There are two primary distinctions between species:
* They cannot interbreed. Either it doesn't work at all or the offspring is sterile.
* They could but do not interbreed. This happens often with some birds that have such different mating signals, they don't cross over.
Everything that can and does interbreed is technicall a difference of subspecies, not species.
This is upsetting some humans now that we've found Cro Magnon, Neanderthal, Denisovan, and some other kind we don't even know what it is DNA blobbed together in the human genome. Those had been considered separate, but well, people fuck, and apparently the results were fertile, so the tree needs a bit of rearranging.
I imagine the same is true in worlds with multiple humanoid races. They fuck, the results are fertile, but most people feel really really awkward about it.
I did something a bit different with the Six Races in A Conflagration of Dragons. Some pairs are cross-fertile, others aren't. Hybrids used to be quite rare. But after the dragons flattened civilization, people mixed more -- and then the hybrids turned out to be fertile with each other. It's actually possible to rack up all four elements in one body, but it takes a few generations to get that far.
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
timeasmymeasure
Well ...
Date: 2019-01-05 02:52 am (UTC)* They cannot interbreed. Either it doesn't work at all or the offspring is sterile.
* They could but do not interbreed. This happens often with some birds that have such different mating signals, they don't cross over.
Everything that can and does interbreed is technicall a difference of subspecies, not species.
This is upsetting some humans now that we've found Cro Magnon, Neanderthal, Denisovan, and some other kind we don't even know what it is DNA blobbed together in the human genome. Those had been considered separate, but well, people fuck, and apparently the results were fertile, so the tree needs a bit of rearranging.
I imagine the same is true in worlds with multiple humanoid races. They fuck, the results are fertile, but most people feel really really awkward about it.
I did something a bit different with the Six Races in A Conflagration of Dragons. Some pairs are cross-fertile, others aren't. Hybrids used to be quite rare. But after the dragons flattened civilization, people mixed more -- and then the hybrids turned out to be fertile with each other. It's actually possible to rack up all four elements in one body, but it takes a few generations to get that far.