Is our use of cesarean sections changing the human species?

A paper released by Mitteroecker et al. in October 2016 revealed an interesting new theory about the effects of the rising use of cesarean sections as a method for childbirth. They have suggested that the recent surge in the occurrence of obstructed labour (due to large fetal size and small pelvic dimensions) may be a result of human obstetric selection.

According to the theory, small pelvis genes are now more frequently being successfully passed onto offspring due to the use of cesarean sections. Babies born to these women previously which would have previously died due to obstruction during labour can now survive and are able to conserve these genes in the population.

Based on this hypothesis, the need for cesarean sections will only increase as the incidence of obstructed labour is expected to keep rising. It may seem shocking that these changes can occur so rapidly, but if the environmental change (i.e. the sudden availability of cesarean sections) is drastic enough, evolution can occur over a single generation.

Despite the logical assumptions made, the research team has failed to provide any concrete evidence for this phenomenon and have only been testing their theory by plugging observed figures into their models. It may not be possible to ever provide a definitive answer to the question of whether or not cesarean sections are behind the prevalence of obstruction during labour, as there are too many confounding factors, but the theory provides an interesting point for discussion.

http://www.pnas.org/content/early/2016/11/29/1612410113

(featured image courtesy of Staff Sgt. Arthur Hamilton, Wikimedia Commons)