The researchers ran computer simulations of different population densities, grouping humans into subpopulations that migrated. The model revealed that at a certain subpopulation density there was an accumulation of ideas and skills. To figure out whether this phenomenon of skill-sharing was real, the team used genetic data to estimate population sizes in different regions at different times. Sure enough, when the critical population density was reached or there was a certain degree of migration between subgroups there was also archaeological evidence of modern human behavior.
It’s especially interesting to think about in terms of what drives evolution. Last year I referenced a paper I had read about how humans evolved because of tools, rather than evolved and then were able to use them. Could these large groups actually have driven human brain development?