Annalee Newitz introduces more theories as to what happened to the human subspecies:
Anthropologists, according to [Professor John] Hawks, often ask the wrong questions of our extinct siblings: “Why didn’t you invent a bow and arrow? Why didn’t you build houses? Why didn’t you do it like we would?” He thinks the answer isn’t that the Neanderthals couldn’t but that they didn’t have the same ability to share ideas between groups the way H. sapiens did.
Their bands were so spread out and remote that they didn’t have a chance to share information and adapt their tools to life in new environments. “They were different, but that doesn’t mean there was a gulf between us,” Hawks concluded. “They did things working with constraints that people today have trouble understanding.” Put another way, Neanderthals spent all day in often fatal battles to get enough food for their kids to eat. As a result, they didn’t have the energy to invent bows and arrows in the evening. Despite these limitations, they formed their small communities, hunted collectively, cared for each other, and honored their dead.
When H. sapiens arrived, Neanderthals finally had access to the kind of symbolic communication and technological adaptations they’d never been able to develop before. Ample archaeological evidence shows that they quickly learned the skills H. sapiens had brought with them, and started using them to adapt to a world they shared with many other groups who exchanged ideas on a regular basis. Instead of being driven into extinction, they enjoyed the wealth of H. sapiens’ culture and underwent a cultural explosion of their own. To put it another way, H. sapiens assimilated the Neanderthals. This process was no doubt partly coercive, the way assimilation so often is today.
Recent Dish on Neanderthals’ extinction here.