we live in social groups. This arrangement has allowed us to expand across the globe, creating livable habitats by feeding, clothing, and learning from each other in otherwise inhospitable physical conditions. We can therefore amass information across generations—stories, recipes, traditions, anything that we can describe—that helps each generation to shape the brain wiring of the next. This trove of intergenerational knowledge lets us actively shape the physical environment, rather than just adapt to it, and to create civilizations.19
