THOR HANSON

By Mendel’s time, plant breeding had progressed to a point where

every region boasted dozens of local varieties of peas, not to

mention beans, lettuce, strawberries, carrots, wheat, tomatoes, and

scores of other crops. People may not have known about genetics,

but everyone understood that plants (and animals) could be

changed dramatically through selective breeding. A single species of

weedy coastal mustard, for example, eventually gave rise to more

than half a dozen familiar European vegetables. Farmers interested in

tasty leaves turned it into cabbages, collard greens, and kale.

Selecting plants with edible side buds and flower shoots produced

Brussels sprouts, cauliflower, and broccoli, while nurturing a fattened

stem produced kohlrabi. In some cases, improving a crop was as

simple as saving the largest seeds, but other situations required real

sophistication. Assyrians began meticulously hand-pollinating date

palms more than 4,000 years ago, and as early as the Shang Dynasty

(1766–1122 BC), Chinese winemakers had perfected a strain of millet

that required protection from cross-pollination. Perhaps no culture

better expresses the instinctive link between growing plants and

studying them than the Mende people of Sierra Leone, whose verb

for “experiment” comes from the phrase “trying out new rice.”