The first part isn’t true. We evolved to do whatever’s necessary to survive and pass on our genes. Whether that’s living in small societies and foraging (and fucking), or farming, or hunting, or living in big cities going out to night clubs so we can get laid. Our bodies haven’t changed too much from those of apes who live in small societies and hunt and forage. But, evolution gave us a huge brain and doesn’t take millennia of evolution to adapt.

Even though are brains are adaptable, there are limits. In many ways the brain processes the world in a way that’s useful for a primate living in a small group in a savanna surrounded by possible threats. For example, if the grass is moving in a certain way, a brain that interprets that as having meaning might survive better than one that doesn’t. Maybe there’s a lion approaching in a stealthy way. That way of assuming there’s a brain behind a pattern leads humans to believe in gods, or to think that ChatGPT is their girlfriend. That’s something that might be a maladaptive trait in the modern world, but not enough for evolution to strongly select against it.

As for hunter gatherers, they didn’t have exercise regimens, or form into regiments.