As much as humans have controlled our environment, we are still subject to Charles Darwin's natural selection theory, concludes an analysis of records of about 6,000 Finnish people born between 1760-1849.
"We have shown advances have not challenged the fact that our species is still evolving, just like all the other species `in the wild,´" said project leader Dr. Virpi Lummaa, of the University of Sheffield´s Department of Animal and Plant Sciences, in a press release. "It is a common misunderstanding that evolution took place a long time ago, and that to understand ourselves we must look back to the hunter-gatherer days of humans."
The scientists wanted to see if demographic, cultural and technological changes of the agricultural revolution affected natural and sexual selection in our species. In order to do that, they needed lots of detailed information. For that, they turned to Finland, which has extensive church records on births, deaths, marriages and wealth status which were kept for tax purposes.
From that data set, the researchers extrapolated statistics on survival to adulthood, mate access, mating success and fertility per mate.
Over the last 10,000 years, they concluded in the project published in the Proceedings of the National Academy of Sciences, natural and sexual selection among humans was still going strong during that time period.
Almost half of the people in the study died before age 15, notes Science Now. If they were susceptible to disease, those genes were not passed along. Another 20 percent did not get married or have children, leading researchers to believe that some traits may have prevented individuals from reproducing and passing on their genes to the next generation.
Of particular note, the experts were surprised to find that selection affect rich and poor people similarly. Also, while sexual selection occurs in males and females, the authors noted a higher variance in reproductive success in males.
"Characteristics increasing the mating success of men are likely to evolve faster than those increasing the mating success of women," principal investigator Dr. Alexandre Courtiol, of the Wissenschaftskolleg zu Berlin, said. "This is because mating with more partners was shown to increase reproductive success more in men than in women."
With one partner, the study showed, the average number of children for men was about five; with four partners, that jumped to 7.5. At the time, there were strict rules against divorce and extramarital affairs in Finland.
"Without a doubt, natural selection occurs in modern humans," Jacob Moorad, an evolutionary biologist at Duke University in Durham, North Carolina, who was not involved in the study, told Science Now.
In fact, one of the study's authors even wonders in an article in U.S. News and World Report if we've evolved into a new species.
"The change from one species to another is something you can only notice with the perspectivity of time," he said. "If we could travel back in time to meet early humans, I'm not sure if we'd be able to reproduce with the people of the time."