Directed evolution
Domestication of crops was one of the most important events in human history. Generation after generation, early humans selected seeds from plants with favourable features to obtain crops that could provide a steady food supply.
In 2006, Israeli scientists suggested that figs were the first crop to be domesticated, around 11 000 years ago. The most significant crops, however, are the cereals – rice, wheat, maize and sorghum.
Modern cereals are the result of generations of selection for plants with beneficial properties. Sometimes, the original plant still exists – maize, for example, is derived from the tropical grass teosinte. Genetic comparisons can thus be made to identify the genetic basis for cereals' useful properties.
Cereal crops, for example, were eventually developed with grains that stayed attached to stalks until harvested, rather than grains that fell ('shattered'). Fine-tuning of two genes recently discovered to control shattering might now help modern farmers produce even better future crops.
Dogs are domesticated wolves. Domestication of dogs started as early as 15 000 BCE, the Romans being among the first to breed dogs for hunting, herding or as guard dogs.
Pedigree dogs have been selectively bred to emphasise particular characteristics. Inbreeding reduces the gene pool, and many breeds of dog are prone to genetic conditions affecting their health. Dalmatians, for example, are often deaf.