The scientists discovered that a genetic mutation present in modern humans might have made the difference between life and death as it created a better smoke adaptation.
The genetic mutation can only be found in humans, and it involves tolerance to toxic materials by fire. As a consequence, humans were able to use fire for heating, protection and cooking, which was not the case with the other hominids.
High concentrations of smoke toxins can lead to respiratory infections. In pregnant women, it can increase the risk of infant mortality and low birth weight.
Due to their smoke adaptation, the ancient humans managed to process polycyclic aromatic hydrocarbons and dioxins, which resulted from the fire.
“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 metabolizing these compounds,” said Gary Perdew, professor in Agricultural Sciences from Penn State.
The secret lays in an aryl hydrocarbon receptor, which helps the body to respond to polycyclic aromatic hydrocarbons. Humans have desensitized to some smoke toxins, as opposed to Neanderthals and non-human primates who respond negatively to the substances released by a fire.
The mutation is located in the ligand-binding domain, said the researchers. The small molecules attach to proteins and help metabolize the toxins.
The scientists believe that the Neanderthals could not resist to being exposed to sources of polycyclic aromatic hydrocarbons, including inhaling smoke and eating grilled meat. The fire toxins are known to be carcinogens and in high concentration, they can produce cell death.
Both humans and Neanderthals knew how to use fire at least a million years ago. Some experts say that the control and use of fire could be tracked to almost two million years ago.
Cooking was very important in evolutionary terms, as it could help humans and hominids to diversify their diets and to allow them to eat roots that might have been difficult to eat otherwise. The fire was also used to provide warmth, to landscape burning, or as a part of agricultural activities.
The gene mutation might be responsible for human’s ability to smoke cigarettes.
The difference of the ligand sensitivity in humans and the hominid Denisovan is a matter of thousands. The sensitivity in humans and Neanderthals has the same level, which permitted both of species to use fire.
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