Insects and animals have evolved some amazing skills -- but, as Robert Full notes, many animals are actually over-engineered. The trick is to copy only what's necessary. He shows how human engineers can learn from animals' tricks.

Bruce Bueno de Mesquita uses mathematical analysis to predict (very often correctly) such messy human events as war, political power shifts, Intifada ... After a crisp explanation of how he does it, he offers three predictions on the future of Iran.

Biologist Mark Pagel shares an intriguing theory about why humans evolved our complex system of language. He suggests that language is a piece of "social technology" that allowed early human tribes to access a powerful new tool: cooperation.

Physicist Brian Greene explains superstring theory, the idea that minscule strands of energy vibrating in 11 dimensions create every particle and force in the universe.

We're all embedded in vast social networks of friends, family, co-workers and more. Nicholas Christakis tracks how a wide variety of traits -- from happiness to obesity -- can spread from person to person, showing how your location in the network might impact your life in ways you don't even know.

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.

Many of the world's biggest problems require asking questions of scientists -- but why should we believe what they say? Historian of science Naomi Oreskes thinks deeply about our relationship to belief and draws out three problems with common attitudes toward scientific inquiry -- and gives her own reasoning for why we ought to trust science.

In this powerful talk, P.W. Singer shows how the widespread use of robots in war is changing the realities of combat. He shows us scenarios straight out of science fiction -- that now may not be so fictitious.

Stephen Wolfram, creator of Mathematica, talks about his quest to make all knowledge computational -- able to be searched, processed and manipulated. His new search engine, Wolfram Alpha, has no lesser goal than to model and explain the physics underlying the universe.

"Babies and young children are like the R&D division of the human species," says psychologist Alison Gopnik. Her research explores the sophisticated intelligence-gathering and decision-making that babies are really doing when they play.

Feelings are complicated. And even more so at work. We like to believe the ultimate professional is stoic, but what important information do we miss when we disregard our emotions on the job? In this episode, Harvard psychologist Susan David helps us break free from the "tyranny of positivity" and embrace the full range of our emotions. After th...

So the Mars Rovers didn't scoop up any alien lifeforms. Scientist Penelope Boston thinks there's a good chance -- a 25 to 50 percent chance, in fact -- that life might exist on Mars, deep inside the planet's caves. She details how we should look and why.

Greg Lynn talks about the mathematical roots of architecture -- and how calculus and digital tools allow modern designers to move beyond the traditional building forms. A glorious church in Queens (and a titanium tea set) illustrate his theory.

Mae Jemison is an astronaut, a doctor, an art collector, a dancer ... Telling stories from her own education and from her time in space, she calls on educators to teach both the arts and sciences, both intuition and logic, as one -- to create bold thinkers.

Neuroscientist Daniel Wolpert starts from a surprising premise: the brain evolved, not to think or feel, but to control movement. In this entertaining, data-rich talk he gives us a glimpse into how the brain creates the grace and agility of human motion.