Why do societies fail? With lessons from the Norse of Iron Age Greenland, deforested Easter Island and present-day Montana, Jared Diamond talks about the signs that collapse is near, and how -- if we see it in time -- we can prevent it.

There's an irony behind the latest efforts to extend human life: It's no picnic to be an old person in a youth-oriented society. Older people can become isolated, lacking meaningful work and low on funds. In this intriguing talk, Jared Diamond looks at how many different societies treat their elders -- some better, some worse -- and suggests we ...

For centuries, we believed the Earth was flat, that the sun rotated around the Earth. These were absolute truths, until ... they weren't. Which of our accepted truths will fall apart in the years ahead? Financier-turned-philosopher Yannick Roudaut believes we're on the cusp of another historical reckoning -- and another renaissance.

An idea permeates our modern view of relationships: that men and women have always paired off in sexually exclusive relationships. But before the dawn of agriculture, humans may actually have been quite promiscuous. Author Christopher Ryan walks us through the controversial evidence that human beings are sexual omnivores by nature, in hopes that...

Days before this talk, journalist Naomi Klein was on a boat in the Gulf of Mexico, looking at the catastrophic results of BP's risky pursuit of oil. Our societies have become addicted to extreme risk in finding new energy, new financial instruments and more ... and too often, we're left to clean up a mess afterward. Klein's question: What's the ...