How did the bastards dominate the earth step by step?
Written by | Tang Bo (National Animal Genetic Research Center, China Agricultural University)
At a time when the box office of the domestic science fiction film "The Wandering Earth" exceeded 4 billion yuan, many fans still remember the American fantasy movie "Aquaman" released more than two months ago. At present, the film's global box office has exceeded 1.13 billion US dollars, of which the Chinese market has contributed about 300 million US dollars, ranking among the top 20 highest-grossing movies in global history.
In the story told in Aquaman, Queen Atlantis falls in love with a lighthouse keeper in the United States and gives birth to a boy, Arthur, with the help of Princess Meera (Orm's fiancée), fights against his brother Aum, who intends to rule the sea and annex the land, and finally defeats the powerful Aum and becomes the sea king who rules the Seven Seas.
Arthur Curry, Aquaman
To Aum, the younger brother of pure seaborn, Arthur was just a half-terrestrial, half-sea "bastard.". Orm did not take his brother Arthur seriously at first, but it was Arthur, the bastard, who defeated himself, regained the throne, and embraced the beauty. Such stories are not uncommon in Chinese and foreign myths, legends and literary works, although they are fictional, but they contain a profound scientific truth, that is, the performance of hybrids is sometimes better than that of pure breeds.
Ever since Austrian priest Gregor Mendel, the father of modern genetics, discovered this law of the inheritance of life through pea experiments, geneticists and breeders have bred a series of new varieties of hybrid crops and animals that have become the main force in agricultural production, and it is these hybrids that feed such a large population and countless domestic animals on the planet. Needless to say, plants and animals, even humans themselves, thanks to the advantages of hybrids, have been able to flourish and evolve and become the masters of the earth.
Today, we will talk about the history of the development of human "hybrids".
<h1>Out of Africa</h1>
Somewhere in Africa somewhere about 7 million years ago, the ancestors of humans parted ways with apes and began a unique evolution of making tools, walking upright, talking, and telling stories.
Later, the ancestors of humans such as Australopithecus, Capable Man, and Craftsman gradually spread throughout Africa; either due to lack of food, or driven by the instinct of animal curiosity, more than 1 million years ago, Homo erectus who really stood up began to move out of Africa and toward Eurasia. These Homo erectus include the Yuanmou, Lantian, and Peking people who lived in the vast lands of China, but these early humans who came out of Africa have gone extinct and are not direct ancestors of modern humans.
For decades, most scientists who study the evolutionary history of humanity believe that modern humans originated from a single population that remained somewhere in southern Africa, and that this branch of humanity began to evolve rapidly about 200,000 years ago to become the immediate ancestor of modern humans, Homo sapiens. However, this theory is being strongly challenged by some new discoveries.
In June 2017, an international research team led by Dr. Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Germany published two important papers back-to-back in the journal Nature. They found a 315,000-year-old Homo sapiens skull in a cave in Morocco, northern Africa, not only pushing the history of modern humans forward by 100,000 years, but also speculating that Homo sapiens did not originate from a single origin in southern Africa, but was a mixture of different races throughout multiple parts of Africa. That is to say, Homo sapiens began to "cross" before they left Africa, so that the "hybrid" descendants produced in this way could go out of Africa and travel to every corner of the earth.
After two or three hundred thousand years of african multiplication, these modern human ancestors, like earlier human ancestors, could not break free from the temptation of curiosity and food, and constantly tried to get out of Africa, and finally 50,000 years ago, a small group of modern human ancestors were fortunate to achieve an unprecedented victory.
The evolutionary success of modern human ancestors, in addition to their own efforts, was aided by the descendants of early Homo erectus who came out of Africa, including genetic contributions. About 50,000 to 100,000 years ago, modern human ancestors went out of Africa, first encountered some mysterious human races evolved from Homo erectus, familiar with and adapted to the Eurasian environment, and began thousands of years of love and killing with these mysterious human races, which created the lonely us in the human family today.
<h1>Fall in love with a neanderthal with big heads</h1>
In 1856, three years before Darwin published On the Origin of Species, in a quarry in the Neander Valley, 12 kilometers east of the city of Düsseldorf, Germany, quarries worked on a humanoid skull and some bones, which archaeologists identified as the remains of an extinct human race, which scientists called "Neanderthals." Later, archaeologists excavated hundreds of Neanderthal remains from Europe and the Middle East.
Neanderthals had significant anatomy differences from early Homo sapiens. They have short limbs, strong bodies, light skin, and more particularly, their brain capacity is even larger than that of modern human ancestors, they can make stone tools, they use fire, and they may have evolved into certain cultures, such as burying relatives.
Modern human skulls and Neanderthal skulls (Credit: theverge.com)
Niren bones Source: wiki
Scientists have been arguing about the taxonomic status of Neanderthals, with some arguing that Neanderthals belong to a completely different race from Homo sapiens, others believing that Neanderthals also belong to Homo sapiens, a subspecies underneath, and that most scientists generally believe that Neanderthals had no genetic contributions to modern humans until 2009, when a sketch of the first Neanderthal genome was published.
On February 12, 2009, an international team of researchers led by Svante Pääbo at the Max Planck Institute for Evolutionary Anthropology in Germany announced that they had deciphered for the first time a sketch of the Neanderthal genome, which was extracted from three small bones belonging to different Neanderthals, unearthed from the Wendyga Cave in northern Croatia. The publication of Neanderthal genome information is a total of about 2 billion base pairs, accounting for about 60% of its entire genome. What is even more shocking to the world is that scientists have found that the population of Europe and Asia contains 1 to 4% of the unique genomic information of Neanderthals, while the indigenous peoples of Africa do not contain it, indicating that modern humans have had mixed with Neanderthals after going out of Africa, and these hybrid descendants have become the ancestors of modern humans. Scientists chose Feb. 12 to publish their sketch of the Neanderthal genome, primarily to mark the 200th anniversary of the birth of Darwin, the founder of evolution. In May 2010, detailed information on the Neanderthal genome sketch was officially published in the journal Science.
Neanderthal skull and Professor Svante Pab (Source: The Washington Post)
Four years later, the team excavated a Neanderthal toe bone from a cave called Denisova in the Altai Mountains, southern Siberia, Russia, and extracted genomic DNA from it, measured the entire genome of The Artenian Anderdians, and found that only 1.5-2.1% of Neanderthal genetic information was found in the modern human genome. In 2017, a paper in the journal Science argued that Neanderthal genetic information accounted for a slightly higher proportion of the Genome of East Asians than that of Western Europeans, of which 2.3 to 2.6% of the East Asian genomes came from Neanderthals, while Neanderthals contributed only 1.8 to 2.4% to the genomes of Western Europeans.
Scientists speculate that Neanderthals lived in Eurasia about 400,000 to 40,000 years ago, while early modern humans left Africa about 50,000 years ago. Many studies have shown that it was 50,000 to 60,000 years ago that early modern humans had just left Africa and set foot on the land of the Middle East, encountered Neanderthals living nearby, and the two sides may have lived together in Eurasia for 5,000 years. There is no direct evidence of a large-scale conflict between the two sides, but by comparing the genetic information of ancient humans, scientists speculate that Neanderthals and early modern humans have loved each other and mixed things up.
In 2015, Dr. Fu Qiaomei from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, as the first author, wrote in the journal Nature that researchers analyzed the dna of early modern humans unearthed in Romania, about 40,000 years old, and found that neanderthal-specific genomic information accounted for up to 9% of the genome of modern humans. That is, the man's great-great-grandparents may have been a Neanderthal among them. This is also the early modern human that scientists have discovered so far that they are closest to Neanderthals.
In fact, early modern humans not only accepted neanderthal genetic gifts, but also successfully passed on their genetic information to Neanderthals 100,000 years ago. In February 2016, researchers from an international group such as the Max Planck Institute for Evolutionary Anthropology in Germany announced in the journal Nature that in the genome of a female Neanderthal in a remote cave in the Altai Mountains in Russia, they had detected genetic information unique to modern human ancestors for the first time, speculating that a small group of modern human ancestors had been mixed with East Asian Neanderthals 100,000 years ago, but then these modern human genetic information disappeared without a trace.
<h1>Collude with the mysterious "Denisovans"</h1>
However, neanderthals were not the only ones who had genetic exchanges with the ancestors of modern humans. Let's go back to the Altai Mountains Denisova Caves on the border of Russia, China and Mongolia, which not only lived Neanderthals, but also sheltered the ancestors of modern humans, but also lived a mysterious human race.
Just a month before the first sketch of the Neanderthal genome was published in the journal Science, a team led by Svante Pab of the Max Planck Institute for Evolutionary Anthropology and anatoli P. Derevianko of the Russian Academy of Sciences wrote in the journal Nature that they had discovered another extinct new species. The researchers performed mitochondrial DNA genetic analysis on a small finger bone fragment that Jerevyanko excavated from Denisova Cave two years ago. They extracted mitochondrial DNA from this small bone fragment and sequenced it, comparing it with the mitochondrial DNA of early modern humans, Neanderthals, bonobos, and chimpanzees, and were surprised to find that the small bone fragment did not belong to early modern humans, nor to Neanderthals, nor to bonobos and chimpanzees. Further analysis found that the owner of the small bone piece shared the same ancestor as the early modern humans and Neanderthals 1 million years ago, so the researchers speculated that the small bone piece belonged to an extinct new species.
In late 2010, the team further analyzed the genomic DNA of the phalange and deduced that the new species was closely related to Neanderthals, possibly 640,000 years ago, and divergent from modern Africans to evolve 840,000 years ago.
Molars that identify "Denisovans" (Credit: David Reich et al., 2010)
Soon, the researchers excavated bone fragments of other individuals belonging to different individuals in the same cave, all with a genetic background similar to that of this new species, so they called it "Denisovans".
Denisovans are close relatives of Neanderthals, and about 17% of their genetic information comes from the latter. In August 2018, an international team of researchers led by Viviane Slon and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Germany, analyzed a small piece of bone from denisova cave in the Russian Altai Mountains, which belonged to a girl at least 13 years old 90,000 years ago, and more surprisingly, her mother was a Neanderthal. The father was a Denisovan, the first time scientists have found direct hybrid offspring of Neanderthals and Denisovans, suggesting that it is very common for these different races to mix with each other after encounters.
Denisovans may have been more promiscuous with modern humans than Neanderthals, and their genetic distribution was not as widespread as the latter. The genetic information of Denisovans is mainly preserved in the genome of modern Asian humans, among which the melanesian genome of Melanesians living in the Pacific islands near Southeast Asia contains 4 to 6% of Denisovan genetic information. A 2016 study reduced that percentage to 1.1 percent, and speculated that another extinct human could have contributed genetic information. Other researchers have found that denisovan contributions are found in the genomes of some of today's Indigenous peoples in Australia and scattered across southeast Asian islands, as well as in the East Asian continent and native Americans.
In March 2018, researchers at the University of Washington, Seattle and Princeton University in the United States wrote in the journal Cell that they used a new referenceless genome detection method to analyze 5639 human genome-wide sequences from Eurasia and Oceania, and found that the genetic information left by Denisovans in East Asian populations was quite different from those in South Asian and Oceanian populations, so it was speculated that Denisovans had at least two crossbreeds with modern humans. This complicates the mixing of modern humans with other ancient humans.
So far, scientists have only found the remains of denisovans in the Denisova caves in the Russian Altai Mountains, and they are all small bone pieces, and their relatively complete remains have never been found, which makes it difficult for scientists to speculate about what the Denisovans look like, not to mention the living habits, living areas and other issues. But they, like the Neanderthals, by intermingling with modern human ancestors, kept their genetic information forever in a part of the modern human genome, and brought unexpected benefits for these modern humans to adapt to the environment and eventually become the masters of the earth.
<h1>Go to the false and become the strong</h1>
During the years of living with their modern human ancestors, Neanderthals and Denisovans also accumulated a large number of harmful genetic mutations due to reasons such as climate degradation, which were inevitably passed on to their offspring who had crossed with modern humans. Although the genetic gifts obtained from the Neanderthals and Denisovans and other human races are not all beneficial to modern humans, modern humans have gradually eliminated unfavorable genes in their short evolutionary history, preserved favorable genes, and been able to climb the plateau, tour Shanghai Island, travel all over the world, and even explore the universe.
As we all know, when the ancestors of modern humans just left Africa 50,000 years ago, Neanderthals and Denisovans have lived in Eurasia for more than 300,000 years, evolving strong adaptability to the local climate, food, pathogenic microorganisms and other environments, and eventually forming some unique genotypes that are compatible with the environment. Modern humans are mixed with these ancient humans, which is conducive to the introduction of these ancient human corresponding favorable genotypes, which can obviously help newcomers to modern humans quickly adapt to the environment, such as the cold climate of Europe, and then branch out and spread all over the world.
Researchers from the Shenzhen BGI Genetics Research Institute, the University of California, and the South China University of Technology have found that the reason why Tibetans in China can adapt to the high-altitude and low-oxygen environment of more than 4,000 meters in Tibet may be because Tibetans inherit an EPAS1 genotype associated with low-oxygen adaptation from Denisovans or their close relatives, which was published in the journal Nature in July 2014.
Researchers at the Max Planck Institute for Evolutionary Anthropology in Germany analyzed the genomes of 112,000 Britons and found that some of the genes associated with skin color, hair color, height, sleep patterns and even smoking status came from Neanderthals.
In October 2018, David Enard from the University of Arizona and Dmitri A. Petrov from Stanford University reported in the journal Cell that Neanderthals and ancient Homo sapiens not only transmitted viruses to each other during intermingling, but also passed on the virus interpoprotein (VIP) gene to the offspring of the two sides. VIP proteins have a variety of functions, such as participating in the immune response, can resist the invasion of specific viruses, especially RNA viruses. Due to genetic mutations, some Neanderthal VIP proteins are resistant to the invasion of certain viruses, especially RNA viruses. In this way, the descendants of Homo sapiens who inherit the Neanderthal VIP gene will gain resistance to more viruses, that is, genetic adaptation, and survive the subsequent mass plague, while those who are not mixed offspring are gradually eliminated. Forbes contributor Dr. Jennifer Raff figuratively likens this phenomenon to Neanderthals and ancient Homo sapiens both poisoning each other and providing each other with antidotes.
Neanderthals and modern ancestors poisoned each other and provided each other with "antidotes" (Credit: David Enard et al., 2018, Cell)
Although Neanderthals and Denisovans and others have completely extinct as human races, their love stories with modern human ancestors have been deeply engraved in our genome and can no longer be erased or erased.
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Thank you Dr. Qiaomei Fu for reviewing and revising this article.
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