Although it sounds like science fiction, people for centuries made genetic changes in animals and plants. The process is called selective breeding and is a crossing of specimens with certain attributes, so after several generations to obtain certain animals or plants. Many of today’s pets (dogs, cats, horses, etc.) As well as vegetables and fruits are highly modified compared to its predecessors going back three, four or more centuries. For example watermelons not look like their modern equivalents, when European settlers brought them to the continent of Africa in the XVII century. Outside they are resembled more of melons, while their interior was not completely red and sweet, but only partly. Through selective breeding they reach its current appearance, even those without seeds are not GMO product, but are still hybrid – a work of fine crosses between different species.
This method may be simple, but it requires a lot of time, and prone to genetic encumbrances. For example, according to research by the American Veterinary Association all 50 most popular dog breeds in the US are at risk of genetic defects. Which can be avoided if people can manipulate the animal or plant genome more precisely. Scientists experimenting in this field for decades.
The first genetically modified mice appeared in the 80s of last century, and in 2003 appeared on the market fish that glow in different colors. They are called GloFish and this effect is achieved as in normal fish was added jellyfish gene that enables them to fluoresce. Thus creating new species of fish with qualities taken from a completely different species.