New research claims our ancient ancestors used to lay eggs; hence, women are more evolved to have wider hips than men.
The study by Barbara Fischer and colleagues from the University of Vienna, states the difference in size between women and men pelvis is the most reliable way to differentiate between the sexes. For years, it has been believed that the reason behind the wider pelvis in women is to allow the passage of babies with wide heads, hence, childbearing hips. But the new study in Nature Ecology and Evolution gives another explanation than childbirth for the wider pelvis in women.
It states the example of Virginia opossum females which also have wider hips despite giving birth to tiny babies as their offspring are one-thousandth the size of the mother. The study provides evidence that the big hips have an ancient evolutionary history that might stem from the study of Chimps.
Chimpanzees are considered to be our nearest ape ancestors and their females have wider hips than males, even though chimpanzees give birth much more easily than humans, implying that wider pelvises were present from way back.After comparing the human pelvis to our closest animal relatives, the researchers discovered the pattern of sex differences is the same.
Talking to Daily Mail, Fisher says they analysed 3D data of pelvis for these two species and found they show the same pattern of sex differences, despite large overall species differences.
According to her, the similarity suggests that the wider pelvis in females were already present in a common human-like ancestor that two species share and the way of childbirth might have been different for our ancestors.
The researchers suggest that wide hips already existed in early mammals and its purpose might have been for laying large eggs relative to adult body size.
Fischer explains that the study shows the evolutionary pattern of the sexually dimorphic pelvis (differing between the sexes) has not been developed by modern humans but is inherited from our ancestors and it might indeed stem from early mammals or amniotes (other animals such as birds and reptiles), who laid large eggs and gave birth to large foetuses.
Research claims the evolutionary mechanisms that allowed for wider hips might have been left in human code, and the genetic and developmental mechanisms to evolve a more spacious female pelvis were already in place didn’t need to evolve anew.