I was thinking more along these lines: http://www.nature.com/scitable/topicpage/evolutionary-adapta... . And that is just about the last ~10,000 years (give or take a few thousands).

> With time, we might devolve to the point where we completely depend on modern medicine to survive and reproduce.

That's a possibility, of course. Then you have to wonder what happens if the social structures crumble or change dramatically and you do not have access to modern medicine anymore?