One English farmer more than doubled the weight of slaughter cattle
In 1700 a bull sold for slaughter in Britain averaged about 370 pounds. By 1786 it weighed around 840. Much of that leap traces to Robert Bakewell, who turned animal breeding into a deliberate science and bred cattle for beef rather than for hauling ploughs. Darwin later drew on such breeders.
Humans were shaping plants and animals long before anyone had a word for it. Wheat, rice and dogs have differed from their wild ancestors for thousands of years, and maize required dramatic change from its wild form, teosinte, in Mesoamerica. Roman treatises around 2,000 years old advised on choosing animals for particular jobs and cited still older experts such as Mago the Carthaginian. In the 11th century the scholar al-Biruni compared the farmer weeding his corn and the forester pruning branches to the same principle.
Not all of it was intentional. Some grains may have grown bigger seeds because of how fields were ploughed, not because farmers picked large seeds, and domestication probably mixed natural and human pressures.
Bakewell made it systematic during the British Agricultural Revolution of the 18th century. From native sheep he quickly produced large, fine-boned animals with long, glossy wool, leading to the hornless, square-bodied New Leicester. It was exported to Australia and North America and fed into many later breeds, even after tastes in meat and cloth moved on; its line survives as the English Leicester, kept mainly for wool. He crossed longhorn heifers with a Westmoreland bull to create the Dishley Longhorn, and his Improved Black Cart horse became the Shire.
Darwin opened On the Origin of Species in 1859 with pigeons, cats, cattle and dogs, using human breeding as an analogy for natural selection while stressing that nature's version has no goal in mind. Breeders still juggle purity against hybrid vigour, since careless crossing can also degrade quality. Fish farming came late to the game: high mortality meant few parent fish, inbreeding and a fallback on wild stock, and species such as eel proved hard to hatch or feed in captivity.
Source: Selective breeding
