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Smoke Effect

Humans and Neanderthals differ at site that falls within ligand-binding domain of the aryl hydrocarbon receptor (AHR) gene, according to a Pennsylvania State University-based team of researchers. They suggest that this difference may have enabled humans to better tolerate smoke from cooking fires.

Penn State's Gary Perdew and his colleagues examined the exome sequences of four Neanderthal and Denisovan individuals and compared them to those from nine modern humans. As they reported yesterday in Molecular Biology and Evolution, they uncovered 90 sites where the archaic hominins were fixed for an ancestral nonsynonymous variant, while the modern humans were fixed for a derived variant. Twenty-seven of those sites didn't have variants listed in the dbSNP database, further suggesting they are highly conserved, the researchers say.

One of these derived variants in humans is Val381 in the AHR gene, and a functional analysis of this variant indicates that humans and Neanderthals had differing abilities to process polycyclic aromatic hydrocarbons, such as those produced by fires.

"We prospered because of this mutation," Perdew tells the Guardian. "I wouldn't say Neanderthals died out because of it, but it could have been a contributing factor."

However, other researchers are skeptical of that interpretation, the Guardian says. "Neanderthals were the ultimate cave-dwelling fire users. If there was some selective disadvantage against this, then they would have died out a long time before they did," says David Wright, an archaeologist at Seoul National University and the University of York. "But they were actually one of the more successful stories in human evolution and lasted a really long time compared to other hominids."