How do we know this? Didn't most humans aggregate in tribes roughly 150 or so? And then civilizations arose roughly 5500 BP (300 generations). What's to say (ca

How do we know this? Didn't most humans aggregate in tribes roughly 150 or so? And then civilizations arose roughly 5500 BP (300 generations). What's to say (cannot be proven) that nature (evolutional psych) and nurture (socialization and norms) optimized for larger communal living with higher intelligence, self-control, etiquette, less violence, etc.? Pinker's The Better Angels of Our Nature is a good read that doesn't exactly address nature/nurture but peers into the trends.