Examine more threats - both natural and man-made - that may endanger civilization. From the far reaches of space to tiny viruses, doomsday sources are many, but so are technologies used to keep the chaos at bay.

Explore the tech developed to create and respond to doomsday threats ranging from very real (nuclear arsenals) to controversial (global warming) to futuristic (nanotechnology, cyborgs, and robots).

Watch these machines make delicious treats for your mouth! Visit Snyder's of Hanover, Utz Quality Foods, Dreyer's Bakersfield, and Masterfoods USA, which makes Milky Way, Snickers, Mars, and M&Ms.

Trace the history of bathing, showering, and oral hygiene, where we reveal the messy truth about what was used before toilet paper and why astronauts wear diapers.