Why did artificial selection interest darwin?

To prove his Theory of Evolution. After studying the different species of finches he found the Galapagos Islands, Darwin focused on breeding pigeons by selecting specific traits of different individuals (this is mainly a method through which different kinds of dog breeds came about). On the basis of these studies Darwin concluded that natural selection and artificial selection acted roughly in the same way. Darwin's decision to enforce a certain trait represented, in a sense, the selective pressure which is present in a natural environment (the law of the fittest).