Overpopulation can impair fertility. A new study explains why

Scientists have reported it for decades: overpopulation can impair reproduction. Crowded chickens lay fewer eggs. Crowded mice have smaller broods. In humans, several studies have associated increased population density with ...

Human childbirth is not uniquely difficult among mammals

Human childbirth is commonly viewed as uniquely difficult and dangerous. The reason: The combination of bipedalism and large brains creates a tight fit between the baby and the birth canal. Research at the University of Vienna ...

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