How much evolutionary change would our descendants need to go through for them to conclude they weren’t Homo Sapiens anymore but in fact a new species? Assume our species as it is now no longer exists so inability to interbreed wouldn’t be a deciding factor. Or will we always consider ourselves to be Homo Sapiens no matter how much we evolve?
- They would need to go through 17 change.
That non-answer is as good as anything else that you can get. Since the biological species idea is based on the ability to interbreed, identification of what were seperate species in the past is speculation very fuzzy at the edges. We can’t even decide if Neanderthals, Denisovians, and modern humans should count as different species and we have complete DNA samples for each of them. Whether people so distant in the future that they might be a different speces are lumpers or splitters is asking about the psychology and philosophy of non-existent theoretical people, and therefore somewhat difficult to answer.
Comparing current species to species long ago is very difficult and largely arbitrary. But it won’t be so into the future. Even if our descendants’ own DNA is radically different from ours, they’ll still, presumably, have preserved records of our DNA. They’d be able to compare their genes to ours directly, and if desired, they could even clone a 20th-century human and see if they could interbreed (or, for less ethical issues, clone a 20th-century animal and test it with similar animals of their time).
Lacking isolation it might never happen. We certainly could interbreed with some of our ancestor species. We’ve already seen that Neanderthal and Denisovan genes exist in the current population. We are certainly talking about many millions of years before significant genetic drift and mutations reach the point where our descendants could no longer interbreed with us, and our ancestor species.
Conventional evolution is too slow for this.
There might well be a point, within a few millenia if not centuries, where we have customized our DNA sufficiently and/or have various cyborg parts, that we classify ourselves as a new species. Being unable to reproduce with 21st century humans might be the least of it.
I know it’s a bit of a hijack, but this tech evolution is likely to happen long before conventional evolution could.
Different species sometimes can make viable offspring and only do not because something about them makes them never choose to interbreed. For example, two species of bird might be so closely related that if they had offspring they’d be just fine, but they mate in different times of year or using different displays.
Obviously none of those concepts translate very well to more intelligent beings like humans.
But exploring it a bit - if 200 years from now everyone makes their babies by growing them in artificial wombs, and no 24th century person would agree to mate and produce babies internally (even though the equipment works, they’rejust revolted by the idea), would that count as a separate “species”?
Probably there are two ways this could go - one, we continue to call ourselves H. sapiens long past the time we’ve drifted away or engineered away from 20th C compatibility, or we split up even while still compatible because ome of us feel they are H. superior or some other eugenicist shit even when still compatible.
Because ultimately, it’s whatever humans who are around at the time who get to make the call.
There’s also the old standby of science fiction of humans colonizing different planets, but space travel being difficult or expensive enough, or becoming so after the collapse of the First Empire, that once colonized, those planets stay isolated. It wouldn’t be surprising to get speciation in a situation like that (though each branch might still refer to itself as the original).
I’m not sure evolution will continue in the traditional sense at all. In the past, evolution happened due to adaptation to environmental pressures (generally speaking). Modern humans have to ability to technologically override any deficiencies in our genes (eyeglasses, wheelchairs, etc) and because of clothing, air conditioning/heating, modern food practices and modern medicine there is less of a need to adapt to pressures from our environment.
The giant headed humans of the future is probably SF.