I’m two days late celebrating what should be a national holiday: Evolution Day, December 20, 2005, when Judge John Jones ruled againt the creationist loons in Kitzmiller et al vs. Dover Area School District.

Presumably, evolution didn’t stop, oh, 10,000 or 50,000 years ago, but continues its workings even unto the present day. Now scientists have some proof. The New Scienist:

t’s very difficult, if not impossible, to observe human evolution in action. But saying it isn’t happening is an increasingly difficult position to defend scientifically. Recent discoveries show that we must reject the idea that human evolution stopped dead 50,000 years ago or more. In fact, there is every reason to believe that it is going on right now.

Take the discovery last year by Bruce Lahn of the University of Chicago of two genes involved in brain development that emerged in recent human history and swept quickly through the population. One, a version of a gene called microcephalin, arose between 14,000 and 60,000 years ago and is now carried by 70 per cent of people. The other, a variant of the ASPM gene, is as recent as 500 to 14,000 years old and is now carried by about a quarter of the global population.

No one yet knows the function of these genes, but Lahn’s discoveries could be just the tip of the iceberg.

Of course, being science, these views are tested and challenged all the time:

It’s clear that the raw genetic material upon which selection could act is being generated all the time - the human genome is not immune from mutations, some of which could confer a selective advantage. But are there any selection pressures at work?

Steve Jones, a geneticist at University College London, has famously argued that natural selection is no longer important for humans. He points out that natural selection works by ensuring that individuals whose genes are best adapted to the prevailing environment are most likely to survive and reproduce. But, he says, in the developed world, survival no longer depends on genes. “Just 500 years ago - yesterday in evolutionary terms - a British baby had only a 50 per cent chance of making it to reproductive age. Now, the figure is around 99 per cent,” Jones says. There is also a more level playing field in the reproduction game. “No longer, as in the Middle Ages, do a few rich men have many children while many of those in poverty are forced into the army or into monasteries,” he says. Jones admits that measuring reproductive success, particularly for men, can be difficult, but he calculates that the changes in survival and reproduction rates have led to a decrease of around 70 per cent in the opportunity for natural selection to act today, compared with the time when our ancestors lived as peasant farmers.

That’s not quite the “zero” natural selection that some reports of Jones’s views have suggested. Even he accepts that genes can still make a difference to survival and reproduction. One obvious example is genes that confer resistance to emerging diseases. Some parts of Africa, for example, have seen an increase in the frequency of a gene called CCR5-32, which offers some protection against infection with HIV-1.

So natural selection is still at work, and some evolutionary biologists believe it would come as no surprise to find many more examples. They point out that we live in an era of rapid technological progress, and hence a fast changing environment, exactly the conditions under which you’d expect natural selection to act. Technological change has clearly driven natural selection in the past. The invention of dairy herding, for example, selected for a gene that gives adults the ability to digest milk sugars. So why not now? It’s not hard to dream up selection pressures that could be acting today. Caesarean sections, for example, could be selecting for genes that allow babies to grow bigger in the womb.

Interesting article, way above my ability to synthesize. Enjoy…