This just in: humans still evolving. Still!?

New research suggests that two genes (Microcephalin 1 and ASPM) that regulate brain size have undergone intense natural selection in the past 5,000 to 37,000 years. Although understanding the role of natural selection in recent brain evolution is interesting and important, the headlines used to report this story are misleading: “Human brain still evolving.” Still?. As if one would expect that humans are not evolving? The actual title of the journal article—Microcephalin, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans—is, of course, much more modest (the keyword here being ‘adaptively’).

When many people think of evolution (if they think of it at all) they tend to conceive of it as something that happened long, long ago. Thus any research that suggests recent evolution comes as a newsworthy surprise. But evolution never stops, meaning the forces of mutation, drift, migration, and—yes—natural selection, too, are always at play. Evolution is an ongoing processes, as we can observe all too well in HIV diversification or antibiotic resistance. There’s actually a subfield known as contemporary evolution that specifically studies changes on recent time scales.

I remember on the final exam for evolutionary biology there was one question on whether or not Americans are evolving. The answer is, of course, yes, but we’re still left to puzzle out the details, as in this new study. The finding is not about human evolution but about adaptive evolution.