We spend about one-third of our lives sleeping. Why? Believe it or not, scientists don't know for sure. But evidence is building that sleep may play a crucial role in strengthening memories and facilitating learning, not just in humans but in most animals.
NOVA scienceNOW visits research labs at the University of Pennsylvania and MIT, where scientists are peering into the brains of dozing flies and rats to understand the connection between sleep and memory. At Harvard Medical School, host Neil deGrasse Tyson tests his powers of learning on a virtual ski machine and a speed typing exercise, and then catches some z's. He discovers that it's not practice that makes perfect, but practice plus a good night's sleep.
As inhabitants of Earth, we humans are relative newbies. In fact, our branch of the evolutionary tree may have split from that of the apes only about six million years ago. But what if we look further back in our primate family tree? What would we find? As correspondent Peter Standring reports, the latest research is revealing that our origins may have been quite a bit humbler than we may have thought.
Scientists have a good idea of what causes earthquakes like those that struck Chile or Haiti in 2010, or in places like California. It's all about sudden movement along the edges of the giant crustal plates that make up the Earth's crust. But another kind of quake exists, one that occurs far from plate boundaries. It's big, it's dangerous, and it could strike anytime in the very middle of America.
Sang-Mook Lee, a professor of marine geology and geophysics at Seoul National University, is paralyzed from the neck down. But that hasn't stopped him: He continues to teach and pursue his research on tectonic plates and the formation of the world's oceans. Outside his academic work, he also has launched a new career teaching others with disabilities and advocating for the rights of disabled people.