Trend in Hominid Evolution

Crucial changes  Bipedalism – most crucial change  Expansion of the brain  Modification of the female pelvis  Reduction of face, teeth, and jaws.  Increased child dependency  Increased meat eating

Bipedalism  Walking on two legs.  Physical environment of Africa was changing.  Tropical forest to open country (Savanna)  Importance  See above the grass  Carry food  Use tools  Long Distance Travel  Costs  Stress on Hips  Blood flow to the brain - gravity

Expansion of the Brain  Increased brain size over the last 2 million years.  Reasons:  Tool making  Warfare  Hunting  Longer life  Language  Female pelvis:  Allowed for larger brained babies to be born.

Reduction of the Face, Teeth, and Jaws  Australopithecus:  Has big teeth and large faces.  Harder to chew food  Homo Erectus and Homo Sapiens:  Reduction in size of the face, teeth, and jaws.  Fire makes food easier to chew.

Other Evolved Traits  Modern humans are relatively hairless  Increased child dependency  Increased scavenging and hunting meat  Development of a division of labor by gender  Sharing of food