Scott W. Simpson, of the Department of Anatomy, School of Medicine, Case Western Reserve University, Cleveland, Ohio, led the research study of fossils found of Homo erectus in Gona, Ethiopia.
Dr. Simpson stated, “Brain size is driving the whole system here…. The most successful individuals in these populations will have positive selection for [big] brains and large pelvises.” [New Scientist: “Big hips, big brain” (November 22-28, 2008, page 17)
The research team was comprised of Simpson, along with Jay Quade, Naomi E. Levin, Robert Butler, Guillaume Dupont-Nivet, Melanie Everett, and Sileshi Semaw.
The title of their paper, published in the journal Science, is entitled “A Female Homo erectus Pelvis from Gona, Ethiopia.”
Their paper states that they discovered a nearly complete “early Pleistsocene adult female H. erectus pelvis from the Busidima Formation of Gona, Afar, Ethiopia.”
Homo erectus (H. erectus) is an extinct species of the genus Homo, an ancestor of modern humans (Homo sapiens).
Please read page two for more on hips, brains, and humans.
H. erectus is thought to have been the first hominin (a group comprising of humans, chimpanzees, and their ancestors) to move outside of Africa, possibly around two million years ago, during the early Pleistsocene period.
And, "This pelvis indicates that neither adaptations to tropical environments nor endurance running were primary selective factors in determining pelvis morphology in H. erectus during the early Pleistocene.”
The widening hips of female H. erectus began as far back as 1.2 million years ago, according to the Simpson-led team.
Their paper states that past studies have indicated H. erectus had narrow hips and tall height because it allowed them to hunt more efficiently—being able to run faster.
However, this study states that wider pelvises would be preferred over more narrow ones because it allows for larger brains to develop.
The fossils they found do not show narrow hips, at least, with female H. erectus.
Although not stated in the study, maybe male H. erectus maintained narrow hips for faster running during hunting, and female H. erectus evolved wider hips for child birth, similar to what we see today in modern males and females.