But communities in sub-Saharan Africa, the middle east, and northwest Europe that used cows for milk have seen a rapid increase in DNA variants that prevent the gene from switching off over the last 7 to 8000 years.
在撒哈拉沙漠以南非洲、中东和欧洲西北部,养牛饮奶族群中,出现DNA 变体激增,在过去七、八千年里阻止了消化奶类基因关闭。