[teridbruse]

I can't believe that.

An interesting article about it
Does a group of indigenous South Americans hold the key to our relationship with maths? Here, an extract from an enlightening new book explains why it just might. When I walked into Pierre Pica's cramped Paris apartment, I was overwhelmed by the stench of mosquito repellent. Pica, a linguist, had just returned from spending five months with a community of Indians in the Amazon rainforest, and he was disinfecting the gifts he had brought back. I asked how the trip had been. "Difficult," he replied.For the last 10 years, the focus of Pica's work has been the Munduruku: an indigenous group of about 7,000 people in the Brazilian Amazon whose language has no tenses, no plurals and no words for numbers beyond five. To get to the Munduruku, Pica had to wait for some locals to take him to their territory by canoe."How long did you wait?" I inquired."I waited quite a lot. But don't ask me how many days.""So, was it a couple of days?" I suggested tentatively. A few seconds passed as he furrowed his brow: "It was about two weeks."The more I pushed Pica for facts and figures, the more reluctant he was to provide them. "When I come back from Amazonia, I lose sense of time and sense of number, and perhaps sense of space." This inability to give me quantitative data was part of his culture shock. He had spent so long with people who can barely count that he had lost the ability to describe the world in terms of numbers.No one knows for certain, but numbers are probably no more than about 10,000 years old. By this, I mean a working system of words and symbols for numbers. One theory is that such a practice emerged together with agriculture and trade, as numbers were an indispensable tool for taking stock and making sure you were not ripped off.Numbers are so prevalent in our lives that it is hard to imagine how people survive without them. Yet while Pica stayed with the Munduruku, he easily slipped into a numberless existence. He slept in a hammock. He went hunting and ate tapir, armadillo and wild boar. He told the time from the position of the sun. If it rained, he stayed in; if it was sunny, he went out. There was never any need to count.Still, I thought it odd that numbers larger than five did not crop up at all in Amazonian daily life. What if you ask a Munduruku with six children how many kids they have? "He will say, 'I don't know,'" Pica said. "It is impossible to express."
Anyway, he added, the issue was a cultural one. It was not the case that the Munduruku counted his first child, his second, third, fourth and fifth, and then scratched his head because he could go no further. For the Munduruku, the whole idea of counting children is ludicrous. Why would a Munduruku adult want to count his children? They are looked after by all the adults in the community, Pika said, and no one is counting who belongs to whom.The reason for researching the mathematical abilities of these people who count only on one hand is to discover the nature of our basic numerical intuitions. In one of his most fascinating experiments, Pica examined the Indians' spatial understanding of numbers. How did they visualise numbers when spread out on a line? In the modern world we do this all the time – on tape measures, rulers, graphs and houses along a street.Pica tested them using sets of dots on a screen. Each volunteer was presented with a figure of an unmarked line. To the left side of the line was one dot; to the right, 10 dots. Each volunteer was then shown random sets of between one and 10 dots. For each set, the subject had to point at where on the line he or she thought the number of dots should be located. Pica moved the cursor to this point and clicked. Through repeated clicks, he could see exactly how the Munduruku spaced numbers between one and 10. http://www.guardian.co.uk/science/20...los-numberland