Millions of years before our hominid ancestors first acquired spoken language, they had the capability of basic arithmetic. We know this by the simple mathematical calculations that chimpanzees, rhesus monkeys, and other present-day apes demonstrate before our very eyes. A new study published this week in the journal Proceedings of the National Academy of Sciences expands upon these findings and looks for the roots of the evolution of human mathematics by examining our contemporary primate cousins.
The study entailed teaching three rhesus macaques to identify symbols that represent the numbers zero to 25. Afterward, the researchers taught the monkeys to use these symbols to conduct some basic addition. Margaret Livingstone, a neurobiologist at Harvard University Medical School and the study's lead researcher, explained that monkeys and humans share the common trait of more easily identifying a symbol representing a number than they can a cluster of objects adding up to that number—their brains and ours can more easily understand a symbol representing 21, for instance, than count up a cluster of 21 dots.
To prove it, Livingstone and her colleagues ran tests that connected varying levels of rewards to individual symbols. In one test after another, they showed a monkey a pair of symbols and tasked the monkey with identifying which one was larger. The larger the number, the bigger the reward the monkey would receive for guessing correctly—the rewards taking the form of orange soda, water, or juice. The monkeys chose the right answer 90% of the time.
This is not the first time that monkeys have crunched numbers under researchers' supervision. In 2007, Duke University researchers sat rhesus monkeys one at a time in front of a computer screen as first one image of several dots flashed and then a second image of a different number of dots flashed. Then each monkey would be shown two images of clusters of dots, of which one showed the correct number of dots from the first two images added together.
The Duke researchers rewarded them with Kool-Aid for the correct answers. Within several weeks, the monkeys were consistently choosing the images with the correct numbers of dots, and the researchers were able to train them to solve even more complex addition challenges.
Other experiments have found even more mathematical capability in chimpanzees. Chimps and humans' shared genetic lineage split apart six million years ago, while rhesus monkeys' genetic lineage diverged from ours 25 million years ago. Rhesus monkeys' much earlier split might account for their lower mathematical processing abilities. Nevertheless, the record would suggest that signs of mathematical thinking date back far longer than many of us might think.
Source : http://www.sciencerecorder.com/news/monkeys-can-do-math-and-so-could-our-ancient-primate-ancestors/
