I don't know what to make of this story. Something's gone wrong somewhere in the reporting.
The sophistication of the human brain is not simply the result of steady evolution, according to new research. Instead, humans are truly privileged animals with brains that have developed in a type of extraordinarily fast evolution that is unique to the species.
"Simply put, evolution has been working very hard to produce us humans," said Bruce Lahn, an assistant professor of human genetics at the University of Chicago and an investigator at the Howard Hughes Medical Institute.
"Our study offers the first genetic evidence that humans occupy a unique position in the tree of life."
Professor Lahn's research, published this week in the journal Cell, suggests that humans evolved their cognitive abilities not owing to a few sporadic and accidental genetic mutations - as is the usual way with traits in living things - but rather from an enormous number of mutations in a short period of time, acquired though an intense selection process favouring complex cognitive abilities.
One has to ask, is this really news? After all, we know for a fact that stone tool-making didn't get off the ground until 2.5 million years ago at most, and that there's no evidence of mastery of fire before the last 400,000 years. It's obvious that intense selection would have had to occur in order for our kind of intelligence to appear within such a short timespan, isn't it?
Prof Lahn's team examined the DNA of 214 genes involved in brain development in humans, macaques, rats and mice.
By comparing mutations that had no effect on the function of the genes with those mutations that did, they came up with a measure of the pressure of natural selection on those genes.
Hmm, I'm not so sure of the wisdom of using fast-evolving species likes rats and mice as outgroups. I'll have to read the actual paper before I pass judgment, however.
The scientists found that the human brain's genes had gone through an intense amount of evolution in a short amount of time - a process that far outstripped the evolution of the genes of other animals.
"We've proven that there is a big distinction," Prof Lahn said. "Human evolution is, in fact, a privileged process because it involves a large number of mutations in a large number of genes.
"To accomplish so much in so little evolutionary time - a few tens of millions of years - requires a selective process that is perhaps categorically different from the typical processes of acquiring new biological traits."
Is it really fair to say that human evolution is "privileged" when of the time-scale one is talking about - tens of millions of years - for only a small fraction (6mya) have humans actually been evolving separately from chimps and gorillas?
As for how all of this happened, the professor suggests that the development of human society may be the reason.
In an increasingly social environment, greater cognitive abilities probably became more of an advantage.
"As humans become more social, differences in intelligence will translate into much greater differences in fitness, because you can manipulate your social structure to your advantage," he said.
"Even devoid of the social context, as humans become more intelligent, it might create a situation where being a little smarter matters a lot.
This would certainly support what I already believe, but how exactly does it follow from this research? I don't see that it does, though in this case I suspect that the fault lies more with a reporter pushing for a definitive explanation where there is none than with the scientist responding.
This looks a lot to me like a big fuss over very little, scientifically speaking, and looking at the abstract of the relevant article doesn't do anything to contradict said suspicion. As far as new insights go, the most I expect from this research is that it will someday help to pin down when exactly traits like language became part of the human repertoire.