A genetic mutation may have helped modern humans adapt to smoke exposure from fires and perhaps sparked an evolutionary advantage over their archaic competitors, including Neanderthals, according to a team of researchers.
Modern humans are the only primates that carry this genetic mutation that potentially increased tolerance to toxic materials produced by fires for cooking, protection and heating, said Gary Perdew, the John T. and Paige S. Smith Professor in Agricultural Sciences, Penn State. At high concentrations, smoke-derived toxins can increase the risk of respiratory infections. For expectant mothers, exposure to these toxins can increase the chance of low birth weight and infant mortality.
The mutation may have offered ancient humans a sweet spot in effectively processing some of these toxins, compared to other hominins.
"For Neanderthals, inhaling smoke and eating charcoal-broiled meat, they would be exposed to multiple sources of polycyclic aromatic hydrocarbons, which lead to cell death at high concentrations," said Perdew. "The evolutionary hypothesis is, if Neanderthals were exposed to large amounts of these smoke-derived toxins, it could lead to respiratory problems, decreased reproductive capacity for women and increased susceptibility to respiratory viruses among preadolescents, while humans would exhibit decreased toxicity because they are more slowly metabolising these compounds."
There is evidence that both humans and Neanderthals used fire, according to George Perry, assistant professor of anthropology and biology, Penn State, who worked with Perdew.
"Our hominin ancestors -- they would technically not be called humans at that time -- were likely using fire at least a million years ago, and some infer an earlier control and use of fire approximately 2 million years ago," said Perry.
Fire would have played an important role for both humans and Neanderthals.
"Cooking with fire could have allowed our ancestors to incorporate a broader range of foods in our diets, for example, by softening roots and tubers that might otherwise have been hard to chew," Perry said. "Cooking could also help increase the digestibility of other foods, both in chewing time and reduced energetic investment in digestion."
Fre also provided warmth, particularly in the higher latitudes, according to Perry.
"Besides heating and cooking, humans used -- and still use -- fire for landscape burning and as part of hunting and gathering, and now as part of agriculture," said Perry.
The study may also lend support to a recent theory that the invention of cooking may have helped humans thrive, according to Perdew.
Via: Penn State