Intelligence Is a Shared Resource
Humanity’s immense ecological success is not owed to raw, individual brainpower or superior innate intellect. When stripped of culturally acquired knowledge, humans are not significantly more impressive than other large-brained apes in tasks related to causality, quantities, or space. Our secret lies instead in the collective brain: the flow and recombination of ideas, skills, and practices among interconnected individuals across generations. This process, known as cumulative cultural evolution, is “smarter than we are” because it aggregates insights without requiring any single person to fully grasp the entire system.
The Power of Causal Opacity
Cultural Evolution Beyond Individual Reason
The effectiveness of cumulative culture often relies on causal opacity, where practitioners faithfully follow procedures without understanding why every step is necessary. This non-intuitive compliance is crucial because many adaptive practices—like the precise grinding and leaching required for manioc detoxification to prevent chronic cyanide poisoning—are too complex or too subtle to be devised in a single lifetime, or through casual individual experience. Individuals who try to use their personal rationality to drop seemingly irrelevant, laborious steps, such as leaching manioc, risk poisoning themselves and their families.
Trust in the Accumulated Wisdom of the Ancients
Natural selection favored individuals who placed faith in cultural inheritance over their own personal experiences and innate intuitions. This cultural learning often involves overimitation, where learners copy a model’s seemingly irrelevant actions when performing a task, even when they can clearly see these steps do not directly cause the outcome. This seemingly “irrational” copying is, in fact, an adaptive strategy to acquire crucial, hidden information embedded in complex cultural packages. By contrast, chimpanzees filter out causally irrelevant actions, succeeding in the short term but failing at the long-term complexity required for cumulative cultural evolution.
The Sociality Multiplier
The size and interconnectedness of human groups are the primary limiting factors on the capability of the collective brain. The expansion of our collective brain hinges on social norms and institutions—like affinal ties and rituals—that knit individuals into vast social networks, often stretching beyond kin. In a world where it’s better to be social than smart, these culturally constructed relationships are essential for sustaining complex knowledge, as evidenced by the dramatic loss of sophisticated technologies, like kayaks and bone tools, when the Polar Inuit were cut off from their larger collective brain.