Following another’s gaze is a hallmark of human learning and socialization from infancy to old age. We change how we follow gazes throughout our life—and an inability to do so may signal autism or other conditions that affect social development.
Like humans, monkeys exhibit the same pattern of following gazes throughout their lives, suggesting the behavior is deeply rooted in our evolutionary past, researchers say.
“Gaze-following is a crucial developmental pathway, which lays foundation for acquiring language and interacting socially,” says Laurie Santos, a psychologist at Yale University. “Here we find that gaze-following emerges in the same way in a species with an entirely different life history.”
For a new study, published in the Proceedings of the Royal Society B, researchers tested how 481 rhesus monkeys living in a preserve responded to the upward glance of a researcher.
Gazing over a lifetime
As with most human babies, infant monkeys began gaze-following from a very early age. However, they tended to take more looks than human babies do to find out what the researcher was looking at, even after three or four glances revealed nothing of interest. By their juvenile years, monkeys became more flexible in their gaze-following and became habituated to repeated gazes over time.
During adulthood, monkeys’ responses were more varied, and they began showing human-like sex differences, with females responding to gazes more than males. Older monkeys—like older humans— then became less sensitive to gaze cues overall.
This is the first study to show such a close relationship between social development in humans and monkeys. Testing such a large number of monkeys will also enable researchers to study individual behavioral and genetic variations between animals, Santos says.
The findings show that monkeys’ social attention follows a remarkably human-like trajectory across age groups.
“Monkeys have different social experiences than humans, grow up much faster than we do, and do not share features of human aging such as menopause—yet they show the same changes as humans in this foundational social skill from infancy to old age” says lead author Alexandra Rosati of Harvard University.
Source: Yale University