Human evolution

The study of humans combined with the study of their fossils and skulls has given rise to a new field called paleoanthropology and the best part is we can really learn a lot about ourselves and our ancestors. So let us proceed…

The best way to go about learning about humans is to find out where a species branched out and when this happened. Through our fossils, now we know that we arose from a super-family of apes called Hominoidea. This family of apes includes many of the currently living species like gorilla, chimpanzee and the orangutan. But scientists have classified the primate tree into more precise groups. All those apes that resembled some sort of a human were put into the group Hominids, which means man-like apes. A genus called was created and those, which were definitely considered to be human, were classified under it. Humans are believed to have split from the apes around 5 to 7 million years back. New biochemical evidence has indicated that the last common ancestor of hominids and apes occurred between 5 and 10 million years ago.

Now we have been referring to comparative terms like partly human etc. but what features do scientists look at before classifying a hominid.

1) The brain capacity or the volume of the brain

2) The teeth arrangement and size

3) Whether the specimen is a biped or not - ability to walk on his two feet4) The age of the fossil

5) Shape and size of the skull.

6) Length of bones

The naming of the specimen is even more elaborate. When you read about each skull, you will read about most of the above features and you can compare them with the modern human.

Why should humans evolve into creatures walking on two legs? Why should such a change happen? It is much harder to explain why we differ from the gorilla and the chimpanzee much more markedly than they differ from one another. Something must have happened to cause one section of the ancestral ape population to proceed along an entirely different evolutionary path. There are two main proposed theories:

1) The Savanna theory: When the great apes lived, in Africa, there was a great drought. The forests began to decrease and the grasslands began to spread. There was only one way for the apes out of this situation - to live in the Savanna. But they had to walk on the grasslands and due to this adaptation, the humans developed bipedalism.

2) The Aquatic Ape theory: This opposes the above theory. The development of bipedalism and other features had begun during the split between the monkeys and apes. The region where they lived was flooded and to breathe, the apes had to keep their heads above the water and to do so they had to stand up straight. Perhaps this flood caused the fundamental changes and later after the floods had receded, the apes settled in different habitat perhaps because they got stranded.

Both the above theories have been described in brief, but no one can ever be sure that one of them is right.