The definition of life is in flux, complexity is overrated, and humans are shrinking.

Viruses are supposed to be sleek, pared-down, dead-eyed machines. But when one microbiologist stumbled upon a GIANT virus, hundreds of times bigger than any seen before, all that went out the window. The discovery opened the door not only to a new cast of microscopic characters with names like Mimivirus, Mamavirus, and Megavirus, but also to basic questions: How did we miss these until now? Have they been around since the beginning? What if evolution could go … backwards?

In this episode from 2015, join former co-hosts Jad Abumrad and Robert Krulwich as they grill Radiolab regular Carl Zimmer on these paradoxical viruses – they’re so big that they can get their own viruses! - and what they can tell us about the nature of life.

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Leadership support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.