The Aquatic Ape Theory
By Dr Elaine Morgan, M.A.(Oxon), D. Litt. Fellow of three Universities. Author of books on human evolution including:
The Descent of Woman (1972), The Aquatic Ape (1982), The Scars of Evolution (1990), The Descent of the Child (1994), and The Aquatic Ape Hypothesis (1997)

Purpose of website

I don’t have enough new material to fill a sixth book on the AAT (aquatic ape theory). Instead, this is an attempt to provide an on-line introduction to the idea for those unfamiliar with it, a brief account of my part in promoting it, and the reception accorded to it, and the current state of play.

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The question

The question confronting all speculation on human origins is why we differ from all the other apes in so many different ways: nakedness, bipedality, and the ability to speak are striking examples. Chimpanzees are genetically closer to us than they are to gorillas, yet display none of these characteristics. It is generally assumed that these differences were caused by some change in habitat or life-style undergone by our ancestors, but not by those of the chimpanzee. The question is, what change?

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The savannah

For most of the last century the accepted answer was that proposed by Raymond Dart - . that the apes’ ancestors remained in the trees while the hominids’ ancestors moved out onto the grasslands, where shortage of fruit and leaves compelled them to become hunters. Perhaps the bipedality helped them to scan the horizon and/or or chase after game? Shedding body hair may have protected against getting overheated in the chase? There was no consensus on exactly how the grassland habitat produced the naked biped but there seemed to be total consensus that it must have done so.

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Hardy

Professor Sir Alister Hardy, F.R.S., when he was a young Oxford marine biologist, noted that a fat-lined hairless skin was more commonly found in aquatic mammals than in terrestrial ones, and conceived that the crucial change may have been a shift to a more watery habitat. In 1960, after keeping silent about this idea for thirty years, he confided it to a small group of sub-aqua enthusiasts. A local reporter took it to the Sunday papers where it dominated the headlines. Wilfred le Gros Clark sternly reprimanded him for airing bizarre views on a subject outside his speciality and bringing Oxford academics into disrepute. He published just two articles, to correct the reporter’s lurid version of what he had said, and his colleagues forgivingly agreed to behave as if it had never happened.

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Morgan

In 1972 I was moved to write a book appealing for parity of esteem between the sexes. I was reacting strongly against Dart’s macho version of human emergence, as relayed by writers like Robert Ardrey and Desmond Morris. It implied that the driving force making us human was the aggression and bloodthirstiness essential to the survival of the newly carnivorous hunting male, however deleterious these changes might be to his mate and her offspring. The only alternative paradigm on offer was Alister’s almost forgotten theory, briefly mentioned in Morris’s best selling The Naked Ape. I found it instantly convincing and with Alister’s permission incorporated it into my narrative.

The Descent of Woman became a popular best-seller, but the scientific community reacted with contempt. That was understandable. I lacked scientific qualifications, the book was politically motivated, the style confrontational and flippant. I wrote it too fast to have done much research. Some still believe it was a tragic setback to Alister’s ideas (he didn’t agree) but it did put them on the map.

Among scientists, rejection was virtually total. I concluded there must be some snag in the aquatic hypothesis, so blatant that the experts couldn’t be bothered to point it out to anyone too stupid to see it for themselves. Years later, when I met Douglas Adams in Oxford, he said that if I wanted to know what the scientists were saying about it, I should try the Internet. It was a revelation. In place of the icy silence, the on-line reaction was loud and hostile, sometimes apoplectic and profane. For a year the main theme of it was to keep assuring me that everybody thought it was rubbish. Everybody!! Why couldn’t I see that? I could see it all right, but I was not convinced that the right way to settle a difference of scientific opinion was by counting heads.

You can get a flavour of the debate at that time by reading the lengthy dossier compiled by Jim Moore which confronts you when you search for Aquatic Ape online. . It is a condemnation not so much of the theory as of me, as its prime promoter in those days. It may convince you that no theory supported by people like E. Morgan could possibly be valid. But that doesn’t necessarily follow. Many valid theories have been defended by people quite as stupid and dishonest as the character he describes.

I embarked on a steep learning curve and in 1982 I published a second book, and later at intervals another three. These books were entirely non-political - AAT itself has no political implications - and of course were not bestsellers. They were addressed less to the general reader than to the scientific community in the hope of eliciting some response or debate.

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Method

I figured that Stage 1 was to list the anatomical differences distinguishing Homo sapiens from all the other apes. No such list seemed to exist. Early Darwinians tended to stress the similarities and minimise the differences , to combat the initial revulsion against believing apes were our cousins. The list of anomalous features in Homo sapiens included among other things bipedalism, the loss of body hair, brain growth, the acquisition of speech, subcutaneous fat, greatly diminished sense of smell, changes in the structure of the nose, and the mouth, and the windpipe, and the sex organs.

Stage 2 was to pick out those differences for which professional scientists already had an agreed explanation. That was an eye-opener. The answer was - and still is - none of them. Possible explanations for several of them have been put forward, but none has commanded consensus. One hundred and fifty years after Darwin wrote The Descent of Man, the jury is still out on why the savannah ape became naked, and bipedal, and learned to speak, etc. etc. That statement is sometimes decried as nothing short of treacherous, because it might give aid and comfort to the creationists. To me it suggested that there was something wrong with the basic assumptions they were making about the habitat. I thought , and still think, that we should not shut our eyes to uncomfortable truths out of fear of creationists.

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Homo and Water

Step 3 was to search for aquatic mammals displaying the features distinguishing people from chimpanzees. As Hardy had noted, there are a number of aquatic mammals - including whale, dolphin, dugong, hippopotamus, manatee - with totally hairless skins. Others like walrus and sea elephant are well on the way to becoming hairless. Most of these animals also have thick layers of subcutaneous fat. In the case of non-human animals, early anatomists had drawn the conclusion that a coat of hair outside the skin is clearly the best means of regulating temperature in air, but it does not work nearly as well in water, where a lining of fat under the skin is more efficient.

I noted too that most aquatic mammals, from the whale down to the beaver, mate face to face, the commonest practice in humans of all races. (The story about tribes who had never heard of this practice and called it “the missionary position” is without foundation.) But that was probably a secondary development - a by-product that would have inevitably resulted from bipedalism, whatever the cause of the bipedalism. The reasons for linking bipedalism with water are two: the obvious fact that any primate walking into the sea or a lake would soon be obliged to get up and walk on two legs if it wanted to keep its head above water, and the fact that wading through water is the on ly circumstances which invariably causes all apes and most monkeys respond by walking on two legs.

Then there is speech. No other mammal on sea or land has learned to speak. But the precondition for being able to speak is acquiring voluntary control over breathing . Breathing is, in most animals, as involuntary as the processes of digestion or the beating of the heart. But all diving mammals have voluntary breath control. To the best of my knowledge, no terrestrial ones have it. That’s why the laboratory rat, which has been trained to do so many clever tricks in order to gain a reward or avoid a punishment, cannot be trained to obtain a reward by squeaking for it.

None of this added up to a proof of Hardy’s theory, but it seemed to constitute enough of a case to merit consideration and debate.

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Opposition

Apart from my amateur status and disastrous start, there were other obstacles in the way of getting a hearing. One was that two separate disciplines were researching human evolution. Comparative anatomists proceeded by comparing the physiology of extant apes and humans. In earlier days that had been the exciting speciality, where the Darwinist action was, but there was a growing feeling that no significant new knowledge was likely to emerge in that field, and fewer people were well versed in the knowledge that had already been gained. Palaeontologists concentrated on the rapidly accumulating store of fossil evidence that had been unavailable to Darwin. They were immensely knowledgeable about bones and teeth. They regarded these fossil remains as “harder” evidence than any data about more perishable organs, which they hadn’t studied in any depth. The need to specialise meant there was not much meeting of minds between the different faculties.

But the biggest obstacle to debate was the solid conviction that Alister’s thinking was simply not needed.. Everyone who mattered knew perfectly well why humans were different. It was because of the savannah. All the papers in all the professional journals treated that as a starting point. All new thinking about human origins was expected to accept that and build on it. Anatomists can speculate about when and why things happened in prehistory but only palaeontologists provide hard evidence of where they happened - and all the newly discovered pre-human fossils being unearthed in Africa were being dug up under a sweltering sun in arid landscapes.

There were some reasons for doubting the savannah hypothesis: for example we are more dependent than most mammals on drinking frequently. Camels are at one extreme of the capacity to go without water for long periods but we are right at the other end. We are the sweatiest creature in the entire animal kingdom, very ill-adapted for a habitat where water is in short supply.

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No case to answer?

The question remained: Why are we so different? One way of dealing with unanswered questions is not to pose them. In the five hundred pages of a definitive Encyclopedia of Human Evolution in 1992 there was no mention of the fact that Homo sapiens has lost his body hair. It seemed to be simply forgotten about by the people collaborating on that venture. Six years later another work of reference appeared entitled Principles of Human Evolution. In this case too, the compilers devoted over five hundred pages to the subject while modestly averting their eyes from the fact that humans are naked.

Another way is to deny that there is any question to be answered. Frederick Wood Jones, Britain’s brilliant doyen of comparative anatomy, held that it was absurd to ask for an explanation of why man lost his body hair, because it was quite untrue. The chimpanzee has more hair follicles to the square inch than we have; it therefore stands to reason that chimps are hairier than we are.

A third way is to take pride in scientists’ willingness to recognise a question that they are not yet equipped to answer, and not waste time speculating about it. Occasionally someone makes a blitz on some of these questions. In America William Montagna decided to devote ten years of intensive study to all the ways in which the skin and hair of humans differs from those of our nearest kin, in the hope of finding why they differ. At the end of that time he had learned a great deal about them and us, but announced that he was no nearer to an explanation of the differences. It makes sense, then, to think about something else and wait for new data to come to light. But as with the other anomalies, a hundred and fifty years is a long wait.

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The citadel

The scientific community has the right and the duty to uphold its own professional standards. One way of safeguarding them is by being selective in making appointments, and another is by peer review - i.e. careful vetting of any material submitted for publication in the professional journals.

Because of the immense prestige attached to the word “scientist”, a great many people would dearly like some of that prestige to rub off on them. They’d like to debate with the professionals, on equal terms, all kinds of concepts that they feel passionately about, from faith healing and telekinesis to Chariots of the Gods, the Abominable Snowman, UFO’s, and Intelligent Design. Clearly they cannot all be accommodated, and any attempt to argue with them would be a waste of valuable time. No good would come of it, since in most cases they have a totally different idea of what constitutes evidence.

In 1960 Alister Hardy’s idea was unanimously consigned to that category. Most scientists can instinctively recognise a goofy idea from a mile off and this one was obviously a humdinger of a goofy idea. Their collective instinct is almost infallible. They are right in 99 cases out of 100. Anyone who protests: “Ah, but this is an example of the hundredth case” is listened to with indulgent amusement, a significant tapping of the temples, and the comment that he - or in my case she - “ thinks she’s a genius - she thinks she’s Wegener!” Such an accusation of folie de grandeur would have reduced me to abashed silence if it had been my own insight that I was going on about - but it was Hardy’s. And he was one of their own, with an FRS and a knighthood to prove it. I also felt that I should refrain from mentioning Wegener if and when - but not until - they stopped mentioning those little green men from Mars.

Alfred Wegener was the classic example of the hundredth case. He kept putting forward what he regarded as evidence that the continents had moved. He found striking correspondences, in geological strata and flora and fauna, between geographical sites now separated by hundreds of miles of ocean. His views were actively debated for nearly twenty years and the opposition tended to be passionate. When he visited Harvard he was howled down, and he died in 1930 knowing that his idea was by then regarded as defunct. It took another thirty years and major breakthroughs in rock magnetism and geochronology and oceanography to lead to the recognition that he had been on to something. Proponents of AAT have always hoped for a similar breakthrough, and in 1995 they thought it had arrived.

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Not the savannah?

Over the years a series of developments had favoured Hardy’s idea. One was the discovery that young babies introduced to water at an early age have no fear of it, but seem to enjoy being submerged in an element that renders them weightless and able to exercise their limbs more freely. That, and the growing popularity of water-birthing, helped to make the aquatic theme more acceptable, at least to laymen, though no one would claim it as hard evidence. There was also an increased interest in dietetics, and in the revelation that the relative amounts of Omega 3 and Omega 6 in the sea food chain were in precisely the ratio most conducive to the kind of rapid brain growth experienced by our ancestors.

Intensive attempts to teach apes to speak confirmed that they could readily use and understand sign language, and all that prevented them from talking was their inability to utter sounds, or inhibit them, by an effort of will - i.e. their lack of breath control. Research into the rapid dispersal of hominid ancestors from Africa to Asia and the off-shore islands led to the belief that they probably migrated along the coastline, around the bottom of India, arriving at inland sites by following the rivers upstream. My suggestion in 1982 that elephants may have descended from aquatic mammal ancestors has gained credence. Observers of the behaviour of savannah chimpanzees in the wild never saw them resorting to bipedal locomotion on the ground, but there were striking filmed shots of gorillas wading bipedally in the swamps of the Congo. On a personal note, criticisms of my lack of qualifications began to fade out. One book The Descent of the Child (with only minimal references to AAT) received uniformly good reviews, and my last book got a notice in Nature which scrupulously refrained from taking sides for or against the ideas it was promoting.

Despite all that, the solid obstacle remained: the fossilised bones of our predecessors, and the apparently unshakable belief that they lived and died on the open plains. In the 1990’s that core belief was badly shaken. A closer study of the flora and fauna found in the same deposits as the hominid fossils proved that the fossilised bones of small mammals and the fossilised pollen of plants belonged to species that were known not to flourish in grassland environments. It was concluded, and is now accepted, that there were proto-hominids walking on two legs in Africa before the savannah ecosystem came into existence. Professor Philip Tobias, one of best-known and most influential proponents of the savannah hypothesis, announced that it was time to think again. “We are back to Square One”, he said.

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Closing the ranks

The question “Why are we so different?” was once again wide open. There might be good reasons for rejecting AAT but the favourite one - “because we’ve got a better answer” - was no longer operative.

Professor Lee Berger was swift to sum up the immediate reaction: “Just because the savannah theory was wrong , that doesn’t mean the aquatic idea is right.” That is certainly true. There may be a third paradigm that nobody has thought of, which would throw a flood of light on the whole question. As yet, though, nothing of that kind has been unveiled.

Another response was to say that nothing has changed, because when scientists used the term savannah , they had always envisaged a landscape containing wooded areas, and rivers flanked by gallery forests, and lakes. My references to the open plains were dismissed as a caricature of what they’d actually had in mind. The difficulty there is that whenever they attempted to explain anything about human anatomy, they still attributed it specifically to the rigours of life on the open plains. Bipedalism, they speculated, might have evolved for speeding after fleeing prey, or peering over tall grasses to scan the horizon, or to lessen the area of the body exposed to the overhead rays of the mid-day sun. None of those purposes would have been served in the shady woodlands. Above all, if our ancestors lived in and around the trees, and the chimps’ ancestors continued to live in the trees, why didn’t they continue to interbreed? . Why would such closely similar habitats turn them into two species so dramatically different from one another?

Everyone kept calm and the conventional wisdom prevailed. AAT remained, and still remains, beyond the professional pale. Students in most universities were tersely given to understand that it was unsound. It was flawed. By this time it had lost the gloss of novelty and could be called old hat. It was said to have been discarded because “fossil evidence in its favour had proved elusive.” Sure it had. There is no scenario for human evolution for which the fossil evidence has not proved elusive. In the case of the savannah theory it proved disastrous.

For more than forty years not one of the most respected peer-reviewed professional journals specialising in human evolution has published any account of the arguments in favour of AAT. Sometimes when a hypothesis is put forward - Peter Wheeler’s speculations on bipedalism, or Dean Falk’s radiator theory about keeping the brain cool - one or other of the journals will call in a panel composed of supporters and challengers and print all the views for and against. But the case for AAT was never presented for debate in their columns.

For the most part they didn’t print attacks on it either, being perhaps reluctant to give it what politicians call the “oxygen of publicity.” But in 1997 the Journal of Human Evolution did publish one such paper, by John Langdon, contesting statements I had made. Some of them had been made twenty-five years earlier and had later been specifically retracted. It was unfortunate that his paper was already in press when my last book was published. He compared AAT with ideas like creationism and Chariots of the Gods etc. and said it belongs to a category of theories - “umbrella theories” - which try to explain too much. He regards that as strong evidence that they are probably phoney, and scientists are right to dismiss them by consensus, without giving specific reasons. However, that test should be used with caution. Darwin’s theory of natural selection addressed an amazingly wide range of questions that had never been answered, and threw light on all of them. AAT addresses exactly the same number and kind of questions as the savannah theory did. Under Langdon’s definition, both or neither should have been condemned.

I enquired about the possibility of publishing a reply to Langdon. I was told that would be inappropriate, because his paper was a general discussion of varying philosophical approaches to research, and by no means a specific attack on AAT. Its title was: “Umbrella Hypotheses and parsimony in human evolution: a critique of the Aquatic Ape Hypothesis.”

Its message was that all the theories are built on conjecture, but “terrestrially adaptive stories are at least as strong as AAT’s.” If so, that’s a good reason why the terrestrial answers should have an equal share of space when the questions are raised in the scientific journals - but not a reason why they should monopolise it. It was also claimed that unorthodox models are easily communicated to laymen, but responsible scientific answers would be over their heads. I don’t believe the issues involved are all that impenetrable. It’s time to list some of the questions and the alternative answers.

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Why bipedal?

As a result of their life in the trees gorillas and chimpanzee, our nearest kin, are capable of walking on two legs, but in the wild they very rarely do, and they have evolved none of skeletal modifications that make us so efficient at it. Habitual wading might explain why our ancestors began to specialise in it.

Terrestrial explanations include picking fruit from low bushes: savannah-dwelling chimps stand up to do that, but drop onto all fours when it’s time to move on. Or the hominids might have become bipedal to free their hands for carrying things. For the females, though, it would have made life more difficult - they would have had to carry their infants in their arms wherever they went, making it much harder to forage or to escape predators.

A savannah theory suggested that if they chose not to rest at mid-day, bipedalism would help them keep cool by exposing a smaller surface of their bodies to the overhead sun, and standing tall would also enable them to catch the breeze. This argument is a familiar proposition, adapted to post-1995 data by changing the term “savannah” to “woodland/savannah” but otherwise unchanged. Another long-standing suggestion is that locomotion on two legs is easier and quicker than on four. But experiments have shown that four a single primate capable of both procedures, running on four legs is quicker than running on two, and consumes exactly the same amount of energy. Recent papers proclaim triumphantly that a human walking on two legs uses a good deal less energy of chimpanzee walking on four. So it does, but only because for at least five million years we have been practising it, and modifying our entire skeletal and muscular anatomy to increase its efficiency.

The latest approach is to suggest that hominid bipedalism needs no explanation because the common ancestor of apes and humans may already have been bipedal. That guess would solve one mystery but introduce two new ones. Why did that common ancestor

take to walking on legs? and why did our hairy cousins abandon the practice while we didn’t?

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Why fat and naked?

The skin of humans, naked and with a lining of fat, was the feature that first planted the germ of the aquatic idea in Hardy’s mind over seventy years ago. The AAT argument is that in water, in animals above a certain size, a naked fat-lined skin is more effective at regulating temperature than a coat of fur. Within the last ten years, two books have been written addressed to the general reader, one about fat and about skin.

“Skin”, by Nina Jablonski, tells us that the best authorities now agree with the traditional explanation: nakedness evolved to keep our ancestors cool. She stresses that when they decided to run about a lot in the mid-day sun, it was especially important for them, with their large brains, not to become overheated. The nakedness therefore was all about sweating. On a hot day a human in the desert can lose more than twelve quarts of sweat, but that still would not keep us cool if we were so hairy that the sweat could not quickly evaporate.

That leaves a few questions. Why should we assume that our ancestors were the only animals on the savanna without enough sense to take a siesta? Going out in the mid-day sun must have been a risky process during the many generations it would have taken before they lost their coats of fur. It suggests the sweatiness must have evolved before the nakedness, because if you shave a patch of wool from a sheep in the tropics, it gets not cooler but hotter. And why are we nakedest and fattest when we are babes in arms, a time of life when we don’t have to run about at all?

Concerning the layer of subcutaneous fat, “The Fats of Life”, by Caroline Pond, appears to reveal that there is no such thing. There is fat in our bodies and “some is located in patches between the superficial muscles and the skin, so it is often called subcutaneous fat, a term that implies, erroneously, that it is firmly attached to the skin.” The word subcutaneous is banished and replaced by the phrase “superficial adipose tissue.”

I can’t quite follow this. Subcutaneous only means “under the skin” and says nothing about attachment. Earlier anatomists called it “hypodermal”- Greek for subcutaneous. But the odd thing is that in Pond’s opinion it is not attached to the skin whereas previous experts had all declared that it was. To the layman it seems clear that the skin of a spaniel or a cat is loose and slides freely to and fro over the underlying tissues, while that of a pig does not. If you pinch your own thigh, you are not just pinching the skin, you’re pinching the fat as well. Is it only the word “firmly” that is in dispute? Has medical science no criteria for determining degrees of attachedness?

On the question of fat in general the book has many new and interesting things to say, but concludes that there is no single explanation for why and when we acquired so much of it.

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The descended larynx

In most animals the larynx (or voice-box, the top end of the wind-pipe) lies in the nasal cavity to facilitate nose-breathing, and is only drawn down into the mouth temporarily, for purposes of panting or uttering sounds. In human babies though, during the first year of life, it begins to move down to a site below the back of the tongue and stays there

for life. The transitional stage is believed to be a factor in SIDS - cot deaths - and to explain why it is so much safer to put babies on their backs to sleep.

The descended larynx in humans is often referred to as a unique attribute. In 2001 it was reported in the red deer and the fallow deer, but only in adult males where the deep tones it produces seem designed to frighten other males. In humans of both sexes it has descended by the age of two.

This condition is almost as rare in sea mammals. (In cetaceans the larynx moves up, not down.) But in 1981 a Handbook of Marine Mammals stated that this feature is found in the walrus, and when I attended a conference on Speech Origins in Wadham College , Oxford, I heard Jan Wind announce that he had recently dissected a dugong and found that it had a descended larynx. I made the suggestion that the descent of the larynx, which leaves a large empty space known as the enlarged pharynx , makes it possible to inhale a large amount of air much more quickly, at a gulp. That might be a distinct advantage while swimming, or on breaking the surface after a dive.

I was accused of disingenuously ignoring the well-known alternative - the Speech Hypothesis. This stated that the enlarged pharynx would “increase our repertoire of vowels.” So it must have evolved for that purpose - to enable us to speak, or speak more clearly. There seemed no way of testing this, since we couldn’t see what happens inside the throats of living persons while they are talking.

But technology marches on. When I was in Boston, Tecumseh Fitch had recently acquired a machine that enables a scientist to do just that. He was watching on the screen what happened when a young girl spoke. Her larynx, it appeared, had not descended. That was a surprise. What was even more remarkable was that no-one had ever noticed anything unusual about her vowels, or anything else about the way she spoke. I can’t say how significant that observation was, nor how common that condition may be. But even one instance of it, it seems to me, conclusively disproves the Speech Hypothesis.

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The fossil record

There’s nothing in the fossil record that proves AAT right, and nothing that proves it wrong. Fossil hunters provide hard data about times and geographical locations. They can tell us which ancestor walked on two legs - but they can’t tell us how it lived. Places now arid were once lush and green, and places now on dry land were once underwater. The savannah theory only survived so long because in former days they often underestimated geological and climatic change.

No one is ever going to find a fossil ancestor and cry “Lo! The first aquatic ape!” The otter, for example, is an aquatic mammal with a skeleton strikingly similar to that of its cousin the polecat, but a totally different life-style. No fossilised bones of its five-million- year-old ancestors could tell us whether they had been aquatic or not.

It so happens that nearly all fossils are of creatures that died by the waterside and their bones sank into the mud or silt: otherwise they would not have been preserved. The mammalian bones most often found in association with ancestral hominids are those of ancestral hippos. However the same sediments may contain the bones of non-aquatic mammals that have visited the water to drink, and happened to die there. So there are two things to remember. (1) One specimen dying by the water can’t prove that all members of its species lived by the water (2) It can’t prove that they didn’t, either.

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Hasn’t AAT been disproved?

It’s hard to find anyone who claims to have proved AAT to be wrong. .Langdon, for example, freely admitted that it was impossible to prove or disprove. Indeed he seemed to think that was one of the strongest arguments against it. It’s condemned on the grounds that it sounds highly unlikely. The water would have been too dangerous - because what about the crocodiles, and the predators that lurk around water-holes, and the water-borne parasites- schistosomiasis and the malaria mosquito?

True. But it would have been just as dangerous on the savannah for a naked biped without fangs or claws or guns. It would have had to visit the water-holes very frequently to replace those twelve quarts of water it was sweating out every day. Modern riverside humans too have to face the parasites and the malaria, but they don’t get wiped out.

Besides, that argument would apply to all the animals known to have moved from a land-based life to an aquatic one. However could the terrestrial ancestors of the dolphins and seals and sea-cows and walruses have survived their first immersion in such a dangerous element, to which they were so ill-adapted? Impossible! But they all did it.

There must surely be simpler explanations, it’s argued. “Our preponderance of superficial adipose tissue may simply be a consequence of our large body size, as it is in large obese carnivores such as bears.” It may or it may not: after all we are smaller than gorillas. “Explanations for hairlessness abound.” Yes - and they’re all different, and are given a fair hearing and seriously debated. AAT just adds one more to the list, but it gets treated differently.

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The present position

AAT cannot be boycotted into oblivion. Awareness of it is still spreading. It was well received in Japan, and a Chinese translation of The Aquatic Ape Hypothesis is now on the market. Books on connected topics sometimes devote a page or two to brushing it under the carpet - perhaps because if it was ignored, lay readers might be scratching their heads and wondering “But didn’t I hear it had something to do with water?” But young scientists studying human evolution today are left in no doubt that if you want to get on in the profession, you don’t go down that road. Daniel Dennett has had better opportunities of verifying that than I have, and he wrote:

“During the last few years, when I have found myself in the company of distinguished biologists, evolutionary theorists, palaeoanthropologists, and other experts, I have often asked them just to tell me, please, exactly why Elaine Morgan must be wrong about the aquatic theory. I haven’t yet had a reply worth mentioning, aside from those who admit, with a twinkle in their eyes, that they have also wondered the same thing.”

If your vision of an ancestral environment contains anything about water, you may adopt one of two strategies. One is to avoid the word “aquatic” like the plague. Substitute “riparian” and you may just get away with it. The other is to preface your remark with some phrase proving that you know you’re not supposed to take AAT seriously. I’m not knocking the authors of the following examples. I can see why they have to use this tone of voice, and I’m grateful for the points they made.

Dr. Holly Dunsworth wrote in a review: “Just because the aquatic ape theory is (thankfully) dead, we should not overlook the possibility that ancient hominins dipped, waded, and wallowed to stay cool like we and many other animals do.” And a paper in the Journal of Medical Microbiology reported : “A final intriguing feature of our specialist parasite fauna concerns the four forms (three Schististoma species and Draninculus medinensis) which depend for their transmission on our entering the water. The feminist diatribe of Elaine Morgan suggesting an aquatic phase in our evolution is dismissed by most anthropologists, but in support of this theory, as far as we know, no other primate had indications of such long-standing association with water.”

(Incidentally, that last quote strikes me as one of the more unanswerable pieces of evidence in favour of AAT )

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Effects of the boycott

The policy of “We just don’t talk about that” makes for a quiet life in academia, but has its disadvantages.

It is often affirmed that a number of serious examinations of the theory have been conducted, and most of them have failed to find support for it. In a non-scientific context - military, say, or political - such examinations are described as “internal enquiries”. The public is rarely told who participated, or the grounds on which they based their conclusions, and when their verdict is announced it comes as no surprise to anyone.

Some people have honourable reasons for not giving open support to AAT. One professor told me that if he went public with it, he would be kept so busy fending off the resultant outrage that it would get in the way of his own research. If you are writing a book outlining the conventional view of human evolution for the benefit, say, of students hoping to pass exams in it, there is a genuine problem. If you invoke a possible aquatic explanation of any single human feature, you’re in danger of upsetting the whole apple-cart. It would tend to undermine the quasi-savannah explanations for all the other problematic features. It would create uncertainties, and when you are teaching the young, one of the prime objectives is clarity. Besides, you can be in little doubt of the answers the examiners will be looking for.

But the cumulative affect of this boycott is stultifying. The online arguments of the seventies and eighties often generated more heat than light, but they did give a stimulus to new research, if only because both sides were eagerly seeking ammunition. There was a spate of papers on eccrine glands - not previously regarded as a hot topic - which overturned the data previously available on the subject. There was research into the relative intensity of the diving reflex in different mammals. There was a classic series of experiments investigating the relative energy costs of walking and running on two legs instead of four. Not all this activity was due to the AAT debate, but some of it certainly was. A spot of controversy does wonders to concentrate the mind on areas where the facts are in dispute.

Another effect of the boycott is that those with an active interest in AAT - and the numbers are growing all the time - find themselves virtually in an intellectual ghetto. Online newsgroups, deprived of opponents willing to debate with them, tend to devote their energies to internal differences of opinion on minor issues - whether the first venture was into salt water or fresh, and whether it happened before, or during, or after the split between hominids and chimpanzees. The points raised are interesting, but can be bewildering to the casual logger-on.

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What’s in a name?

A word about “the aquatic ape.” It’s sometimes said that that phrase is one reason why so many people reject Hardy’s proposition out of hand. If they’ve read none of the books, it conjures up a fictional ancestor resembling the mermaids and selkies of myth and folklore, and who wants to waste time reading that rubbish?

I first used the words after reading somewhere the (dubious) proposition that almost every order of mammals includes at least one aquatic or semi-aquatic species - among mustelids the otter, among bears the polar bear, among moles the desman, and so on… “But there is no aquatic ape.” I thought maybe there is, and maybe we are it. I used it as a book title, and it stuck. I didn’t foresee the consequences if that, and I apologise.

The question follows “What exactly then are you asking us to believe?” But this is not a cult. There’s no Authorised Version. I believe water played a role in determining the course of human evolution, but as to exactly what happened and when and where and why, your guess on those issues is as good as mine. I’m told that’s too vague, because people can’t cohere around anything so nebulous. I’m not convinced of the need to cohere. The impulse to do so is the direct result of the vehemence of the opposition encountered up to now by anyone questioning the conventional scenario. That vehemence is quite disproportional and irrational. Those who encounter it feel like a persecuted minority, so we’re tempted to react by seeking a degree of solidarity that cannot be achieved. .

A definition? The furthest I would go is: “Most of the species-specific features of Homo sapiens remain unaccounted for. In discussing the possible environmental constraints most likely to have given rise to them, nothing can be ruled out. A waterside habitat is a strong contender.”

The question has been asked : If AAT is no more flawed than any and every other scenario put forward, “How can it become accepted as a good model?” The answer lies in the passage of time. The people at the head of the profession have invested a lifetime of intellectual capital in the orthodox model; their ideas were formulated at a period when any rational alternative to that was unheard of. For their successors, whatever their convictions, those ideas will not be unheard of. The shock of the new will have worn off. If the aquatic model has enough going for it - and I believe it has - it will prevail.

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Present and future

Natural selection was the key that solved innumerable mysteries about plants and animals of all descriptions - except one. The vocal and hairless bipeds have come no nearer to understanding why they alone are vocal and hairless and bipedal. That can become irksome, so sometimes a revelation is announced which may catch the headlines, and sound like progress.

One recent example was the (“new”?) suggestion that our ancestors shed their body hair because it harboured fleas and other parasites. It was first put forward in the nineteenth century by a man called Mr. Belt, and Darwin didn’t think much of it then. Another example was the revelation that orang-utans sometimes move on two legs in the trees to reach the fruit at the end of the branches. That was relayed to the popular press which hailed it as a break-through, destined to transform our entire approach to human evolution. With all due respect, how can it do that? Our branch of the family split off from the Asian apes somewhere around eleven million years ago. How can the behaviour of one extant Asian species account for the differences between chimps and humans, who shared a common ancestor in Africa until around 5 million years ago?

But it was worth a try, and it was published. It seemed to signal that the field is still wide open for leaps of the imagination, which can then be challenged and discussed. Unfortunately, it is not that wide open. In the second edition of Principles of Human Evolution, Roger Lewin and Robert A. Foley confirm : “It is certainly the case that most textbooks on human evolution - including this one - simply ignore the aquatic model.” They make the obligatory reference to visitors from outer space and include AAT in the same category, but concede that compared to other “alternative” theories this is the most cogent. They pose the $64,000 dollar question: “What is it that makes it reasonable to discuss one model and dismiss another out of hand?”

A good question. It remains unanswered.. I believe it is impossible to devise an answer that would leave AAT on the same side of the watershed as the visitors from outer space. It’s impossible because the only thing the two models have in common is the reception meted out to them by the scientific community. If anyone can come up with such an answer, I will stop making waves. I will apologise to all concerned for having wasted their time. I will follow the example set by the professionals, by going quietly back to Square One.

Elaine Morgan

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