If collective survival was the driving influence, we would have been in favor of suicide for people who were a "burden", like cancer patients.

http://www.straightdope.com/columns/read/2160/did-eskimos-pu...

Assisted suicide isn't a new freedom - we had it in the past, it went out of favor, and now it's favorable again. Ancient Greece had radical and crazy practices (infanticide, certain sexual pairings) that are revolting "right now". Having to come to terms with those particular practices isn't something that I look forward to doing in the future.