The Polycystic Ovary Syndrome and recent human evolution

The Polycystic Ovary Syndrome (PCOS) is a complex endocrine disorder characterised both by reproductive and metabolic disturbance, and is the most common cause globally of ovarian infertility. It is also a familial polygenic condition, linked genetically to both Type 2 diabetes and the metabolic syndrome. The striking evolutionary paradox of this prominent genetically-based condition, which impairs fertility, is that not only should it have diminished in prevalence, but it should have done so rapidly – unless there has been some form of balancing selection. The emerging discipline of evolutionary medicine can provide important insights into the causes and patterns of occurrence of common diseases such as PCOS. In this paper we review the impacts of PCOS on infertility, fecundability and lifetime reproductive success and then critically appraise published hypotheses about the evolutionary origins of PCOS and related conditions.

► PCOS, a heritable yet common cause of ovarian infertility is an evolutionary paradox.
► This paradox has spawned a number of evolutionary hypotheses, which here are appraised.
► The concurrence of metabolic and reproductive elements in PCOS is the key to evolutionary understanding.
► Human reproductive ecology and nutritional history have shaped vulnerability to PCOS.
► Fertility selection has the power to rapidly reduce PCOS prevalence.