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Monkeys Have Geometric Skills On Par With Human Preschoolers, Study Suggests

If you’ve ever gone hiking and reached a fork in the trail, you may be confronted with two triangles: one pointing right, one pointing left.

You know the direction they’re pointing has meaning, but at the same time, you know these are two of the same shapes, rotated to signify direction.

That ability to recognize geometrically identical shapes, even when they’re rotated, often comes in handy for human beings – but it turns out we’re not the only animals capable of doing it.
When it comes to understanding geometry, a lack of formal education may be one of the only things holding back our primate relatives.
Scientists at Carnegie Mellon University led a team to investigate just how different our understanding of shapes is from that of other primates.
Their findings come from experiments involving eight adult monkeys – four rhesus macaques (Macaca mulatta) and four olive baboons (Papio anubis), 55 preschoolers (ages 3-6) from the United States, and 77 Indigenous Tsimane’ adult volunteers with minimal formal education.They also used a subset of data from a previous study that included baboons, French preschoolers and first-graders, and French and Indigenous Himba adults, analyzing it in parallel.

“By studying adults with informal geometry education alongside adults who formalize geometry education (like in the US), and children and monkeys, we could ask which aspects of geometric reasoning emerge naturally and which are strengthened specifically through education,” developmental neuroscientist Jessica Cantlon told ScienceAlert.

Monkeys may not have the same symbolic understanding of geometric shapes that we do, but their ability to recognize rotated triangles, rectangles, trapezoids, and others in a line-up is pretty much on par with untrained human minds.

Participants of all ages and species were required to complete a matching task using a touchscreen. The goal was to find pairs of shapes with the same geometry (e.g., two right-angled triangles) that might be rotated slightly differently or scaled to different sizes, among a jumble of geometric shapes

Participants received little instruction about the task and were told to ‘figure it out’ by trial and error.

Correct answers elicited a positive ‘bing’ sound, with the primates and children being given a reward. In the monkey’s case, this was a cereal pellet; for the kids, a sticker.

“The most surprising finding is that young kids, before receiving any formal math education, are struggling with the task as monkeys do,” Jialin Li, a psychology researcher and the paper’s co-first author, told ScienceAlert. “We found the overlap between kids and monkeys is almost as much as kids and adults.
Succeeding at such a task requires an abstract understanding of geometric features that was once thought unique to humans – but not anymore”When you and I look at these shapes, the matching shapes seem obvious – but for young children and monkeys, they really have to think hard about the geometric properties because the matching shapes are different sizes and orientations,” Cantlon added.

“The results suggest that abstract thought is not an all-or-none ability that suddenly appeared in humans. Instead, some of the cognitive foundations of mathematical reasoning appear to be shared across primates, with human education and culture building on these ancient biological capacities.”For human adults, the task was much easier, likely because of their ability to draw more heavily on each shape’s symbolic features, such as symmetry, the length of sides, whether they are parallel, and the degree of angles.

Indeed, analysis of the data showed that children and monkeys tended to rely more on intuitive processing, while adults leaned more heavily on the symbolic approach, unconsciously abstracting the core geometric rules that define similar shapes.

This suggests the stronger use of symbolic representation, the authors write, is learned, perhaps through formal education, rather than being an inherent quality of human intelligence.Perhaps scientists will have to start enrolling the monkeys in geometry lessons to uncover their true potential.

“Our study shows that formal education strengthens symbolic geometric representation but that there are already abstract geometric intuitions in humans – intuitions about metric properties and angles – that are shared with other primates,” Cantlon said.

“Rather than creating mathematical thinking from scratch, schooling may refine and extend ancient cognitive abilities that evolution has been shaping for millions of years.

The research was published in Proceedings of the National Academy of Sciences.

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