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Sexual Selection

April 6, 2006

When amoebas want to reproduce, they just divide in half. If only our lives were so easy.


Why sex pays. I’m Bob Hirshon and this is Science Update.

Ever think about sex and wonder, "Why bother?" No, me neither. But biologists do wonder why complex organisms bother with sex, when simple creatures just split in two. They know that sex helps stop the spread of deadly mutations because it combines the genes from two organisms. But sex is also much slower because finding a mate takes time. Emmanuel Tannenbaum is a mathematical biologist who studies sex at Ben Gurion University in Israel.

EMMANUEL TANNENBAUM (Ben Gurion University, Israel):
So there are various theories out there, but it’s largely regarded as one of the unsolved problems in evolutionary biology.

His model shows that organisms that take a long time to develop and reproduce—like humans—don’t lose that much more time looking for mates, so the benefits of sex are worth the costs. But for quickly replicating organisms, like bacteria, sex isn’t worth the time. I’m Bob Hirshon, for AAAS, the science society.