Sperm

Imagine yourself back to the mid 1600's, a time when the scientific importance of lenses and their manipulation was just beginning to dawn on great minds like Galileo and Robert Hooke: you could begin to study the hitherto hidden worlds of the very far and the very small.

Enter Antonie van Leeuwenhoek (father of microbiology) and Nicolaas Hartsoeker (credited with postulating the spermatic homunculi theory). These two chaps decide to look at seminal fluid under a microscope (who wouldn't?) and what they found would revolutionize our understanding of the origin of life, which the following clip from RadioLab's latest episode dramatically captures through superb sound editing.

Legend has it that Harsoeker was so freaked out by what he saw that he did not do any microscopy for the next two years :)

Check out The Invisible World,

or learn about the female orgasm in The Biology of Love.

.