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2 Theories of Human Evolution

There is considerable evidence that Humans evolved from animals.  However, the exact details of the intermediate steps are less clear. There are many variations on the basic theory.  In particular, we are significantly different from our nearest relatives, the Chimpanzees and the Bonobos.  In fact, just looking at these two animals, you might be fooled into thinking that their nearest relative was the Gorilla rather than the Human Being.

Here I want to examine two of the variations on the Theory.

Savannah Theory

The more commonly accepted theory is that we evolved on the open savannah.  The idea is that we developed our upright method of walking both to free our hands and to be able to see further. We would be able to see predators from a greater distance.

I should explain that last statement.  The theory of evolution by natural selection simply means that the ones which survive are the ones best able to survive.  They are the ones who have babies to carry on the group, so our ancestors who tended to stand up survived.

Aquatic Ape Theory

This was another idea. It appeared to explain many things. The theory is that at one time in our evolutionary past we went through a semi aquatic phase.  Naturally, if animals wade regularly, being more upright is an advantage. 

We would also have access to the rich food sources of the seaside like shellfish.  Our use of tools would also be encouraged by the need to prise the shellfish off the rocks.

Years ago, I read a book about this theory.  It was extremely interesting, but I was not convinced the theory is correct.

Our Relatives

It is believed that we are descended from an extinct animal called Pan prior.  This was also the ancestor of the Chimpanzee, Pan troglodytes, and the Bonobo, Pan Paniscus.

We can look at these two species to find similar evolutionary paths emerging.

Bonobo

This is the most aquatic of all the apes.  It is also the one that walks the most like us and stands up the most.  They live in an area of equatorial rainforest in The Democratic Republic of the Congo.  They spend quite a lot of time in the water, and eat water plants and water creatures including fish that they catch as well as things from the land.

It is definitely possible to see many Human like characteristics emerging in the Bonobo.

Savannah Chimpanzees

Although we generally think of the Chimpanzee as a jungle animal, some of them have taken up living on the open Savannah.

Savannah Chimps spend more time upright than Jungle Chimps, although probably not as much as Bonobos.  They have also taken to using caves a little.

Chimps and Leopards

Chimpanzees recognise that Leopards are dangerous animals.  If Savannah Chimps are faced with a Leopard the Chimps will attack it.

 Imagine you were a leopard faced with a large group of Chimpanzees.  The ones facing you will be the larger and more aggressive males.  They will be making a lot of noise as well as throwing everything in reach at you.  Savannah Chimps can throw rocks hard and accurately as well as using any small trees or branches as clubs.   The Leopard will beat a hasty retreat.

Savannah Chimpanzees will sometimes make unprovoked attacks on Leopards, and kill both the adults and the young ones.

Chimps and Lions

Lions are more powerful than Leopards, and can hunt in groups.  But a group of Chimps will stand up to a pride of lions.  Neither side attacking.

Chimpanzees are similar in size and strength to our ancestors.  Looking at how Chimps survive on the Savannah we can see that our ancestors could have survived in the same way.

Summary

Both the competing theories seem to be plausible.

Aquatic Humans

It is interesting to note that modern Humans are more aquatic than any modern ape.  Some groups of people spend as much time in the water as on land.  In Zamboanga in the Philippines there is a group of people whose children seem to be able to swim as early as they can walk, and even very young children will dive for coins thrown by the tourists.
 
I have seen a report that these people have a greater amount of webbing between their fingers than most people, but I have been unable to confirm this.
 

Young Chimpanzee
 
Young Human
 
Bonobo

Human