of a popularizer of ideas than a real scientist. Regardless, she was awarded an honorary ''Doctor of Letters'' by Glamorgan University in December 2006.<ref>[http://news.glam.ac.uk/news/en/2006/dec/18/glamorgan-honours-wales-finest Glamorgan Honours Wales' Finest]</ref>

==The hypothesis==
The major divergence between the great apes and hominids can be placed somewhere between 5-7 million years ago (mya) based on the [[fossil record]]. During this time significant differences in anatomy developed including:
*'''Bipedalism''', which the theory claims was assisted by the supporting effects of [[water]].<ref>A Theory on the Evolution of the Habitual Orthograde Human Bipedalism &mdash; The "Amphibisce Generalistheorie": Niemitz, C</ref>
*'''Hairless skin''', with the exception of the head which still needed to be shielded from the sun. Meanwhile primates such as baboons and vervet monkeys which live on the savanna have neither lost their hair nor developed an upright posture.<ref name=aquatic />
*'''Increased subcutaneous fat'''<ref>Was man more aquatic in the past? (NewScientist): Hardy, A.</ref>
*'''Greatly expanded brain size''', which was promoted by the protein-rich fish diet.
*'''A hooded nose''', which prevents water from entering the nostrils.<ref>Evidence for the unique function of docosahexanoic acid (DHA) during the evolution of the modern hominid brain (Lipids): Crawford, M et al</ref>
*'''Greasy skin with an abundance of sebaceous glands''', which can be interpreted as a waterproofing device.<ref>Kingdon, Jonathan. (2003) ''Lowly Origin'' Princeton University Press, 242</ref>
*'''Expressive faces''', since communicating through body language is difficult when wading in deep water or swimming but communicating through facial expression is still possible.<ref name=aquatic />

Elaine Morgan, the primary proponent of this hypothesis, claimed that these traits are common in aquatic [[mammal]]s.  She claimed that these demonstrate [[convergent evolution]] of mammals living in an aquatic environment.  The aquatic stage would have been about 5 mya until about 2.5 mya when the grassland expansion begun.

==Objections to the hypothesis==
[[Image:Bottlenose Dolphin.jpg|thumb|Ma-ma--ma-ma]]
There are several problems with this idea. The first is that convergent evolution predicts adaptations serving similar function, not necessarily similar structure. A platypus bill looks like a duck bill because it solves the precise same problem (sucking bugs out of mud); but the wings of a bat, a bird, and a bumblebee are products of convergent evolution in solving the problem of flight, but are structurally very different. Morgan's convergent evolution adaptations focus on structure. 

The second problem is that evidence provided for the hypothesis is equally well accounted for by savanna-based adaptations without needing to posit an aquatic phase of human development.

* Loss of body hair: lower [[parasite]] load and maintenance through [[sexual selection]]. Furthermore, many aquatic mammals have actually kept their body hair.<ref>Pond, Caroline M. 1991 "Adipose Tissue in Human Evolution", pp. 193-220. The Aquatic Ape: Fact or Fiction? Edited by Machteld Roede, Jan Wind, John M. Patrick and Vernon Reynolds. Souvenir Press: London.</ref>  Several other savanna species have also lost much of their hair including elephants, rhinoceroses, and naked mole rats.  Although both elephants<ref>[http://www.elephant.se/elephant_evolution.php?open=Evolution%20of%20elephants aquatic elephant evolution]</ref> and rhinoceroses<ref>[http://home.intekom.com/ecotravel/Guides/Wildlife/Vertebrates/Mammals/Big_5/Rhino/Rhino_Evolution.htm aquatic rhinoceroses evolution]</ref> are theorised to have evolved from aquatic ancestors so they may not be the best counter-examples—yet the only modern rhinoceros that spends much of its time in the water is the hairy rhinoceros.
* Diet: the fatty acids for the [[brain]] were present in sufficient quantities on the savanna.
* Diving reflex: terrestrial mammals show this too; there has been insufficient study of other apes to use this as evidence that humans are special in this regard.
* Body fat: The quantities seen in present-day humans accord with those seen in domesticated mammals, ''i.e.'' we're quite well fed compared with wild dumb beasts. 
* Bipedalism: the hypothesis compares humans to quadrupeds, but we went from quadrupedal locomotion to brachiation; bipedalism follows quite readily from that.  
* Descended larynx: speech. The human larynx is not shaped like that of aquatic mammals, and descended larynxes are also seen in deer as well as other animals.<ref>W. T. Fitch and D. Reby, [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088793/ The descended larynx is not uniquely human.]  Proc Biol Sci. 2001 Aug 22;268(1477):1669-75. doi: 10.1098/rspb.2001.1704. PMID: 11506679; PMCID: PMC1088793.</ref>
* Nose shape: again, speech. Speech was rather important in human development, oddly enough.
* Sebaceous glands: not actually found in aquatic mammals. Appear to be sexually dimorphic (highly active in adolescent human males, scent receptors highly active in adolescent human females).
* Swimming: humans really aren't that good at swimming. Dogs and [[cats]] do about as well.

A third major problem is there are actual characteristics indicative of aquatic mammals which humans notably lack. Aquatic mammals are testicond and have internal testes to insulate the gonads; humans are not testicond. Aquatic mammals also store large amounts of [[oxygen]] in the blood rather than the lungs, a trait also lacked by humans.

The Aquatic Ape Hypothesis cannot easily explain why these features were maintained after our ancestors supposedly left the water and moved to savannas. <ref>[http://johnhawks.net/weblog/topics/pseudoscience/aquatic_ape_theory.html Why anthropologists don’t accept the Aquatic Ape Theory]. johnhawks.net, 25 January 2005.</ref>

Furthermore, there's good evidence that many of the traits claimed to fall under the umbrella of the aquatic ape hypothesis evolved at radically different points in human evolutionary history. Fossils from 4.4 mya display bipedalism, while still possessing small brains long after, and not evolving sparse body hair until even later still.

One of the largest problems with the hypothesis is that since the 1960s, rather than improving and gathering evidence, the hypothesis has become more nebulous and vague. Rather than some specific aquatic phase, modern aquatic ape hypothesis supporters cite anything from fresh water millions of years ago, to salt water habitation more recently, to several different aquatic phases or even a general proximity to water to a greater degree than other apes. Incidentally, other apes and even some monkeys sometimes gather food from water and may stand bipedally to do this.<ref>Carsten Niemitz, [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819487/?tool=pmcentrez The evolution of the upright posture and gait--a review and a new synthesis.] Naturwissenschaften. 2010 Mar;97(3):241-63. doi: 10.1007/s00114-009-0637-3. Epub 2010 Feb 3. PMID: 20127307; PMCID: PMC2819487.</ref><ref group=note>The last suggestion could make sense because evolving humans being more intelligent than other apes would better find ways of getting to food in any lake, river, stream, coastal environment where they happened to be. Perhaps there was no specific aquatic phase; instead there could have been evolving pre-humans/humans making use of water when there happened to be water-based resources in their area, but they remained able to manage in times of drought — after all, that is how modern humans behave.  This in itself could perhaps have enabled us to evolve some limited adaptations to water. Theoretically there could have been a limited aquatic phase and the readiness of evolving hominids to use water opportunistically after this phase was sufficient to maintain some aquatic adaptations.</ref>

There are also anti-science objections lodged against the creation of the hypothesis because Morgan had the idea first and then simply found differences between humans and other apes and composed ''ad hoc'' reasons associated with water. One could [[cherry pick]] data for many such pet theories without any merit behind them, whilst making them sound good on paper.

==Reception==
The aquatic ape hypothesis has mostly been ignored by palaeoanthropologists, and its strongest reception has been in popular literature and magazines. Very little research has been published in scientific journals directly supportive or critical of the hypothesis.<ref>[http://www.aquaticape.org/whyanthro.html  Why don't anthropologists mention the AAT/H much?]</ref> Morgan blamed the poor reception to the idea on people's perception of herself personally, since she had no advanced degree.

Supporters of the hypothesis claim that this lukewarm reception resulted from the fact that Elaine Morgan was not a member of the palaeoanthropological establishment. Detractors maintain that the lack of convincing evidence may have played a role.

==Modern aquatic primates==
[[File:Onsen Macaque.JPG|thumb|right|165px|Japanese macaques keeping warm in Jigokudani hot springs]]
* Japanese macaque (''Macaca fuscata'') &mdash; since they live in a cold climate, during the winter, they frequent certain hot springs to keep warm.
* Certain [[bonobo]]s spend a certain amount of time in water, either in the shallows or crossing it. 
* [[Chimpanzee]]s swim and walk bipedally in water.<ref>Marc Lallanilla, [http://www.livescience.com/39039-apes-swimming-video.html Who Knew? Apes Can Swim and Dive]. Live Science, 20 August 2013.</ref><ref>[http://www.youtube.com/watch?v=12nGEauhFNc Swimming and diving behavior in apes]. Stefano Di Criscio, YouTube.</ref> Apparently the chimps use a kind of breaststroke.<ref>[http://www.sciencedaily.com/releases/2013/08/130814100212.htm First documented report of swimming and diving in apes]. Wits University via Science Daily, 4 August 2013.</ref>
* [[Orangutan]]s have been known to spend time in water and swim.
* Some monkeys in [[Thailand]] have also been filmed diving into water.<ref>[http://www.youtube.com/watch?v=5ixnXfcqlQc Cliff diving monkeys]. TransumOrg, [[YouTube]].</ref> The Proboscis monkey loves swimming too.<ref> [http://www.youtube.com/watch?v=y6jjntyeQQo Proboscis Monkey Swimming]. MrSelamat Ethio, YouTube.</ref> 

And, of course, [[Homo sapiens]]. Certain humans live in deserts etc, but some humans, especially those in the Indian Ocean islands, spend a lot of time in the sea, pearl diving, etc. Others are keen swimmers across distances of sea. While many humans are not currently "aquatic", a notable minority are.

==See also==
*[[Endurance running hypothesis]]
*[[Stoned Ape Theory]]

==External links==
*Elaine Morgan's [http://www.elainemorgan.org/ web site].
*[http://www.primitivism.com/aquatic-ape.htm Elaine Morgan] quoted on the aquatic ape theory.
*A [http://www.aquaticape.org/quotes.html strong critic] of Elaine Morgans's [[quote mining|quoting]] techniques.
*An [http://www.newscientist.com/channel/opinion/mg18624962.000-interview-the-natural-optimist.html interview] with... Elaine Morgan!
*Elaine Morgan [http://www.ted.com/talks/elaine_morgan_says_we_evolved_from_aquatic_apes.html talking about the hypothesis] at TED, 2009.
*[http://www.theguardian.com/science/2013/apr/27/aquatic-ape-theory-primate-evolution Big brains, no fur, sinuses … are these clues to our ancestors' lives as 'aquatic apes'?]

==Notes==
{{reflist|group=note}}

==References==
{{reflist|2|80%}}

[[Category:Animals]]
[[Category:Evolution]]
[[Category:Hominids]]
[[Category:Pseudoscience]]

Categories: Animals, Evolution, Hominids, Pseudoscience