Cattle-raising people in East Africa and northern Europe have gained a mutation that helps them digest milk as adults.

东非和北欧的养牛人发生了基因突变，这样能够帮助他们在成年后消化牛奶。

The paragraph provides examples of recent adaptations, such as people in the Ethiopian highlands adapting to living at high altitudes and cattle-raising people in East Africa and northern Europe gaining a mutation that helps them digest milk as adults.

该段提供了最近适应的例子，例如埃塞俄比亚高原的人们适应了高海拔地区的生活，东非和北欧的养牛人获得了一种突变，可以帮助他们成年后消化牛奶。