Its probably many of those issues, i dont want to appear racist or anything but i had wondered about their brains tbh, its possible that although they have had contact they have evolved diffently, slightly tho. And its a possibility that the brain might evolve depending on its use, as other parts of the body do too. If u look around it might be inherent racism but there does seem to be cultures or societies that tends to produce great minds or good workers compared to others, but im just theorising. language itself is a vast tool, not only is it how we communicate, mankinds biggest asset is his language and his opposible thumb
, but it also affects how we think, i think in english and pictures, thats me being pretty honest and self observant i feel. When writing this post i think in english what i want to say and easily know how to use letters to form words to form sentences etc. to write here, now if ur thinking continuously in a non-expansive way, and i mean ur concentrating on survival and dont think of more 'higher' things like god society etc. and its like this within ur family for a long time, years maybe generations then ur brain is going to adapt, what we use for numbers and logic might be totally taken over in those amazonians brains by something else and that would mean its impossible for them to grasp these concepts. iv heard stories and seen tv programs about ppl with strokes that cure mental illness or that completly alter their view of the world, i saw a report on a guy who had a stroke and couldnt comprehend his own reflection, another guy had a stroke and to him the right hand side of everything he was aware of didnt exist, i.e. if a mirror was in front of him he couldnt grab a pen being held behind his right ear but could grab the pen behind his left ear. not only this but cups placed with the handles pointing to the right would be dropped etc. also i would like to say that each individual person is only a mutation of a basic genotype and that all the different races or hair colours or whatever are only caused by biological mutation and growth, it would be no surprise to find that semi isolated ppl have developed differntetly to others, if they were identical in the way they thought id be worried as science would be wrong :/