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E. Male Biological Clocks Wind Down, Too

Narrator: This is Science Today. Although men can continue to father children long after women reach menopause, research indicates that even the male biological clock winds down. Andrew Wyrobek of the Lawrence Livermore National Laboratory co-led a study of ninety-seven healthy men, ages 22 through 80.

Wyrobeck: What we found was that there were small declines in the amount of semen that was produced. But a tremendous drop in the motility, or motion, of the sperm. So the sperm became progressively less motile as the men aged.

Narrator: While there have been previous indications of these age effects in men, most of the studies were conducted in the clinical population.

Wyrobeck: I think this study emphasizes the importance of understanding the father's contribution to a healthy child. What this study points out is that age is a contributing factor. We have to now learn more about whether genetics also contributes, so that if you are more susceptible to having chromosomally damaged sperm than somebody else might, we have to understand that.

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