I'm not sure your comment is relevant to the discussion. The concept of species, when it involves sexual reproduction, is pretty straight-forward: mating produces fertile offspring.

Your remark is only relevant when nit-picking corner cases involving asexual reproduction, which I don't expect to be the case in Neanderthal-Human cross-breeding.

Thanks, I just spent 30 minutes debating what a species was with a friend because of this article. The ring species concept clarifies quite a lot.

Sure, but there is no evidence this is a ring species situation is there? It just seems like bringing an edge case into a simple situation.

Thank you. This is seriously amazing.

It's not easy to define species following a common basic definition that applies to all taxonomy ranks, specially when asexual reproduction takes place.

But this is not the case being discussed here.

With higher mammals that is not the case, and the definition of species is already well established: sexual reproduction results in fertile offspring.

Svante Paabo, who led the group that sequenced the Neanderthal genome and discovered we interbred with them, had to decide whether to give a species- or local name to the Denisovans. The argument that carried the day was that “species” is such an ill-defined biological concept that it’s a sterile intellectual exercise arguing over it; and if they’d gone with, say, Homo altaiensis rather than Denisovans, it would’ve been extremely hard to take it back (“Neanderthal Man,” 2014, Ch. 23).

Considering Paabo secured funding from the German government for a brand-new research institute in ancient human DNA and related subjects, including the right to decide what city to build the institute in and hiring authority over the initial staff, and given that he had an advance agreement with Science to publish the Neanderthal genome, I think some of these discoverers aren’t that exercised by whether they make it onto the cover of National Geographic.

> So, in general, the field of biological anthropology has leaned towards identifying new species when possible.

Cite?

You’re not presenting your sources accurately.

The full quote from [1]:

> No evidence of Neanderthal mitochondrial DNA has been found in modern humans. This suggests that successful Neanderthal admixture happened in pairings with Neanderthal males and modern human females.

The full quote from [2]:

> A 2016 study presented evidence that Neanderthal males might not have had viable male offspring with AMH females. This could explain why no modern man to date has been found with a Neanderthal Y chromosome.

Also from [2]:

> Positive evidence for admixture was first published in May 2010. Neanderthal-inherited genetic material is found in all non-African populations and was initially reported to comprise 1 to 4 percent of the genome. This fraction was later refined to 1.5 to 2.1 percent.

A somewhat interesting fact is that by this definition two groups of humans can be different species simply by not being able to reach each other due to a impassable barrier

It also breaks down if you use it on very broad scales. Species are easier to separate when their common ancestor is outside your frame of reference.

For historical and cultural reasons; you could also ask why North and South America are considered separate continents and why the Arctic is considered a continent at all. The tradional seven-continents model predates modern geology and is a mix of geological, cultural, and linguistic categorization. We might also divide them by continental plates, in which case Eurasia and Africa are distininct continents. Another approach is contiguous landmasses, which leads to a four-continents model which has Afro-Eurasia, the Americas, Antarctica, and Australia along with their associated islands. There are various other models; which you prefer depends on your definition of continent and your reasons for dividing them.

You're right that there is a definition by which “a different human race” is a sensible designation, but personally I think the concept of “race” belongs in the bin. There are many things we could sensibly call “æther”, yet we avoid the terminology because historical science papers used the word to describe a concept that's now so obviously wrong it's amusing that anybody ever thought it was the case.

Science always brings in modern-day politics. Science, in its purest form, doesn't know of silly human foibles like “ethical restraint” or “but that's almost certainly fatal”; if scientists acted purely on scientific inquiry, the scientists who didn't kill themselves in a hair-brained scheme would either be in prison or on the run.

The classification of humans into “races” is historically associated with pseudoscientific drivel that was never particularly based on reality (much, much less so than the idea of æther); even if you've found a “race” classification that actually does have an element of truth in it, giving it the same name as the Göttingen school's scientific racism is probably not a good idea.