A recent study suggests modern humans might have evolved to cope with the toxic particles in smoke. Giving us an evolutionary advance over our ancestors and helping modern humans emerge.

Researchers from Penn State University discovered a genetic mutation between modern humans and Neanderthals that suggests humans might have developed an adaptation gene to cope with smoke. The study explains how Neanderthals and early humans exposed themselves to the carcinogens found in the fire’s smoke, in order to cook, keep warm and hunt. The exposure might have caused health issues in our ancestors.

Researchers found that the genetic mutation, helped modern humans to cope with the chemicals by desensitizing their responses to polycyclic hydrocarbons. Image Credit: One Orange Dot

The study led by Gary Perdew, from Penn State, found a difference in what researchers call the “aryl hydrocarbon receptor.” The receptor is in charge of regulating how the body responds to polycyclic aromatic hydrocarbons, which are harmful chemicals. Researchers suggest this might be the cause that made human beings develop harmful habits such as smoking.

Archaic humans

Modern humans arrived at the face of the Earth, after a long progress of evolution and adaptation. The science world has constantly evaluated and investigated the progress of evolution, to understand better where we come from.

The evolution timeline of humans sees Neanderthal’s as the most recent ancestors of modern humans, since they became extinct 40,000 years ago and inhabited by humans. According to researchers, this species DNA is almost exact than a modern human’s with a 95% similarity. However, Neanderthals were far less evolved and had genetic disadvantages when compared to humans.

They worked, and hunt with tools made out of bone had an archaic language and gathered in social groups. There have even been reports of ancient buildings or houses made by Neanderthals out of pure bone. However, the species disappeared when humans started to show up around Eurasia; theories suggest Neanderthals weren’t able to adapt to climate changes, and they couldn’t compete with modern humans. A recent study might explain the advantages modern humans had over this archaic species of ancestors.

The ability to control fire is considered to be a major step forward in our evolutionary history. Image credits: International Business Times

Human adaptation

Researchers suggest Neanderthals were exposed to this carcinogen chemicals since they lighted up fires in caves and ate charcoal-broiled meat. The constant exposure to this hydrocarbons could have caused respiratory problems and cell death.

However, modern humans with the genetic mutation were able to process the toxins without having substantial harmful effects.  Providing them with evolutionary advances that protected their health.

“If you’re breathing in smoke, you want to metabolize these compounds and get rid of them. However, you don’t want to metabolize them so rapidly and cause overt cellular toxicity,” said lead author, Gary Perdew.

According to the study, the overload of smoke exposure from Neanderthals could have caused not only respiratory issues but the decrease of reproductive capacities in women and make younger Neanderthals susceptible to respiratory viruses.

Researchers assure modern humans prospered thanks to the genetic mutation, allowing them to cook and use fire for several other purposes such as hunting or as weapons further ahead in history.

To conclude the study’s results, researchers had to consider nine pairs of genes belonging to modern humans and one that belonged to a person that lived almost 45,000 years ago.

Researchers compared the human DNA, with the DNA of three Neanderthals and with one sample of a Denisovan, which was found in a cave in Siberia. At first, researchers thought the differences in the receptor wouldn’t be so dramatic.

“We thought the differences in aryl hydrocarbon receptor ligand sensitivity would be about ten-fold, but when we looked at it closely, the differences turned out to be huge,” said Perdew, lead author from Penn State.

The discovery could be one of the first palpable signs of human evolution and adaptation to the environment, researchers suggest. Results, also help a previous investigation that suggested cooking helped humans to thrive.

Researchers are currently working on inserting the human receptor into a mice, to test its tolerance and behavior. The team of scientists would have hoped to insert the Neanderthal’s receptors to test smoke tolerance.

Skeptic reception

Even though the study might have proven one of the greatest evolutionary advances in modern human history, the results might be considered inconclusive or need more proofs. Since the samples used weren’t sufficient.

Researchers had small samples of the Neanderthals and Denisovan, which many might consider inconclusive. The Guardian has reported the feedback on the study of fellow scientists to prove the skepticism about the study,

Several reviews have questioned the fact that Neanderthals could have been that susceptive to fire and smoke since they had so much exposure to the chemicals and lasted for a long time. Scientists suggest if the findings were conclusive Neanderthals would have been extinct before. Researchers of the study, are currently working on understanding and figuring out where and why the mutation took place.

Source: The Guardian