Babies may train to cry months before birth | National Geographic

When a human baby cries immediately after birth, this is a sign of good health. Since the baby has never breathed, the first inhale and exhale sound like a squeak.

How do babies make a sound they’ve never made before? Is their first cry really the beginning of the development of speech?

It turns out that babies practice crying long before they even make a sound. That is, if they look like clawed monkeys, then they are human cousins.

In a recent study published in the journal eLife, scientists used dozens of consecutive ultrasounds of pregnant clawed monkeys to show that fetuses showed crying faces about two months before birth.

The researchers were able to distinguish these expressions from other mouth movements that babies make in the womb. They then compared these to the facial expressions the babies made after birth when they started calling their parents. The patterns and duration of the expressions were so consistent that researchers strongly believe she was practicing crying, even though the animals were not yet able to make a sound.

Hawk monkeys are among the smallest species of monkeys. Adult specimens weigh only 225 to 255 grams, which is roughly the equivalent of a cup of sugar. There are more than twenty species of claw monkeys, all of which originated from South America. Although they are physically different from humans, they are primates. This means that they are more closely related to sane man They are more suitable for understanding human development and behavior than traditional laboratory animals such as lab mice.

In the 1970s and 1980s, a number of ultrasound scans on pregnant women showed that babies make crying-like faces while in the womb. So says Daniel Takahashi, co-author of the study and animal behavior at the Brain Institute at the Federal University of Rio Grande do Norte in Brazil. However, it was difficult to monitor these results over time, due to the discomfort that pregnant women experienced with having frequent and frequent ultrasounds.

“The claw monkeys are apes that talk a lot and have many characteristics in common with humans,” said Takahashi, who worked with the Princeton Neuroscience Institute during the study.

In this way, both males and females raise their offspring. And unlike other primates, such as infants, cannibals are relatively helpless at birth.

Translating the key findings to humans will help explain when speech development begins, according to Takahashi. Studying the antenatal period rather than the moment of birth can help identify problems with speech or motor development early.

“A lot of things happen in the womb that could be related to what happens next,” he says.

Claw monkeys love marshmallows

Before the researchers could examine the clawed monkeys with an ultrasound transducer, they first had to teach the animals to sit still. While this might seem like a near-impossible task for an animal navigating frantically through the rainforest canopy all day, scientists have a trick up their sleeve.

Takahashi says clawed monkeys love high-energy foods. “And they really love marshmallows.”

With rewards in hand, each of the four pregnant clawed monkeys was examined two to three times a week. This always took 45 minutes max. Ultrasound began on the 95th day of pregnancy, when the children’s faces were first distinguished. This continued until birth at 146 days.

Talon monkeys usually have twins and often have triplets and quadruplets. Scientists have not been able to distinguish between children while they are in the mother’s womb.

So in three out of four pregnancies (twins and quadruplets), the scientists combined the results of all the faces they could scan.

The basic building blocks of spoken language

Perhaps one of the most notable aspects of the study, Takahashi said, was that the number of movements eligible to be practice slogan phrases increased over time.

Practice calls have also changed.

For example, in the first scans, fetuses only expressed the practice of crying at the same time that they moved their heads. The two movements slowly separated as the fetuses developed, Takahashi says. At some point they get to the point where they can open their mouths in a fake cry, without moving their heads.

Although clawed monkeys never reach the linguistic level of humans, this indicates that their communication evolves and improves over time.

“Of course we cannot study the full complexity of language in other species, because each type has its own communication system,” says Andrea Ravinani. He is involved in Comparative Bioacoustics and is a research group leader at the Max Planck Institute for Psycholinguistics. We can search for the basic building blocks of spoken language. I think that’s what those authors did in this article.

Ravinani, who was not involved in the study, discovered the subtle rhythms in lemurs’ voices. He found the idea of ​​looking for evidence of sound production before sounds were possible to be “quite cool”.

According to him, it can be compared with the way children begin to walk on all fours before walking upright.

“I study the evolution of mammalian vocalizations in other species, especially seals,” says Ravinani. ‘This is what we do. We are trying to find out what preceded it.

Ravinani says there is debate in the scientific community about how the development and behavior of clawed monkeys can be beneficial to humans. But for the vocal traits explored in this study, he thinks they are excellent.

“In my humble opinion, they can provide us with more insights than chimpanzees,” he says.

This may seem paradoxical, given that chimpanzees are more closely related to humans than claw monkeys. However, recent research has shown that clawed monkeys can learn new calls and even dialects as they age. This indicates that they are better laboratory animals for research into vocal development and plasticity.

As long as you don’t run out of marshmallows.

This article was originally published in English at nationalgeographic.com

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