Fire is a very useful thing to control. It allows you to make the most of the food you have available, to rid your food of diseases, and to stay warm and safe from unwanted predators. But fire also brings a few disadvantages: in addition to the risk of uncontrolled fires, smoke can also be toxic and dangerous to inhale.

Some researchers had speculated that resistance to smoke (and other toxins) is one of the traits that helped humans survive when Neanderthals didn’t. But a new study claims otherwise.

We’ve long known that Neanderthals aren’t the brutes they were once considered. They were every bit as sophisticated, resilient, and creative as humans were — and yet, there aren’t any Neanderthals around today, so they must have been weaker in some sense. In 2016, one study suggested that toxins may have been the Neanderthal Achilles heel. A group of American scientists studied a receptor protein, finding that Neanderthals are up to a thousand more times more sensitive than humans, and this may have led to their downfall. But in the same year, another study came out concluding the exact opposite.

The other group, which included Professor of Archaeology Wil Roebroeks and molecular biologist/toxicologist Jac Aarts, found that Neanderthals had more gene variants that neutralized the harmful effect than modern humans, which suggests more protection against toxins.

Understandably, Aarts and Roebroeks were puzzled. After all, here were two seemingly convincing studies that concluded opposite things. So they wanted to understand what was happening, and teamed up with North American researchers for a new study.

They used human cells rather than the rat cells of previous studies, and were able to confirm their previous findings. The “Neanderthal and modern human dose-response curves almost coincide,” the researchers note, suggesting that Neanderthals were just as resistant to smoke and toxins as humans — even though they admit that this puts their results “strongly at odds” with other studies.

Instead, the study suggests, it’s modern humans that may be the anomaly: detoxification proteins are more dominant in ancient hominins, chimpanzees and gorillas than in modern humans.

Prehistoric use of fire is a crucial aspect for understanding these ancient cultures. The study is also significant and topical in light of recent events, like the wildfires in Australia from earlier this year. We still have much to learn about the way these proteins work in the human body, but understanding how they work in Neanderthals may also help us better understand our own bodies.

Journal Reference: Jac M M J G Aarts et al. Evolution of Hominin Detoxification: Neanderthal and Modern Human Ah Receptor Respond Similarly to TCDD, Molecular Biology and Evolution (2020). DOI: 10.1093/molbev/msaa287