A key theme from The WEIRDest People in the World by Joseph Henrich is the idea that cultural evolution can have real biological and psychological impacts on humans. Culture is often thought of as something that sits on top of our biology, influenced by the biological changes that evolution favors. But Henrich argues that culture can also shift our biology, by changing our brains.
In the introduction to his book, when calling this out as a key theme, he writes, “beliefs, practices, technologies, and social norms – culture – can shape our brains, biology, and psychology, including our motivations, mental abilities, and decision-making biases. You can’t separate culture from psychology or psychology from biology, because culture physically rewires our brains and thereby shapes how we think.”
For Henrich, this is evident in the way in which reading changes the physical structures of our brain. Our brains can adjust and change based on what we need them to do. Asking them to read a lot changes how brains are internally organized and structured, and that ends up creating further changes in how we perceive the world, how we think, and how we behave. Cultural practices can shape the brain which can then shift the way our thinking operates.
That is why we cannot separate culture and cultural evolution from psychology, biology, and human evolution as a whole. How we interact with and cooperate with others, what traits are favored and passed along, and what cultural practices spread and evolve are all intertwined in complex ways.