I have long been interested in human evolution, and especially in the very early split between ancestors of chimps and humans. I like to think of bands of very early hominids in that pristine environment six million years ago (6 mya), especially the females and their babies. What caused the two lines, one arboreal and the other bipedal, to split off? Why have humans lost their hair, are fatter than chimps, and are able to talk?
These are questions that have long lain beyond the reach of archaeology and palaeontology – and it appears, modern doctors.
“Humans evolved as long distance persistence runners on the arid Savannah of south and East Africa. We acquired our ability to regulate our body temperature during prolonged exercise in dry heat despite quite large reductions in total body water – no other mammal has the equivalent capacity.”
This was the beginning of a recent article in the BMJ by Timothy Noakes, Discovery Health Chair of Exercise and Sports medicine, Cape Town. It was an excellent account of how humans are able to regulate their water balance relying on thirst alone, and how unnecessary it is for us all to be exhorted to drink more and more fluids.
However, the beginning dismayed me. Yet again the “savannah” hypothesis is being trotted out to account for why and how we diverged so much from the primate line which had occupied the arboreal niche for so long. The main problem (out of very many) with this “theory” is that the savannah did not exist in Africa at the time hominids were beginning to go about on two legs. The savannah, with its endless grassy plains, did not come into existence until 2 mya, long after skeletons of early hominids had shown clear evidence of bipedalism. There is no evidence at all that the savannah played any part in the crucial changes – bipedalism, subcutaneous fat, hairlessness, our loss of smell, our ability to sweat or our ability to talk, let alone our big brain, that distinguish us from the chimpanzees, as these were already there before the savannah appeared.
The trend to bipedalism started much earlier. The ancestors of chimps and humans started to diverge between 6 and 7 million years ago and the skeletons of Ardi, dated at 4 mya and Lucy at 3 mya, showed that bipedalism was well under way by then. Ardi is very much in transition with features both of tree dwelling and bipedalism while Lucy is definitely bipedal though not terribly good at it – her knees would not lock and her feet would not allow for any sort of running. The savannah did not appear until 2.5 million years ago and indeed by then the process had gone on for long enough for some hominids to be able to do long distance running. So whatever started bipedalism off it was not the prospect that some time in the future man would need to be a long distance runner on the savannah. It was just that by that time bipedalism had advanced to such an extent that early hominids could expand their habitat into it.
Most of the other characteristics peculiar to humans had also probably come into being in the intervening four or five million years, well before the savannah made its appearance.
So why do doctors and scientists like Timothy Noakes, and most notably palaeontologists, still seem to think this is the only explanation? I think this is because of a tendency amongst scientists to ignore any suggestions that do not come from their own kind – especially if that someone is a woman.
There is another good theory which explains all of these developments simply and elegantly – the Aquatic Ape theory, first suggested by Sir Alister Hardy and promulgated in the 90’s by a series of very popular books by Elaine Morgan, who originally was a writer for television.
To me, and I would have thought to anyone (such as a doctor) who is interested in our physiology as well as our skeleton, this is an enormously attractive theory. According to it, our ancestors, tree dwelling African primates, suddenly found their terrain covered with water. This could well have happened in the north east of Africa at about that time (6 million years ago) due to movements of tectonic plates. Many will have drowned and some moved away back to the trees, but some were trapped at the water’s edge. This they found to their liking. Their diet was excellent with abundant marine and coastal life, easily caught by primates with hands used to grasping. It was rich in protein and omega 3 fats – good for brain development. However this wasn’t a quick trip to the seaside – it lasted about 3 million years, long enough for considerable adaptations to have been made to the anatomy and physiology of these early hominids.
Firstly, hairiness would have been very unhelpful. Wet hair does not insulate. At first there may have been changes in sebaceous glands which secreted sebum, the only purpose of which is to waterproof hair (such as with seals and otters). This is now seen in foetal development with the lanugo and sebaceous glands growing in parallel in the latter half of pregnancy. But the lanugo is shed just before birth and, after producing the vernix, (which protects the skin from amniotic fluid), the sebaceous glands disappear except for on the face, back and pubic areas. And in the meantime the foetus is putting on fat as fast as it can, not, as in most mammals, around the gut, but just under the skin, in fact bonded to the skin in a way not seen in any other mammals except those which have gone back to the sea such as elephants and sea cows. The hair, even protected by sebaceous gland secretions, became functionless and was lost. It was a good choice – subcutaneous fat is an excellent insulator in water. It also increases buoyancy and of course protects against famine.

So these small primates in shallow water and on the beach in temperatures which were very high at that time, could easily control their body temperature and could stay in this environment, eating food on the seashore and diving and fishing.
Now enter bipedalism, which came partly because of streamlining of the body shape for swimming and diving (would a gorilla have made an Olympic diver?) and partly because the hominids would have spend a lot of time walking on two legs in shallow water – allowing them to carry things, particularly babies. Once the hair had gone, babies could not hang on as can chimp babies, and have to be carried, and if babies don’t survive the species dies. These two developments – hair loss and bipedalism – must have happened gradually in order for babies to be reared. Note that hair remains on the head, which would have been out of the water so the older baby and small child could always hang on to that. As these early hominids spent more time erect they would have become better at walking bipedally, but it must have been a very long process – Lucy was not an efficient walker, but at least would not have had the dangers of practising unaccustomed walking on the savannah, where she and her offspring would have been easy prey.
It also explains speech – chimps can only make involuntary sounds, and teaching them to speak has been found absolutely impossible. But we can because we learned to control our breathing while diving (due to our descended larynx), and even primitive speech would have been an excellent way of communication. Speech, I think, started very early, much earlier than most scientists assume, and would have taken a long, long time to be really useful, as it would need a much bigger brain to develop proper language.
We don’t have a very good sense of smell either do we? Of course smell isn’t much use in the water and whales and dolphins have also poor sense of smell. Really, for land mammals as we are now, this was a terrible loss. Smell is incredibly important to all other mammals.

As the pelvis adapted itself to bipedalism, it became less easy to give birth to big babies. But babies were growing bigger, and especially their heads. The foetal brains were getting bigger due to this excellent food source of fish and marine animals, rich in omega 3 fatty acids. So what happened was that mothers gave birth earlier and earlier to less mature, or even premature babies. Those whose babies were born with heads too big would have suffered obstetric disasters and would not survive. Human babies therefore became the most helpless at birth of any other mammals. Once born however, the babies’ brains could grow rapidly, and the rest is history – high intelligence, language and social skills. These changes must have been completed after Lucy’s time, as her skull is not much bigger than any other primates.

And back to the article mentioned above, indeed we use sweat cooling to regulate our temperature in hot environments. Thirst is a very powerful drive – humans deprived of water will think of nothing else but the need to drink – but it is not the same with salt, which is also crucial to life. So infants in developing hot countries used to die of dehydration and salt depletion, and this was only prevented by the magic formula of a teaspoon of salt and a teaspoon of sugar in clean water, which was pioneered in the sixties. It has saved so many babies’ lives. The fact is, we don’t go seeking for salt (although we really like it when it is there). But we would not have needed to in an aquatic environment, because salt is very plentiful in food, whereas fresh water would be scarce and only available on coastal inlets.

Later the sea dried up but by then, these hominids were ideally placed to take advantage of many new environments, including the savannah. But the favourite one seems to have been a beach combing one, as several million years later the first humans out of Africa beach combed their way around the world, as proved by DNA evidence.

All these ideas and many more were researched and thought out by Elaine Morgan in her very readable series of books. The theory has never been proved, but hasn’t been disproved either, and it is at least as worthy of consideration as some of wild speculations of modern scientists. Some evidence may lie under the sea but soft tissues do not fossilize so it is very unlikely that paleontologists are ever going to be able to answer these questions. But the scientific world has not even considered this theory academically – it has been totally ignored. There are no papers in the literature that discuss it seriously, and certainly nothing that even remotely challenges it.
Probably the reason is that Elaine Morgan was not a scientist, and academics are not inclined to discuss a theory not by one of their own, despite the fact that all the books are completely referenced with scientific papers and books. They appear to have decided the best strategy is to say nothing at all about it, which seems extremely childish, although hardly unknown in science. Many theories such as the tectonic plate theory were ignored or ridiculed for decades before acceptance came.
At least they should produce more compelling reasons, for instance about why we lost our hair than the one most commonly quoted – to get rid of our parasites! (Babies and bathwater come to mind!)
To me, this very attractive theory which chimes in so well with what we know about ourselves, should be the mainstream theory that the general public hears about, rather than the male dominated savannah hypothesis (Man the Hunter bringing back the food to the women and children huddling somewhere out in the grassland). Why do we love water, showers, baths, and rivers to clean ourselves with? Other primates don’t. Why was most human expansion originally round the coasts? Why do we all love to be beside the seaside when the weather is hot?
Elaine Morgan died in 2013, age 92, without any discussion of this very interesting theory in the scientific world. I think it is high time that this was remedied. Perhaps DNA evidence is the way forward if only scientists could find a way to look this far back. But in the meantime we could at least discuss it!