system
Given the following post, respond as if you're commenting on Reddit:
human
Interbreeding Between Homo Sapien and Neanderthals

I read that scientists believe there was interbreeding between humans and Neanderthals, to the point that Neanderthal genes remain in our DNA. 

But humans are the species homo sapien and Neanderthals are homo neanderthalensis. I thought the definition of species was the inability to breed.
gpt
Species-level distinctions are extremely difficult to make with extinct species. The designation of Homo neanderthalensis as a species separate from modern humans was made in the 19th century and has stuck around largely intact since then. Genetics research that shows evidence of interbreeding between humans and neanderthals has all come out within the last decade. The two remain a separate species, and will continue to remain a separate species largely on the basis of convention, though there is a possibility that neanderthals could eventually go back to being called Homo sapiens neanderthalensis, as they were sometimes called during the latter half of the 20th century.