LIFE SCIENCE

If you don’t know each other well, the dog’s tail can talk


At the end of July, the reporter photographed a beagle at the Changping Experimental Base of the Institute of Genetic Development of the Chinese Academy of Sciences. The puppy gradually quieted down from the panic of initial contact and violently wagging its tail, occasionally making eye contact with the observer. Photo by Feng Lifei

As the saying goes, the eyes are the windows of the soul. For dogs, the tail is a window of emotion.

“When they are happy, their tails will be wagged cheerfully; When angry, their tails will be cocked vertically; When scared, they will run away with their tails between their legs. Years of research have made Zhang Yongqing, a researcher at the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences, understand the domestic dog in detail.

Recently, Zhang Yongqing’s team, together with Yu Shan, a researcher at the Institute of Automation of the Chinese Academy of Sciences, and Wei Pengfei, a researcher at the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences, used artificial intelligence deep learning algorithms to find that dogs’ tails “do speak”: the tails are tilted to the right, and their relationship with people is more familiar.

They also found that, similar to human fingerprints and gait, each domestic dog exhibited unique and stable tail-wagging features. The results were recently published online in the journal iScience.

“This is a very important and creative study in both biology and computational science.” A reviewer review.

The tail is more friendly with a right wagging

At the end of July, in a laboratory on the edge of a green test field in Beijing’s Changping district, there were occasional bursts of dog barking. There are eighty or ninety beagles, large and small, here.

According to Zhang Yongqing, this is the “001” project of Beijing Dog Research. In the past three years, Zhang Yongqing and his team have constructed a spatial-temporal expression map of the whole brain proteome of domestic dogs, and used experimental dogs to study the association between human atherosclerosis and cardiovascular and cerebrovascular diseases. Recently, they aimed at the dog wagging its tail.

“Animal behavior is a demonstration of brain function, and its social behavior is also crucial to the survival of individual animals. The tail wagging of domestic dogs is an important social behavior in the interaction between dogs and dogs and between dogs and people. Ren Wei, the first author of the paper and a doctoral student in Zhang Yongqing’s team, said.

The team first found that during three days of interaction with people, the tail swing of the domestic dog gradually shifted from its left side to the right, and the phenotype of each dog was very stable, indicating that the lateralization of its tail swing was a sensitive indicator of familiarity.

“In short, when interacting with unfamiliar people, the dog’s tail wags to the left; When interacting with familiar people, the tail wags to the right. Zhang Yongqing said.

The study also found that just as everyone has a unique fingerprint and gait, dogs also have unique and stable tail wagging characteristics.

Based on this, the study introduced the concept of “attractors” in the study of dynamic systems into the tail wagging pattern analysis, and found for the first time that the tail wobbling of domestic dogs is composed of an attractor-like state with a stable rocking trajectory and an unstable transition state. “The class attractor state refers to the stable and repetitive patterns shown in the tail wagging trajectory of the dog, such as the circular trajectory and the ‘figure 8’ trajectory.” Yu Shan, co-corresponding author of the paper, explains.

21,000 deep learning times, received in a month!

This biological discovery is inseparable from the support of artificial intelligence deep learning technology.

More than a decade ago, Italian scientists have analyzed dogs wagging their tails, mainly through recording videos and manual observations, the resolution of the data is low, and the analysis is difficult to penetrate. With the advancement of computer vision technology, it is possible to use deep learning algorithms for more comprehensive and in-depth quantitative analysis.

“Deep learning here is the process of inputting pictures of dogs into a neural network model, using the different parts of the body (such as the back, tail root, tail tip, etc.) artificially marked in some pictures to train the model, and the model learns to automatically identify these body parts in a large number of new pictures.” Yu Shan introduced.

The collaborative team built a three-dimensional motion tracking technology platform based on deep learning, and systematically studied the trajectory of the tail movement of 13 beagle dogs during interaction with humans. In total, they analyzed more than 21,000 times the dog wagged its tail, including the speed, amplitude and distance at which the tail moved. On this basis, a quantitative study of the tail-wagging characteristics of dogs when interacting with humans was carried out, and the dynamic details of domestic dog behavior that were previously undetected were found.

The authors say that these results together reveal the complex characteristics and composition of tail wagging behavior in domestic dogs during interaction with humans, providing a unique experimental paradigm for studying the social behavior and underlying neural mechanisms of domestic dogs.

Zhang Yongqing said that people generally think that the left and right brains have a division of labor, and positive and negative emotional states are related to the activation of the left and right sides of the human prefrontal cortex. “We speculate that wagging the tail to the left may be accompanied by activation of the right brain, while wagging the tail to the right may be accompanied by activation of the prefrontal cortex of the left brain.” He said, “The left brain is responsible for processing positive emotions, indicating that the tail wagging to the right is a sign that the dog is happy or comfortable; The opposite situation may mean that the dog is scared or nervous. ”

According to reports, this is the first research using artificial intelligence methods to analyze the emotional behavior of domestic dogs. Its innovative and interesting nature made the paper successfully accepted after only one month of submission.

The beagle of the experimental base is photographed by Ren Wei

Dog tail research “not to be underestimated”

What is the significance of this study? Zhang Yongqing said that both life science and medical research require animal models, and in the past half century, the laboratory mouse model has played a huge role internationally, but there are many questions that cannot be answered, such as the neural mechanisms related to emotion or the pathogenesis and treatment of mental illness. To this end, the world is looking for more effective model animals.

“After more than 30,000 years of domestication, domestic dogs are characterized by their spirituality and ability to communicate effectively with people. Emotions and abilities such as mood and sorrow, jealousy, loyalty, and self-discipline can be vividly displayed, so life sciences, medicine, and even psychology can use domestic dogs as model animals. He said.

Research using domestic dogs as model animals has so far won two Nobel Prizes in Biology or Medicine, including Papalov’s pioneering achievements in the physiology of the digestive system in 1904 and Frederick Grant Banting’s discovery of insulin in 1923, which saved thousands of diabetics.

“The study of human emotions is one of the 125 major internationally recognized issues published by The Journal of Science, and the future of domestic dogs will certainly have a unique contribution in this regard.” Zhang Yongqing believes that China has two advantages in dog research: China’s dog gene editing technology is at the forefront of the world; Socio-cultural tolerance allows for relevant research. This makes China hope to make breakthroughs and contributions in the study of neural circuit mechanisms of social and emotional communication through domestic dog models.

In Yu Shan’s view, the intersection of disciplines will become more and more important in the future. Just as deep learning helps to discover the law of wagging a dog’s tail, the intersection of disciplines has given biological research powerful new tools to explore deeper mechanisms. “Biology is an experimental science, a more accurate analytical method that makes the observation of biological phenomena move from qualitative to quantitative, and then to the understanding of the mechanism.” He said.

Photo courtesy of The Beagle dog ren Wei in the play

Zhang Yongqing said that the Chinese Academy of Sciences has the advantage of discipline integration in this regard. He hopes that through more in-depth interdisciplinary research, improve the ability of scientific and technological innovation, through the domestic dog as a medical and health model animal to carry out research, the next ten or even twenty or thirty years can provide scientific and technological support for China’s life sciences and population health, and occupy a place in the international related research field. (Source: China Science Daily Feng Lifei)

Related paper information:https://doi.org/10.1016/j.isci.2022.104747



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