Aquatic Ape Human Ancestor Theory

Aquatic Ape Theory - What is it?

A Brief Summary of AAT - key arguments

A Brief History and Key Proponents of AAT

When / Where / How?

Ape to Human Evolution Timeline

Alternative theories of human evolution

Wikipedia and the scientific community

... Anatomical Evidence
... Bipedalism
... Birth and babies
... Brain
... Breath control
... Descended larynx
... Diet
... Diseases
... Fat
... Fingers, toes and feet
... Furlessness
... Hair and baldness
... Human ailments
... Kidneys
... Language & Song
... Menopause
... Nose
... Olfactory sense
... Pachyostosis
... Paranasal Sinuses
... Platycephaly
... Reverse osmosis
... Sexual features
... Sleep (USWS)
... Surfer's ear
... Sweating
... Tears
... Underwater vision
... Viruses
... Waterside environments

. Homo Ancestors
... Trachillos bipedal hominids
... Homo erectus
... Homo neanderthalensis
... Sea Gypsies/ the Moken
... Homo sapiens - water afinity
... Coastal Migration
... Pan and Gorilla ancestry
... Semi-Aquatic Animals

. Testable Hypotheses
. Fossil evidence
. Genetic evidence
. Paleoecological evidence
. Retroviral marker in apes
. Acheulean handaxes

A call to scientists...

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AAT, Wikipedia and the scientific community

If the Aquatic Ape Theory is really so obvious, why aren't we hearing about it more often or learning about it in school? Below I have included some answers as written by Richard Ellis, American Museum of Natural History, New York, USA, Marc Verhaegen and Elaine Morgan.


In a 2000 article published in BBC Wildlife, Simon Bearder, a professor of anthropology at Oxford Brookes University and a member of the IUCN Primate Specialist Group, wrote a comprehensive summary of the AAH that began with the question: “How do you upset a gathering of biological anthropologists?”, and answered it: “Just mention the words ‘aquatic ape hypothesis’.” [1]. Bearder believes that Morgan’s suggestions are worthy of consideration, and concludes his article thus: “So, is it really true that the ancient causes of our unique way of life are still a mystery? Or is it more of a mystery why the ideas of Elaine Morgan and others have often been systematically ignored by professional anthropologists? Why are the possibilities of an amphibious origin not subjected to rational debate, scrutiny and research? These questions are hard to answer without concluding that prejudice and dogma have reigned far too long… It is a challenge for future generations of anthropologists to expose these ideas to research and analysis to see if they survive close scrutiny, rather than continuing the denial of their predecessors and pretending there is no case to answer.”

Despite Morgan’s willingness to subject her hypothesis to any test that anyone might suggest, mainstream anthropologists, with a couple of exceptions (see Chapter 15*), have ignored her. It may be, as Daniel Dennett [2] wrote, “that she is not only a woman, but a science writer, an amateur without proper official credentials … But in this case, I wonder, many of the counterarguments seem awfully thin and ad hoc. During the last few years, when I have found myself in the company of distinguished biologists, evolutionary theorists, palaeo-anthropologists, and other experts, I have often asked them to tell me, please, exactly why Elaine Morgan must be wrong about the aquatic ape theory. I haven’t yet had a reply worth mentioning, aside from those who admit, with a twinkle in their eyes, that they have often wondered the same thing. There seems to be nothing
inherently impossible about the idea: other mammals have made the plunge, after all. Why couldn’t our ancestors have started back into the ocean and then retreated, bearing some telltale scars of this history?”

In The Aquatic Ape Hypothesis [3], Morgan included numbered references, because, she said, “After disputing for 25 years with professional scientists, I have learned to respect the high standards they set themselves, and expect from others, in identifying their sources.” She also wrote: “The questions posed by the Aquatic Ape Theory are important and valid. The answers it offers are speculative, but no more so than any other available model. It is now generally agreed that the last common ancestor of apes and men lived in Africa in a landscape that was a mosaic, a mixture of trees and grassland. One subgroup of these animals – for some reason – began to change. First they stood up on their hind legs and began to walk bipedally; at some point the hair on their bodies changed direction and ultimately they became functionally naked; the larynx descended and was relocated below the tongue; they became fatter; forgot how to pant; lost their apocrine glands and much of their sense of smell; their sebaceous glands proliferated; their nostrils pointed in a new direction; finally, they evolved larger brains, gave birth to more immature babies, and learned to speak. There may be sound reasons why the aquatic model, like the savannah one, will in the end after careful scrutiny have to be abandoned. But there is no case for rejecting it out of hand. Over the past decades it has been adjusted and modified to meet valid objections and to accommodate new data. For those who have assumed that there is something inherently untenable about it, it is time to think again.”

Obviously, the fact that Elaine Morgan is a woman does not automatically validate (or negate) her hypothesis, and, given the nature of The Descent of Woman [4] – and its publication at the height of the burgeoning women’s movement – those who refuse to acknowledge her theories are doing exactly what she says has happened throughout discussions of human evolutionary history: relegating women to the kitchen and nursery.

Elaine Morgan deserves to be taken seriously. The AAH is too important to be dismissed as a joke or as a hypothesis developed only in support of the women’s movement, and the supporters of the hypothesis ask enough questions to make offhand dismissal impossible. Examining the history of Homo sapiens, we are categorically unable to explain the considerable differences between humans and other primates: upright, bipedal stance, hairlessness of the body, subcutaneous fat layers, larger brains and the power of speech. Accepted evolutionary theory suggests that these
characters evolved in response to environmental influences, and that the human body did not accidentally attain the form that it now has. There may not have been an ‘aquatic’ period in human development, but assigning all those unique adaptations to evolutionary happenstance isn’t much of an explanation either.


*Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution, Mario Vaneechoutte, Algis Kuliukas and Marc Verhaegen (Eds), 2011 Bentham Science Publishers. Ellis, Richard. Chapter 13: Aquagenesis: Alister Hardy, Elaine Morgan and the Aquatic Ape Hypothesis, p.196-197

The Aquatic Ape evolves: Common Misconceptions and Unproven Assumptions about the so-called Aquatc Ape Hypothesis

by Marc Verhaegen

Human Evolution 28: 237-266, 2013

While some paleo-anthropologists remain skeptical, data from diverse biological and anthropological disciplines leave little doubt that human ancestors were at some point in our past semi-aquatic: wading, swimming and/or diving in shallow waters in search of waterside or aquatic foods. However, the exact scenario—how, where and when these semi-aquatic adaptations happened, how profound they were, and how they fit into the hominid fossil record—is still disputed, even among anthropologists who assume some semi-aquatic adaptations. Here, I argue that the most intense phase(s) of semi-aquatic adaptation in human ancestry occurred when populations belonging to the genus Homo adapted to slow and shallow littoral diving for sessile foods such as shellfish during part(s) of the Pleistocene epoch (Ice Ages), presumably along African or South-Asian coasts.


The term aquatic ape gives an incorrect impression of our semi-aquatic ancestors. Better terms are in my opinion the coastal dispersal model (Munro 2010) or the littoral theory of human evolution, but although littoral seems to be a more appropriate biological term here than aquatic, throughout this paper I will use the well-known and commonly used term AAH (Aquatic Ape Hypotheses) as shorthand for all sorts of waterside and semi-aquatic hypotheses (note paleoanthropologists sometimes use AAH for African-Ape-Human clade).

Popular and semi-scientific websites about AAH (e.g. Wikipedia) and even some supposedly scientific papers (e.g. Langdon 1997) appear to contain several biased or outdated views on AAH, giving lay-people and new students of AAH wrong impressions of our ancestors’ likely waterside past. Many of these unproven prejudices are widespread, not only among AAH opponents, but also among proponents. Some of these misconceptions find their origin in the original writings of the ‘father of AAH’ Sir Alister Hardy (e.g. on the timing of our aquatic past, and on the transition towards it), in the books of Elaine Morgan (who has done most to promote AAH) or in common interpretations of AAH proponents (e.g. on bipedalism, and on laryngeal descent). Others derive from wide-spread interpretations and unproven assumptions in popular writings on human evolution, or even in more scientific papers, for instance, on savanna adaptations, on running, hunting and meat-eating, and on australopiths being human ancestors.
This paper first briefly discusses the AAH website in Wikipedia. Then it lists a number of popular misconceptions on AAH by opponents as well as proponents. Thereafter it discusses a few important aspects of AAH, such as bipedalism and speech origins. Finally, it briefly provides a possible scenario of ape and human evolution.

Wikipedia: a reliable source?

While Wikipedia is generally a fantastic instrument, usually providing recent and reliable information to lay-people, this is perhaps not always the case in highly controversial topics like human evolution. In spite of the efforts of AAH enthusiasts to update the Wikipedia website Aquatic Ape Hypothesis, the editors of the website appear to take a conservative approach (which in other instances might be a safe strategy). As a result, the AAH website is considerably biased and outdated, relying chiefly on the 1987 Valkenburg conference (Roede et al. 1991), while overlooking most recent literature on AAH.

For example in the first paragraph, instead of referring to a few dozen recent peer-reviewed and detailed publications on different aspects of AAH, Wikipedia refers solely to the only anti-AAH peer-reviewed paper, now sixteen years old: “An extensive criticism appeared in a peer reviewed paper by John H. Langdon in 1997. Langdon states that the AAH is one of many hypotheses attempting to explain human evolution through a single causal mechanism, and that the evolutionary fossil record does not support such a proposal; that the hypothesis is internally inconsistent, has less explanatory power than its proponents claim, and that alternative terrestrial hypotheses are much better supported. AAH is popular among laypeople and has continued support by a minority of scholars. Langdon attributes this to the attraction of simplistic single-cause theories over the much more complex, but better-supported models with multiple causality.”

However, the article fails to mention that Langdon’s paper has been thoroughly answered in peer-reviewed publications not mentioned by the Wikipedia article. Suffice it to say that Langdon merely gives his personal thoughts without scientific argumentation. AAH is no simplistic, single-cause theory. On the contrary, waterside hypotheses provide an extra viewpoint to human evolution, not discussed by conventional anthropologists: AAH not only considers forest- and open plain dwelling, but also the possibility that human ancestors at some time lived along coasts, rivers, swamps etc. AAH is internally consistent, and, compared to purely terrestrial hypotheses (forests vs. plains, tropical vs. cold, scavenging vs. hunting, etc.), it offers incomparably greater explanatory power, as shown below as well as in the many recent publications not consulted by Langdon.

The Wikipedia AAH article bluntly declares: “There is no fossil evidence to support the AAH”, but fails to refer to relevant publications (e.g. Walter et al. 2000, Gutierrez et al. 2001, Joordens et al. 2009, Munro 2010). In fact, our extensive reviews of the literature as well as the malacological (mollusc) and other paleo-environmental evidence suggest that virtually all archaic Homo sites are connected with abundant edible shellfish (Verhaegen et al. 2007, Munro 2010, Table 5 in Munro & Verhaegen 2011).

The Wikipedia article also states without argument: “Several theoretical problems have been found with the AAH.” In our opinion, the littoral theory instead offers theoretical as well as practical solutions to several problems in conventional paleo-anthropology, as shown below.
The site continues: “some claims made by the AAH have been challenged as having explanations aside from a period of aquatic adaptation … most of these traits have an explanation within conventional theories of human evolution.” But the older and more conventional ideas suggest that human ancestors evolved from forests or trees to more open plains, without considering alternatives. These open plain ideas are anthropocentric just-so interpretations: uniquely-human (not seen in non-human animals) constructions attempting to fit the human condition. For instance, they ‘explain’ fur loss by heat, and subcutaneous fat by cold, not considering the possibility that human ancestors, like all mammals that are both furless and fat, could have spent a lot of time in the water. All the purported objections by conservative anthropologists have been addressed and answered in recent publications on AAH, not cited in Wikipedia’s entry (e.g. Verhaegen et al. 2007, Munro & Verhaegen 2011).

The Wikipedia article claims that human traits such as bipedalism and laryngeal descent have been considered by proponents to be pro AAH arguments. However, this is not the general AAH opinion, currently. According to Hardy’s method (comparative biology), neither bipedalism nor laryngeal descent can be considered as pro AAH arguments. There are no bipedal (semi)aquatic animals apart from (wading) birds, and even the semi-aquatic penguins are only bipedal when outside the water. The same holds for laryngeal descent. For instance, Cetacea have ascended (intra-narial) larynges, not descended. These matters have been discussed (see also below) in several publications not mentioned in the Wikipedia article (e.g. Verhaegen 1993, Verhaegen & Munro 2007).

The article is also biased in citing anti-AAH comments, while failing to mention the obvious responses. One opponent claims that AAH “explains all of these features … twice. Every one of the features encompassed by the theory still requires a reason for it to be maintained after hominids left the aquatic environment”, yet seems to be unaware of the existence of phylogenetic inertia as well as of rudiments in evolution, and has apparently not heard of the title of Elaine Morgan’s book The Scars of Evolution: as Morgan explained repeatedly, AAH is based on embryological, anatomical, physiological etc. remnant traits of our past that are not typically seen in terrestrial mammals. She quoted Stephen Gould: “the remnants of the past that don’t make sense in present terms—the useless, the odd, the peculiar, the incongruous—are the signs of history.”

Equally selective is the Wikipedia article’s mentioning Greg Laden’s anti-AAH comments in 2009, yet omitting Laden’s more recent and positive blog on AAH (Laden 2013). The Wikipedia article mentions the recent eBook on AAH (Vaneechoutte et al. eds 2011), but then cites from Langdon’s review of that book, instead of discussing the fifteen actual contributions in the eBook. The site verbosely writes about Langdon’s opinion (outdated and no longer relevant, see above), yet not about recent peer-reviewed critiques of Langdon’s publications (Kuliukas 2011, Vaneechoutte et al. 2012). It also does not mention many intriguing contributions in the eBook on different aspects of AAH, and it misrepresents or omits our own chapters on Miocene ape and australopith evolution, on Pleistocene Homo, and on speech origins.

These are only a few examples, but they support the idea that the Wikipedia article is prejudiced toward outdated and ill-informed opinions on what AAH is as defined and misunderstood by its critics rather than on the recent publications exploring the theory itself. Of course, the same can be said about some similarly unscientific blogs and websites on the Internet mentioning AAH. [1]

In her book, The Naked Darwinist (2008), Elaine Morgan sets out to answer some of the main objections to the Aquatic Ape Theory.


The aim of this section is to outline the AAT response to some of the stock questions about the physiology of Homo sapiens. In it I hope at least to convince you that the mental activity involved is in no way different from, inferior to, or wackier than the orthodox scientific method. It is exactly the same method. It merely starts from a different premise: that a watery habitat may have played a part in shaping us. I know that some readers will be pre-disposed to regard that proposition with scepticism. So before getting down to specifics, it might be worth recapping some of the non-specific reasons for rejecting it that I have heard voiced from time to time.

1. “The palaeontologists have found no confirmation of it.”
They have found nothing that proves it and nothing that disproves it. They have found things that disprove the Savannah Theory.

2. “The hominids could not have lived by the water because of crocodiles.”
That depends on the location. Africa has a long coastline and it has no salt-water crocodiles. Inland, some of its rivers are so teeming with tilapia fish that the crocs are too lazy and well-fed to tackle any more demanding prey. Besides, how would those ancestors have been any safer on land? Imagine a small naked primate in the middle of a plain - we are told that the first ones were no more than four feet high - with no fangs or claws to fight off lions and leopards and packs of hyenas, no night vision to detect the approach of nocturnal predators, and slow-developing helpless
young unable to run away.

3. “If our ancestors had been aquatic we would be more stream-lined.”
We are in fact far more stream-lined than any other primate. Look at the sleek silhouette of a high diver cleaving the surface of a swimming pool, and try to imagine the silhouette of a gorilla attempting the same manoeuvre. But it takes a very long period of 100% aquatic life for any mammal to acquire the torpedoshaped outline of a porpoise. I have never imagined that our ancestor’s experience of life in water was on anything like that scale.

4. “Morgan keeps changing her story. In the beginning she said one thing, now she is saying another.”
Of course I keep changing my story. So does everybody else in the business, and they would be fools if they did not. In 1972 it was being confidently asserted by all the leading experts that the split between apes and humans occurred twenty million years ago, that Africa in the Pleistocene was in the throes of a horrific drought, and that bipedalism was a consequence of life on the savannah.

5. “The people best qualified to judge are against it.”
The people considered best qualified to judge are the people who have spent most of their lives learning and teaching about the current orthodoxy. They are naturally the ones most resistant to change. And they are in a position to ensure that supporters of change find it hard to get promoted or have papers accepted for publication.

7 “I know some people who believe in it and also believe in astrology and ESP and all that stuff.”
What does that prove? True, anyone’s mind can be too open. (It can also be too closed.) But A. R. Wallace believed in spiritualism, and Isaac Newton dabbled in some distinctly weird forms of alchemy. Those facts do nothing to invalidate Natural Selection or the Law of Gravity.

8. “Some of them have this Eureka moment when they hear of it and don’t look for any evidence. That’s no way to do science.”
True. But I have come across near-apoplectic, knee-jerk reactions against it, from people who are proud to say that nothing could possibly induce them to read any books about it. I would reckon these manifestations just about cancel each other out.

9. “The picture she gives has got vaguer as time goes on, instead of clearer.”
Not just my vision, but everybody’s vision of what happened millions of years ago has grown vaguer as more facts come to light. I remember when David Pilbeam could point out that all the hominid fossil remains discovered up to that date could be contained in a shoe box. There was a general expectation that when there was enough of them, it would become possible, by joining up the dots, to reconstruct the genealogy of Homo sapiens with a straight line of “begats”, the way St. Matthew traced a family tree from Abraham to Christ. But by now the number of specimens runs into
four figures, and the anticipated family tree has turned into something less like a poplar tree and more like a gooseberry bush, with dozens of branches. It appears that at one time there may have been a profusion of different species of anthropoid primates, and most of the lineages led to dead ends. How has that affected my own thinking? Hardly at all, because one thing I am anxious to clarify is the question I set out to answer. It was, and is, “Why are we so different from chimpanzees?” The complexity of the gooseberry bush bothers me not at all. The fact remains that, at one point in that proliferating chart, there is one specific intersection, dated - according to estimates which are still occasionally the subject of controversy - somewhere between four and seven or eight million years ago, the point at which the descendants of the LCA - the Last Common Ancestor of chimps and humans - began to diverge into two separate lineages, neither of which petered out. Humans and chimpanzees are both alive and kicking, and the number of ways in which they differ from one another is staggering. It is on a totally different scale from the distinctions between any other pair of species with a comparable chromosomal gap, like lion/tiger, or horse/donkey. Zoom in on that intersection, and ask yourself “Why? What could possibly have happened?”


[1] Bearder SK. Flood brothers: The origin of bipedalism. BBC Wildlife 2000; 18: 64-8.
[2] Dennett D. Darwin's dangerous idea: Evolution and the meanings of life. New York: Simon & Schuster 1995.
[3] Morgan E. The aquatic ape hypothesis – the most credible theory of human evolution. London: Souvenir Press 1997.
[4] Morgan E. The descent of woman. London: Souvenir Press 1972.

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