Radiolab [HIGHLY RECOMMENDED]
Why so many sperm? We turn to the animal kingdom to answer that question, which lands us on a tour of sperm battles in ducks, flying pig sperm, and promiscuous whippoorwills. We ponder the necessity of males in a world where sperm can be frozen and kept for all eternity. And we sit quietly in a stark sonic space with a widow struggling to keep some essence of her husband alive.
Why So Many Sperm?
Matthew Cobb takes us back to 1677, when Anton Van Leewenhoek first identified sperm and there was much talk of 
souls and miniature men residing in the seminal fluid. Upon observation it became clear that there were an awful lot of those little guys that never turned into babies! Jad wonders: why so many sperm? Bird-sex specialist Tim Birkhead, of the University of Sheffield, explains what effect imperfect monogamy has on reproductive strategies. Then sperm physiologist Joanna Ellington and her pig Hazel give us some insight into the obstacles sperm must overcome in their odyssey from their male originator to their female destination.
Fatherhood
In this segment, Ari Daniel Shapiro introduces us to a young woman and her years-long search for the man whose donated sperm was used in her conception. Kathleen LaBounty has thought long and hard about what fatherhood means, about the psychology of genetic relationships, and about the complicated emotions tied up in family, responsibility, and identity. Her persistence and determination brought her into strangely intimate contact with complete strangers, who had some surprising and unexpected reactions to her sudden appearance in their lives.
Deep Freeze
Genetics researcher and author Steve Jones speculates on how males got their start, and then presents us with a biological mystery: Why have males hung around so long? Males don’t appear to be biologically necessary. In fact, some species, says Steve, have done away with them entirely. But surely males have some use? Steve makes one argument for why we need men … or at least a freezer full of sperm. NPR’s Nell Greenfieldboyce tells us how news of a new technology allowing the extraction of sperm from a man posthumously impacted a grieving New York widow named Leisha.