An experiment with ordinary toys has helped reveal that these tiny New World monkeys use special sounds to name and communicate with each other in the rainforest, a discovery that shows the complexity of nonhuman primate communication.

Scientists believed that the ability to name each other (vocally “mark” and recognize other members of one’s species) was one of the highest cognitive functions innate to humans. Later, such behavior was discovered in large dolphins (bottlenoses), elephants, and some species of parrots.

Recently, employees of the Edmond and Lily Safra Center for Neuroscience and the Benin School of Computer Science and Engineering at the Hebrew University in Jerusalem (Israel) showed that something similar to nouns also exists in non-human primates (ordinary toys). Callithrix Jacchus. An article on this subject was published in the magazine. Science.

The authors of the discovery recorded conversations between the pairs of toys, as well as their interactions with the computer. 10 people participated in the study Callithrix Jacchus from three different groups: Adonis (male, seven years old), Keto (female, six years old) and Ella (female, two years old); Bhumi (female, six years old), Brahma (male, seven years old) and their three cubs; Dia (female, seven years old) and Dionysus (male, six years old).

All families were placed in separate cells in a large room measuring 3.8 x 2.6 metres, divided into two parts by a curtain equipped with a surveillance system and a series of microphones.

One pair of subjects sat behind two enclosures: a small toy made of wire mesh, the other a large toy made of perforated clear plastic. Before each test, a curtain was raised so the animals could see each other. After a few minutes, the curtain was lowered and the experiment began, lasting 1.5 hours.

Scientists conducted a total of 281 sessions with all the primates. They engaged in dialogue with each other by emitting characteristic cries (something like a high-pitched “fi” – an example). In each session, an average of 116.15 ± 53.2 fi’s given by a game were recorded.

The researchers then conducted an additional experiment in which the role of the second primate in the pair was played by a computer that reproduced the sounds recorded in the first phase. A total of 20 sessions were conducted. One monkey (Brahma) had to be removed from the sample because in all cases its cry was directed only at its cage neighbor Bhumi.

The “phi” analysis showed that female characters labeled their relatives in this way. In addition, each subject perceived and responded correctly to a shout directed at him. Primates in the same group used similar signals to “call” other individuals. According to the scientists, this type of “marking” helps the prey animals to maintain contact with each other and maintain the harmony of the group in the dense tropical forests around them.

“Our discovery highlights the complexity of social communication in games. They do not use these sounds only to locate themselves, as previously thought: they are also needed to address specific relatives,” stressed Guy Oren, head of the study.