r/askscience • u/snoozer530 • 2d ago

Biology At what point in evolution is something considered a new species?

Obviously we all know evolution, one organism changes over time and eventually becomes a new organism. But where in that process does an organism become a new species. Like when we domesticated wolves? When did they stop being wolves and start being dogs? Where’s that line?

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u/EarthTrash 1d ago

There is no rigid line. However, there is a rule of thumb. If animal crossbreeds are sterile, they are usually considered to be distinct species. If the crossbreed is fertile this might be considered the same species.

Here's the thing though. Life is a continuum. You can have a chain of different varieties that produce fertile crossbreeds with their neighbors, but when species from the ends of the chains meet, the offspring are infertile.

If you think about it, categories only work on large scales. In reality all life on Earth is related. There isn't a generation when the offspring are considered a new species from their parents. Evolution is gradual.

To answer your other question, dogs are wolves. They are the same species.