6 ideas
Expeditions like Burke and Wills in Australia and Franklin's crew in the Arctic died of starvation and scurvy in environments where local foragers lived for generations. Their intelligence and supplies could not substitute for accumulated local know-how about processing nardoo seeds, hunting seals, or building shelter. Individual brainpower, stripped of an inherited cultural toolkit, is not enough to survive even in a place other humans thrive.
A group's innovative capacity depends on its size and interconnectedness, because more minds sharing and recombining ideas generate and preserve more improvements. When populations shrink or become isolated, as in Tasmania after its separation from mainland Australia, complex skills are lost through imperfect copying and fewer skilled models. Technological sophistication tracks social network size, not individual IQ.
Cultural practices are refined over generations through small copying errors and selective retention, producing adaptive solutions no one designed or fully understands. Manioc detoxification in the Amazon removes cyanide through a laborious multi-day process whose purpose practitioners cannot explain, yet skipping steps causes chronic poisoning years later. Blind faith in tradition can therefore be more adaptive than individual reasoning.
Humans evolved to decide whom to learn from by using cues: copy the successful, copy the prestigious (those others watch and defer to), copy the majority, and copy those similar to you. Prestige is a distinct status system from dominance, based on freely conferred deference in exchange for access to a skilled model's knowledge. These biases explain why people imitate celebrities even outside their domain of expertise.
Once cultural know-how like cooking, tools, and persistence hunting became reliable, natural selection favored genes that depended on it. Humans evolved small guts and weak jaws because cooking pre-digests food, and larger brains because learning from others became the key to survival. Gene-culture coevolution makes us a self-domesticated species that cannot survive without the culture it built.
Rules on kinship, food sharing, marriage, and ritual persist because groups that adopted them outcompeted, absorbed, or were copied by groups that didn't. Intergroup competition selects for norms that expand cooperation beyond kin, and humans evolved norm psychology, internalizing rules and punishing violators, to navigate this environment. Seeing institutions this way reveals apparently arbitrary customs as solutions shaped by group-level selection.