Daniel Kish has been blind since he was 13 months old, but has learned to "see" using a form of echolocation. He clicks his tongue and sends out flashes of sound that bounce off surfaces in the environment and return to him, helping him to construct an understanding of the space around him. In a rousing talk, Kish shows how this works -- and asks us all to let go of our fear of the dark unknown.

As humans, we can perceive less than a ten-trillionth of all light waves. "Our experience of reality," says neuroscientist David Eagleman, "is constrained by our biology." He wants to change that. His research into our brain processes has led him to create new interfaces -- such as a sensory vest -- to take in previously unseen information about the world around us.

How do vaccines prevent disease -- even among people too young to get vaccinated? It's a concept called "herd immunity," and it relies on a critical mass of people getting their shots to break the chain of infection. Health researcher Romina Libster shows how herd immunity contained a deadly outbreak of H1N1 in her hometown. (In Spanish with English subtitles)

Rob Knight is a pioneer in studying human microbes, the community of tiny single-cell organisms living inside our bodies that have a huge — and largely unexplored — role in our health. “The three pounds of microbes that you carry around with you might be more important than every single gene you carry around in your genome,” he says. Find out why.

Just like us, the monarch butterfly sometimes gets sick thanks to a nasty parasite. But biologist Jaap de Roode noticed something interesting about the butterflies he was studying — infected female butterflies would choose to lay their eggs on a specific kind of plant that helped their offspring avoid getting sick. How do they know to choose this plant? Think of it as "the other butterfly effect" — which could teach us to find new medicines for the treatment of human disease.

How much of what you think about psychology is actually wrong? In this whistle-stop tour of disproved ideas, Ben Ambridge shares nine popular ideas about psychology that have been proven wrong -- and uncovers a few surprising truths about how our brains really work.

You may remember neuroscientist Miguel Nicolelis — he built the brain-controlled exoskeleton that allowed a paralyzed man to kick the first ball of the 2014 World Cup. What’s he working on now? Building ways for two minds (rats and monkeys, for now) to send messages brain to brain. Watch to the end for an experiment that, as he says, will go to "the limit of your imagination."

2041 will be a pivotal year for our planet. That year will mark the end of a 50-year agreement to keep Antarctica, the Earth's last pristine continent, free of exploitation. Explorer Robert Swan — the first person to walk both the North and South Poles — is on a mission to ensure that we extend that treaty. With passion and vigor, he pleads with us to choose the preservation of the Antarctic for our own survival.

"Save the rainforest" is an environmental slogan as old as time — but Tasso Azevedo catches us up on how the fight is actually going these days. Spurred by the jaw-dropping losses of the 1990s, new laws (and transparent data) are helping slow the rate of deforestation in Brazil. Is it enough? Not yet. He has five ideas about what we should do next. And he asks if the lessons learned in Brazil could be applied to an even bigger problem: global climate change.

What do you call a veterinarian who can only take care of one species? A physician. In a fascinating talk, Barbara Natterson-Horowitz shares how a species-spanning approach to health can improve medical care of the human animal -- particularly when it comes to mental health.