The primacy of scaffolding within groups for the evolution of group-level traits.

Although both a "simple dyad or a population of thousands" are groups, these are, respectively, face-to-face embodied groups and collective symbolic groups. We applaud Smaldino for recognizing and describing the concept of the group-level trait. As an expansion, we propose an evolutionary-developmental model of face-to-face groups that scaffolds theorizing the evolution of cultural group-level traits.