Scars of Evolution - Broadcast 2
 Two-part 'mini-series' on the Aquatic Ape Hypothesis, narrated by David Attenborough broadcast in April 2005
Thanks to Christina Bjornstad for transcribing this.

David Attenborough looks at the accumulated evidence of the Aquatic Ape Hypothesis.
? There is no one Aquatic  Hypothesis.   It depends what you mean by semi-aquatic.  Do you mean a toe in the water?

DA: In the first programme we traced the reactions to the Aquatic Ape Hypothesis as first suggested by Sir Alistair Hardy in 1960 and then fully developed by the writer Elaine Morgan.    The hypothesis claims  that the features that distinguish humans from other apes: standing upright, naked, and sweaty,      swimming and diving,  with our very fat babies,  big brains, language skills are best explained as water adaptations.  In other words, that we diverged from the other apes by moving to a lake, seashore environmental niche for a considerable length of time in prehistory.  For how long exactly, where and when it occurred, and whether indeed it has ever stopped are all open questions.  But what is increasingly apparent is that the exploitation of aquatic resources was an essential component of the early human evolution.  For forty or more years the acceptable crucible of humanity was the open savannah grasslands of Africa and the aquatic alternative was ridiculed.   Then really since the early 90’s the consensus began to fall apart.  Why? What new evidence had come to the fore the last 10 or so years to cause such a paradigm shift? To drive the anthropological mainstream off the savannah and with a certain amount of pushing and shoving and cautious hesitation, down to the water’s edge. 

We’ll start with the brain.
Michael Crawford Institute of Brain Chemistry and human nutrition in London:  It was manifestly clear that this idea of Homo sapiens evolving a big brain through fierce competition on the savannahs of Africa with the big cats and all the rest of it was just rubbish.  I mean there was absolutely no parallel example of evolution of a brain on the savannahs.   Every single species without exception lost its relative brain size as it evolved bigger.

When we came to do the studies on the reasons why there are different sizes of brains in different animals, and realized that the brain required fat; 60% of the structural material  is fat. So where do these fats come from.  When we did these studies it all sort of fits together.

DA:  Michael Crawford and his team have established two crucial facts.  First  that the brains of all other savannah animals had shrunk in relative size, as they evolved larger bodies.  By contrast, the human brain had grown three-fold.  But secondly and more important, they demonstrated that to evolve a larger brain you need an abundant supply of Omega-3 fatty acids.  Especially DHA. but also crucially iodine.  And the only place to find that accessible and abundant supply of brain selected nutrients was at the shoreline, in the marine food chain.

MC:  When one compares the land base  with this universal collapse of  brain size with what goes on in the brain system.    I mean you’ve got the .dolphin  which as about the same body weight as the zebra.   The zebra’s got about  360-70 grams of brain in its head, The dolphin’s got 1.8 kilograms.  It’s just phenomenal.  The only way Homo sapiens could end up today with 2% of his body mass as brain would be to find an ecological resource that would provide him with the nutrients they would require for the brain to grow.  And the only place you could do it is at the coastlines.

DA:  Some researchers were still skeptical.  They suggested that the brains or the bone marrow of  big game on the savannah might supply  essential DHA.  But if that were the case, then surely the dominant predators, the big cats, far better equipped than the small fruit-eating hominid ape to crunch through bones and skulls, would have got into the brain and marrow first and thereby grown their own big brains.  Well, they haven’t.
MC:  Believe you me, if you want to try to get the brain out of a buffalo skull, you would need a hacksaw to do it.  It’s no joke.  And it would certainly not gone round and trying for argument’s sake.  And by the time you got it home to where the women are, it would probably be festered and be foul.  Whereas by contrast, it would be totally natural for a woman at that time being heavily pregnant which is the most important physiological time for brain growth, to be able to walk around the coastline, and pick up food.  At that time it would have been incredibly rich.  The richest food resource on the planet on your doorstep.

DA:  Dr Steven Cunnane worked with Professor Crawford in the 1980s and 90s unraveling the story of how the large human brain came about.  He was increasingly struck by another curious feature of humans:  that our babies are quite extraordinarily fat.  Newborn chimps and gorillas by contrast, have no fat at all.
SC:  Our babies have a ten-fold increase in fat, in the last 12 weeks before birth.  A ten-fold increase in their total body fat.  So you’re talking about 30% of that baby’s weight is brain and body fat.  Now a chimpanzee’s brain is almost as big as an infant’s brain at birth, but it has no body fat to speak of whatsoever.  So it abandons brain expansion at birth, because it can’t run it.

DA:  By contrast, the human brain trebles in size from birth to around age 10.  And there’s another persuasive aspect of the theory.  It’s predictive.  It predicts that because iodine and other nutrients in the marine food chain are essential to the evolution of the human brain, then if we switched to a new land-based diet, that is poor in those nutrients, brain function will suffer.  And that’s exactly what has happened.  According to the World Health Organization Report in 2004, iodine deficiency amongst inland populations, affects around 740,000,000 people worldwide.

MC:  In  corela..school children, 60% of them, are iodine deficient.  I saw exactly the same in Indonesia when I was there for World Health Organization, 60% of the school children, 

the same number,  had palpable goiter.  When we got to the fishing villages, not one.  So this nutrient lack which has happened as a consequence of population expansion has brought about some serious degenerative disorders. 
DA:   Even for pillars of the anthropological mainstream, including former editor of the Journal of Human Evolution, Professor Leslie Aiello, the marine food chain account of brain evolution is becoming compelling.  And it’s tied up with another compelling story, of migrations.

LA:  Personally, I feel that the dietary and nutrition side of things would be a very interesting area to research further.  Because  there’ many convincing argument that migration would be easier along the seashore , type of environment.  But, you know, we need to be able to address the features.  We need to be able to test them in a scientific manner.

DA:  Marc Verhaegen, a Belgian medical physician, who has researched and published widely in support of the aquatic ape hypothesis describes the boom years of the Homo erectus dispersal across the globe.  This early hominid relative of ours arguably experienced a greater brain growth than any other branch of the hominid family tree.

MV:  About 1.8 million years ago we suddenly find fossils of homo along the warm coasts of the old world.  We find them from Algeria, over the Dmanisi..,in Georgia, to Iran they’ve found tools near paleo…Lake.……Also Java…Jakarta…so suddenly, one point eight million years ago they find them everywhere.
DA:  But why did it happen then?  Was there an environmental catastrophe, or perhaps a population boom that drove these early bipedal hominids first to the beach, and then around the coastline. What pushed them?

MV:  I don’t think it was a push.  Perhaps better call it a pull. It was an opportunity.  I see it like this, at the beginning of the Ice Ages there was an enormous amounts of water that were kept as ice at the poles.  And so there was a drop of 100 meters or more of the sea levels and on the continental shelf there came an enormous space free, probably abundant in aquatic in shellfish and crabs  And  so was  certainly an opportunity for our ancestors.

DA:  And the story took a dramatic step further in October last year. When newspapers from across the world put a startling image in their front pages.  It was a picture of …homo floresiensis.  A curiously small hominid fossil discovered on the Indonesian Island of Flores.  The adult was only 3 feet tall.  Mike Morewood and his colleagues who made the extraordinary discovery, nick-named it the Hobbit.  But from one perspective this Hobbit skeleton, dated to 12 thousand years ago, was just a follow up albeit a long one, to another remarkable find by the same team a few years earlier.  Peter Brown, the professor of archeology and a lead member of the team.

PB:  On Flores we have a sight called man o mingo where there are ,,,,,dating from 530.000 years ago.  Looks like some tool making bipeds got to Flores at least by 840,000 perhaps earlier.  The concern was never so much the date, but how they got to Flores  small island………………………Maybe they were stegodon…jockeys.  Maybe they rode  on the backs of elephants between the islands.  Another likely….they could have built water crafts, and ride them from island to island, if you can see the next island,…….would have been  actually the process.  In the 1930’s  a man called …..said Australia  was populated by a pregnant woman on a log with a dog.  If obviously takes more than one pregnant woman on a log to populate an island, it could have just been an accidental process rather than intentional. In boats.  We will never really know  but it would appear we can be certain of is  that water had to be crossed  to get there.
DA:  After decades passed, and the evidence accumulates, in sometimes unexpected directions, Elaine Morgan is still going strong.  At 84 and with……gout,  she doesn’t see any difficulty getting to Flores.

EM:  I expect maybe we were riding on the backs of elephants, or else we drifted across in some kind of craft.  But if you are an anthropoid ape or some  variation of an anthropoid ape, you don’t get to construct crafts unless you are very confident in the water already, and quite happy with crafts.  I also think that at that stage we would have been perfectly capable of swimming across.
DA:  Swimming.  When did humans learn this considerable skill?  As Professor…Erica Schagatay .an authority on apneic breath control would argue that we learned it at about the same time as we learned to dive in the water.  And if you consider what you have to do to skin dive, well most importantly you have to hold your breath.  Then you find something very interesting.  In land mammals, including our primate cousins, chimps and gorillas, breathing is entirely involuntary.  You can’t get a chimp to hold its breath.  Breathing is as unconscious as the beat of its heart.  And it is for us humans too a lot of the time.

ES:  Most of the time our breathing is completely automatic.  Not something we have to think about.  While we’re asleep our breathing pattern is completely run by…autonomic systems .of the brain.  We don’t stop breathing when we sleep
DA:  But there are other times for example like now while I’m talking to you, that perhaps I might want to emphasize a particular word, I then switch to voluntary conscious control of my breathing.  It’s second nature and we do it all the time.  But it gets even more intriguing.  When we look at the fully committed aquatic mammals, dolphins.  Dolphins and some whales have actually lost the ability to switch back again from conscious breathing to unconscious breathing.  One might ask then so how do they sleep?  Well, it’s fascinating.  Brains scans of dolphins show that when they sleep, and they sleep for the very typical mammalian 8 hours a day, they can only let one half of their brain sleep at any one time. They have to keep the other  half awake to ensure that they surface regularly for a breath of air.  So there’s a fantastic symmetry to how the whole range of mammals handle breathing.  Fully aquatic, exclusively conscious;  fully  land based, exclusively unconscious.  But as semi aquatic, we can switch between the two, as and when it suits us.  And if you want support of this idea, that expert breath control is necessary for speech, listen to this:

Hoover:  “Hey….Over heere….hey hey……over here……

DA:  It’s the voice of Hoover, a popular character in Boston, who had a 2 column obituary in the Globe and Mail  when sadly he passed away in 1985. 

Hoover:  “Yayaya…..hello there ….hahaha….hey hey…come over here…”

 DA:  Hoover died at the grand old age of 14.  See, Hoover was a harbor seal.  It’s said he was the only non human  mammal  ever to make sounds of human speech.  By all accounts, he learned the phrases from the couple who rescued him as an orphan in 1971, George and Alice Swallow, and who raised him for the first few months in their bath.

Not everyone, however, is convinced about which came first, speech or swimming.

Prof Leslie Aiello:  Language is obviously one of the primary human adaptations.  And breath control is essential to language.  But breath control can be used for other things as well as language.  One of them is swimming.  So our ability to swim, controlling our breath and all, might be just a by-product of our ability to speak.  It’s as reasonable a hypothesis as turning around and saying we can speak because we went swimming

DA:  Well, It’s an interesting possibility.  What we do know is that both the diving response and natural swimming ability are displayed extremely early in the growth of the human infant.  Indeed they are strongest at birth.

Susan Vervel:  In the Indonesian….water people, the traditional way of giving birth was to go in the sea.  But the missionaries now try to make this population stop.  They were still trying to practice it because it was so much easier for the women to give birth in water.  And also the children of course…there are babies swimming from very early age.  They swim and dive very well before they can walk. Some people get very worried with babies born in the water.  It’s going to drown, because the babies first response is to take a deep breath.  But human beings are amazing.  When they’re born, they still have intact the diving reflex, or we call the duck reflex.  Which means if there’s water on the face there are receptors from the face that will close the throat up.  So actually the baby will not inhale water.  Once air hits the baby’s face, the receptors will trigger off the breathing response  and it will take the deepest breath  that it will take for its whole life.  So the baby’s quite safe to be born underwater.  The longest I’ve seen a baby under water is about a minute.  And that’s quite a long time

DA:  Susan Vervel is consultant midwife at Abberbrooks Hospital in Cambridge.  With many years experience training midwives, water birthing, she’s still impressed at how very comfortable humans are, both mother and baby, with giving birth in water.
SV:  After water  birth both mother and baby seem to be very relaxed after being under water.  They come to the surface they take their first initial deep breath and they settle quite quickly and the mother holds the baby skin to skin.  The cord which is attached to the placenta, in most cases, is just long enough for the mother to bring the baby to the breast.  Again evolution has worked really well in our favor so if the mother was on her own in a river for example, she doesn’t need anyone to help her.  She can bring the baby to the breast.
DA:  It seems extraordinary that humans, reputedly a land mammal should find giving birth in water a perfectly natural thing to do.  Professor Peter Wheeler Dean of Science at Liverpool  …John Moors….University is a leading opponent of the Aquatic Ape Hypothesis and has argued for many years that it’s misguided and wrong.  He believes that giving birth in water could not be an evolutionary adaptation because it would be simply too cold for the baby

PW:  Human babies lose heat very easily.  Cause they are very small….body ratio.  And even….they start to lose body heat or additional body heat at temperatures as low as 33, 34 degrees centigrade which is 2 degrees below body temperature.  So even in air they’ve got problems.  In water they’d probably be even greater.  The baby would have to start producing heat  maybe one or two degrees below body temperature, and if water temperature falls a couple of degrees below that, they can’t maintain their body heat production to maintain their temperature at a stable level and they’ll die.  So when you see pictures of babies swimming around in water this is warm water.  This is the sort of temperatures you get in natural water bodies at sea, they would die very quickly.

DA :  Susan Vervell is more worried about the opposite problem.

SV:  What we do know when there have been babies who need to go to the special care, the water has been too hot.  When I was talking to some of the home midwives in Moscow recently, a couple of them were taking women to the Black Sea, where the women would go up to waist height and maybe crouch down with support and give birth to their babies under water in the summer in the Black Sea, where the temperatures is down to 19 or 20 degrees, which for me would be quite chilly.

DA:  There is one other odd feature of human birth. It’s so odd, indeed it’s thought to be unique to humans but it’s not much studied or written about in the medical literature.  It’s call vernix caseosa Latin for cheesy varnish.  And it’s the name of the fatty greasy coating of the human infant when it’s born.

SV:  From a midwifery perspective I saw a baby…….water with a lot of vernix over its whole body……

DA  In other words, if the baby has an excessive vernix all over it’s probably a sign that it’s slightly premature.  It’s been suggested that it waterproofs the skin when it’s submerged in the amniotic fluid in utero.  But if so, then surely all mammals would get this protection.  But they don't.  Apparently it's only human babies who arrive covered in a layer of grease, looking, as Elaine Morgan described it, rather like a cross channel swimmer.  Dr Peter Jackson blackenbery obstetrician at Cambridge University for 30 years has written:

“As far as I know vernix caseosa is a purely human condition, and I do not believe that it occurs in neonatal animals.  It’s interesting that it does not occur in the other primates except human beings.  Looking for vernix in animals produces no references.”

 

 Now over the years one of the arguments against the aquatic ape hypothesis was that it makes no testable predictions.  But this case of the apparent uniqueness of vernix seemed more and more intriguing.  Could it really be unique?  Why would it be so?  And moreover a possible test suggested itself.  If entering water during labor really is a semi aquatic evolutionary adaptation of some antiquity and not a recent ….of civilized societies then one could make a prediction.  Other semi aquatic mammals should have it too. Mammals who either give birth in water or swim soon after being born would also have a coating of vernix.  So in the course of making these programmes, we’ve scoured scientific literature.  Nothing.  We contacted professors of mammalian physiology in Europe, Japan, and the United States.  Nothing.  Vernix really was unique to humans.  We wrote to marine biologists in Norway, Russia, and Alaska.  They reported back that they had never seen it.  It was a dead end.  A human curiosity.  Then just a month ago, a week before we’d finished recording, we got a call.  Professor Don Bowen in Nova Scotia northern Canada.

DB:  For a period of about 10 years we had an opportunity to handle newborn harbor seals on a regular basis.  And certainly if you do handle one, within minutes or so of birth, they are covered with waxy substance.  It’s very noticeable, in fact if you handle a pup with bare hands, your hands are coated with it.  It’s all over the entire body of the animal.  Harbor seals enter the water usually within about a half hour to an our of birth and are able to swim with the mothers almost immediately.  We always assumed that it was analogous to the vernix that humans are born with.  We actually never pursued it in a systematic way.
DA:  Now this is interesting.  As far as we’re aware, it’s the first time that vernix has been reported in an animal other than a human.  So do other species of seal have vernix as well?

DB:  Most seals do, but the concentration is noticeably less.  That is if you handle a newborn grey seal, you can feel a slight waxiness to the fur.  But certainly the concentration of vernix is much less than it is on harbor seals.  Then in other seals it seems to be even less so.  The concentration is noticeably reduced compared to……They probably on average don’t enter the water  until they’re a week or  ten days old.
DA:  These are the only observations. And have not been systematically studied and written up.  But from what But from what Professor Bowen reports, there appears to be some basic correlation between the amount of vernix of an infant at birth and how soon it takes to the water.  It would almost seem to be a case of  “the thicker, the quicker.”
DB:  Certainly  spotted seals and some of the other small…..social seals in the north pacific, I would assume have it, but nobody’s really reported it.  It is something that I think is fascinating.  I’d very much like to follow it up.

DA:  Over these 2 programmes, we’ve tried to trace the history of The Aquatic Ape Hypothesis to see how reactions to it have changed over the last 45 years.  Although it still provokes fierce debate, the evidence bit by bit, year by year,  really does seem to be accumulating in its favor.  Perhaps like Wegener and his continental drift, the tide really is turning toward Alistair Hardy and Elaine Morgan and their proposal that our earliest human ancestors were born not on the grasslands or the forest, but in the shallows and lagoons and the margin between sea and land.  Last year a book was published by 2 very  eminent and mainstream paleoanthropologists, David Cameron and Collin Groves in which they state  “At first the Aquatic Ape Hypothesis was simply ignored as grotesque and perhaps unworthy of discussion because proposed by an amateur.  But Morgan’s latest arguments have reached a sophistication that simply demands to be taken seriously.

….:  I’m not totally against it but I’m not for it either.  I think the take home message on this is as with anything there are probably kernels of truth.

EM:  I think in 10 years we’ll be over the cusp.  The tide is beginning to turn in that direction.  I think it’ll pick up speed and I think that a lot of people will bring up their own reason 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.  And I don’t know whether I’ll be allowed to say it but I’m confidant it’s going to come