Summary: Human babies\u2019 babbling is more than cute noise\u2014it\u2019s a feedback-driven learning strategy that sets the foundation for language. A new study shows that marmoset monkeys, despite being distant relatives, also babble and learn faster when adults respond, suggesting a shared mechanism.<\/p>\n
Researchers found that humans and marmosets both undergo rapid brain growth right after birth, unlike chimpanzees and macaques, making them especially sensitive to social feedback. These findings reveal how brain development and caregiving environments interact to support the emergence of communication skills.<\/p>\n
Key Facts<\/p>\n
Babbling Feedback: Both human and marmoset infants learn vocal patterns more quickly with adult responses.Brain Growth Timing: Humans and marmosets share a post-birth brain growth spurt that fosters vocal learning.Social Caregiving: Multiple caregivers responding to calls amplify learning opportunities in both species.<\/p>\n
Source: Princeton<\/p>\n
When a baby babbles and their parents respond, these back-and-forth exchanges are more than adorable-if-incoherent chatter \u2014 they help to build a baby\u2019s emerging language skills.<\/p>\n
But it turns out this learning strategy makes humans an oddity within the animal kingdom.<\/p>\n
Only a handful of other species \u2014 including a few songbirds such as cowbirds and zebra finches \u2014 learn to \u201ctalk\u201d by noting their parents\u2019 reactions to their initial coos and gurgles.<\/p>\n
How did humans become adept at learning language this way?<\/p>\n
A\u00a0new study\u00a0across multiple members of the primate family tree suggests the answer may lie, in part, in newborn babies\u2019 fast-growing brains.<\/p>\n
Published August\u00a019 in the journal\u00a0Proceedings of the National Academy of Sciences,\u00a0the findings\u00a0come from research on a squirrel-size monkey called the marmoset.<\/p>\n
Babbling beyond humans<\/p>\n
In the wild, marmosets use their high-pitched calls to stay in touch when they\u2019re out of sight of one another in the thick dense forests of northeastern Brazil.<\/p>\n
Just over a decade ago, while studying marmoset vocalizations, Princeton professor of neuroscience and psychology\u00a0Asif Ghazanfar\u00a0and colleagues noticed that baby marmosets go through a\u00a0babbling phase, just like humans do.<\/p>\n
As newborn marmosets grow, their first sputtering cries transform into the more whistle-like calls of adults. The researchers also found that baby marmosets who\u00a0received more frequent adult feedback\u00a0during their babbling bouts were quicker to catch on. They learned to produce adult-like calls significantly faster than the controls.<\/p>\n
\u201cThat was a pretty big \u2018aha!\u2019 moment,\u201d Ghazanfar said.<\/p>\n
These studies, published in\u00a02015\u00a0and\u00a02017\u00a0by Ghazanfar with his then-postdoc\u00a0Daniel Takahashi, now at the Federal University of Rio Grande do Norte in Brazil, were some of the first evidence of what appeared to be vocal learning in another primate.<\/p>\n
But humans and marmosets last shared a common ancestor some 40 million years ago. Even our closest living relatives, chimpanzees, need very little tutoring to make the sounds of their kin.<\/p>\n
\u201cSo that kind of presents a puzzle,\u201d Ghazanfar said.\u00a0<\/p>\n
Since then, the researchers have been trying to figure out why humans and marmosets arrived at such similar learning strategies despite being so distantly related.<\/p>\n
Neural growth spurt supports learning<\/p>\n
In the new study, led by Princeton Ph.D. student\u00a0Renata Biazzi, the researchers collected and analyzed previously published data on the brain development of four primate species including humans, marmosets, chimpanzees and rhesus macaques, from conception to adolescence.<\/p>\n
The results suggest that, in early infancy, the brains of humans and marmosets are growing faster than those of other primates. Importantly, most of that growth happens not in the confines of the womb, as is the case for chimpanzees and macaques, but right around the time they are born and first experience the outside world.<\/p>\n
In marmosets, as in humans, this also happens to be an incredibly social time, Ghazanfar said. That\u2019s because marmoset moms, like human mothers, don\u2019t raise their offspring without help. Babies interact with multiple caregivers who respond to every cry.<\/p>\n
\u201cThey are a handful,\u201d Ghazanfar said.<\/p>\n
And because their brains are still developing, \u201cthat means that the social environment an infant is born into has a tremendous influence\u201d on their learning, he added.<\/p>\n
Using a mathematical model, the researchers were able to show how these early interactions, when coupled with rapid brain growth, set the stage for vocal skills to develop later on.<\/p>\n
Baby talk<\/p>\n
Next, the team plans to look into whether adult marmosets use specific sounds when interacting with infants, much like human adults use \u201cbaby talk\u201d to communicate with our babies.<\/p>\n
By looking at the only other primate whose infants are capable of using feedback to learn sounds, scientists hope to better understand how a child goes from cooing and babbling to, say, negotiating their way out of chores or joining the debate team.<\/p>\n
This doesn\u2019t mean that other primates can\u2019t change up their calls later in life.<\/p>\n
\u201cWe\u2019re only talking about vocal learning during infancy,\u201d Ghazanfar said. \u201cThis is the period when their brains are especially malleable.\u201d<\/p>\n
Funding: This work was supported by a grant from the National Institute of Health (R01NS054898).<\/p>\n
About this language and evolutionary neuroscience research news<\/p>\n
Author: Daniel Vahaba<\/a>
Source: Princeton<\/a>
Contact: Daniel Vahaba \u2013 Princeton
Image: The image is credited to Neuroscience News<\/p>\n