It appears that when fire was discovered, a new selective force was created among hominins. This force arose not out of the positive aspects of fire - the cultural and nutritional advantages it afforded - but the negative. Anyone who has inhaled smoke while huddled around a campfire, or got it in their eyes when the wind suddenly switched, knows empirically that smoke is a chemical irritant. Recent discoveries suggest that extinct hominins were at a disadvantage in the harnessing of fire. 

     

     The first discovery, published in Molecular Biology and Evolution, identifies a genetic mutation present in humans that is not present in other vertebrates. This mutation, which is present in AHR caused increased transcription of enzymes in the cytochrome P450 enzyme family, which metabolize foreign molecules. The study shows that a Ala 381 Val substitution in human AHR is the cause of the increased activity (1.) The researchers involved postulate that the toxins in smoke may have selected for this mutation. 

    The discovery of fire, while distinguishing us in an advantageous manner, may have simultaneously led to cultural practices with negative effects. Biologists at the University of Wales have used mathematical modeling to formulate the theory that fire, while bestowing numerous advantages on its discoverers, may have led to the facilitated transmission of infectious diseases. Increased exposure while sitting around the fire led to transmission, and inhalation of the smoke led to lung damage. 

Works Cited 

1. Troy D. Hubbard, Iain A. Murray, William H. Bisson, Alexis P. Sullivan, Aswathy Sebastian, George H. Perry, Nina G. Jablonski, and Gary H. Perdew

Divergent Ah Receptor Ligand Selectivity during Hominin Evolution

Mol Biol Evol (2016) 33 (10): 2648-2658 first published online August 2, 2016 doi:10.1093/molbev/msw143