www.ted.com Louise Leakey asks, "Who are we?" The question takes her to the Rift Valley in Eastern Africa, where she digs for the evolutionary origins of humankind -- and suggests a stunning new vision of our competing ancestors.

www.ted.com Chris Abani tells stories of people: People standing up to soldiers. People being compassionate. People being human and reclaiming their humanity. It's "ubuntu," he says: the only way for me to be human is for you to reflect my humanity back at me.

www.ted.com Martin Seligman talks about psychology -- as a field of study and as it works one-on-one with each patient and each practitioner. As it moves beyond a focus on disease, what can modern psychology help us to become?

www.ted.com First, Keith Barry shows us how our brains can fool our bodies -- in a trick that works via podcast too. Then he involves the audience in some jaw-dropping (and even a bit dangerous) feats of brain magic.

www.ted.com Speaking at the most recent EG conference, author, philosopher, prankster and journalist A.J. Jacobs talks about the year he spent living biblically -- following the rules in the Bible as literally as possible.

www.ted.com Speaking at TED in 1998, Rev. Billy Graham marvels at technology's power to improve lives and change the world -- but says the end of evil, suffering and death will come only after the world accepts Christ. A legendary talk from TED's archives.

www.ted.com Why do we crave love so much, even to the point that we would die for it? To learn more about our very real, very physical need for romantic love, Helen Fisher and her research team took MRIs of people in love -- and people who had just been dumped.

Physicist Freeman Dyson suggests that we start looking for life on the moons of Jupiter and out past Neptune, in the Kuiper belt and the Oort cloud. He talks about what such life would be like -- and how we might find it.

www.ted.com In this prescient 2005 talk, Clay Shirky shows how closed groups and companies will give way to looser networks where small contributors have big roles and fluid cooperation replaces rigid planning.

www.ted.com

The wonderful Nellie McKay sings "Mother of Pearl" (with the immortal first line "Feminists don't have a sense of humor") and "If I Had You" from her sparkling set at TED2008.