Sperm carry half the genes needed for human life. In this hour of Radiolab, we'll share some basic questions and profound thoughts about reproduction. To begin: why so many sperm?

We turn to the animal kingdom for answers. Next, we ponder fatherhood, and wonder what the future holds for men in a world where sperm can be frozen and kept for all eternity. We end quietly, in a stark sonic space with a widow struggling to keep some essence of her husband alive.

GUESTS:

Tim Birkhead,  Matthew Cobb,  Joanna Ellington,  Nell Greenfieldboyce,  Steve Jones,  Kathleen LaBounty and  Ari Daniel Shapiro

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