New data suggest a weaker connection than some have posited:

When it comes to certain physical characteristics, such as hair and eye color, the groups studied followed diverging evolutionary trajectories. But the the researchers found that genetic predispositions to disease actually converged over time. In some ways, our ancestors became less alike; in other ways, they became more similar.

So while the study didn't measure genes associated with neurological development or cognitive powers, we should be careful about automatically assuming that different groups of people evolved different degrees of intelligence -- a cautionary echoed by geneticists.

"There is not evidence at all of any population differences in genes associated with neurological development or cognitive performance," wrote study author Lluis Quintana-Murci in an email. "In addition, I even wonder if there are genes really associated with 'cognitive performance.'"

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