How do women get endometriosis?

How do women get endometriosis? This question has baffled investigators for nearly a century, and the pathogenesis of endometriosis remains an enigma to this day. While Sampson's retrograde menstruation theory is widely accepted, the gaping divide between the near-ubiquity of retrograde menstruation and the moderate prevalence of endometriosis has been difficult to explain. Now, Mumusoglu and Hsueh have provided some much-needed clues by proposing that endometriosis is likely a result of maladaptation of the evolutionary baggage to dramatically changed societies and cultures. These changes are profound, sweeping and across the board, resulting in myriad mismatches between the evolutionary legacy and the changed societies, which, in turn, have generated many potential risk factors for endometriosis that were completely absent in hunter-gatherer societies. These risk factors could conceivably account for the glaring gap between the ubiquity of retrograde menstruation and the moderate prevalence of endometriosis. This perspective may force the viewing of endometriosis from a fresh angle, providing a roadmap for future epidemiological studies, and potentially providing the prospect of development of novel ways for disease prevention and treatment.