What is the difference between selective breeding and genetic modification?
For centuries people have changed organisms' genetic make-up by choosing individual plants and animals with particular traits, like fast growth rates or good seed production, and breeding from them. This is selective breeding and is, in a sense, similar to evolution by natural selection. During this process thousands of genes are transferred. But selective breeding happens only within closely-related species.
Genetic modification allows us to alter an organism's DNA with much greater precision - genes can be transferred or manipulated singly. Genetic modification can also overcome species barriers, allowing genes to be used in new ways. Some argue that this is inherently risky and unnecessary.
Both selective breeding and genetic modification are useful techniques, but genetic modification can produce a wide range of characteristics that are not possible with selective breeding.