Magazine article USA TODAY

Parasites Get Credit for Our Sex Lives

Magazine article USA TODAY

Parasites Get Credit for Our Sex Lives

Article excerpt

It seems we may have parasites to thank for the existence of sex as we know it. Biologists have found that, although sexual reproduction between two individuals is costly from an evolutionary perspective, it is favored over self-fertilization in the presence of co-evolving parasites. Sex allows parents to produce offspring that are more resistant to parasites, while self-fertilization dooms populations to extinction at the hands of their biological enemies.

A report in Science affirms this Red Queen hypothesis, an evolutionary theory whose name comes from a character in Lewis Carroll's Alice in Wonderland, who says: "It takes all the running you can do to keep in the same place." The idea is that sexual reproduction via crossfertilization keeps host populations one evolutionary step ahead of the parasites, which are coevolving to infect them. It is within this coevolutionary context that both hosts and parasites are running (evolving) as fast as they can just to stay in the same place.

"The widespread existence of sex has been a major problem for evolutionary biology going back to the time of Charles Darwin," says lead author Levi E Morran. …

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