Question: if you mix genes of two different animals together will it make a whole different kind of species?

Nick Groves-Kirkby answered on 11 Nov 2013:

This is a really good question!

In general it’s difficult to make a new kind of species in this way. In mammals (like us), genes are organised in a complex way that is specific to a particular species. For example, mixing the genes of a cat and a dog doesn’t create a new species, because the cat genes and dog genes don’t know how to talk to each other, and the new cat/dog cells don’t work properly.

Some closely related animals can breed together, and they produce what we call ‘hybrids’. Donkeys and horses can breed to create a different kind of animal called a mule. Mules are usually infertile though, so we don’t think of them as a new species (part of the definition of a species is the ability to breed).

Lions and tigers can also breed to produce new kinds of animals, called ‘ligers’ or ‘tigons’. Again, these are usually infertile so aren’t a new species, but they are kind of cool.

In simple animals like bacteria, things are very different. Bacteria don’t have males and females like we do. Instead they usually breed by cloning (making exact copies) of themselves.

However, bacteria usually live in large, closely packed groups and they very often pass genes to their neighbours. We can copy this process in the lab, and can move genes around between bacteria and other simple animals and plants fairly easily. We use this process to make genetically modified (GM) crops, for example, by adding genes that increase plant growth or protect against insects.

For the moment, the idea of mixing two complex animals together to make a new species is definitely science fiction. If you could make your idea work and create the cat-dog, then you’d probably win a Nobel Prize and be very rich and famous!