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Comment by qubax | Hacker News Reader

> Is it strictly correct to say Neanderthals became extinct if we carry some of their DNA?

Yes. Neanderthals as a population don't exist anymore.

The house cat and tiger shares 95% of the same genes. If tigers disappeared, you wouldn't consider it an extinction because we have house cats around?

https://www.csmonitor.com/Science/2013/0918/House-cats-and-t...

Also, the common ancestors of humans and the common ancestors of cats became extinct a long time ago. Are you saying those "creatures" aren't extinct because humans and cats are around?

Edit: An additional example for those interested. Birds today share same genes as tyrannosaur rex.

https://www.scientificamerican.com/article/how-dinosaurs-shr...

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The house cat and tiger had a common ancestor; the Neanderthal WAS an ancestor of modern humans.

Saying "neanderthals as a population don't exist anymore" tells us nothing, because no ancient population exists anymore - they have all been replaced by their descendants. "Extinct" is not the same as "dead".

If we make a phylogenetic tree showing descent, extinction would mean the tree ends - there are no descendants. This is clearly not the case for Neanderthals.

The argument you are making here seems to be that Neanderthals and Homo Sapiens are not distinct species - which seems reasonable to me, given that the populations interbred to the degree they did.

The set of all the descendants of a given species is a valid concept, but it is not the definition of a species (note, for one thing, the awkward self-referentiality if it were.)

None of the extant speciation criteria seem testable across time, so the species distinction between an ancestor and its progeny seems difficult to navigate. This sort of event, of a species vanishing through the slow evolution of its progeny, is called "pseudoextinction" to distinguish from the other, true 'extinction' (the last surviving member of a lineage dies). In this case since we know that Neanderthal DNA lives on in its H. Sapiens descendants we can safely call this "pseudo" rather than a true extinction.

You can rephrase his example to e.g. wolves and chihuahua as one of the more absurd, but accurate, examples to confirm his point and challenge yours. And the interesting thing is is that was a crazy fast speciation by artificial selection. Not only does the "ancient population" still exist, but it'd be quite bizarre to suggest that wolves were not extinct, if they did go extinct, because chihuahuas exist. Speciation, even from a direct ancestor, is very much a thing.

For interbreeding purposes, wolves and dogs (including chihuahuas) are still the same species since they can create fertile offspring.

It seems mechanically challenging for wolves and chihuahuas to create offspring.

> Yes. Neanderthals as a population don't exist anymore.

But then neither is the Homo Sapiens of that era, surely?

> The house cat and tiger shares 95% of the same genes. If tigers disappeared, you wouldn't consider it an extinction because we have house cats around?

If they interbred now and there was gene transfer within that 5%, I think that would be an entirely different situation to the one you describe.

The picture that is often painted of the Neanderthal following a parallel evolutionary course to 'us', Homo Sapiens. But 'us' is actually a hybrid of the two.

> Also, the common ancestors of humans and the common ancestors of cats became extinct a long time ago. Are you saying those "creatures" aren't extinct because humans and cats are around?

Of course not, and you seem to be entirely misunderstanding my question.

If humans and cats somehow interbred and the ongoing population of cat-human hybrids was what carried on, identifiable fully as neither, the picture is much more grey.

> Birds today share same genes as tyrannosaur rex

Really? Surely this claim would require the sequencing of the T-Rex genome, which I'm guessing is an impossibility.

Maybe not so impossible? https://www.nsf.gov/news/news_summ.jsp?cntn_id=111466

Strictly speaking, all liveforms on the planet share same genes because they descended from a common ancestor. You probably have 50% of common genes with plants and quite a few with microorganisms.

IIRC, ~70% with bananas.

it sounds like quite a stretch to say everything shares the same genes. A lot of the genes have come into existence long after distant species split apart, and other genes have disappeared from one specie while continuing in others.

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