Neanderthals became extinct in Europe although they had been used to the climate for a long time and had survived in very harsh circumstances, something significant had to happen so that some 28,000 years ago there would no longer be any Neanderthals.
The most recent investigations about the extinction of the Neanderthals focus on comparing the shape of the brain of four Neanderthals. Two were found in France, one in Israel and the other in Gibraltar. The skulls of these Neanderthals were compared with the skulls of specimens of Homo sapiens living at the same time.
Investigators wanted to study the size of the cerebellum, the cerebellum being a part of the brain whose function was considered secondary until recently. Although dividing the brain into zones such as lobes is useful for its study, it's a way of studying it that doesn't seem very suitable for analyzing cognitive changes throughout evolution.
It was known that the Neanderthals' brains were larger than ours, but they found another small difference that was not known. Homo sapiens had the largest cerebellum relative to the rest of their brains, even though the Neanderthals' brains were larger than those of the sapiens. Perhaps this was the reason or one of them for the disappearance of the Neanderthals, although it's still one of many theories.