The Mysterious Downfall of the Neandertals: Scientific American

The Mysterious Downfall of the Neandertals: Scientific American: "Research led by Rachel Caspari of Central Michigan University has shown that around 30,000 years ago, the number of modern humans who lived to be old enough to be grandparents began to skyrocket. Exactly what spurred this increase in longevity is uncertain, but the change had two key consequences. First, people had more reproductive years, thus increasing their fertility potential. Second, they had more time over which to acquire specialized knowledge and pass it on to the next generation—where to find drinking water in times of drought, for instance. “Long-term survivorship gives the potential for bigger social networks and greater knowledge stores,” Stringer comments. Among the shorter-lived Neandertals, in contrast, knowledge was more likely to disappear, he surmises."

And of course the old farts became shamans and invented religion to provide them with a livelihood. They couldn't hunt or gather any more, but they could demand a sacrifice to God who provided all the lore that made the hunt successful. Then anything that God didn't eat they did.