Humans first tamed wild animals about 12,000 years ago. They quickly found that they could change the animals over time by controlling how they were reproduced.
Breeding fast horses with other fast horses created even faster horses. The same trick worked with plants. Wheat, corn, potatoes, apples, rice—every plant that gives us food today has been bred to be more useful. Yet for years, nobody could explain how this process worked. Finally, in the late 1800s, scientists discovered the secrets of heredity—the passing of genes from generation to generation.
