Natural Selection

Evolution of Humans

What is Natural Selection?

Natural selection is the gradual change of a species. They evolve to better adapt to the evironment that they live in. For example; the peacock. The female peacock will only chose the biggest, brightest male for a mate, eventually the smaller, duller peacocks died out.

Natural Selection in Humans

Changes in The human Skull.

Scientific research has shown a substantial amount of change in humans, not only in appearance but also in behaviour.From about two and a half million years ago to the present the size and shape of the human skull, the face and braincase in particular, has changed dramatically.Around 2.5 million years ago the brain case was smaller and the face was longer and slightly curved in comparison to todays skull where we have a large brain case and a smaller flatter shaped face. Over the last 3.5 million years the brain capacity has increased by 800cc.

Behavioural Changes.

A little over 2.5million years ago humans started creating rock tools. Back then the tools consisted of a cobblestone and a "hammerstone". The hammerstone was bashed againt the cobblestone which send small shards of sharp rock flying off. These small flake like shards were a useful tool for cutting meat off the bones of animals. Around 1.5million years ago humans started to make really big flakes of rock and then bashing the edges the entire circumference of the flake resulting in the edge to be sharp the whole way round and this being the oldest known handaxe. Around half a million years ago we see that stone axes became smaller until eventually we see the origin of the arrowhead. Around 100 000 years ago we see the origin of the bone harpoon

Changes in size and shape of the human body.

The Changes in the size and shape of the human body are quite evident. Millions of years ago the human body was shorter and a little hunched over. As the years moved on the human body became taller and straighter until eventually we end up with what we have today.

BY TANYA THAMS