Fires, Food and the Evolution of Human Detoxification Capabilities

A study by a Leiden-Wageningen group shows that present-day humans are biologically poorly equipped to deal with the toxins they are regularly exposed to in smoky environments: compared to earlier hominins, we modern humans are probably even worse off. The study appeared in Molecular Biology and Evolution. The results are startling given the ‘pyrophilic’ nature of Homo sapiens.

The use of fire is a defining characteristic of the human lineage, with pyrotechnology being one of the most powerful tools developed during human evolution. Fire afforded humans with benefits affecting many domains of their lives, including diet, thermoregulation, social interaction and the landscapes early humans lived in.

Learning about the use of fire

Within Leiden’s Faculty of Archaeology, the prehistory of fire use is an important research topic. We address it with a variety of projects. These include studies into the effect of heat and diagenesis on organic materials, fire production by early humans, research on 'fire-free' cultural and biological adaptations to higher latitudes and past and present hunter-gatherer fire use in their landscapes.

The toxic effects of smoke

Beyond benefits, fire use also came with costs, including serious health hazards. According to a 2018 WHO report, millions of people yearly die a premature death as consequence of exposure to smoke from using fire daily. Thereby, they are being exposed to the toxic components of smoke. The new study specifically focuses on a protein called ‘aryl hydrocarbon (Ah) receptor’. This receptor serves as a sensor that detects toxic compounds in the cell, including compounds present in smoke.

Evolutionary perspective on current health problems

We studied the different gene variant, or alleles, that code for this receptor. It appears that the less (!) protective, 'high-risk' alleles are more common in modern humans.

This puzzling pattern offers great depth to the understanding of the human ability to deal with toxins. It shows that an evolutionary perspective can help us understand current day health problems, also in the developing world. This is only the next piece of the overall puzzle that depicts present-day Homo sapiens.