Search results
Results from the WOW.Com Content Network
Although the selective advantages of lactase persistence have been discussed, there have been studies of ethnic groups whose populations, despite relying heavily on milk consumption, currently have a low frequency of lactase persistence. [13] A study of 303 individuals from the Beja tribe and 282 individuals from various Nilotic tribes in Sudan ...
Thus, even in the case of lactase-persistence there is a huge time delay between the onset of a new habit and the spread of the adaptive allele and so milk consumption may have been restricted to children or to lactose-reduced products. Another example of mutation positively selected by the switch to agriculture is the number of AMY1 gene copies.
Added Portugal and Spain to the 60-70% range that the sources claim. There are other inaccuracies in the map. 08:54, 12 July 2017: 512 × 402 (124 KB) Joe Roe: Recoloured sample locations based on the actual value at that location. 21:13, 3 July 2017: 512 × 402 (94 KB) Joe Roe: User created page with UploadWizard
In humans, in non-dairy consuming societies, lactase production usually drops about 90% during the first four years of life, although the exact drop over time varies widely. [190] Lactase activity persistence in adults is associated with two polymorphisms: C/T 13910 and G/A 22018 located in the MCM6 gene. [191]
[23] [24] In areas with lactase persistence, it is believed that by domesticating animals, a source of milk became available while an adult and thus strong selection for lactase persistence could occur; [21] [25] in a Scandinavian population, the estimated selection coefficient was 0.09-0.19. [25]
Lactase persistence in humans evolved relatively recently (in the last 10,000 years) among some populations. Around 8,000 years ago in modern-day Turkey, humans became reliant on newly-domesticated animals that could be milked; such as cows, sheep, and goats. This resulted in higher frequency of lactase persistence. [77]
The majority of humans actually follow this protocol as well, and down-regulate lactase production around 3-5 years of age. Interestingly, though, the majority of caucasians, mainly those from northern european background, continue to have elevated lactase activity all the way into adulthood, and so they exhibit “lactase persistence”.
The study also contradicts suggestions that European farmer populations of the Cucuteni-Trypillia and Globular Amphora cultures contributed ancestry to Yamnaya, as Yamnaya lack the additional hunter-gatherer ancestry found in European farmers, and carry equal proportions of Anatolian and Levantine ancestry, unlike European farmers who carry ...