The fireside hypothesis: was there differential selection to tolerate air pollution during human evolution?

It is believed that sometime around 1.9 million years ago early hominid ancestors began to migrate out of Africa. Migration north and away from the equator would have forced early humans to encounter seasonal fluctuations in temperature. As a means of adapting to cold climates, the use of fire undoubtedly played an important role. We hypothesize that progressive exposure to toxic airborne particles produced from combustion created selective pressure to develop an adaptation to the inhalation of smoke. In this paper we test this hypothesis using archival data on the incidence of different cancers among geographically distinct human populations. As predicted from evolutionary theory, the incidence of lung cancer is inversely proportional to the ostensible reliance on fire of geographically different groups during human evolutionary history.