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Science!: Hammerheads, Fly Sex and Evolution

Lauren Admire | 30 Nov 2009 21:00
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Are Humans Still Evolving?

Are humans still evolving, and if so how? Four different theories give vastly different predictions as to where the human race is heading.

The first prediction claims that human evolution is no longer occurring. Anthropologist, Ian Tattersall, says that "Because we have evolved, it's natural to imagine we will continue to do so, but I think that's wrong."

According to Darwin's theory, evolution occurs when a mutation causes a benefit in a population, and is thus passed down throughout generations. However, this generally only happens in small, isolated populations. Because the human population is neither small nor isolated, and in fact crossbreeds quite regularly, meaningful evolution cannot occur.

Further, the credo of "survival of the fittest," no longer holds any bearing since medical advances have made it so that the weak do not necessarily perish. Everybody stays alive and passes on their genetic material, which essentially cancels out the processes of natural selection.

"In this situation, the fixation of any meaningful evolutionary novelties in the human population is highly improbable," Tattersall says. "Human beings are just going to have to learn to live with themselves as they are."

The second prediction claims that humans are still evolving, and will continue to do so.

According to evolutionary biologist Stephen Stearns, "There is this idea that because medicine has been so good at reducing mortality rates, that means that natural selection is no longer operating in humans."

However, his team has found that human evolution is occurring on nearly the same rate as other living things. Stearn and his team analyzed the data from a 60 year study on North American women, concentrating on identifying traits which are important to human health. These traits affected the number of children the women had over their lifetime; measuring these effects allowed the researchers to make short-term predictions about how each trait will further evolve.

Further, sexual selection is still alive and well. Women and men alike are still able to choose the traits they prefer in a mate; the more powerful, the better. With constant, consistent advances in technology occurring, this sexual selection will become stronger, because " the more advanced the technology gets, the greater an effect general intelligence will have on each individual's economic and social success, because as technology gets more complex, you need more intelligence to master it," claims Geoffrey Miller, an evolutionary psychologist. "That intelligence results in higher earnings, social status and sexual attractiveness." Hmm, looks like nerds will rule the world, after all.

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