Tubs

I don't like hot tubs.

Can hot tubs make you infertile?

In the checkout line at a supermarket in downtown Nairobi, a conveyor belt moves bags of potato chips, snack foods, processed meats and cheeses, tubs of margarine and bottles of cooking oil.

The technology behind seed storage is impressive. Some seeds at the national seed storage lab might remain viable for 600 years. To show me how they could survive so long, Dr. Walters leads me to a room that's relatively warm, though it contains sealed tubs of liquid nitrogen that are 10 times chillier than the big cold storage room. She unseals a cryogenic tub, and when I reach inside, my hands feel surprisingly comfortable.