Human empathy is not a new thing. The behavior you describe would be entirely dependent on culture. You could easily imagine a culture where people with down sy

Human empathy is not a new thing. The behavior you describe would be entirely dependent on culture. You could easily imagine a culture where people with down syndrome were venerated as a gift from the gods. Outside of these extremes it's entirely plausible that members of the tribe who needed to be looked after were simply looked after. Your imagination of all historical societies as entirely savage is incredibly reductive.