On Our Own Two Feet

by Stephen Whitt

Odyssey

Humans have developed a very strange skill: bipedality. Bipedality is walking on two feet, and is unique to primates and rare among all animals. It is very old, and came long ago, before humans developed big brains.

Chimpanzees are NOT our ancestors; they simply share a common ancestor. But take a look at their skulls, anyway. Compare it to a human skull, and there are differences everywhere. For example, the human face is quite flat, while a chimp’s face sticks out. Also, the human’s skull case is HUGE compared to the chimpanzee’s one, as well as all other animal skulls. But a very big difference is the foramen magnum. This hole allows our spinal cord to connect with the brain, through the skull. The chimp walks in all fours its foramen magnum is angled backward and downward. However, the human’s foramen magnum is right at the bottom.

If you compare those two skulls to a third, the skull of Australopithecus Afaresis, you will see that although our ancestor’s body is very similar to ours, its skull and a chimp’s skull are extremely like each other, with the face sticking out and a smaller brain case. But the foramen magnum, like ours, is at the bottom, proving that Australopithecus Afarensis walked on two legs.

There are many debates about why we started walking bipedally. It was thought to be for freeing our hands for tools, but our ancestors were walking on two legs long before stone tools were invented. Other people think that we did it to walk across Africa’s hot and growing savannah in search of forests, but it was proved that our ancestors were already walking in forests, before the African forests started shrinking. So some think that we walked because we had to wade across rivers or streams, or even swim across ancient seas. One man, C. Owen Lovejoy, thinks that they were useful for freeing our arms to carry food for our mates. Whatever it is, nobody has shared a proven theory for why we started walking on two legs...

"Humans are very strange."

Whitt, Stephen. "On Our Own Two Feet." Odyssey 1 Oct. 2009: 26-28. Print.