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A new study by University of Pennsylvania researchers investigating recent signals of positive selection of genes across human populations reveals the concurrent emergence of alcohol dehydrogenase (ADH) gene variant in various populations across the globe without direct genetic heritage. The study has been published in the journal Nature, Ecology & Evolution utilized the 1000 Genome Project data and analyzed 2500 individuals from 20 populations across four continents.
ADH is a group of enzymes normally present in humans to break down the alcohol. But the emergent gene variant of the ADH increases enzyme activity resulting into the less effective breaking down of the alcohol consequently, leading to adverse physical response to alcohol consumption.
People with this specific genetic variant may feel sick after drinking alcohol and henceforth, are unlikely to develop a taste for alcohol or become alcoholic.
Humans with red-green color blindness, see a different spectrum blame it to the dichromacy (two types of cone cells) rather than trichromacy (three types of cone cells) in normal Humans. Have you ever imagined what would have happened if we had not been blessed with trichromatic vision and how we developed this, thank our fruit-hunting ancestors, claimed by a report shown at the annual meeting of AAAS, which publishes Science.
Few of the primate species (our early ancestors) have three different types of light-sensitive cone cell in eyes (trichromacy) rather than two which makes primate exceptional and allows humans to explore what we think of as the standard spectrum of color. As per the hypothesis, the satandard explanation for trichromacy in primates, is that it allowed them to see colourful ripe fruit more easily against a mostly green background of the forest. The rhesus macaque (a particular Old World monkey), has a genetic discrepancy to offer a convenient natural test of this hypothesis. A common mutation makes some females have three types of cone cells whereas others having two only. Based on a study report including >20000 individual observations of 80 different macaques feeding from 30 species of trees on Cayo Santiago, Puerto Rico, researchers can say with some confidence that wild trichromatic female monkeys do certainly seem to trace and eat fruit quicker than dichromatic females monkeys, leading strong support to the idea that this differentiating advantage of trichromacy over dichromacy helped drive the evolution of trichromacy in Humans and other relatives.