Walking on Two Legs and Freeing the Hands

Shariq Ali
Valueversity

In the history of human evolution, certain changes transformed not only the human body but also the destiny of humankind itself.

One of the most important of these changes occurred when our ancestors gradually shifted from walking on four legs to walking upright on two legs. In scientific terms, this process is called bipedalism. It was this evolutionary step that later paved the way for the development of the human brain, the skilled use of hands, tool-making, and ultimately civilization itself.

According to scientists, one of the key indicators of this transformation is an opening in the skull known as the foramen magnum. This is the point where the spinal cord connects to the brain. In four-legged animals, this opening is positioned toward the back of the skull because their heads are angled forward.

However, as early humans gradually began to stand upright, the foramen magnum slowly shifted downward and toward a more central position so that the head could balance properly on top of the body. Even today, scientists examine the position of the foramen magnum in ancient fossils to determine whether a creature walked on two legs or not.

This evolutionary transition began approximately six to four million years ago in Africa.

Early hominins such as Sahelanthropus tchadensis and later Australopithecus afarensis — famously known as “Lucy” — clearly show this shift in the position of the foramen magnum. This suggests that although they were not fully modern humans, they had already taken important steps toward upright walking.
Not only the skull changed — the human foot evolved as well.
In tree-climbing apes, the big toe is separated and adapted for grasping branches.

During human evolution, however, the big toe gradually aligned with the other toes so that the body’s weight could be supported more efficiently.

Arches developed in the feet, making walking and running more effective. The legs became longer, the hips wider, and the spine gradually developed its characteristic S-shape, helping the body remain upright while distributing weight in a balanced manner.

Scientists believe that several factors may have driven this remarkable transformation. Dense African forests were shrinking while open grasslands were expanding.

Walking upright allowed early humans to see farther across the landscape, conserve energy, reduce direct exposure to the sun’s heat, and perhaps most importantly — free their hands.
Those free hands eventually made tools, carried children, hunted animals, and laid the foundations of civilization itself.

Thus, bipedalism was not merely a new way of walking. It was the decisive turning point in human evolution that opened the path from an ordinary animal to a thinking, creative, civilization-building human being.