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Lactase persistence or lactose tolerance is the continued activity of the lactase enzyme in adulthood, allowing the digestion of lactose in milk. In most mammals , the activity of the enzyme is dramatically reduced after weaning . [ 1 ]
Lactose intolerance is the ancestral state of all humans before the recent evolution of lactase persistence in some cultures, which extends lactose tolerance into adulthood. [9] Lactase persistence evolved in several populations independently, probably as an adaptation to the domestication of dairy animals around 10,000 years ago.
Recent human evolution refers to evolutionary adaptation, sexual and natural selection, and genetic drift within Homo sapiens populations, since their separation and dispersal in the Middle Paleolithic about 50,000 years ago. Contrary to popular belief, not only are humans still evolving, their evolution since the dawn of agriculture is faster ...
Sedentism facilitated the development of agriculture, including the cultivation and domestication of wild cereals and animals. The domestication of cattle in northern Europe and parts of Africa facilitated the spread of a genetic mutation that allowed lactose tolerance, and Wade believes this is evidence of culture and evolution interacting. [19]
[h] People of the Nordic Bronze Age and Corded Ware show the highest lactose tolerance among Bronze Age Europeans. [i] The study also found a close genetic relationship between the Corded Ware culture and the Sintashta culture, suggesting that the Sintashta culture emerged as a result of an eastward expansion of Corded Ware peoples.
After a time, certain colonies began to grow. However, the EbgA protein is an ineffective lactase and does not allow growth on lactose. Two classes of single point mutations dramatically improve the activity of ebg enzyme toward lactose. [24] [25] and, as a result, the mutant enzyme is able to replace the lacZ β-galactosidase. [26]
Lactose, or milk sugar, is a disaccharide composed of galactose and glucose and has the molecular formula C 12 H 22 O 11.Lactose makes up around 2–8% of milk (by mass). The name comes from lact (gen. lactis), the Latin word for milk, plus the suffix -ose used to name sugars.
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