The Waterside Ape
Transcript of BBC Radio 4 broadcast 14 & 15 Sep 2016
Numbers given are minutes:seconds in the iPlayer Radio version.
Sir David Attenborough considers whether new evidence will help a once widely ridiculed theory of human origins move towards mainstream acceptance.
In 1960, the eminent Oxford marine biologist Sir Alister Hardy proposed a revolutionary idea – our human ancestors had started their existence not on the wide savannahs of Africa, but had become accustomed to living alongside water, swimming and diving in the shallows, collecting the abundant food and learning to use language and fashion tools. Hardy asserted that this adaptation to living at the waterside would also account for a whole range of peculiarities about the human form, including the layers of fat beneath the skin, the relative lack of body-hair, the development of language and speech, and what has been called our ‘runaway brains’.
Perhaps surprisingly, it was a screenwriter rather than a scientist, Elaine Morgan, who took up Hardy’s theory and, for over 40 years, progressively refined the evidence for the idea. Most mainstream paleo-anthropologists ridiculed and rejected the Hardy-Morgan thesis for decades, but some influential scientists asked for the proposal to be approached with an open mind.
Sir David Attenborough first considered the controversial theory on Radio 4 in 2004. In this new series of two programmes, The Waterside Ape, he brings us up to date with the story and the evidence put forward since then – both for the hypothesis and also for its continuing detractors.
Back in 2004, Sir David asked Elaine Morgan how long it would take for the aquatic adaptation theory to become a mainstream account of human origins. She answered, “I’ll give it ten years.” As we review the new evidence, has she been proved right?
0:00 Free diving
“The holding the breath phenomenon I think is very important. And when you see what they call free divers, the ones that go down. It’s just unbelievable. When I see a free diver I think, Alister Hardy, this is aquatic man.”
SC: Free diving is a mystery still, which I think is why it holds so much fascination for people, but through scientific research we are beginning to get more clarity on how our bodies are able to perform these fairly miraculous feats. I’m Sara Campbell, I’m a British free diver I went from being a beginner to having three world records within the course of nine months, which as far as I know was unheard of. Free diving is meditation, there’s no two ways about it.
DA: Sara Campbell’s story of going from her first lesson in 2006 to breaking 3 world records a mere 9 months later is an extraordinary one. And yet as we’ll learn later in the programme, breath-hold diving is a skill anyone can learn thanks to the mammalian diving reflex a set of physiological changes in the body that are triggered as soon as you put your face in cold water. Marine mammals exhibit the strongest reflex as do diving birds. We also have it, but to a lesser extent. And curiously among humans it is our babies in their first six months that express it most strongly.
Today and tomorrow we are going to investigate why that might be. It’s a fascinating story that stretches for millions of years ago right up to the present day. Did humankind begin on the dry wide savannahs of Eastern Africa or were our origins besides tracts of water like lakes, rivers and even the sea shores. It’s a debate that has divided experts for years. Why humans are so very different from our nearest genetic neighbours, the chimpanzees and bonobos is a universal fascination. Charles Darwin set an enormous ball rolling with his theory of evolution by natural selection, first making the connection between humans and apes long before genetics provided the proof. Ever since then, fierce debates have raged, and indeed they still do, about where, when and why human beings came to be so different and in so many ways from the other apes. Why do we prefer to stand and move about on two legs, why we’ve lost most of our body hair and grown our massive and complex brains along with a large external nose which is rather poor at the job of detecting smells. And how we learned to voluntarily control our breathing, a skill without which we would never have learned to speak. Or indeed to dive under water as Sara Campbell reminds us so powerfully.
SC: So from the surface down to 100m my lungs will reach one eleventh of their size. My heart-rate will drop from around 60 beats per minute on the surface to probably around 20 beats per minute at depth. You’re allowing yourself to fall deeper and deeper and deeper and deeper into the ocean away from the most direct source of life force which is the breath. Some people say it’s crazy. Those who have experienced it recognize that there is a real magic and profoundness in the free fall. Literally and figuratively.
3:57 Shoreline or savannah
DA: For a terrestrial mammal, one that has made its home on land and has managed to occupy almost every environmental niche that the planet can offer, from city to prairie, from dry desert to high altitude plateau, there is one location that to this day is favoured by humans above all: the shoreline. A 2010 report from Columbia University’s Earth Institute calculated that roughly half of all humans live within a coastal strip just 60 miles wide. By contrast all of our closest primate cousins, the chimps, bonobos and gorillas, live as far from the coast as it is possible to reach, deep in the forests of central Africa. Darwin explained that organisms adapt through natural selection to the conditions of the habitat that they occupy. So it might be reasonable in the case of the primates to ask if our chosen habitats have had an effect on how we have diverged as a species. It’s an approach that led to the development of one view of human origins, the Savannah theory or Man the Hunter, which held sway for most of the 20th century and is still the story told in standard textbooks today. It proposed that we split from our nearest relatives the chimpanzees, because our forest home died back and we were forced to walk upright in order to fight and hunt on the open savannah. The two key figures in establishing this theory were Raymond Dart a South Africn anthropologist, and Robert Ardrey an American screenwriter who met Dart and ran with his idea. Historian Brian Deer relates how the story evolved.
BD: So I’m here in the Evolution room of the Natural History museum in London and I’m standing by a cabinet showing three examples of homo erectus, standing man. The guy who kicked all this off was a guy called Raymond Dart and he published a paper in 1953 and it was entitled ‘The Predatory Transition from Ape to Man’. Man’s predecessors, he said, differed from living apes in being confirmed killers; carnivorous creatures that seized by living quarries by violence, battered them to death, tore apart their broken bones, dismembered them limb from limb, slaking their ravenous thirst with the hot blood of victims and greedily devouring livid writhing flesh. This was taken up by Robert Ardrey and this is how he summarized it in his book African Genesis published in 1963. “We learned to stand erect in the first place as a necessity of the hunting life, we learned to run in pursuit of game across the yellowing African savannah and lacking fighting teeth or claws we took recourse by necessity to the weapon.”
DA: it was a hard violent vision of human origins, inspired quite possibly by the brutal and unremitting wars of the 20th century itself. But in these two programmes we are going to tell the story of a different idea. It’s an alternative account of human origins to the savannah theory and we’ll trace it from its awkward origin on the public stage in 1960 right up to the present day. In particular, we are going to look at the evidence that has been published over the last 10 to 15 years and to ask whether finally that original idea, a simple and really quite modest explanation of the way that humans are the way we are, but one that has provoked huge controversy over the decades, has now reached a tipping point to mainstream acceptance. One person who did more than anyone to develop and research the idea, once she’d heard of it, was Elaine Morgan, an award-winning Welsh playright. Here she is in 2004 explaining what really got under her skin about the savannah theory.
EM: I started out with pure irritation about people like Robert Ardrey not because of what they were saying, because they were only saying what all the scientists were saying, but they were popularizing it, and I wasn’t a scientist, it was the popular version that I was reading. They were being very male centred and I thought it didn’t work and I disliked the way that everything about female was accounted for by her need to suck up to the men so that they’d give her a bit of meat. I thought you wouldn’t have a whole species evolving along such extraordinary lines for the benefit of the male unless it was at least not disadvantageous to the female. I thought this was very maladaptive for her and evolution doesn’t work like that. There must be another explanation.
09:00 Women divers
DA: Elaine Morgan made the very reasonable point that the human could not have evolved by favouring only one sex. The female as well as the male had to find her new adaptations advantageous if they were going to stick. There is at least one distinctive human feature that women have in a much more pronounced form than men and that is a layer of subcutaneous fat tightly bonded just under the skin. Other land mammals don’t have this fat layer whilst a number of marine mammals do and women have a much thicker layer than men. We also know that the subcutaneous fat does at least two things, it provides buoyancy and also insulation against the cold.
We met up with Erika Schagatay a professor of biology at her lab in Östersund University in Sweden. Erika has worked with and studied free diver Sara Campbell who we heard from earlier, but she’s also lived and worked with many of the traditional diving communities that still make a living from diving all round the world today. Those who work in the colder more northerly waters such as the Uma in Japan and the Henyor of Korea are almost exclusively women. And not just any old women but very old women.
ES: We study human performance underwater and it’s striking for a land mammal to see how well the human body works under water. Humans can be compared to many semi-aquatic animals in the performance. So we had 45 women from Hegurajima participate in the study. We logged the dive depths and dive times but to our surprise this group of young to old divers into 6 categories, the results from the study was that they keep the same productivity and dive times and depths until the age of 75. That is quite striking because for working on land or for sports on land people are known to peak between 25 and 30. Our results showed quite strikingly that when working in water your peak performance lasts for much longer than on land. The oldest woman in our study was 97 and she was thinking of retiring and I asked her why? She said It’s not a problem to dive for me and the doctor is completely happy with me continuing. But I’ve been a professional diver for 81 years and I want to do something else now.
DA: Across the straits in Korea, the Haenyeo or sea women also continue diving for a living into a ripe old age. And 70 year old Che yun gee and 91 year old Go in no still dive for many hours a day.
“I was in primary school and they were recruiting.. The Haenyeo said ‘don’t go to school, come and work with us.’ so I went out and started catching sea food. I swapped them for rice cakes, that’s what I liked. Basically I did it for sweets. It’s hard, really hard, but we have to do it for a living. When you go into the water, the water gets into your ears, so I put plugs of mugwhat into my ears, to keep the water out.”
12:53 Auditory Exostosis
DA: A very wise precaution, using ear plugs. Among cold water swimmers divers and surfers today there’s a common condition known as auditory exostosis, known in the west as surfer’s ear. The Korean Haenyeo divers swim all the year round and the water at around 15° is cold enough that some of them can get these protective bones growing in their ears. Peter Rhys Evans is an ear nose and throat surgeon in London.
PRE: These little bones in the ear, these are called exostoses, they are small bones that grow in the deep part of the outer ear canal. The curious thing is they’re only seen in swimmers. The development of these little bones depends on how much the person swims, so in the general population it’s about 2-6%, but in surfers who have surfed for 10 years it’s 80-85% of them have these little bones in the ear canal. So I thought that if they were able to find these bones, or exostoses in early hominid skulls, then that would be definite fossil evidence that these early men were swimming and hunting for food. And in recent years they have demonstrated these little bones in neanderthals and in homo erectus. They have been definitely described as exostoses to narrow the ear canal to presumably protect the ear drum. So this is fossil evidence to verify this aquatic ape theory or the Waterside theory as it’s now called. There doesn’t seem to be any other cause. They’re not seen in the general population of people that don’t swim.
DA: Some geologists believe that fossil exostoses may have been caused by ear infections. But medical specialists such as Peter Rhys Evans are clear that the particular pattern of bone growth that are called trifoliate and in both ears is only caused by repeated immersion in cold water. Fossil examples regularly crop up in skulls from Peking Man at around 700,000 years to Atapuerco in Spain at half a million years ago. And they continue down to more recent ice age skulls in both Homo Sapiens and Neantherthal from Australia to the Mediterranean. Stephen Munro of the National Museum of Australia has been looking at fossilized human remains of Homo Sapiens at a place called Cow Swamp.
SM: Interestingly in Australia they seem to be associated with what we call the robust Cow Swamp-type specimens, so these are homo sapiens in the last ice age, about 20 or 10,000 years ago. They have a high incidence of the ear exostoses and they are found predominantly with fresh water mussels which are found in the Murray Darling region.
DA: Nick Fleming sometimes dives with fellow marine archeologist Ehud Galili off the coast of Haifa in Israel exploring sunken villages from the last ice age.
NF: If the water is flopping backwards and forwards over your ears every day, that bone starts to change. It has to be quite a bit but Ehud Galili has reported at least a dozen maybe twenty skeletons from underwater sites where people were living in fishing villages about 8, 9, 10,000 years ago and they do have that bone change from having been swimming a lot.
16:55 Alister Hardy
DA: In these two programmes, today and tomorrow, we’re asking two simple questions: how long have our human ancestors been living at the shoreline and have we adapted or evolved in this tidal zone where the land meets the water and where there’s a good living to be made diving for shellfish in the shallows. It turns out that people have been asking and trying to answer those very questions ever since since Anaximander in 600 BC. This Greek philosopher made the astute observation that the extended infancy of humans would be hard to sustain in a purely land-based animal. Fast forward to 1942 and a German biologist, Max Westenhöfer suggested in his book The Unique Road to Man that water had played a much bigger role in human evolution than was commonly acknowledged. The very same question had occurred a decade earlier to a young marine biologist Alister Hardy who in 1930 was building his academic career at Oxford. In a zoological textbook of the time he had come across the question of why is it that humans, uniquely among land mammals, have a layer of fat bonded tightly to the skin. Hardy thought he had a very good answer, but it was such an unexpected answer that he kept it under his hat for 30 years until he had become a Fellow of the Royal Society. By then he thought, well the water must be safe by now, he’d just try dipping a toe in so to speak. So he accepted an invitation as an after dinner speaker at the British Sub Aqua Club in Brighton. He didn’t think a few harmless remarks would cause trouble. But it made rather a bigger splash than he had anticipated.
AH: “I wanted to get a good professorship. I wanted to be a fellow of the Royal Society. But I couldn’t do that while holding the aquatic ape theory. So, quite candidly, I kept it smothered it up. But there came a time when I was invited to be guest speaker at a dinner organised by the British Sub Aqua Club at Brighton. I thought, now, it doesn’t matter. Maybe the Brighton Argus will report it but that will be all. Now the awful thing was, this was a Friday night. On Sunday, almost every Sunday newspaper carried great banner headlines ‘Oxford professor says man is a sea ape’ and the most appalling rubbish and I thought, well, I daren’t go back to Oxford now.”
DA: Zoologist Desmond Morris, author of many best sellers including The Human Zoo had been a student of Alister Hardy’s and went back to visit him soon after the balloon went up “I said ‘Good heavens Alister, what have you done’” He said:
AH: “ I went to give a talk to the Sub Aqua Club in Brighton. They asked me to give a talk and I said yes and then realised I didn’t have anything to talk about, then I remembered a moment a very special moment when I was reading an old book about human evolution and I came across a sentence which said ‘homo sapiens is the only primate which has a subcutaneous fat layer beneath the skin.’ I’m a marine biologist and as soon as I saw this sentence, and it said, ‘we don’t know what the function is’ and I thought well I know what the function is, because as a marine biologist I knew what this subcutaneous fat layer was. It was blubber!”
DM: “And I said , yes Alistair but blubber only occurs in marine animals or mammals that have gone back to the water, and he said exactly.”
AH: “Of course I then had to write an article to refute this saying no this is just a guess, a rough hypothesis this isn’t a proven fact. And of course we’re not related to dolphins. I wrote this piece and put it into a journal and it was published. And now it seems to have caused even more trouble because all the traditional anthropologists who believe that man came down out of the trees and out onto the savannah and became hunter-gatherers as a next step are horrified to think that there might have been an intermediate phase when we went through an aquatic period where we were feeding in the water and that changed our bodies.
DA: With hindsight, perhaps Hardy was right to be horrified by the popular reaction. Once the press decided to label something with a catchy slogan, in this case ‘man related to dolphins?’, it can be very difficult to shake it off. Even today, more than 50 years later, it’s a label that has stuck.
21:50 Deep or shallow water
RF: The original argument was that we shared features with marine mammals. The features we shared with marine mammals were all ones associated with complete immersion and deep water dwelling. Things like subcutaneous fat and the streamlining of the body and the hairlessness, these are all deep water ones.
DA: Speaking on a somewhat scratchy line from the Lake Turkana fossil beds in Kenya, Robert Foley, Leverhulme Professor of Human Evolution at Cambridge University:
RF: Why are we bipedal? Why unlike other primates do we have no hair? Why do we have a large brain? What is the context in which humans evolved? The aquatic ape people say the context is the ocean, but I think the scientific answer is those traits helped our ancestors survive in the particular savannah environments in Africa in the last five million years or so.
DA: Complete immersion in deep water ocean is certainly a vivid way to caricature Hardy’s idea of a shore-based living. It’s not very different from the same catchy headline response that Hardy provoked in 1960. But it does differ markedly from what he wrote, which is as follows:
AH: My thesis is that a branch of this primitive ape stock was forced by competition from life in the trees to feed on the sea shore fish sea urchins etc in the shallow waters off the coast, wading about at first paddling and toddling along looking for shellfish, man gradually went farther into deeper water. I see him diving for shellfish, burrowing crabs and bivalves with his hands at the bottom of the shallow seas. He would naturally have to return to the beach to sleep and to get water to drink. I imagine him to have spent at least half his time on the land.
23:38 Growth of Aquatic ideas
DA: Hardy died in 1985. His intriguing speculation might have died with him, had it not been for fortuitous puff of oxygen for its flame. It was from Desmond Morris that I first heard of the Waterside model. In 1967 Desmond published his huge best seller The Naked Ape and in the roundup of theories for why humans as the only hairless primate, he included a couple of paragraphs on Hardy’s idea, describing the same shoreline existence, feeding on shellfish learning to stand upright in the water, learning to swim and to dive in shallow water to collect the readily available bounty there. He also made a prediction: “finally the aquatic hypothesis needles the traditional fossil hunters by pointing out they have been singularly unsuccessful in unearthing the vital missing links in our ancient past and gives them the hot tip that if only they’d take the trouble to search around the areas that constitute the African sea shores of a million years ago they might find something that would be to their advantage.” He wrote that in 1967 and it would not be an exaggeration to say that in the years since there has been a sea change at the heart of both archeology and anthropology. Fifty years on, it’s no longer regarded as a fringe interest to do research into early human dependence on aquatic resources. In fact, it’s one of the hottest topics there is. In 2010, a cover story for the prestigious journal Scientific American featured Curtis Marean of Arizona State University who was writing about his team’s groundbreaking research into early human dependence on shellfish on the coast of South Africa. So what was the title of the article?
CM: The one in 2010 was “When the Sea saved humanity”? (laughs) No it wasn’t my title, I can’t remember what my title was, I’m sure it was boring.
DA: To be quite clear, Professor Marean’s research is not into sites a million years old, as Desmond Morris had recommended. Marean’s findings are much more recent, at a cave system called Pinnacle Point.
CM: In 2007 we published a paper in Nature that reported on evidence for the first time that humans expanded their diet to seafood. That’s dated to about 160,000 years ago. The main species they have there are mussels, you have them in the UK in the rocky intertidal zone and sometimes they’ll totally cover the rocks. Normally to collect them, just go down there at a low spring tide and literally just shovel big chunks of them off the rock and to cook ‘em you can take sand and they would put burning charcoal on top of the sand, then you brush the charcoal off, then you push the mussls into the sand and they cook inside and don’t open up and then you grab them out of that hot sand and eat them and they’re very nice that way. And then the second animal that they collected a lot was a big sea snail. I have a reasonably large fist and the ones they were collecting were bigger than that. I regularly go down and get them myself as I love to eat them and you have to go down under the water a little bit and you pull them out and put them on the fire and they cook inside the shell and they pop out. That foot is really tasty and is a big package of meat.
DA: Marean theorizes that the population at Pinnacle Point around 200,000 years ago was the very group that came out of Africa and gave rise to homo sapiens. But there was also an earlier Out of Africa event at 1.8M years ago and that was our immediate predecessor species, homo erectus, the first standing man. Described earlier by Brian Deer in the Natural History Museum. He was a heavy dense boned hominid with a long fat skull a big nose and a propensity for long distance migrations, as far as we can tell, along the coasts.
MV: Now we know that it happened when Homo erectus spread along the coasts, the African and Eurasian coasts, probably at the beginning of pleistocene, of the ice ages, when the sea levels dropped and there became new territories available for a handy and intelligent ape who could feed on all sorts of waterside food.
DA: Belgian physician, writer and researcher Marc Verhaegen. Apart from Elaine Morgan, arguably no one has done more research over the last 40 years into the aquatic ape model. He’s widely credited on both sides of the debate for his painstaking anatomical analysis that points to a shallow diving habit in homo erectus and her descendants.
MV: Well we don’t know for sure but it’s certainly possible that during the glacials that a lot of continental shelfs became available for omnivorous, ape-like creatures who found mussels and crabs at the seaside, the location for those is not necessarily the savannah, it indicates shallow water adaptation and more importantly are the very heavy and thick bones of homo erectus. This is uniquely seen in other mammals and other animals in shallow divers and mostly in salt water, a typical littoral adaptation. Dense and big bones are fragile they break very easily, so it’s not an adaptation to land but it’s clearly an adaptation to diving regularly in shallow water.
29:57 Elaine Morgan
DA: Marc Verhaegen’s interest in an aquatic model was first sparked by a book published in 1972 by Elaine Morgan. She wasn’t a scientist nor yet an anthropologist. She was the BAFTA-winning television playwright from the Welsh valleys we heard earlier, with a degree in English from Oxford University. In the late 60s she had read Desmond Morris’s Naked Ape; she had also read the books by Robert Ardrey, an American screenwriter who brought to life the story of man the hunter racing over the savannahs of Africa. But a number of things about the story didn’t seem to Morgan to make sense. In particular, the way early man had run about on two legs supposedly to chase down big game. Also why had we lost our fur? The female of the species didn’t seem to get a look-in, not to mention the children or the babies, who as Anaximander the Greek philosopher had noted, remained functionally helpless for so much longer than other animal infants. When reading the Naked Ape, Morgan had been fascinated by the reference to Hardy’s alternative idea that humanity had gone through a semi-aquatic phase and that it resulted in the adaptations that make us so different from the other primates. So she contacted Alister Hardy and asked if would mind if she ran with the idea. Hardy gave her his blessing and so in 1972 she wrote The Descent of Woman. This was the decade when the second wave of feminism was rising and Elaine Morgan had no time for mincing her words.
EM: Why did they stand upright? The popular version skimmed very lightly over this patch of thin ice. Robert Ardrey says simply ‘we learned to stand erect in the first place as a necessity of the hunting life’. But wait a minute, we were quadrupeds. Try to imagine any other quadruped discovering that: a cat, a dog, a horse, and you’ll see that it’s totally nonsensical. Other things being equal, four legs are bound to run faster than two. The bipedal development was violently unnatural. Next question: why did the naked ape become naked? It’s claimed that he would experience considerable overheating during the hunt and the loss of body hair would be of greater value for the supreme moments of the chase. There were two sexes around at the time and I don’t believe it’s ever been all that easy to part a woman from a fur coat just to save the old man getting into a muck sweat during his supreme moments. What was supposed to have been happening to the female during this period of denudation? This problem could have been solved by dimorphism, the loss of hair could have gone further in one sex than the other. So it did of course. But unfortunately for the Tarzanists, it was the stay at home female who became nakedest and the overheated hunter who kept the hair on his chest.
DA: Descent of Woman was an international best seller and sold especially well in America. With book clubs pushing it and serializations in magazines including in Vanity, Fair Elaine Morgan was invited over to do a publicity tour in 1973 appearing on a string of talk shows. As a middle aged Welsh housewife with a husband and three teenage sons to look after, it posed some obvious challenges. But she had been a professional writer for more than 20 years and she wasn’t easily fazed; after all she had been finding ingenious ways to fit her career into a family structure ever since the children were small. Her middle son, Gareth Morgan remembers the eaarly days
GM: When we lived at the Birches, I was a toddler. It wasn’t abandoned but it was very run down, it was very very basic. Stone floors, cold water, the loo was an outhouse, a little wooden shed perched over a stream, very very remote, very isolated and very exposed to the wind and weather, but my mum loved it. And so did we by all accounts. I must have been 2, 2 and a half and no doubt a persistent pest when she was trying to get some work done. So she quickly thought of a solution and invested in a play pen so that she would be undisturbed. But her approach to it was that she got in the play pen with the typewriter while I had the run of the house. And that’s kind of how it was all the time I was growing. She was immersed in her writing and although she looked after us all very well I did get an immense amount of freedom because as long as I was out of the house and in the woods she had the peace to carry on with her work.
DA: Although the Descent of Woman was a huge best-seller, it was a work of popular science and as such, the academic community felt entitled to ignore it. She was a non-scientist. Elaine Morgan’s response was to engage with the legitimate scientists on their own terms, to become legitimate herself. So she put the feminist critique to one side, took out the flippant digs at Tarzanists, added scientific illustrations and made sure to reference every paper she quoted from. Her next book in 1982 was titled simply: The Aquatic Ape, a theory of human evolution. Sir Alister Hardy wrote a forward to it in which he dealt straightforwardly with the complaint from scientists that Morgan was not one of them and could therefore be ignored.
AH: “As a professional zoologist, I would point out that some of the greatest contributors to evolution theory had no academic training in biology. Without suggesting that Elaine Morgan is a second Darwin, I would remind them Darwin himself abandoned his medical course in Edinburgh and took a pass degree in theology in Cambridge. Alfred Russel Wallace began his career as a land surveyor and never went to university at all. And Mendel entered a monastery at an early age. It is enthusiasm which carries people forward to add to knowledge. Elaine Morgan has that zest.”
DA: Over the next 20 years, Morgan wrote 4 more books on this theory taking on criticisms and correcting mistakes wherever her evidence was shown to be unsafe. By the time she published The Aquatic Ape Hypothesis in 1997, her reviews talked of a case well enough made for it no longer to be ignored. In 2004, Radio 4 broadcast a series called Scars of Evolution which examines the Hardy-Morgan aquatic theory for and against. At the end of it, Elaine Morgan, by then 83 years old gave a prediction about which way the tide of opinion was headed.
EM: I think in 10 years we’ll be over the cusp. The tide is beginning to drift in that direction. And I think it will pick up speed, and I think that a lot of people will bring up their own reasons why they think that the difference between man and the apes had something to do with water. I go no further than that. But they all seem to be trickling in that direction. I don’t know if I’ll be alive to see it but I’m confident it’s going to come.
37:43 Objections to the thesis
DA: Sadly Elaine Morgan died in 2013. But her prediction that water and human evolution would become the headline story, looks increasingly plausible. Research into evolution at the waterside, as we heard earlier from Curtis Marean and Stephen Munro amongst others has indeed picked up considerable speed in the last fifteen years and tomorrow we’ll look at some really eye-opening research from just the last few years. Down the years there have been two principal objections to the Hardy-Morgan thesis that early humans underwent important evolutionary adaptations while making a living at the waterside.
One objection was the lack of fossil evidence. As we heard earlier, the fossil evidence for early humans relying on aquatic food resources, both fresh water and marine, has been emerging steadily in the last twenty years. In tomorrow’s programme we will find out quite how far back in time the newly emerging evidence for a dedicated shore-based existence goes.
The second and regular complaint was that the waterside model made no testable predictions. It merely made comparisons between human physiology and certain marine mammals. It didn’t count as proper science. Many opponents went further calling it pseudoscience and you can still find such dismissals and accusations on-line today. So back in 2004 in the Scars of Evolution series a testable hypothesis was raised concerning that curious substance Vernix caseosa. Vernix is the waxy grease that humans babies are born with and is still widely described in the literature as being unique to humans. So if Elaine Morgan was right and Vernix truly was an adaptation to entering the water at or soon after being born, then it should be present in other animals with that habit—the marine mammals. But there appeared to be no references at all. After searching the marine mammal literature nothing. After contacting seal sanctuaries and marine veterin3arians around the world, nothing. It looked like vernix was just an oddity with no adaptive benefit for those being born in water after all. Then a week before broadcast there was a call back from Professor Don Bowen in Newfoundland. He had spent 10 years studying seals in northern Canada and reported that yes, when handling newborn harbour seals, they were covered in a white grease that got all over his hands. He’d wondered if it was related to human vernix but hadn’t pursued the idea. It was a fascinating observation, but no more than that. No one knew whether it was actually related to Vernix at all and Professor Bowen didn’t have any samples and that might have been the end of the Vernix story. But in tomorrow’s programme we’ll bring the story bang up to date with some fascinating research from a team at Cornell University who submitted a paper on Vernix to Nature just a month ago.
The Waterside Ape part 2
Transcript of BBC Radio 4 broadcast 15 Sep 2016
0:00 Recapitulation of first episode
EM: I think in 10 years we’ll be over the cusp. The tide is beginning to drift in that direction and I think it will pick up speed. A lot of people will bring up their own reasons why they think that the difference between man and the apes had something to do with water. I go no further than that. But they all seem to be trickling in that direction.
DA: That was a recording of Elaine Morgan in 2004 predicting that the idea of humans evolving at the waterside instead of the savannah, first wading and then diving and foraging for seafoods would be accepted into the mainstream within a decade. So, was she right? It was a theory first proposed by Sir Alistair Hardy a marine biologist at Oxford in 1960 and in the 1970s, Elaine Morgan a playright from the Welsh valleys, picked up the idea and ran with it. Her series of books about the theory started with an international best seller, The Descent of Woman. In yesterday’s programme we recounted the clash of two very different views of where human beings come from. Did we stand upright and lose our fur in order to hunt and kill big game on the plains of Africa, as anthropologist Raymond Dart and screenwriter Robert Ardrey had written: “Man had emerged from the anthropoid background for one reason only, because he was a killer.” Or did we find a much less demanding environment as Hardy, Morgan and many others have argued? One where the food didn’t run away so fast, but sat obligingly right there on the sea floor for us to pick up at our leisure.
Near the water’s edge, foraging in relatively shallow waters, as well as spending time on land for things like shellfish and aquatic crabs, things that aren’t going to run away or swim away from you; you don’t have to be fast; you just need to be able to hold your breath for a minute or so, go under the water a few metres, pick up a few shellfish and you’ve got yourself a feed; something that pregnant women can do, something that nursing women can do.
DA: Yesterday We also explored some of the evidence that has been coming to light in the last 10 or so years in support of the Hardy-Morgan theory of a waterside phase of human evolution including fossilized examples of surfer’s ear
PRE: You look at someone’s ear and see them and you say ‘oh you’re a keen swimmer’ and they say ‘how do you know?’and over recent years they have demonstrated these little bones in Neantherthals and in Homo Erectus.
DA: And Curtis Marean introduced us to the delights of how to cook mussels and sea snails on a camp fire around 200,000 years ago.
CM: You have to go down under the water a little bit and you pull them out and then you can bring them back and just put them on the fire and they cook inside the shell and they pop out and that foot is really tasty, is a big package of meat.
DA: Today, I’m glad to say, we’ve got more cooking on the programme: 50 kilo catfish at two million years ago and water lily popcorn at just under a million. Giant freshwater mussels at merely half a million seem barely worth putting on the specials board.
3:40 Wading on two feet
DA: Of all the many features of the human body that distinguishes us from other primates such as our hairlessness, our massive brains, our ability to control our breathing and thereby to speak, our large noses but poor sense of smell and many others, one feature is more visible than any other. We move on two legs not four. Specialists call it bipedal locomotion; over my own career, observing animals in many different habitats, I’ve had the opportunity to see our primate cousins up close and on a number of occasions we filmed chimps seeking out water plants and their roots in forest pools or crossing shallow rivers; the striking but not altogether surprising result of their entering water is that they stand up on two legs. The water provides buoyancy and they are able to wade bipedally through the water. When they return to dry land, they return quite naturally to a quadrupedal gait. Japanese macaques do the same when they enter the sea to wash their food; probosis monkeys in Borneos do the same when crossing rivers. It’s always seemed a good explanation to me for how our human ancestors might have adopted an upright stance. Richard Wrangham, Professor of Human Evolution at Harvard University:
RW: For me, going to the Okavango Delta in northern Botswana was a really eye opening moment because there is something I think like 10,000 baboons living there and what the baboons do when they can’t find food is to very often wade in the shallow water and pick up the roots of water lilies just like chimps and bonobos will do when they have the opportunity to do so, they will walk up to their armpits in order to be able to pull plants out of the mud that are not heavily embedded in it but just need a little bit of a tug, and then walk back to the land to eat them. So this gives us a model for why an animal that is quadrupedal originally would want to spend some considerable time on two legs. I would hope that a combination of increasing realization that the foods were in wet places with some biomechanical tests will give people confidence that this really is a reasonable way to approach one of the most important moments in human evolution.
DA: Algis Kuliukas at the University of Western Australia has carried out just such biomechanical tests, measuring muscle and joint performance to establish the relative efficiencies of the typical rolling bipedal gait of chimps and the upright two-legged locomotion of humans.
AK: The remarkable thing about the way humans walk is that we’re very efficient and the reason for that is because we have extended limbs. We’re almost falling forward with style as we walk. We did a series of experiments comparing human walking on land and in water at different gaits so even if the bipedalism would be very inefficient on land, in waist deep water that inefficiency is cushioned by the buoyancy of the animal and these scenarios provide a continuum of depths from waist or chest-deep water right through to dry land. It encourages bipedalism and more efficient bipedalism all the way. I think it’s the perfect scenario for this.
DA: It isn’t yet the hypothesis that students are most commonly taught but perhaps its time has come. Other theories for why we stood up include energy saving, to free our hands for carrying things and even endurance running. But one of the explanations for bipedalism that is very widely taught is an idea proposed by Professor Peter Wheeler, Dean of Science at Liverpool John Moore’s University.
W: I don’t know whether this is actually an explanation for its originating or whether it enabled humans to move into more open country but we have demonstrated quite convincingly that bipedalism certainly offers significant advantages in open equatorial environments so what we’ve done is by moving upright we’ve kept hair on the surfaces most directly exposed to the incoming radiation, and the hair on the head and potentially the shoulders gets very hot indeed sometimes you’re talking about temperatures reaching 60 or 70°C, so the areas pointing to the front act as a shield and its the areas that are not pointing at the sun when it is at its most intense which are able to lose the hair. Humans have quite long cranial hair that will cover the shoulders but also you tend to get hair quite strongly retained on the upper shoulders, the outer upper arms and the very upper layers of the spine. But of course it is possible that it was already a biped and what this did was to enable it to colonize these more open equatorial environments.
DA: As Professor Wheeler acknowledges his theory may not account for the origin of standing upright in the hot sun. After all, learning to stand up is a risky business at the best of times. Out on the open ground there has to be an advantage pretty quickly to make you want to do it again. If any predators in the vicinity spot you practising and make a pounce you’ll get back on four legs pretty sharpish if you’re going to escape and live to fight another day. Baboons are the only primate to have ventured out onto the savannah and they’ve stayed resolutely on four legs except for those occasions when they stand up to wade into water to get food.
9:48 Fish food
KS: A good number of the hominins living around three to two million years ago were eating sedges and papyrus and this puts them directly in the water.
DA: Kathy Stewart is a research scientist and departmental head of paleobiology at the Canada Museum of Nature:
KS: There are no ifs and buts about it, oxygen isotopes show that they were very water dependent. So he/she were actually spending a lot of time eating sedges in the water. and this is how they became familiar with fish and this was just an extension of living by the water.
DA: Kathy’s research into the fossil beds of East Africa where some of the earliest hominins or members of the ancestral family have been found, was critical to understanding what they were actually eating. Working in East Africa as a PhD student, Kathy was asked to sift through the piles of left-over dirt from the site where the humans remains were found to see what she could find. She got quite a surprise. Fossilized bones of large catfish in substantial quantities and so far as she could see, they had been cut with stone tools. Over the years, Kathy has become such an expert on fish fossils she has been nicknamed the Fish lady in the local language.
KS: Fish lady or fish woman, yes that’s me: mamaya samaki. (laughs) Well I look back at Kathy Stewart in the 1990s saying I think maybe hominins were eating fish and just kind of polite smiles. People saying ‘sure Kathy’ patting me on the back; my colleagues were actually very tolerant and supportive and a lot of the early hominin sites which are around 2M years old and people thought that fish in archeological sites of that age were just washed in remains. But when I started to look at the Olduvai Gorge sites, 3 sites in particular had a lot of fish remains and they all seemed to be Clarius, the catfish and I was thinking that Clarius, which is a large catfish, is not something that would be washed in and it turns out that if early hominins were looking for an easy to get nutritious large meal, Clarius was their food. Clarius can grow up to 2m long and it spawns up-river and it spawns in shallow grassy floodbanks of the river and people can just walk in and with bare hands pull these things out and toss them on the bank, and bang them on the head with a rock so they don’t swim back in, and there’s your meal.
DA: It took about 20 years but finally in 2014 Kathy Stewart’s initial suggestions that our ancestors were deliberately catching fish 2M years ago in East Africa were confirmed in the journal Nature by David Braun and Will Archer. Instead of relying on the trusty friend of the fossil hunter, the 10 times magnifying glass, Braun and Archer use powerful microscopes to analyse Kathy Stewart’s fishbones. The cutmarks showing deliberate preparation of the fish were clear as day. Here’s one of the authors of that study, Will Archer, from the Max Planck Institute of Evolutionary Anthropology in Leipzig.
WA: So rapidly decreasing lake levels tend to leave pools of water stranded on the beach; catfish often get caught in these pools and as they dry up gradually catfish get stranded; they were 50kg upwards, huge catfish and interestingly in the late dry season, this is the time when aquatic resources, catfish is what I’m talking about, when the lipid content is really at its highest level. It’s just before they breed at the beginning of the second rains. So aquatic resources would have been in peak condition at the time of year when terrestrial resource quality was really at its seasonal minimum.
DA: Archer and Braun told a clear story. They pointed out that the protein in meat has nothing like the nutritious value of the fat or lipid content. It’s why in many parts of Africa today, even communities that subsist on very little will avoid eating animal meat in the dry season. This is because the level of the lipids, those specialised fat molecules that provide the structure and function of the cells is simply too low and that can be injurious especially to pregnant women. But catfish were the opposite; at the end of the dry season, just as red meat was becoming inedible, the spawning catfish had their highest content of fats and lipids. It was the perfect source of highly nutritious fatty acids, not least for the brain.
Stephen Cunnane a professor of medicine in Canada has spent years joining the dots between brain evolution and dietary fat. It seems you can’t do one without the other. One essential line of dots led back to Kathy Stewart.
SC: I called her up and said, Kathy you don’t know me but you’ve shown something extremely important, because this is strong fossil evidence that we were consuming catfish and talapia and the cut marks on those bones suggest that it was intentional and that fits very well with a nutritional and biochemical story that some of us have been developing for some time, so it was an eyeopener for her and it was a wonderful point of coming together between two fields of paleoanthropology and nutrition which have worked together a lot since on this topic. And this connected with us because these are freshwater fish which have a reasonable amount of omega-3 fatty acids, not as much as the cold water fish but still a very good source not only of omega-3 fatty acids like DHA but a cluster of important nutrients for the brain including iron, iodine and so on, so the people who thought these nutrients were important for human brain function and hence for human brain evolution were always really in search of a smoking gun and her first paper of ’94 on this topic was for us a smoking guns in terms of fossil evidence that fish was being intentionally consumed at a stage in human evolution when the brain was not fully anatomically the size that it is today.
16:27 The Savannah hypothesis
DA: Meanwhile in the gated bastion of paleoanthropology, trouble was stirring. By the late 1990s even the most establishment figures had conceded that the savannah hypothesis was in trouble. The inescapable fossil evidence was that savannahs as we know them today had simply not existed when humans first stood up. So it was that in 1995, Philip Tobias, the most decorated scientist of his generation in South Africa and nominated three times for a Nobel prize, made a courageous statement declaring that the previously accepted hypothesis needed to be rewritten. Here he is, speaking back in 2004:
PT: To a large London audience with a histrionic gesture, I said the savannah hypothesis is no more. Open that window and throw it out. At Sterkfontein and other South African sites and East African ones these early hominids were all accompanied by woodland and forest species of plants and animals. Of course, if savannah is eliminated as a primary cause of selective advantage of going on two legs then we are back to square one.
DA: But he knew it wasn’t really back to square one, and in 1998 he published a paper entitled Water and Human Evolution in which he credited, amongst others, Elaine Morgan, author of Descent of woman and Scars of Evolution. He wrote ‘Paradigm changes I like to think flow overwhelmingly from new evidence and where the evidence is sound and even irresistible they should be embraced.’ It was an extraordinarily courageous declaration. More than any other publication it removed the stigma from the aquatic theory of Alistair Hardy and Elaine Morgan and exhorted the mainstream to go to the waterside, the lakes, estuaries and coastline to tell our earliest human story, just as Desmond Morris had encouraged them to do 30 years earlier. So, did the paradigm begin to shift?
18:54 Increase in aquatic research
JJ: I was very curious to see how the past twenty years what has happened, how mainstream the idea of how something aquatic in human evolution developed.
DA: We caught up with Dr. Josephine Joordans in Amsterdam where she works as a paleo-ecologist at Leiden University.
JJ: I fed several key words like aquatic, fish, shell, marine coast and shore into the search function of the Journal of Human Evolution. What you see is that until 2002 it’s like silence; zero, one, two hits maybe but nothing is happening. From 2003 onwards it’s picking up and steadily increasing. What you see in 2014 is a real peak in hits. But that’s because there was a special issue then on aquatic resources and the possible importance for human brain evolution and of course the very fact that there is such a special issue is again telling something.
DA: One of these recent papers on aquatic resources was by Professor Naama Goren-Inbar who has been researching a site in the Jordan valley for many years. The site is known as GBY and dates back to almost a million years ago. She titled the paper ‘Beneath Still Waters’.
NGI: We are digging in black wet mud. The fact that the water logged gives us a fantastic opportunity to have a look at very old remains which usually are not conserved which are the organic remains particularly the botanical ones.
DA: In addition to substantial evidence that these early humans were catching and preparing huge carp and catfish from the lake they lived beside, there was another even more remarkable find: water lily nuts. Now the thing about this water lily is that its plant is ferociously thorny and you have to wait until the nuts have sunk to the bottom of the pond and ripened before diving to collect them.
NGI: The issue of collection is extremely difficult since this is a very thorny plant, entirely covered by very vicious thorns. In order to find out more about this phenomenon we decided to go and search in India in the Bihar, a way in which traditional fishermen gather the water nuts and process them. So in Bihar the group of fishermen go in groups to collect the nuts. They dive and they collect with their hands the nuts. The diving can be in 2m deep but it can also be up to 5 or even 7m deep.
DA: The notable thing about this nut is that it makes great popcorn.
JJ: They first roast it, and then they take it and in a very fast motion they put it on an anvil and with a heavy wooden hammer they give a blow on the surface of the nut and as a result of this blow the nuts explode and they are becoming something which is similar to popcorn. We should bear in mind that they were hunters, that they hunted elephants and hippos and deer, so in addition to the aquatic aspect we discussed previously we have a very large library of the terrestrial aspect. All in all, if we look at all the different aspects I would say that their cognitive abilities were extremely developed.
22:45 Home erectus
DA: What does the research of the last 15-20 years begin to tell us? First, that our upright mode of walking was established at least 3-4M years ago. From analysis of the wet environment they were living in together with the observations of other primates today, one idea is steadily gaining acceptance, that they learned to stand upright by wading in shallow water maybe waist deep. Second, at 2M years ago, we know that our ancestors were catching and filleting very large catfish, rich in fat, among other aquatic and terrestrial foods. After migrating out of Africa at 1.8M years ago, our ancestor homo erectus followed the coastlines around the world. They reached as far as China and Indonesia in the east and Northern Europe in the west. Then at around 7-800,000 years ago we have fossil evidence from the waterproofing bones in their ears and from their dense flat skulls and limb bones, that they were shallow water diving, not living in the water but making a living from it, diving for water lily nuts and sluggish catfish and using their increasingly sophisticated brains to get creative in the kitchen.
Then, just last year, Jose Joordans and Stephen Munro published a paper that got global headlines. They had decided to take another look at the collections brought back by Dutch paleoanthropologist Eugène Dubois who had discovered Java man in the 1890s. Dubois had been looking for what used to be called the missing link, the hominid stage between chimpanzees and modern humans. Now some fossil hunters are fairly selective about what they box up and ship home. Dubois was a veritable trawler.
JJ: I opened all the boxes and all the shells inside were the same. They were all the same species and all the same size and they looked really boring. It was only later when I stepped back and was at home doing some housework that I realised that this is really odd, that you find such similar shells in such large quantities in a collection. It’s not like a natural assemblage. That fact was living in the back of my mind, and when Stephen came and looked at the shells and he made photos of each and every one of them and later when he got back from Ethiopia and Australia he looked at the photos and then he noticed on one of those big boring shells this strange geometric pattern and that set the ball rolling
SM: When we looked at them, we noticed they’re very similar in size, about 11 or 12 cms across, you could fit them perfectly in your hand.
DA: Stephen Munro of the National Museum of Australia.
SM: So here we have homo erectus, the first time that homo erectus was discovered living on the edge of a river and exploiting the shellfish that were in the river for consumption and also marking them in a zigzag manner which tends to be the oldest type of markings that we’re aware of of this kind and these have been dated to about 500,000 years old.
26:17 Brain Development
DA: In yesterdays programme, Curtis Marean from Arizona State University described how he had discovered that large mussels and sea snails were the most dependable all year food source at the tip of South Africa 200,000 years ago. And not just a reliable food supply but the richest source of omega-3 fatty acids, also known as DHA, as well as iodine and iron, the essential building blocks for evolving a large and complex brain.
SM: Twenty years ago nobody had even heard of omega-3 fatty acids and now everybody is popping fish oil tablets every day, because we know that omega-3 fatty acids are absolutely crucial to the development of visual acuity, the development of the brain. That food resource is crucial to the development of a cognitively complex and healthy human and the best place to get that food is low on the marine food chain. Where does it come from? It comes from algae. Some really high quality grasses have it, but algae is your best source and it’s those molluscs that eat that algae that are your best place to get it.
DA: Over the last half-century, one person has done more than anyone to establish that the marine foodchain was the essential resource for humans as they evolved a big brain. Michael Crawford is Director of the Institute of Brain Chemistry and Human Nutrition at Imperial College, London
MC: There are of course people who say that the land-based food web would have provided DHA from eating the brains of buffaloes and things like that, bone marrow, etc. etc. To be frank with you, this is not an option. There is no evidence whatsoever of any comparable evolution of brain size in the land-based system. In fact the contrary is the truth. As animals evolved bigger and bigger body sizes, so in relation to the body their brains shrank. You take a zebra for example This has about 300g of brains. Horses have what they call walnut size brains Take a comparable body weight mammal in the sea, the dolphin, it’s 1.8 kg of brain. Come on guys. It is just so simple There is no way, I’ll say it absolutely deliberately, that the evolution of a large brain on the savannahs of Africa was impossible. The only way it could have happened was with the resources of the marine food-web which initiated the growth and development of the brain in the first place.
DA: There are still some paleoanthropologists who are not convinced that the marine foodchain was essential for growing a large brain. They argue that there were other land-based foods available that contain DHA or omega-3 fatty acids and could have helped to evolve a large brain like ours. There’s not a lot of DHA in land-based plants so the best source of DHA inland is the brains of other animals. Twenty years ago a skeleton of homo heidelbergensis, an extinct species that was wiped out along with the Neanderthals was found in Boxgrove in West Sussex. Chris Stringer from the Natural History Museum describes its diet.
CS: When we go back to our ancestors, say half a million years ago of humans, we’ve got remains from Boxgrove of scavenging or hunting of humans, possibly the species homo heidelbergensis, and there people were butchering the carcasses of horse and deer and even rhinocerous, at least four rhino skeletons and these have been systematically butchered and every bit of meat that has been taken off that carcass, they’ve broken the bones to get the marrow out, they’ve broken the skulls to get the brain out, so that’s going to be a rich source, and eating brains, especially if you can get primary access, which it looks like they had at Boxgrove, you willcertainly get all the nutrition you need to maintain and run your own brain, so I think that probably provides sufficient means of getting the nutrition we needed to evolve and run a bigger brain.
DA: Michael Crawford again:
MC: It’s not just DHA. It’s also things like iodine. Now today we have 2 billion people at risk of iodine deficiency disease. With the inland food-web not only being poor in DHA but also poor in iodine and a whole bunch of other trace elements such as you find in the marine food-web, it’s just not possible that any primate could have evolved a large brain on the inland food web.
31:25 Vernix Caseosa
DA: Back in 2004, when we made an earlier series about the aquatic ape hypothesis of human evolution, we ended with an intriguing report from a marine biologist in Canada. There’s a substance called Vernix Caseosa, Latin for cheesy varnish, and it’s the whitish waxy grease that human babies are born with. Elaine Morgan had written that it makes human babies look like cross-channel swimmers covered in grease to keep out the cold. Although it was always described in the textbooks as being unique to humans, what if it was, as Morgan had surmised, an adaptation to entering the water soon after being born. Then shouldn’t it also be found in aquatic and marine mammals with that very habit? It turned out that Professor Don Bowen in Canada had seen something similar. He had 10 years experience in handling newborn harbour seals and as he said there is a whitish grease that covers the newborn seal pup’s body and it tends to get all over your hands when you pick them up. This was an observation, nothing more. We didn’t know if it was really like vernix or something different entirely, we had no samples and no means of conducting the chemical analysis and that looked to be quite probably the end of the vernix story.
But one person who listened to those programmes was Professor Tom Brenner of Cornell University and he was intrigued. As a chemist and specialist in mass spectrometry he had spent many years researching the biochemistry of human vernix. So when he heard this observation of vernix potentially in another species he set off on the hunt.
TB: To cut a long story short, we eventually found marine mammal centres on the west coast in California who were willing to collect samples. We analysed the vernix of sea lions and humans in the same way by mass spectrometry and we found that they were extremely similar both in their structure and in their quantity. We found that the structure of the molecules were similar and we found that the distribution of the various molecules were similar. So they were strikingly the same and we also did some quantitative analysis which told us they were being produced, at least in the context of the vernix, in a very similar way. An extraordinarily exciting result, and in fact we also saw this in a single harbour seal that we were able to acquire and we saw the same thing there and so I’m almost willing to say this probably extends to all marine mammals. In fact, we’ve even done some more recent analyses that indicate that squaline, an intermediate biochemical in the synthesis of cholesteral is found in human vernix and also in marine vernix. Another indication that these two substances are performing similar functions in the two species.
DA: According to the Cornell team’s analysis vernix is not unique to humans as was believed but is in fact shared by marine mammals. They’re hopeful their analysis will spur the identification of vernix in other species too because the more animal models they have to work with the better. Meanwhile Tom Brenner can only make a speculation as to why sea lions, seals and humans share this curious feature.
TB: My speculation about these branch fats that are in the g.i. trackable humans and marine mammals is that some sort of environmental commonality has caused this evolution to occur. Those that are born on the shore are often in the water soon after they’re born on the shore so they’ll be jumping right into the water in an hour or two after being born, so there may well be exposure to marine microorganisms right at the shoreline that are different to the microorganisms that a terrestrial animal would be exposed to. Hence possibly explaining the commonality of the fat composition of vernix between humans and marine mammals.
MC: But this is just an absolute clincher!
DA: Michael Crawford again.
MC: It identifies a physiological phenomenon about which there is absolutely no question that links us to marine mammals, in a behavioural sense. At some point in our history, as Alister Hardy said, we were more aquatic than we are today. Now we didn’t go as far as the marine mammals. We never became committed in the way they did. Because we could also enjoy the fruits of the land and we were enjoying the best of both worlds. I think with the evidence of vernix being shared with marine mammals, the case is closed. The remaining question is where and when. My guess is that it actually started when we separated from the great apes. We found, wandering down a river we came to an estuary and saw these sea birds noshing on the seafood and hey guys, we don’t have to climb trees any more. It just fits so neatly with what you’d expect from nature. She wouldn’t leave the richest food resource on the planet unoccupied.
37:23 Where and When?
DA: So that leaves us, as we heard Michael Crawford say, with the remaining question of where and when did these physiological adaptations evolve? Of all questions, these are what researchers in human evolution try to answer. Alister Hardy and Elaine Morgan suggested that human adaptation to a shore-based existence started as far back as 5 or even 7 million years ago. Michael Crawford tends to agree. Marc Verhaegen argues for a more recent phase as homo erectus set off around the coastlines 2 million years ago. Curtis Marean goes more recent still with to the origin of our modern species homo sapiens at around 200,000 years ago. Peter Wheeler thinks it’s too early to call.
PW: There’s a lot of evidence that aquatic environments particularly marine environments were very important to our own species from 50-100,000 years onwards so if we’re seeing features or adaptations in modern humans we don’t know at what stage they were acquired. Now it may be possible to determine that by some genetic studies in the future but at the moment I would be very wary to see any feature in the human as one that must have been acquired 3M, 4M, 5M years ago as opposed to being acquired in the last 50-100,000 years.
DA: With luck, and perhaps sooner than we think, the study of comparative genetics will shed some light on when exactly it was that the human line became so attached to a waterside existence that we started to adapt both phyically and cognitively to its bounty. In the meanwhile what we can say is that the last 20 years have seen a major shift in our approach to thinking about human origins. The focus has moved steadily down to the shorelines of freshwater lakes, brackish estuaries and the sea coasts. The evidence both in the fossil record and in comparative biochemistry and nutrition has emerged at a faster rate in the last decade, than anyone, except perhaps for Elaine Morgan would have predicted. And it suggests that the most likely reason why humans are physically different in so many ways from all the other primates is that we learned to exploit the rich and easy pickings of the shoreline, wading and shallow diving to forage for food, as many human communities still do today.
Elaine Morgan said back in 2004 that the waterside model of human evolution would be over the cusp and into the mainstream within 10 years. Was she right? John Parkington, Professor Emeritus at the University of Cape Town, followed by Elaine Morgan’s middle son Gareth, Stephen Munro, researcher in human evolution, and to play us out, Kathy Stewart, head of paleobiology at the Canada Museum of Nature.
JP: We’re certainly over the cusp. The main thrust of it is I think much more acceptable now than it was then. I think there’s a lot of the detail that still has to be worked out but I think there are enthusiastic supporters where there weren’t very many 10 or 15 years ago.
GM: We’re not only over the cusp, we’re hurtling down the other side at 90 miles per hour and the destination is clearly in sight.
SM: I think we can take the good parts of Hardy’s ideas and Morgan’s ideas, and Veerhaegen’s ideas, combine them with the great work that has been done by the paleoanthropologists in other areas and we should be on our way to solving a lot of the problems we have in human evolution.
KS: Elaine Morgan was a smart woman. She just made things so logical. Maybe going fishing or pulling catfish out of streams isn’t as sexy as striding across the landscape but I think it’s a more realistic picture. Things change and it’s 2016!