How Did Ancient Humans Learn to Count?
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Feature F. D’ERRICO F. Prehistoric accounting? Markings made on a hyena bone by a Neanderthal might have recorded numerical information. HOW DID ANCIENT HUMANS LEARN TO COUNT? Recent archaeological studies and other analyses have spurred researchers to construct some of the first detailed hypotheses describing the prehistoric development of number systems. By Colin Barras ome 60,000 years ago, in what is and he thinks that the hyena bone — found he was venturing into territory that few now western France, a Neanderthal in the 1970s at the site of Les Pradelles near scientists had explored: the ancient roots picked up a chunk of hyena femur Angoulême — stands out as unusual. Although of numbers. “The origin of numbers is still a and a stone tool and began to work. ancient carved artefacts are often interpreted relatively vacant niche in scientific research,” When the task was complete, the as artworks, the Les Pradelles bone seems to says Russell Gray, an evolutionary biologist bone bore nine notches that were have been more functional, says D’Errico. at the Max Planck Institute for Evolutionary strikingly similar and approximately He argues that it might encode numerical Anthropology in Leipzig, Germany. Research- parallel, as if they were meant to information. And if that’s correct, anatomi- ers don’t even agree, at times, on what num- Ssignify something. cally modern humans might not have been bers are, although a 2017 study2 defined them Francesco d’Errico, an archaeologist at the alone in developing a system of numerical as discrete entities with exact values that are University of Bordeaux, France, has an idea notations: Neanderthals might have begun represented by symbols in the form of words about the marks. He has examined many to do so, too1. and signs. ancient carved artefacts during his career, When D’Errico published his ideas in 2018, Now the origin of numbers is attracting 22 | Nature | Vol 594 | 3 June 2021 ©2021 Spri nger Nature Li mited. All ri ghts reserved. ©2021 Spri nger Nature Li mited. All ri ghts reserved. increasing attention as researchers from a chicks3 can instantly recognize quantities words and written signs that are used to repre- variety of fields address the problem from up to four, a skill known as subitizing. Some sent them, must be produced by cultural evo- different vantage points. animals are also capable of ‘large-quantity lution — a process in which individuals learn Cognitive scientists, anthropologists and discrimination’: they can appreciate the dif- through imitation or formal teaching to adopt psychologists are looking at contemporary ference between two large quantities if they a new skill (such as how to use a tool). cultures to understand differences among are distinct enough. Creatures with this skill Although many animals have culture, one existing number systems — defined as the could, for example, distinguish 10 objects that involves numbers is essentially unique to symbols that a society uses for counting and from 20 objects, but not 20 from 21. Six- humans. A handful of chimpanzees have been manipulating numbers. Their hope is that month-old human infants also show a similar taught in captivity to use abstract symbols to clues buried in modern systems might illu- appreciation of quantity, even before they represent quantities, but neither chimps nor minate details of their origins. Meanwhile, have had significant exposure to human cul- any other non-human species use such sym- archaeologists have begun looking for evi- ture or language. bols in the natural world. Núñez suggests that a dence of ancient numerical notations, and distinction should therefore be made between evolutionary biologists with an interest in what he has dubbed the innate ‘quantical’ cog- language are exploring the deep origins of nition seen in animals and the learnt ‘numeri- number words. These studies have spurred cal’ cognition seen in humans2. researchers to formulate some of the first “The origin of But not everyone agrees. Nieder argues that detailed hypotheses for the prehistoric devel- numbers is still a neurological studies show clear similarities opment of number systems. between the way in which quantities are pro- And an infusion of funding will stimulate relatively vacant niche cessed in the brains of non-human animals and more studies in this area. This year, an inter- in scientific research.” how the human brain processes numbers. He national research team with a €10-million says that it is misleading to draw too firm a (US$11.9-million) grant from the European line between the two behaviours4, although Research Council will start to test different What all of this suggests, says Andreas he agrees that human numerical abilities hypotheses, as part of a broader effort to Nieder, a neuroscientist at the University of are much more advanced than those of any study when, why and how number systems Tübingen, Germany, is that humans have an other animal. “No [non-human] animal is able appeared and spread around the world. The innate appreciation of numbers. That arose to truly represent number symbols,” he says. project, called the Evolution of Cognitive Tools through evolutionary processes such as nat- D’Errico’s analysis of the Les Pradelles bone for Quantification (QUANTA), might even pro- ural selection, he says, because it would have could help to provide some insights into how vide insights into whether number systems carried adaptive benefits. the earliest stages of number systems took are unique to anatomically modern humans, Others interpret the evidence differently. shape. He studied the nine notches under a or were conceivably present in nascent form Rafael Núñez, a cognitive scientist at the Uni- microscope, and says that their shapes, depths in Neanderthals. versity of California, San Diego, and one of and other details are so alike that all seem to the leaders of QUANTA, accepts that many have been made using the same stone tool, An instinct for numbers animals might have an innate appreciation of held in the same way. This suggests that all Although researchers once thought that quantity. However, he argues that the human were made by one individual in a single ses- humans were the only species with a sense of perception of numbers is typically much more sion lasting perhaps a few minutes or hours. quantity, studies since the mid-twentieth cen- sophisticated, and can’t have arisen through (At some other time, eight much shallower tury have revealed that many animals share the a process such as natural selection. Instead, marks were carved on the bone, too.) ability. For instance, fish, bees and newborn many aspects of numbers, such as the spoken However, D’Errico doesn’t think that this individual intended to produce a decora- tive pattern because the marks are uneven. For comparison, he has analysed the seven notches on a 40,000-year-old raven bone from a site of Neanderthal occupation in Crimea. Statistical analysis shows that the notches on this bone are spaced with the same sort of reg- ularity seen when modern volunteers are given a similar bone and asked to mark it with equally spaced notches5. But this type of analysis also shows that the marks on the Les Pradelles bone lack such regularity. That observation — and the fact that the notches were generated in a single session — led D’Errico to consider that they might have been merely functional, pro- viding a record of numerical information. Marks of sophistication The Les Pradelles bone is not an isolated find. For instance, during excavations at Border Cave in South Africa, archaeologists dis- covered an approximately 42,000-year-old MATTHEW HORWOOD/GETTY MATTHEW baboon fibula that was also marked with Some researchers suggest the mind extends beyond the brain to fingers and other objects. notches. D’Errico suspects that anatomically modern humans living there at the time used Nature | Vol 594 | 3 June 2021 | 23 ©2021 Spri nger Nature Li mited. All ri ghts reserved. ©2021 Spri nger Nature Li mited. All ri ghts reserved. Feature the bone to record numerical information. In QUANTA will use data from anthropology, cog- are still in use around the world. For example, the case of this bone, microscopic analysis nitive science, linguistics and archaeology to linguists Claire Bowern and Jason Zentz at of its 29 notches suggests they were carved better understand those social factors, says Yale University in New Haven, Connecticut, using four distinct tools and so represent four D’Errico, who is one of the project’s four prin- reported in a 2012 survey that 139 Aboriginal counting events, which D’Errico thinks took cipal investigators. Australian languages have an upper limit of place on four separate occasions1. Moreover, ‘three’ or ‘four’ for specific numerals. Some of he says that discoveries over the past 20 years Bones of contention those languages use natural quantifiers such show that ancient humans began producing However, QUANTA researcher Núñez, along as ‘several’ and ‘many’ to indicate higher val- abstract engravings, which hint at sophisti- with some researchers who are not involved ues9. There is even one group, the Pirahã peo- cated cognition, hundreds of thousands of in the project, cautions that ancient artefacts ple of the Brazilian Amazon, that is sometimes years earlier than was once thought. such as the Les Pradelles bone are challenging claimed not to use numbers at all10. In the light of these discoveries, D’Errico has to interpret. Karenleigh Overmann, a cognitive Overmann and other researchers stress that developed a scenario to explain how number archaeologist at the University of Colorado in there’s nothing intellectually lacking about systems might have arisen through the very Colorado Springs, highlights those difficulties societies that use relatively simple number act of producing such artefacts.