ABSTRACT
Contents Introduction.................................................................................................. 78 Prevalence of Polycystic Ovaries and PCOS and Phenotypic Differences in the Expression of Associated Traits ................................ 79 Genetic and Developmental Predispositions to PCOS ..........................80 Evolutionary Perspective on PCOS: Seasonality and Unpredictable Environments ..................................................................... 82 Why Is PCOS Not at Even Higher Levels in Modern Populations? ..... 87 Critical Analysis of the Evolutionary Perspective on PCOS .................88 Do Evolutionary Hypotheses Relating to PCOS Aid Clinical Practise? ........................................................................................................ 89 Conclusions .................................................................................................. 91 Acknowledgements .....................................................................................92 References ..................................................................................................... 92
Introduction Stein and Leventhal’s nding of polycystic ovaries, which they eponymously described as part of a circumscribed clinical syndrome,1 has evolved to become a nebulous entity with polycystic ovaries as a prominent component. Biochemical aspects, both endocrine and nonendocrine, have become part of a wider polycystic ovary syndrome (PCOS), recognised as a very common cause of anovulatory infertility.2-4 While the original Stein-Leventhal syndrome described multiple ovarian cysts, obesity, hirsutism, menstrual abnormalities, and amenorrhoea, symptoms of PCOS also include acne and androgenic alopecia. Obesity, when it occurs, tends to include centrally distributed adipose tissue. These features, singly or together, are not evident in all affected women.5 Despite this, most show a degree of insulin resistance.6 PCOS is thus a complex endocrine disorder, for which the diagnosis is not always straightforward.6,7 However, many practitioners now agree that it can be dened on the basis of at least two of the following features in combination: presence of polycystic ovaries on ultrasound examination, oligo-or anovulation, and clinical or biochemical evidence of androgen excess.5
