Yeah tooth and claw survival of the fittest isn't really Darwinism, i'm working from memory so I may have some of the things wrong, it's been a few years... I think someone mentioned earler about that. But yeah take humans for instance who are social beings and work by co-operating, that's a big part of what makes a species fit enough to survive.

The idea is that within a society, most people are altruistic. There are some people who take advantage of this altruism, but they are in the minority, too many people who aren't altruistic and the society of co-operation collapses. Or something. Been a while.