I have read before that mortality was a biological design engineered to encourage diversity and increase chances of survival of the species. Nature doesn't really care about an individual life, after all, just the whole . If an immortal "vampire" race existed, they'd become weakened by lack of diversity over time. However, I'm all for figuring out ways to live forever. I think we're somewhat past the point in our species where we can have significant evolutionary change due to our lifestyles, barring a huge global catastrophe or illness.