Thank you so much for your excellent, informed response. Your first-hand experience in the Kalahari is amazing. There are so many things I’d love to talk about related to what you wrote.
I think you are right, that this is a very, very old system of inter-relations between people, and marks something very important that separates us from the other apes. Reading Robert Sapolsky’s research with baboons, the equivalent of “inter-marriage” is adolescent males transferring to a new group. The prospective member hangs out on the edges of the new group for a very long time as something of an outcast, no one interacting with him, grooming him. His stress hormones are through the roof (Sapolsky studies stress hormones). Then, gradually, one of the lower-status members comes over and starts some grooming him and he works his way into the social network of the group. He could eventually be the alpha male, since all of the adult males originated in other groups. But in baboons, or chimps, or any other primate, this does not lead to strong social ties between groups. Baboons and chimps are hostile to other groups. Somehow humans developed the ability to create these extra-group social bonds, which gradually led us to modern civilization, where we can have polite transactions with total strangers.
In thinking about the contrast between your experience in the Kalahari and the historical anthropology I’ve read, mostly about California, I was wondering how the landscape might have affected how the people have adapted. I’ve never been to the Kalahari and correct me if I’m wrong, but I suspect these tribes you speak of in the South Eastern Kalahari all had access to to pretty much the same natural resources. That is, they all hunted the same animals, gathered the same plants, and were surrounded by similar geology. In such a situation, trade wouldn’t be useful, they already have all of the same things.
(One of the many things I’m curious about is how they tip arrows. I’ve read about the use of poison on arrows in the Kalahari, but I’ve only seen fairly recent arrows with metal tips. I’m sure they make arrows last a long time, but I’m curious where the tips come from and what they traditionally used to tip them. Since arrows are very durable, they can be a very low-frequency trade item that would be hard to witness. Good arrow point materials are often concentrated in particular geological formations.)
The geography of California is extremely varied. A narrow strip of coastline along the Pacific Ocean with occasional bays and estuaries, low coastal mountains, many covered in redwood forest, mild climate inland river valleys not far from the coast, valleys further inland with more extreme temperatures, the ridge of the tall, snow-capped Sierra Nevada mountain range to the east, a string of volcanos, deserts, a gradual change in the climate from south to north. The equivalent gathering to what you describe could include people with ready access to different natural resources not shared by their neighbors. Tribes could have neighbors in different directions living in totally different environments. California natives not only traded, they developed a widespread form of shell money for indirect exchanges.
I suspect that human cultures originally arose in situations much like what you witnessed first hand. I think what you saw is what is at the core of being human. Then, when humans spread out across the world into more varied terrain, such as coastlines, these people who naturally shared the kinds of social bonds you describe had access to different resources and an incentive to share with each other. If a novel natural resource was hundreds of miles away and many tribes over, they would have to pass through many hands on their way from the inland volcano to sea shell rich shoreline. Tribes in the high mountains had sea shells, and those far from any volcano had obsidian.