Main thesis: cultural knowledge creation and propagation is humanity’s ecological niche

  • What is cultural knowledge? Everything we learn by copying others, using success, age, prestige (the assessment of others), and self-similarity as cues to target whom to learn from; our ability to pass knowledge culturally instead of having every individual rediscover everything on their own explains the success of our species
  • Once we crossed the threshold into cumulative cultural evolution, we became genetically increasingly better at cultural learning through natural selection; this process of gene-culture co-evolution is the central force driving human genetic evolution over the last 2 million years - languages, cooperation, and tools are products of this process

What is the most compelling evidence for gene-culture co-evolution?

  • Our biology is optimized for cultural learning
    • Big brains with slow wiring up (myelin plasticity until late 20s)
    • Long development period (childhood and adolescence)
  • Our biology is dependent on cultural learning
    • External food processing through culturally acquired practices (cooking, chopping) has freed our digestive system to be much simpler, and our mouths and teeth much smaller than other primates
    • Tools for hunting and fighting (blades, spears, axes, snares) have replaced the big muscles of other primates
    • This freed up energy to power our brains (using 25% of our energy vs. 8% for other primates)

When did our species start possessing knowledge that no single individual could have discovered on their own in one lifetime?

  • Starting cumulative cultural evolution is a chicken-and-egg problem: once up and running, it can create a rich cultural world full of adaptive tools, techniques, and know-how that can more than pay for the cost of building and programming big brains, but in the beginning, there’s not much to learn from others and natural selection wouldn’t favor expensive big brains and long development periods
  • Generating and sustaining technological complexity requires collective brains linked by social networks and galvanized by social norms - our lineage probably danced around the starting point for a long time while living in small groups
  • Around 2 million years ago, we have evidence of external food processing techniques and hunting tools built by Homo Erectus that indicate crossing this threshold

What are the other major thresholds our species crossed increasing its ability to create and pass knowledge culturally?

Timeline Event New Knowledge Creation New Knowledge Propagation
2 million years ago Cumulative cultural learning in Homo Erectus Individual behavioral trial and error for hunting and food processing Behavioral copying and teaching within small social groups
70,000 years ago Sophisticated spoken language in Homo Sapiens Thought about abstract concepts
Real-time criticism and improvement of ideas through discussion		 Oral teaching within larger social groups
5000 years ago Written language Better thought through writing: working memory, organization and clarity, iterative process Writing and reading: transfer across generations and social groups, over extended time and space
600 years ago Printing press - Much broader writing and reading, more accurate copying
400-300 years ago Enlightenment Widespread rational knowledge creation: conjecture and experiment/criticism (see David Deutsch) -
30 years ago Internet - Eternal archive and instant search from anywhere of all knowledge
Next few decades AI Machine knowledge creation: from making researchers and entrepreneurs more productive to discovering new knowledge autonomously Machine knowledge propagation: from AI-powered search and synthesis to personal AI teachers


The most striking question from this timeline is: Why did it take so long to cross the first few thresholds? Why did it take almost 2 million years to develop spoken language? Another 65,000 for written language? And another 5,000 to start systematically creating knowledge rationally?

In contrast, we are just 400 years into systematic rational knowledge creation, 30 years into an eternal archive and instant search of all knowledge, and we’re already on the verge of the next frontier: machine knowledge creation and propagation. How fast can humanity go from here?