"Sexy" Science

I was recently in Chicago for the annual AAAS meeting. The AAAS (American Association for the Advancement of Science) is the largest professional science organization in the world. Some 10,000 people participate in the meeting - so it can be a bit overwhelming, to say the least.

This year, though, I had a mission. I focused in large part on the many sessions dealing with evolution. Evolution was a big part of the conference clearly because of the famous naturalist Charles Darwin's birthday (he turned 200 on Feb. 12, in case you hadn't heard).

One of the more entertaining sessions I went to featured Dr. Olivia Judson, an evolutionary biologist at Imperial College London, author, television personality and New York Times blogger. Her session dealt with the topic of evolution and sexual behavior.
Even Darwin understood that there was such a thing as 'sexual selection,' where animals evolve certain features to attract mates (like the peacock's flashy tail). But according to Dr. Judson, there are some pretty crazy examples of ways animals have evolved to mate. For instance, the male green spoon worm is 200,000 times smaller than the female so that it can live in its mate's reproductive system and fertilize her eggs directly.

Or take the case of apes. Female gorillas mate with one male at a time. Because there is no competition among the males for that female, the males don't need to produce as much sperm. So they have smaller testicles. Chimps, on the other hand, aren't so monogamous - the females will mate with lots of males. That means the more sperm a male produces, the more likely he will fertilize that female's eggs. Not surprisingly, male chimps have far larger testicles than gorillas. This is all part of the study of 'sperm competition.' (Read more on Dr. Judson's blog at:

Then there is the black-headed duck. The female duck lays her eggs in another bird's nest so she can abandon them and they then hatch on their own. What this means is that the baby duck needs to have innate knowledge from the minute it is born of how to find its relatives, how to feed and protect itself, etc. So these behaviors have to be genetically encoded.

This is not so clear-cut in humans. We know that human babies raised without any human contact do not develop properly. So unlike in the black-headed duck, human behavior goes beyond genetics and must require some environmental influence. It's the old 'nature versus nurture' question all over again.

The one point that was clear from all of Dr. Judson's highly entertaining examples of sexual evolution is that the influence of genetics and the environment on behavior is a very exciting field that could help us understand much more about evolution and sex.
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