I feel like it was more learning to work together that’s made us so successful compared to other animals. Not having to spend our lives solely dedicated to hunting/growing food for ourselves and our families has allowed people to specialize in other fields. The advancement of science wouldn’t have been possible without people collaborating and working together, though conflict has also played a role as well. Ruthlessness only works for a small number of individuals who exploit the good will of others, but the whole thing falls apart if everybody was always ruthless.