Research
When did the Neanderthals live?
Current estimates say the Neanderthals lived during a period that spans 200,000 years -- between 30,000 and 230,000 years ago.
Did Neanderthals and Homo sapiens ever live together?
Recent evidence from central France that the two co-existed for at least 1,000 years. Some archaeologists think that eventually 
Neanderthals merged with Homo sapiens and were compeltely assimilated. Others think the Neanderthals died out after the last Ice Age. Still others think that Homo sapiens either conquered the Neanderthals or pushed them into an unsustainable environment.
What kind of social structure did the Neanderthals have?
There are suggestions that the Neanderthals had a elaborate set of roles within their groups. One such indicator is the evidence that individuals with traumatic injuries were kept within the social group. If an individual was, for example, wounded, he or she was not cast out as a non-productive member, but was instead cared for and healing attempts made.
Did the Neanderthals bury their dead?
It appears so. Some anthropologists also believe that Neanderthals had rituals that indicate belief in afterlife. Burial sites discovered include animal antlers buried with bodies of Neanderthals, multiple burial mounds in a single location, and flower fragments next to bodies. However, more recent studies indicate that the flower fragments were an accident, not intentional.
What did they eat?
Meat. More meat. A little fish. And more meat. By some estimates 90% of their diet was meat. If game was scare, the Neanderthals went hungry, a fact that might have contributed to their 
extinction. And since they typically lived far from saltwater, some scholars think the Neanderthals might have suffered from iodine deficiency. They ate ancient versions of caribou, cattle, horses, and bison.
Is there any evidence of Neanderthals in North America?
No. Current scientific thought dictates that Neanderthals never came here. However, as it’s impossible to prove a negative, Kaye George felt comfortable in creating a fictive North American Neanderthal tribe in her novel Death in the Time of Ice.
What did the Neanderthals use for tools and weapons?
The Neanderthals made their own tools. Artifacts uncovered at different sites include stone axes, stone knives, stone spears, and woooden bows with stone-tipped arrows. Hey, they called this the Stone Age for a reason!
A few of the many sources used by George in her research:
In Search of the Neanderthals
by Christopher Stringer and Clive Gamble.
Ice Age Mammals of North America
by Ian M. Lange
The Neandertals
by Pat Shipman and Erik Trinkaus
Smithsonian National Museum of Natural History
Grave Shortcomings in Current Anthropology
Glacier photo credit to Marina and Enrique of Flickr.
Caribou photo credit to Travis S. of Flickr.