Even though the modern human is a primate, and thus a member of the primate family, humans look very different from their monkey cousins.

Human feet are different from monkey feet because of what we call divergent evolution. Divergent evolution is what happens when a closed population splits off and becomes a new species. The two new species even though closely related start to develop new traits to better help them fit into their environments.

For example, a small part of a population of birds gets blown off course. In their new habitat there are many fruits. The birds with the beaks best able to eat the fruits live longer and have more children. Yet back where the birds were originally from the birds with the beaks best suited to eat grubs live longer and have more children. Thus the birds slowly evolve into two different species.

The same principle of divergent evolution also applies to humans. Human feet are different from monkey feet because humans started to walk upright on the ground. This meant they no longer needed to have hand like feet for swinging in trees. The feet changed shape to better allow for speed and balance on two feet rather than balance and grip in the trees.

Human Feet

Monkey Feet

Embryology can also be used to show divergent evolution. For example the human embryos start out with a tail much like the monkey embryo's tail. Then as the human embryo becomes older, the tail becomes smaller and smaller until it disappears from the outside of the body. Human and monkey feet also start out similar and end up different. The primate embryos all develop toes from the foot plate but the size of the toes and their placement on the foot is different depending on the species. The human toes are lined up straight while the monkey has one toe off to the side, more like a hand.