Domestication of animals leads not only to changes in their behavior, but also to the development of certain physical characteristics. The suppression of aggression causes the muzzles and horns to shorten, increases the flexibility of the ears, changes color, and so on. The new study published in Biology Current assumes that monkeys, like people, can participate in the process of ” self-domestication” by changing the physical characteristics depending on relations with neighbors.
Monkeys, like humans, can “tame” themselves
The term “domestication” is more commonly used in the context of the domestication of animals by humans, but this is not always the case. Some researchers, since Darwin’s time, believed that humans were “domesticated” by choosing partners that displayed less aggressive and more social behavior. To confirm the hypothesis, scientists conducted experiment on monkeys.
The common marmoset ( Callithrix jacchus ), a small monkey that lives in the forests of Brazil, demonstrates a high degree of social tolerance and can communicate with relatives through vocalization. Cubs learn this vocalization in the same way that human children learn to speak – with the help of their parents.
One of the famous markers of domestication of these monkeys is a white patch of fur on the forehead.
To investigate the relationship between white fur spots and vocalization development, the researchers observed three pairs of newborn twin monkeys. Scientists used computer “parent simulation” – the system was programmed to communicate with the twins in the mother’s voice.
In the experiment, which was conducted over two months, the computer responded to one calf in a pair ten times more often than the other. The twin, who received more feedback from the “parent simulator,” had the white spot on his forehead brighter and larger faster. Scientists believe that the development of this marker is associated with neural crest cells, a collection of stem cells that migrate throughout the body in the early stages of development.
One of the derivatives of neural crest cells are melanocytes, which contribute to pigmentation. The researchers argue that the act of learning to “talk” acts as a kind of conditioned self-domestication reflex that affects the developing body of the young monkey.
Scientists believe that this discovery may help to figure out how human evolution took place. This is the first experimental evidence that interactions within a species lead to self-domestication.