People must first learn to speak – in the first few years of life they acquire this ability through experience and social interactions. But what about our relatives? Until now, the sounds and vocal development of monkeys were largely innate and instinctive. But the observations in the common ape monkey refute this: they also develop their full communication skills only with time and reliance on experience.
It is well known that people learn their language through experience and social interactions with others. Human voices change dramatically, especially in the first year of life, and become more and more linguistic: what is at first screaming or laughing soon turns into gossip and later the first words. In the case of monkeys, on the other hand, it was previously assumed that their development of sounds, gestures, and facial expressions is largely predetermined by physical maturity and occurs during the first few weeks of life.
What is predetermined and what has been learned?
One reason for this: Previous studies have shown, among other things, that deafness or social isolation due to parental absence have little or no effect on monkey babies’ voice development. Despite these obstacles, the animals seem to develop a largely natural vocal repertoire. Jasmine Goltkin of the University of Tübingen explains.
In a study, Gültekin and her colleagues have now examined to what extent the later development of speech in monkeys is somewhat mechanistic. To do this, they observed the proper development of six common snails from early childhood to sexual maturity at the age of 15 months. During this period, the scientists recorded the vocalization behavior of the examined animals using microphones every month. In total, approximately 150,000 hadiths were recorded and analyzed.
Flexible use of language through experience
The result: Previous ideas about the linguistic evolution of monkeys do not seem to apply at least to common marmosets. “Our results show that vocalization behavior in common monkeys, similar to the first few months of human life, changes during various stages of development from the first few weeks after birth to adulthood,” explains Kurt Hammerschmidt of the German Primate Center. All species-specific vocalizations are already present in the first month after birth and many developmental changes in vocal structure, such as the duration or frequency of calls, can be largely explained by physical maturation.
However, experience with language acquisition was essential. “While changes in phonemic structure can be explained primarily by physical growth or maturation, we found that the flexible use of these sounds over the course of evolution indicates mechanisms of experiential learning, which is one of the key characteristics of human language evolution,” says Gültekin. .
It has been shown, for example, that young monkeys increasingly use a particular call once they are no longer carried but rather run independently. The observed increase in calls may be due to the fact that sons are trying to get their parents’ attention, the researchers said. “We also show that monkeys increasingly produce different and unique vocalization sequences as they mature, suggesting that different learning mechanisms underlie the development of call transmissions.”
human language development model
“These results are evidence of a prolonged stage of plasticity during vowel development of the common lobster,” the researchers summarized. From their point of view, the primate species is a suitable animal model for studying the evolution of language more closely. “Our work provides an important building block for a better understanding of the evolutionary underpinnings of human language development in early childhood,” explains Gültekin. “It creates the basis for future studies of how social interactions affect language development.”
Source: Deutsches Primate Center GmbH – Leibniz Institute for Primate Research, Article: Science Advances, doi: 10.1126/sciadv.abf2938