Selective breeding is the process of selecting specific organisms for reproduction while overlooking others based on their traits. Animals, plants, or even humans with certain desired traits are selected while others with undesirable traits are avoided. Over time, selective breeding results in a being with the desired traits exaggerated more that usual.
Applications of selective breeding
In many cases, animals are bred selectively to product a breed of that animal which is, for example, taller than most others. This is especially done with animals which are popular as pets, work animals, and material sources.
Dogs and cats are very popular house pets, but different people have different preferences. For this reason, there are many breeds of these pets available today. Some are bred for their size, like Great Danes, or bred for their superior hunting ability, like Bloodhounds.
For centuries, animals used for labor have been bred for their traits. The strong ones where generally more useful, so they were favored. For example, there are many breeds of horses, each with advantages and draw-backs.
Cows are a great example of animals which are bred for what they produce. Cows are sometimes bred so that their milk supply is greater or in all, or contains a greater percentage of cream. Some such breeds are Ayrshire, Brown Swiss, Guernsey, Holstein-Friesian, Jersey, and Milking Shorthorn. They are also sometimes bred for meat. These tend to be almost polar opposites of dairy cows, since the milk is not important. Rather, the focus is generally on growth rate and body mass. Some favored breeds are Angus Cattle, Ankole-Watusi, Beefmaster Cattle, Braford Cattle, Brahman Cattle, Charolais Cattle, Chianina Cattle, Dexter Cattle, Fakeford, Galloway Cattle, Gelbvieh Cattle, Hereford Cattle, Maine Anjou Cattle, Pinzgauer Cattle, and Polled Hereford Cattle.
By far, the most controversial kind of selective breeding is among humans. This kind of selective breeding is called eugenics. In theory, and willing population could participate in a eugenic effort, but this never has happened- and probably never will. In general, it is forced upon one group of people by another. In any case, eugenic efforts label certain human traits as better than others. When human traits start being classified as superior and inferior, unwarranted discrimination results. Eugenics was a large part of the aggressive suppression and assault of those who were not of the "master" (Aryan) race, according to the Nazi party in the early 1900s. The Western World's resistance to the barbaric treatment and genocide which "lesser" races were forced to face became known as World War II.