Originally born from the same root, why have you become a human?

Originally born from the same root, why have you become a human?

Chinese scientists reveal evolutionary differences between humans and non-human primates

Originally born from the same root, why have you become a human? Originally born from the same root, why have you become a human?Chinese scientists reveal the evolutionary differences between humans and non-human primates Chinese scientists reveal the evolutionary differences between humans and non-human primates Chinese scientists reveal the evolutionary differences between humans and non-human primates

Related experimental data and imaging (photo courtesy of the research team)

"Where am I from?"

This is one of the three ultimate questions of philosophy
.

According to Darwin's theory of evolution, the origin of mankind is due to biological evolution driven by natural selection

However, compared with existing non-human primates such as monkeys and apes, humans have significant advantages in many advanced cognitive functions, especially the ability to use language and complex tools, which may constitute "the reason why people are humans.
" Basis
.

In order to answer this long unanswered question, scientists at home and abroad have made various attempts, but they have not clarified because of the lack of reliable technical means
.

Recently, the team of Jiang Tianzi and Fan Lingzhong, researchers from the Brain Network Group Research Center of the Institute of Automation, Chinese Academy of Sciences, and Cheng Luqi and Wang Jiaojian from the School of Life Science and Technology of the University of Electronic Science and Technology of China used the idea of ​​the brain network group map to draw the cross-species of the subapical lobules of the primate brain The brain connection map reveals the evolutionary differences in the asymmetry of the subapical lobules between humans and non-human primates, provides new clues to the origin and evolution of human language and tool use, and provides new evidence for clarifying why humans became humans
.

Recent studies published in international journals eLife on

eLife

"This is definitely an outstanding research result!" After the article was published, Professor Danilo Bzdok of McGill University in Canada sent a congratulatory letter to Jiang Tianzi
.

Traditional methods cannot effectively clarify differences

Traditional methods cannot effectively clarify differences

Regarding the evolutionary study of human language and the use of complex tools, traditional methods mainly use fossils and observe the behavior of close relatives of humans such as monkeys, apes/chimpanzees
.

"However, fossil and behavioral studies can only tell the differences between humans and non-human primates, but cannot clarify the causal relationship between evolution and brain function.
It is still necessary to observe the long-term evolutionary process and do related research on the plasticity of brain function.

.

" Jiang Tianzi told "China Science News

Later, comparative neuroanatomy tried to establish the evolutionary model of brain functional areas in different species by analyzing the differences in cell morphology in the corresponding brain regions of different primate brain anatomy (cell construction methods)
.

"Such methods are not only time-consuming and labor-intensive, but also cannot be widely used in group studies, which greatly limits cross-species comparative studies and the conclusions that can be obtained
.

" Fan Lingzhong said

With the advent of magnetic resonance imaging technology, researchers have used brain imaging methods to compare the structure of human language-related brain regions with human closely related species, such as macaques and chimpanzees.
The anatomical differences in corresponding brain regions, such as the classical language area, Broca The volume of the area, the depth of the temporal transverse sulcus, and the volume of the left and right hemispheres are symmetrical in order to study the origin of language function
.

What is quite dramatic is that structural magnetic resonance imaging studies overturned the hypothesis that the lateralization of the brain in the language area is the origin of human language
.

Researchers have found that East African baboons and chimpanzees also show significant asymmetry, which shows that only the asymmetry of brain morphology and structure is not enough to clarify the function of the human brain, especially the specificity and evolutionary origin of language

"Therefore, studying the origin of specific functions such as language from the differences in the connection patterns that determine brain functions has become a new way to solve this problem
.

" Jiang Tianzi said

In fact, as early as 2008, James Rilling, a researcher at the Yerkes National Primate Research Center at Emory University in the United States, used diffusion tensor imaging (DTI) to find a nerve fiber bundle in the brain, the dorsal arcuate bundle, which is in It is almost non-existent in monkeys, small in chimpanzees, and very large in human brains
.

Since then, almost all comparative neuroscientists have paid attention to this fiber bundle for related research on the origin of language
.

"At present, the biggest problem in the study of brain structure and fiber bundles in humans and non-human primates is how to determine the homology of brain functional areas and connecting fiber bundles among different species?" Cheng Luqi, the first author of the paper The doctor believes that the reliability of the previous research results on the evolution of cross-species brain structure and function still needs to be further verified
.

The brain network group map is different

The brain network group map is different

During the interview, the reporter learned that the team’s previous research broke through the bottleneck of traditional brain atlas drawing, proposed a new idea of ​​“using brain connection information to draw brain atlas”, established a theoretical method system for drawing a new generation of human brain atlas, and successfully drawn A brand-new human brain atlas, the brain network group atlas
.

"To study the origin of language and the use of complex tools, the first thing to determine is the functional homology of humans and other non-human primates in related brain regions
.

" Wang Jiaojian said that they first extended the brain network map to map non- human primates .

Subsequently, on this basis, the researchers determined the functional homology of different species through a more refined brain map, thus laying the foundation for accurate structural and connection pattern comparison analysis
.

Specific to this achievement, the researchers first used magnetic resonance imaging technology to obtain structural magnetic resonance and diffusion tensor magnetic resonance imaging data of humans, chimpanzees and macaques, and used the most relevant apical lobules for language and tool use as the research object.
The structural asymmetry of the subapical lobules of three primates was analyzed by structural magnetic resonance imaging
.

The study found that similar structural asymmetries were found in chimpanzees and humans, but no similar patterns were found in macaques
.

"This shows that the separation of the apical and lower leaflet structure occurred after the common ancestor of the three species, but before the common ancestor of chimpanzees and humans
.

" Jiang Tianzi said

In addition, the researchers further used diffusion magnetic resonance imaging to map the brain connections of humans, chimpanzees, and macaques at subregional scales of the subparietal lobules, and found that the asymmetry of the brain anatomical connection pattern presents a gradient among the three primate species.
An evolutionary model
.

"There is no brain connection asymmetry in rhesus monkeys that are more distantly related to humans, but in chimpanzees that are closer to humans, brain connection asymmetry has begun to appear, and this asymmetry is more widespread in the human brain
.
" Cheng Luqi said that the above findings indicate that the asymmetry of the brain structure and its anatomical connection pattern is the internal biological basis that drives the evolution of language and the use of complex tools
.

Looking forward to finding more new evidence

Looking forward to finding more new evidence

Nowadays, brain science has become a hot spot in global research and the commanding height of technological competition
.
Especially in recent years, more and more brain science research has shifted from rodents to non-human primates
.

Many industry experts said that this study shows that drawing a cross-species brain network group map must become a bridge that promotes non-human animal models to human brain research
.

"This is not only an important breakthrough in deciphering the unique high-level cognitive functions of the human brain, but also an important science for establishing non-human primate models that focus on brain diseases, and for in-depth study of the pathogenic mechanism of human brain diseases and general artificial intelligence.
Meaning
.
" Jiang Tianzi said
.

But no research can be smooth sailing
.

Fan Lingzhong told China Science Daily that one of the main problems they encountered in their research was how to determine the homologous brain regions of different species and the theoretical methods for cross-species comparative research
.

In order to solve this problem, the joint research team conducted in-depth literature research in the early stage, launched many conference discussions, and conducted a large number of pre-experiments from different angles, and finally determined that by drawing a cross-species brain network group map The method to solve the problem of the research program
.

"After the preliminary results and thesis were completed, we held several remote meetings with George Washington University professor Chet Sherwood, Beijing Normal University professor Gong Gaolang, and University of Electronic Science and Technology of China team members to discuss the results and the writing of the paper
.
" Fan Lingzhong said
.

During the submission process, the reviewing editor highly praised this work because it supports the evolution of the asymmetry of the anatomical connection pattern of the subparietal lobules.
This kind of brain connection already exists in chimpanzees and may be related to the evolutionary origin of human language functions.
Related
.

The reviewers believe that this study provides a clearer view of the evolutionary history of the human brain
.

"In the next step, we will first draw a multi-scale brain network map of non-human primates such as macaques and chimpanzees, that is, the macaque brain network map
.
We will further build a cross-species brain map of evolution-related brain functional areas.
To further analyze the evolutionary relationship between brain structure and function in different species, establish the origin of the evolution of human brain specific functions, and provide new evidence for answering why we became humans
.
" Jiang Tianzi said
.
(Source: Zhang Siwei, China Science News)

Related paper information: https://doi.
org/10.
7554/eLife.
67600

https://doi.
org/10.
7554/eLife.
67600