What’s fascinating about being alive is that we’re all products of an evolving species. Think about it, why are our brains capable of doing what they do? This wasn’t always the case. When did this start and what has been the timeline of its development? An act as simple as walking is also a sign of evolution. This ability and the theories behind why this happened, provide a look at the early development of homo sapiens.

In the July 2010 National Geographic issue, Jamie Shreeve writes in an article on the evolution of bipedalism:

Consider Ardi’s [the skeletal remains of Ardipithecus ramidus, a human-like species from about 4.4 million years ago] foot. All later hominids, including Lucy have a big toe that lines up with others toes, helping to provide the propulsive force in upright-walking, long the hallmark of our lineage. Ardi’s big toe instead splayed out to the side, like those of apes – the better to grasp on to limbs when clambering about in the trees. Yet Ardi’s foot also contains a small bone called the os peroneum – retained in the hominid lineage from ancient apes and monkeys but almost never seen in chimps and gorillas – that keeps the bottom of the foot more rigid.

Ardi’s pelvis also bears witness to a primitive primate caught in the act of becoming human. The human pelvis has undergone a major overhaul to adapt it for upright walking – a locomotor juggling act requiring one limb or the other to be suspended in the air while the other pushes forward. As far back as Lucy, 3.2 million years ago, our hip bones had become broader and shorter to enlarge attachment areas for gluteal muscles that stabilize the supporting hip joint. In contrast, chimp pelvises are narrow and long and provide more rigid support for climbing but force chumps to lurch side to side when walking upright. Ardi’s upper pelvis is short and broad and shows other features rarely seen except in hominids, such as a protrusion on the inside edge of the pelvis where bone was added during development ot bolster support for a bipedal stride. Yet the lower pelvis is thoroughly apelike, with attachments for massive hind-limb muscles needed for effective climbing.