Researchers at Penn State have discovered a mutation in the gene for the aryl hydrocarbon receptor which would desensitise an individual’s reaction to the aromatic hydrocarbons in smoke from cooking fires, and in meat roasted upon them, and through exposure to burning vegetation in the environment. This would cause these chemicals to be broken down more slowly in the body which, they hypothesise, would present a less toxic burden to body cells. The mutation is ubiquitous in modern humans but was not shared by Neanderthals who, therefore, might have suffered more from respiratory problems associated with smoke inhalation, a range of cancers, decreased reproductive capacity and an increased susceptibility to respiratory viruses.
Smoke tolerance, the researchers say, could have given our immediate human ancestors a competitive edge in a world where the use of fire for heating, ground clearing, and cooking had become widely adopted.
You can find the research paper here in the Journal of Molecular Biology and Evolution and you can read popular accounts of the discovery in Science Daily and at Physorg.