The most significant driving force behind evolution, of course, is natural selection. But what is it that's being selected? Seems simple enough on the surface. An individual organism - a whitetail deer, an oak tree, a bacterium - has a trait that results in an increased likelihood of survival or reproduction. As a result, it leaves a few more offspring than its neighbors. But it runs deeper than that. Since those beneficial traits are the results of the organism's genetic makeup, it's at the level of the gene that selection typically acts. Certain organisms are fortunate enough to carry, in their genome, copies of genes that produce traits that are, in a relative sense, "better" than the traits displayed by other members of the population.

We know that, over the course of human evolution, a host of mutations have accumulated in our current genome. Until recently, however, it's been difficult to actually put our finger on particular beneficial genes. Our ability to do so has been complicated by the fact that, when a gene is selected and becomes more abundant in the genome, a lot of "junk", neighboring genetic material which is selectively neutral, is carried along. An interesting story at ScientificAmerican.com discusses recent work published by a group led by Pardis Sabeti, an assistant professor in Harvard's Department of Organismal and Evolutionary Biology. Sabeti's research team has used a battery of statistical techniques to identify the particular beneficial gene in blocks of genetic information. Among the strategies employed are an examination of the ancestry of particular genomes. Comparing groups that developed under different environmental pressures helps shed light on the whether genetic variation is a beneficial mutation, or just background noise.

The technique resulted in a hundredfold increase in the ability of the researchers to localize a selected gene, and allowed them to identify a number of beneficial variants. These included a gene affecting pigmentation, one related to sensory perception, and a gene called "large" that may be associated with resistance of some African populations the virus that causes Lassa fever.

As advances in techniques allow us to rapidly accumulate massive amounts of genetic information, our ability to extract some meaning from it becomes critical. Techniques such as those developed by Dr. Sabeti and her team may provide the key.

Oh, and one more thing...



What's the significance of the music video? Well, take a look at the lead singer.

That's Pardis Sabeti - Rhodes scholar, Harvard geneticist, architect of groundbreaking research in human genetics... and lead singer of the alternative rock band Thousand Days.

So, what did you do today?