Some random remembered dits:
Some Aussies did various comparison tests with a sample group of Abos. 1 was a Kim's Test - so: Toy car, Coin, Matchstick etc. Abo's didn't do too well - ergo, sub intelligent.
Change the items to, Pebble, Twig, Leaf etc. Very different result.
Also, there are different types of thought processes and understanding. Some hunter gatherer types think sequentially (something to do with going from a location and returning to it). Other societies can think in abstract, non linear patterns - things don't have to have obvious connections.
I think some Inuit types visualise things in 3D (maybe because they live in areas you can sink into, snow, sea)
Their bone carvings - rare - were traditionally done for reasons other than decoration and were not meant for keeping. IIRC they're viewable from any direction - let's face it, they're not meant for putting on a mantelpiece so aren't constrained to one dominant plane.
Primitive tribes (i.e. in remote areas with no dependence on more sophisticated civilisation) may have no need for literacy, numeracy or record keeping. If they have such primitive animist belief systems as worshipping sun spirits, water spirits etc. they seem to be generally accepting of the fact that without sun, water, etc - they will die!
Whereas, in our intelligent, advanced and sophisticated societies, with various developed religions...
many believe we're going to go to heaven/paradise.
But they wear loincloths so they must be simple.
Some things are even more basic than that. Speaking a language like English uses the left side of the brain which deals with logic and reasoning.
If you speak a tonal language (Mandarin, Thai) both the left side and the part of the right side of the brain that deals with music are involved.