The fossils which decorate our family tree are still so scarce that there are still more scientists than specimens for them to work on.
If all items were put together all of the physical evidence for human evolution could be placed with room to spare in a single coffin.
The roots of the human tree seem to be firmly planted in Africa, where every once in a long while one of them becomes exposed by wind and water and falls into the hands of a dedicated band of fossil hunters.
The study of human pre history has become a complex expensive discipline practised by teams of specialists who are skilled at statistical techniques and adept at squeezing meaning out of seemingly unrelated measurements.
Because of the lack of evidence we are forced to weave dedicated structures around rare and isolated bones and we have to say that while we may be sure of some things, on others we could be hopelessly wrong.
There is room in the wide spaces between the fossils for a wide range of interpretation. Current experts differ in loud and noisy and newsworthy ways. However, considering there sometimes vocal exchanges there are things on which they do agree.
The current agreements go something like this;
20 million years ago, in the mild period known as the Miocene, there lived a flourishing population of generalised, primitive, hairy apes.
None of them looked like any apes that are around today, for remember that our current chimps and gorillas have also been developing over the last 20 million years, however, some of them had characters such as enlarged molar teeth, which hint at a change of diet and a move toward humanity.
It is assumed that sometime during the drier Pliocene, between 19 and 6 million years ago, one or more of these ancient apes moved away from the forest and out onto the hot open savannah, where they became more and more bipedal, ultimately producing a creature with an erect body and bearing similar to that of a modern man. This topped by the head of an older ape.
This is what was found in the Afar triangle in Ethiopia in 1974 and christened Lucy.
No one will dispute Lucy’s right to be considered as a direct ancestor of ours along a single line of evolution, but some believe that we split off from a common ancestoral stock earlier than Lucy’s date of three and a half million years ago, and they believe that we have had larger brains for a long time before that.
Both in fact agree that the change, whatever its nature took place during the Pliocene and was prompted by the rugged life on the plains of Africa.
It is a reasonable scenario. The only problem is that there is not a single piece of evidence to support it.
No Pliocene fossil containing any missing links has ever been found in Africa.
Beyond Lucy there is nothing that we have from four to ten million years ago.
For one six million year period all we have is an arm bone, a jaw bone with a single molar in it, and a single molar tooth. This is all the evidence we have for a time period where a vital human transformation took place.
Modern apes seem to have sprung out of nowhere. Biological evidence shows that we both had a common ancestor, but as with ourselves they too have no history, no fossil record. Less even, than ourselves.
We share 98% of our genetic material with Chimpanzees. The similarities between us and apes are evident and easily understood. It is the differences that are perplexing.
So, why are our backs straight, our skins bare and our lives laced with words.
What exactly is in the genetic 2% that makes us uniquely human and that makes our posture and intellect so different from theirs.
For some reason we spent a large part of the last ten million years rushing through evolutionary adaptations while the apes changed relatively little.
Something happened to us that didn’t happen to chimps and gorilla’s. What was it?
Theorys abound and dependant on your tastes you can choose any of them from the Biblical through to environmental and many in between.
The problem is that with the lack of fossil evidence a scientist can assume that we were created by mice to make them cheese and no one has the power to deny him his theory.
What we really need to do is look at the gap between Lucy and the Pliocene and think of what could have happened in this 6 million year gap that could make such a drastic change on our bodies.
I think that there is only one theory. It makes no assumptions about Genes, or tools. It doesn’t assume that hunting is a way of life.
It is a simple theory that says we had an ancestor who spent a lot of time swimming. One who left the forest about the time of Lucy and instead of going directly onto the open savannah, spent a few million years messing around in the water. An aquatic ape.
It has happened before to other groups of animals, and other mammals have taken to the water before us. Some of these have evolved into whales and dolphins, seals and otters.
So if reptiles, ungulates and carnivores , not to mention birds can take to the water, why not a primate?
An ape that went swimming more than ten million years ago, and was still in the water a few million years later would have some very important changes.
It is likely for instance that like whales and dolphins they will have lost their hair.
With the exception of a burrowing rat and a highly artificial breed of miniature Mexican dog, all hairless mammals in the world today are either aquatic, or spend a lot of their time in or around water.
Fur is great as an insulator against both heat and cold when dry. Wet it loses its ability to trap a layer of air next to the skin and becomes a liability.
The fact that we, the only naked apes have kept a layer of hair on our heads may have something to do with protection from the sun. But it may also have another use. In the last twenty years we have discovered to our astonishment that human babies are able to swim almost from birth. They are perfectly happy with their heads underwater and stop trying to breath the moment they are submerged. They behave calmly and gaze around with no sign of fear.
For children like this an aquatic life poses no problems, and for a parent long hair floating on the water while they search for shellfish gives the child contact. This may also explain why it is predominantly men who lose their hair at an older age, as it was the female who was usually with the sibling.
Another unusual thing is that humans have a dive reflex. The moment that we submerge ourselves our pulse rate cuts from 70 to 30 beats per minute and our bodies use less oxygen. It is a reflex that we share with seals and otters and other water based mammals.
Yet another consequence is the change in sexual behaviour, all aquatic animals mate belly to belly, it is more streamlined and the rear entry practiced by fully land based mammals is practically impossible. So in water mammals like dolphins and whales the female sex canal is tilted forwards, and they procreate face to face. The human female sex canal is also tilted forwards, we are in fact the only primates that can reproduce in this way.
Humans are the only mammal that walk constantly on hind legs. A few marsupials hop on powerful back springs made tripod by a muscular tail. But we are unique.
Two legs are not faster or more energy efficient than four. Being bipedal does make it easier to see over tall grass and it frees the hands for carrying, but in almost every other way it is precarious. If we fall over we hurt ourselves.
Ground living monkeys rise up on hind legs, but only when they need too, so there must have been something really vital for us to make this change, perhaps something as vital as breathing.
Try crawling into the sea on all fours, you cant stay there, the water forces you to lift and stand straight for as long as possible. Then when you float, like an otter, it is easier to float long and straight.
Aquatic animals live in an environment where it is often difficult to see and smell each other, and as a result many of the aquatic mammals have developed powerful systems of vocal communication.
However, even with this theory there is in fact very little difference between human and chimpanzee vocal chords.
The thing that is different is that we have learned to use air differently, we had to learn to hold our breath and to release it slowly. We had to learn how to channel air and take control of our lungs. It’s not hard to take the final step and wonder if we did this by diving a little deeper every million years or so.
There is something about the aquatic ape theory that feels right. It is a radical reinterpretation of the current ‘facts’ that have no evidence, but the historical establishment tend to hold it at arms length. However if you talk to a biologist they may see things differently.
So I wonder if in looking for the real missing link, it may not be the great plains of Africa, but perhaps a quiet beach, or a wide river that provides the next Lucy, and maybe we will have to re-establish a missing part of our family tree and have an ancestor known as Homo Aquaticus.
