東亞早期人類的一個至關重要的基因突變

來源: 吃與活於 2021-09-27 19:26:48 [檔案] [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次 (4530 bytes)

EDAR V370A

在距今三萬年前的西伯利亞至黑龍江流域，早期到來人們麵臨最近一個冰川末期冰天雪地的環境，生存不易。寒冷的天氣讓人們穿起了獸皮，遮蓋著大部分的皮膚，陽光不足，維生素D的合成不足，新生兒得到的營養有限，存活下來的不多。

然而長生天在這個時候賜給這群人中的一個上麵提到的基因突變。這個突變使人出現鏟型門齒，汗腺密度增加，頭發粗壯。對婦女而言，這個突變更帶來小而結實的乳腺，並且乳腺管道分叉，能夠更有效率地把母體的營養輸送給嬰兒，使嬰兒得到足夠的營養(如維生素D)而存活下來的可能性大增。

有了這個突變的東北亞人的後代突破了一個生存繁衍的瓶頸，在東北亞的大地上生存下來並不斷擴展生存空間，成這片土地的主人。

如今93%的漢族人攜帶這個突變，而白人和黑人則幾乎不攜帶這個突變。

可以想象，有熊國的後裔帶著西亞通過大草原通道傳來的車馬和青銅器南下的時候，手持竹簽木棍的黎民的確沒有什麽能阻擋這個基因突變的傳播。

參考

https://en.m.wikipedia.org/wiki/Ectodysplasin_A_receptor?

A derived G-allele point mutation (SNP) with pleiotropic effects in EDAR, 370A or rs3827760, found in most modern East Asians and Native Americans but not common in African or European populations, is thought to be one of the key genes responsible for a number of differences between these populations, including the thicker hair, more numerous sweat glands, smaller breasts, and the Sinodont dentition (so-called shovel incisors) characteristic of East Asians.^[9] It has been hypothesized that natural selection favored this allele during the last ice age in a population of people living in isolation in Beringia, as it may play a role in the synthesis of breast milk under Vitamin D-poor conditions.^[10]^[11]^[12] The 370A mutation arose in humans approximately 30,000 years ago, and now is found in 93% of Han Chinese and in the majority of people in nearby Asian populations. This mutation is also implicated in ear morphology differences and reduced chin protrusion.^[13] The derived G-allele is a mutation of the ancestral A-allele, the version found in most modern non-East Asian and non-Native American populations