It's not an "eternity" by any means, but it's enough for selection to take place. Humans are thought to have developed lactose tolerance within the last 10k yea

It's not an "eternity" by any means, but it's enough for selection to take place. Humans are thought to have developed lactose tolerance within the last 10k years, for example (probably closer to 6k, if I remember correctly). In other observed cases, significant selection occured in just a few decades [1]. [1] http://news.nationalgeographic.com/news/2006/07/060714-evolution.html http://news.nationalgeographic.com/news/2006/07/060714-evolu...