Although there were likely never hordes of hoary old ones, just as in recent hunter-gatherer societies three living generations was probably normal for Neanderthals. And growing up with grandparents matters, for two key reasons. First, casual babysitting is extremely useful, as it frees adults to find more food or do other tasks. Second, in addition to reinforcing what children learn from parents, grandparents are more likely to be competent in complex skills, whether producing hafting recipes, tracking or even medical care.
