Hominid Development

Looking at the hominid bush can be very confusing. Inner lapping dates and names, all based, for the most part, on partial fossils found among the millions of pieces of debris in Africa. For the purpose of this extremely brief paper, we will not concentrate on the individual finds and developments those finds imply, but instead look at the progression of the general changes within the hominid record. Specifically, I will examine two areas of the hominid development – the changes that led to bipedalism and the development of larger brain capacity.

Bipedalism, something that we take for granted, was not an easy change for hominids, however it was an extremely important aspect of evolutionary development. “The advent of bipedalism is not just a major biological transformation but a major adaptive one as well” (Leakey, 1994) as it “is the key feature differentiating early hominids from the apes” (Kottak, 2008). It took an alteration of at least three areas of the body to allow hominids to begin the journey to bipedalism. One area was the placement of the spine in relation to the skull. The hole at the bottom of the skull, the foramen magnum, of hominids changed from being toward the rear of the skull to being in the center of the skull, so that “the skull was balanced on top of an erect body – a trait unique to species that move upright” (American). It was this placement that was a representation of the adaption to walking on two feet rather than two legs.

Another area in which hominids showed adaptation for bipedalism was in the development of the humanoid foot. Unlike other primates, the hominid foot “have a big toe that is in line with other toes” (American) which is designed to help with balance. Also, the arch and the heel adapted to accommodate the change in weight distribution

A third area of development that the hominid bush went through to adapt to bipedalism was in the shape of the pelvis. In diverging from the other primate species, the hominid bush developed a wider and shorter pelvis. “With bipedalism, the pelvis forms a sort of basket that balances the weight of the trunk and supports the weight with less stress” (Kottak, 2008). This change in the fossil record is a clear difference between the hominid bush and the lineage of other primates.

While bipedalism is one way in which the hominid fossil record evolved, there was another significant evolution that can be seen changing from one hominid species to the next. This was the size of the cranium. In early hominid species, particularly the Australopithecines, the cranium size averaged “around 300 to 500 cubic centimeters, or roughly the same as a modern great ape” (American). There was a significant “jump in the size of the brain that occurred with the evolution of Homo hablis” (Leaky, 1994) this increase continued throughout the evolution of the Homo genius. Homo ergaster, for example, had a brain