Glue was found on well-preserved tools from 50 kya:
Traces of ancient “glue” on a stone tool from 50,000 years ago points to complex thinking by Neanderthals, experts say.
The glue was made from birch tar in a process that required forward planning and involved several different steps.
It adds to mounting evidence that we have underestimated the capabilities of our evolutionary cousins.Paul Rincon, “Neanderthal ‘glue’ points to complex thinking” at BBC News
As noted earlier, they were assumed to be subhuman because, in any Darwinian scheme, someone must be the subhuman.
If they are accepted as human, of course, in a progressive scheme, they must be either vile perpetrators or hapless victims. Demonstrating that they achieved things risks putting them in the class of vile perpetrators. Maybe they stole the idea for glue from homo erectus?
See also: Once again, did Neanderthals speak?
Neanderthal Man: The long-lost relative turns up again, this time with documents