Photo: Men Have Biological Clocks Too, Sperm Study Says

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In a scanning-electron-micrograph image, the three sections of human sperm are vibrantly visible: the head (which penetrates the egg), the midsection (packed with mitochondria to provide energy for movement), and the tail (which provides propulsion).

A new study says sperm degrade over time, resulting in a sort of biological clock for men.

Photograph by Yorgos Nikas/Getty Images

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