If you’re one of those people who can do maths – we’re talking standard deviations here, imaginary numbers, formulas that stretch the width of a whiteboard – well, you can relax. For the rest of us, it turns out that the natural maths we all do – say, to judge the size of a crowd – is no sign of our evolutionary prowess. In fact, when it comes to rough additions and subtractions, monkeys do pretty much as well as university students.
Counting the dots: part of our evolutionary toolkit
An article published in January in the open-access journal PLoS Biology describes an intriguing experiment by researchers at Duke University, North Carolina. Elizabeth Brannon and Jessica Cantlon set out to discover whether humans’ ability to count sets of objects non-verbally is a capacity we share with other animal species, as part of an ancient evolutionary mechanism for survival in the wild.
The researchers pitted two female rhesus monkeys against a group of 14 US college students, with the task of estimating numbers of dots on a computer screen. Crucially, the subjects did not have time to count the two sets of dots that were shown to them – symbolic maths, producing precise results, is a faculty that seems to be unique to humans – but had to estimate, choosing between two options for the correct sum.
The students, as it turns out, did pretty well, hitting the right result 94% of the time over 40 different addition problems. But then so did the monkeys, coming in with a respectable 76%, well over what would have been achieved by chance alone. The researchers were careful to vary the ratio of the wrong answer, so that this could be either higher or lower than the correct total.
Humans and other animals share a primitive mathematical ‘toolkit’ dealing in approximate, analogue representations of numerical values.
What this means, Brannon and Cantlon suggest, is that humans and other animals share a primitive mathematical ‘toolkit’ dealing in approximate, analogue representations of numerical values (NB: don’t try this line with your bank manager). In other words, we have a sense of rough quantities, independent of any numbers we might use to describe them. This may have evolved among different species as a useful tool to determine, for example, the number of animals in an unfamiliar group during territorial disputes or a relatively abundant food source during foraging: this bush rather than that one. Interestingly, the faculty appears to apply for distributions in time as well as space – how many orangutans just climbed that tree? Don’t ask me, ask an orangutan.
This insight into our mathematical origins may prove useful to you in a number of ways. Firstly, as a means of keeping mathematicians in their place – huh, a monkey could do that stuff! More generously, it might also entice you to check out the wonderful Public Library of Science (PLoS), the world’s leading collection of open source scientific journals. All articles in their peer-reviewed journals are available online free of charge, to be downloaded, copied, distributed or used in any way you like, provided the original source is credited.
This includes, of course, the scientific article which inspired this piece: Basic math in monkeys and college students, alongside hundreds of others stretching back to 2003. A web essential for science students, or anyone interested in the internet’s best ideas.
