What is the main conflict in The Clan of the Cave Bear by Jean M. Auel?

The story concerns a young girl named Ayla who is orphaned by a natural disaster and then adopted by a group known as the Clan. Ayla is very different from the Clan: physically, she is blond and blue-eyed and the people in the Clan are stocky and dark; she is expressive, sensitive, and smart and they are dour, plodding, and cold. Historians and anthropologists immediately reacted to Auel's book, maintaining that her assumptions about Neanderthal life were not realistic.