Did you know that fewer than 20 percent of giggles and guffaws in everyday conversation are in response to humor? Or that nervous tittering is an instinctive reaction to a perceived threat? In this episode, we probe the deep and ancient mysteries of laughter, a “universal part of the human vocabulary,” and explore its many roles in human communication.

How long ago did humans begin speaking to one another — was it fifty thousand years, or maybe more? Were stone-age cave paintings created by female shamans, summoning a connection to the spirit world? In this inaugural episode, we look back on a forgotten time to explore the earliest roots of human communication.