Scientists Challenge a Long-Held Belief About Why Human Childbirth Is So Difficult
A recent study, published in Proceedings of the National Academy of Sciences, fundamentally challenges the long-held "Obstetrical Dilemma" theory, which posits that uniquely difficult human childbirth stems from an evolutionary compromise between bipedalism and large-brained infants. Researchers compared birth canal tightness across 18 mammalian species, revealing that a "tight squeeze" is common, not exclusive to humans. This new data suggests that the relative difficulty of birth, measured by the fetal head-pelvic inlet ratio, is widespread, potentially reshaping our understanding of reproductive evolution.




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