Humans 'still evolving'

Darwinian "survival-of-the-fittest" laws continue to shape human evolution in the modern age, research led by the University of Sheffield has confirmed.

Humans are subject to the forces of natural selection just like any other species, say scientists.

A popular misconception is that humans stopped evolving when they took up farming and embraced monogamy.

But evidence from detailed church records of almost 6,000 Finns born between 1760 and 1849 suggests this is not so.

Researchers analysed data on economic status, births, deaths and marriages to examine four key natural selection factors: survival to adulthood, mate access, mating success, and fertility.

They found that the Finns' natural selection opportunities were on a par with those seen in the wild.

Differences in early survival and fertility were responsible for most of the variation in fitness, even among wealthy individuals.

Strict adherence to monogamy did not limit the potential for natural selection.

Dr Virpi Lummaa, from the University of Sheffield's department of animal and plant sciences, said: "We have shown advances have not challenged the fact that our species is still evolving, just like all the other species 'in the wild'. 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."

She added: "We have shown significant selection has been taking place in very recent populations, and likely still occurs, so humans continue to be affected by both natural and sexual selection. Although the specific pressures, the factors making some individuals able to survive better, or have better success at finding partners and produce more kids, have changed across time and differ in different populations."

The findings are published in the journal Proceedings of the National Academy of Sciences.

Co-author Dr Alexandre Courtiol, from the Wissenschaftskolleg Institute for Advanced Study in Berlin, Germany, said: "Characteristics increasing the mating success of men are likely to evolve faster than those increasing the mating success of women. This is because mating with more partners was shown to increase reproductive success more in men than in women. Surprisingly, however, selection affected wealthy and poor people in the society to the same extent."

Finland has some of the best available data for such research thanks to detailed church records of births, deaths, marriages and wealth status which were kept for tax purposes. Movement in the country was also very limited until the 20th century.

PA