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B. Men Have a Biological Clock, Too

Narrator: This is Science Today. When it comes to reproduction, it turns out that men have a ticking biological clock, too. A new study conducted by researchers at the Lawrence Livermore National Laboratory and the University of California, Berkeley, found that with each passing year, semen quality in healthy adult men declines. Study co-author, Andrew Wyrobeck of the Livermore lab, explains.

Wyrobeck: We found that the ability for the sperm to swim fast and forward seems to decline almost immediately with age, starting in the twenties. So the decade of the thirties is less efficient than the twenties and forties is less efficient than the thirties.

Narrator: While there have been indications of these age effects in men, previous studies have only been done in the clinical population. Wyrobeck says their research is one of the first large studies of healthy men in the general population.

Wyrobeck: What it means in the most simplistic fashion is that fertility is a couple issue. If a man of marginal fertility is with a woman of marginal fertility, they may have a problem, so it needs to be considered as a couple issue.

Narrator: For Science Today, I'm Larissa Branin.