Stag hunts or rearing environments?

Tomasello et al. have made the case that shared intentionality distinguishes humans from our nearest living relatives. What accounts for the difference? The answer they offer is Stag Hunt choices faced by ancestral foragers. Noting problems with that answer, I urge attention to a promising alternative stimulated by Tomasello et al.'s own findings. It comes from Sarah Hrdy, who posed the question, "Why us and not them?" The answer she nominated is distinctive rearing environments in our lineage, with consequences for selection on motives and capacities for social engagement at the youngest ages.