A genetic mutation may have helped modern humans adapt to smoke exposure from fires and perhaps sparked an evolutionary advantage over their archaic competitors, including Neanderthals, according to a team of researchers. Modern humans are the only primates that carry this genetic mutation that potentially increased tolerance to toxic materials produced by fires for cooking, protection and heating, said Gary Perdew, the John T. and Paige S. Smith Professor in Agricultural Sciences, Penn State. At high concentrations, smoke-derived toxins can increase the risk of respiratory infections. For expectant mothers, exposure to these toxins can increase the chance of low birth weight and infant mortality. The mutation may have offered ancient humans a sweet spot in effectively processing some of these toxins -- such as dioxins and polycyclic aromatic hydrocarbons -- compared to other hominins. The researchers suggest that a difference in the aryl hydrocarbon receptor -- which regulates the body's response to polycyclic aromatic hydrocarbons -- between humans, Neanderthals and other non-human primates may have made humans more desensitized to certain smoke toxins. The mutation in the receptor is located in the middle of the ligand-binding domain and is found in all present-day humans. https://www.sciencedaily.com/releases/2016/08/160802192629.htm
There is another remarkable mutation that sets humans apart from other hominids is in the chromosome count. Whereas have 48 (2x24) chromosomes, humans have 46 (2x23) chromosomes. This is due to the fusion of two chromosomes in our ancestor into a single, but much longer chromosome. Please Register or Log in to view the hidden image! http://www.gate.net/~rwms/hum_ape_chrom.html IMO, this apparently beneficial mutation may well be the evolutionary emergence/origin of homo sapiens. btw. this may be of interest: http://phenomena.nationalgeographic...e-46-chromsomes-this-pond-creature-has-15600/
