What is the most recent widespread positive mutation (evolution) of humanity?

by Winspear

I am aware that evolution is an ongoing process and this question is probably anthropological in nature and possibly subjective. I wasn't sure whether to post it in askscience instead, but figured for a mutation to be "widespread" it would have had to be a historical question. Edit: If the answer lies in the last 10,000 years ago, it probably differs by race also, so please don't answer entirely subjectively with racial bias!

Reedstilt

You may want to give /r/AskAnthropology a try as well.