Author: Tina Hesman Saey / Source: Science News
Humans’ gift of gab probably wasn’t the evolutionary boon that scientists once thought.
There’s no evidence that FOXP2, sometimes called “the language gene,” gave humans such a big evolutionary advantage that it was quickly adopted across the species, what scientists call a selective sweep. That finding, reported online August 2 in Cell, follows years of debate about the role of FOXP2 in human evolution.
In 2002, the gene became famous when researchers thought they had found evidence that a tweak in FOXP2 spread quickly to all humans — and only humans — about 200,000 years ago. That tweak swapped two amino acids in the human version of the gene for ones different than in other animals’ versions of the gene. FOXP2 is involved in vocal learning in songbirds, and people with mutations in the gene have speech and language problems. Many researchers initially thought that the amino acid swap was what enabled humans to speak. Speech would have given humans a leg up on competition from Neandertals and other ancient hominids.
That view helped make FOXP2 a textbook example of selective sweeps. Some researchers even suggested that FOXP2 was the gene that defines humans, until it became clear that the gene did not allow humans to settle the world and replace other hominids, says archeaogeneticist Johannes Krause at the Max Planck Institute for the Science of Human History in Jena, Germany, who was not involved in the study.
“It was not the one gene to rule them all.”The FOXP2 sweep theory first ran into trouble in 2008, when researchers discovered that Neandertals also had the two amino acid tweaks (SN Online: 11/14/08). That meant the change happened at least 700,000 years ago, before humans and Neandertal became separate branches of the hominid…
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