At 17:30 pm on October 3, 2022 Beijing time, the 2022 Science Nobel Prize Awards Season officially started. The first published award is consistent with previous years, and it is still the Nobel Prize in Physiology or Medicine .
The Nobel Prize in Physiology this year has once again become unpopular. Svanter Parbo, the culmination of ancient human evolutionary biology, enjoys all the bonuses, and 's mRNA vaccine, which had been highly praised before, continue to miss the award. The achievements favored by the Nobel Prize Committee are either of great practical significance to human society or answering key scientific questions. The results of the Physiology Award this year belong to the latter, which answers the basic scientific question of "What is the difference and connection between the human genome and other extinct ancient humans?"
This article will explain relevant knowledge points to you in plain language, so that you can understand it at first glance.
Image source: Nobel Prize Official Website
Human "cousin" used to be active on the earth
Today, the total number of human beings is 7 billion, and they leave their footprints on almost every inch of land on this planet. But historically, during the evolution process, the initial group size and regional distribution of human beings can only be said to be a "spark fire" - although it is a prairie fire, it is still too early to dominate the world. Any natural disaster can extinguish the spark of human evolution. In fact, the expansion of ancient humans was not as simple as real-time strategy games. If you are not careful, the entire race may die. Our close relatives, , Neanderthals, failed to achieve the continuation of the ethnic group and disappeared into the long river of history about 30,000 years ago.
, the genetics relationship between Neanderthals and modern human ancestors, has always been a topic of great interest to people. Neanderthals and humans have similar space-time evolution trajectories, but they failed to eventually grow. Why did they become extinct? Moreover, scientists and the public want to know whether these close relatives of ancient humans had ever had intersections with the ancestors of modern humans? Or go further, we hope to know what is the reason why modern humans stand out in this evolutionary competition?
Neanderthal distribution range, source: Wikipedia
years old—— Challenges faced by Parbo
Before DNA structure and sequence are effectively parsed, the above problems can only be deduced through archaeological remains excavation, and there is a lack of critical scientific evidence. After the
DNA sequencing technology gradually matures, it seems to have the conditions, but unfortunately, DNA is a macromolecular organic substance, and its storage time in the environment is very limited. Tens of thousands of years are enough to degrade intact DNA into meaningless fragments. Since the early 1990s, Pabo has focused his energy on the analysis of ancient human DNA, and he adopted a strategy of sequencing starting from mitochondrial DNA.
mitochondrial DNA is a special type of DNA in cells. their sequence length is much shorter than that in nucleus , and the genetic information content is much less, but this also means that sequence resolution is less difficult. In addition, cells contain a large number of mitochondrial DNA copies, which greatly increases the probability of successful analysis.
Finally, Parbo parsed a small mitochondrial DNA sequence from a Neanderthal bone 40,000 years ago. After comparing with modern humans and chimpanzees, Parbo confirmed the genetic uniqueness of Neanderthals from a genetic perspective, and also determined the evolutionary differentiation of ancient human ancestors and chimpanzees as 7 million years ago.
Ancient human DNA is very easy to degrade or be contaminated. Source: Nobel Prize Official Website
Neanderthals and Denisovans
In the years since, Pabo has continuously improved the sequencing methods of ancient human DNA and reduced potential pollution from other organisms and human DNA during the sequencing process from various channels. Finally, in 2010, after 20 years of unremitting efforts, Pabo successfully completed a task that was previously considered impossible to accomplish - realizing the Neanderthal whole genome sequencing .Successful sequencing greatly promoted the progress of related research, and after that, genome alignment technology revealed that modern human ancestors and Neanderthals began to differentiate about 800,000 years ago.
Pab's work continues. In 2008, a primitive human phalanx, 40,000 years ago, was unearthed in the Denisova Cave in Southern Siberia, and its DNA was preserved in an extremely intact. The Parbo team immediately sequenced it and published relevant genome sequencing results since 2010. A gratifying result emerged, and people found that its genetic characteristics were significantly different from those of modern humans and Neanderthals. A new ancient human species was born, and the Denisovans were born.
Evolution map of humans, Neanderthals, Denisovans and chimpanzees, Source: Nobel Prize official website
Denisovans, like Neanderthals, are close relatives of humans who have become extinct. Through DNA sequencing , Pabo's results further revealed that modern humans contain about 1% to 6% of the two genes, and this gene exchange occurred about 70,000 years ago. This proves that in the past hundreds of thousands of years, modern human ancestors have intermarried with the above two, and both are one of the ancestors of modern humans.
Our bodies are flowing with their blood
Pab's research results have created a new field of research in paleogenomics, which outlines the evolutionary map of modern humans.
When modern human ancestors walked out of Africa and began to expand their footprints to Eurasian , the Neanderthals and Denisovans had already thrived in the western and eastern Eurasian continents respectively. During the process of advancing westward from the eastern end of the Eurasian continent, the ancestors of modern humans had genome exchanges and fusions with the above two, and there were similar marriage behaviors between the Neanderthals and the Denisovans.
In addition to macro-evolutionary path descriptions, Pabo’s research field has also made it possible to study the evolution of independent genes. For example, a study published in the journal " Nature " in 2014 found that among the Tibetan and Sherpa populations, genes that show stronger tolerance to high altitudes originated from the Denisovans.
Genetic exchange between human ancestors and Neanderthals and Denisovans, Source: Nobel Prize Official Website
The question of human beings is still on the way, but it may be possible to occasionally "self-touch"
Pabo's research spans 30 years has made the implementation of the above results possible. Now we can initially answer the questions at the beginning of the article, but there is still no definite conclusion about why Homo sapiens stands out in the competition with other ancient humans.
Some studies believe that although Neanderthals have the skills to use tools, their tools themselves seem to evolve much slower than Homo sapiens of the same time span, which may indirectly prove that Homo sapiens have more advanced wisdom. In any case, the evolutionary success of Homo sapiens is obvious to all, whether it is strength or luck, it is true.
After the results were announced, a reporter asked the jury members: "Do you think the award results for this year are unpopular?" The answer she received was, "I am very happy that this achievement can become a surprise for Phabo, which is a very important topic for mankind."
Phabo's research results allow people to travel through hundreds of thousands of years of prehistoric times and see things that have happened in the long river of evolution and have affected to this day. This is itself worthy of the pride and pride of all mankind.
Produced by: Popular Science China
Author: Lu Xiuyuan (Doctor of Biomedical Science)
Supervised by: China Popular Science Expo
China Popular Science Expo is Popular Science Cloud Platform of the Chinese Academy of Sciences, sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high-end scientific resources of the Chinese Academy of Sciences, it is committed to disseminating cutting-edge scientific knowledge and providing interesting science and education services.
