Above is SETI's Big Science podcast with an episode on us self-aware animals. Within is a fascinating bit on bonobos, our closest relatives, and their peaceful, matriarchal, and hyper-sexual society. The bonobo bit starts 16 minutes 30 seconds into the show but the whole show is worth the listen.
I'll try a bit of summary here.. Bonobos, instead of being male dominated with lots of violence in their societies like the chimpanzees, are matriarchal with little to no violence and aggression - they enjoy much more open relationships, with much less tension, much less fear of manipulation, and much greater cooperation. Chimps are excellent cooperators too, but their cooperation breaks down when emotions get in the way (like with us humans, emotion often constrains cooperation).
This reduced social tension and increased openness and trust is presumably linked to the bonobo's focus on play and their constant and indiscriminate sexual activity - between all members of the group with little regard for gender or age - sex as greeting and social bonding - sex for conflict resolution and sex for post conflict reconciliation.
Anyway, give it a listen - Vanessa Woods, the author of The Bonobo Handshake takes the comparison between our two closest cousins nicely further. The bonobo handshake, by the way, is when two females rub clitorises together with ever increasing frenzy until orgasm - this fosters great bonds between the females who cooperate to 'correct' any of the much larger males if they begin to exhibit chimp-like violence or aggression. Oh and males have their version of the handshake too.
Also came across this nice (though long) video interview with the author, here: http://www.youtube.com/watch?v=5CGMJiGe6u4
UPDATE: found this great related TedTalk here: Isabel Behncke: Evolution's gift of play, from bonobo apes to humans
"I just came back from a community that holds the secret to human survival. It’s a place where women run the show, have sex to say hello, and play rules the day.”
"Chimpanzees are well known for their aggression. Unfortunately, we have made too much of an emphasis on this aspect in our narrative of human evolution. Bonobos are the other side of the coin."