It goes back much further than that. GP linked to the Wikipedia article on universals. During the late middle ages there was a furious debate about whether species (taking the term in its very broad philosophical sense) could be said to exist, or whether all categorization was done by human beings applying labels. To me, it seems one of the most fundamental questions in all philosophy.

I wasn't saying it's a new discovery. My first link mentions Darwin who wrote about in the 19th century.

It is a discovery for people who are taught that the distinctions between species are very clear and then learn otherwise.