Evolution and humans: language genetics is complex (Evolution)

by David Turell @, Friday, August 03, 2018, 18:20 (75 days ago) @ David Turell

A FoxP2 gene was thought to be the primary cause 200,000 years ago. It isn't:

https://www.nature.com/articles/d41586-018-05859-7?utm_source=briefing-dy&utm_mediu...

"The evolution of human language was once thought to have hinged on changes to a single gene that were so beneficial that they raced through ancient human populations. But an analysis now suggests that this gene, FOXP2, did not undergo changes in Homo sapiens’ recent history after all — and that previous findings might simply have been false signals.

“The situation’s a lot more complicated than the very clean story that has been making it into textbooks all this time,” says Elizabeth Atkinson, a population geneticist at the Broad Institute of Harvard and MIT in Cambridge, Massachusetts,

***

"Despite such questions, the 2002 study has never been repeated. It was based on the genomes of only 20 individuals, including just a handful of people of African ancestry, says Atkinson: most came from Europe, Asia and other regions. She and her team have now re-examined the gene’s evolutionary history using a larger data set and a more diverse population.

"They found that the signal that had looked like a selective sweep in the 2002 study was probably a statistical artefact caused by lumping Africans together with Eurasians and other populations. With more — and more varied — genomes to study, the team was able to look for a selective sweep in FOXP2, separately, in Africans and non-Africans — but found no evidence in either.

“'It’s good that it is now clear there is actually no sweep signal at FOXP2,” says evolutionary geneticist Wolfgang Enard of Ludwig Maximilian University of Munich in Germany, who was a co-author of the 2002 study.

"Even if there was no recent evolution of FOXP2, there is still plenty of evidence that the gene is involved in language, says Simon Fisher, director of the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands, and a coauthor of the 2002 study. Mutations in FOXP2 cause language disorders in humans, and in mice the gene is important for vocalizations and movement — both functions that are crucial to human speech.

"Language is complicated, and was never going to be explained by a single mutation in modern humans, Fisher adds. “We need to embrace more-complex accounts that involve changes of multiple genes. In that sense, FOXP2 was only ever going to be one piece of a complex puzzle.'”

Comment: Considering the complex anatomic changes required, many genes have to be involved.


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