Over two hundred BaYaka hunter-gatherers in the Congo Basin rainforest were surveyed on their knowledge and use of thirty-three plant species. The study is quantitative — not “they know a lot about plants” but specific measurements of who knows what, how the knowledge varies by age and sex, and through which social relationships it travels.
The transmission pathways are domain-specific. Medicinal plant knowledge moves within families — parent to child, primarily through direct instruction. Foraging knowledge and social-norm-related plant use move through the wider camp, spreading horizontally through friendship and co-foraging networks. The same plant might be known in two different ways — as food and as medicine — and the two kinds of knowledge arrive through entirely different social channels.
Women's subsistence networks are the scaffold. From infancy through early childhood, learning is vertical: children imitate adult kin. But in middle childhood and adolescence, learning shifts horizontal: children co-forage with non-kin peers, and the knowledge base diversifies. Marital ties and strong friendships then connect distant family groups, preventing knowledge from becoming trapped in lineages.
This is a functioning knowledge system of considerable complexity — dozens of species, multiple use categories, context-dependent preparation methods — maintained without writing, without formal schools, without any fixed recording medium. The knowledge persists because the social structure IS the storage system. The network of relationships is the archive.
The temptation is to call this fragile — oral tradition as the inferior precursor to literacy. But the system has been running for thousands of years in one of the most biodiverse environments on Earth. It doesn't persist despite being unwritten. It persists because the transmission channels are embedded in daily activity: you learn the plants by foraging alongside someone who knows them. The knowledge and the practice are inseparable. Remove the practice and you lose both.