There are a couple of ...

There are a couple of watersheds in human evolution. Most people are comfortable thinking about tool use and language use as watersheds. But the ability to play non-zero-sum games was another watershed.
 Jonathan Haidt

Quotes from the same author

What set us apart from most or all of the other hominid species was our ultrasociality, our ability to be highly cooperative, even with strangers, people who are not at all related to us.
 Jonathan Haidt
But the most important lesson I have learned in my twenty years or research on morality is that nearly all people are morally motivated. Selfishness is a powerful force, particularly in the decisions of individuals, but whenever groups of people come together to make a sustained effort to change the world, you can bet that they are pursuing a vision of virtue, justice, or sacredness.
 Jonathan Haidt
If I have a mission in life, it is to convince people that everyone is morally motivated - everyone except for psychopaths.
 Jonathan Haidt
If our goal is to understand the world, to seek a deeper understanding of the world, our general lack of moral diversity here is going to make it harder. Because when people all share values, when people all share morals, they become a team.
 Jonathan Haidt
Sports is to war as pornography is to sex. We get to exercise some ancient, ancient drives.
 Jonathan Haidt