more (at source): “People learn from their parents or teachers in their group, and this model demonstrates you have to have a critical number of people learning to develop complexity,” Adam Powell, 28, a co-author of the study and a doctoral student at the London university. “The actual invention of all these technologies was probably very common, but was only passed on as density increased.”

The thing that comes to my mind as being the (relevant) crucial benefit of communities is division of labor. Not having to know every skill involved in producing things (be it for survival or convenience), you're able to focus more of your time to specific avenues of necessity and pleasure. Thus, deeper levels of knowledge can be obtained and innovations will occur more readily.