Early humans are said to have a genetic mutation which helped adapt to smoke exposure from fires. This genetic mutation served as an evolutionary advantage over other homo groups like Neanderthals, who were extinct 40,000 years ago.
Neanderthals were closely related to modern humans with 99.5% similar DNA.According to the findings of Researchers at Pennsylvania State University, a mutation in the aryl hydrocarbon receptor that regulates body’s response to poly-cyclic aromatic hydrocarbons was found only in the early human beings.
This may have made the beginning of the people more desensitized to the smoke toxins. Polycyclic aromatic hydrocarbons are chemicals which are released while burning oil, coal, trash, gasoline, wood, tobacco or other organic substances such as charcoal-broiled meat.
Our early ancestors who were around the smoky caves developed this mutation which helped us to come this far. According to Gary Perdew, Professor at Pennsylvania State University (Penn State) in the US, “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,”
This mutation which helped in the evolution is located at located in the middle of the ligand-binding domain and is even found in present-day humans. The altered DNA must have helped effectively processing the polycyclic aromatic hydrocarbons and dioxins.
“If you are breathing in smoke, you want to metabolise these hydrophobic compounds and get rid of them. However, you don’t want to metabolise them so rapidly that it overloads your system and causes overt cellular toxicity,” Perdew added.
According to the evolutionary hypothesis, Neanderthals lack the mutation hence, if Neanderthals were exposed to large amounts of these smoke, it could lead to respiratory problems, decreased reproductive capacity for women and increased susceptibility to respiratory viruses among preadolescents resulting their extinction.
On the other hand, humans’ exhibit decreased toxicity because they are slowly metabolising these compounds than Neanderthals, researchers said.
“For Neanderthals, inhaling smoke and eating charcoal-broiled meat, they would be exposed to multiple sources of polycyclic aromatic hydrocarbons, which are known to be carcinogens and lead to cell death at high concentrations,” added Perdew.
The scientists examined the genetic material of nine modern human beings and compared with 45,000-year-old three Neanderthals and one member of Denisovans in Siberia. The mutation was absent in Neanderthals and Denisovans but found in modern man.
The study was published online at journal Molecular Biology and Evolution. The team plans to study the gene further to know where it came from and how it evolved.