Why is it said that the cradle of human origin is both Africa and southern Asia?

In chronological order:

1. Asian origin theory (before the 20th century)

2. Early "African origin" theory

3. "Multi-regional origin hypothesis" (or direct evolution theory)

4. "Eve hypothesis"

5. "African origin hypothesis" (or single-region origin theory) )

6. The new theory of modern human origins of "regional continuity"

The following is from "Beijing and History":

1. The Origin of Humanity

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The development of science and technology has changed human life and changed people's views on the world. These changes in perceptions involve changes in people's understanding of themselves. Born two hundred years ago, Darwin proposed his theory on the origin of species after completing a long journey around the world as a naturalist. In the introduction to "The Origin of Species" he wrote: "I firmly believe that species are not immutable; those so-called species of the same genus are all direct descendants of another, usually extinct species, just as the varieties of a given species are all recognized as descendants of that species. I also believe that natural selection is the most important way of variation, although not the only way." Darwin believed that his theory was true. In fact, to this day, the evolutionary theory of natural selection has become an immortal basic idea in the life sciences. This theory also became an obvious truth to people.

The theory of evolution provides the most fundamental theoretical basis for scientists to explore the origins of human beings. The motivation for exploring the issue of human origins may come from human curiosity. Humans are just about the most curious animals. Where do we come from? Who are the ancestors of mankind? These questions are probably the most interesting. However, none of the mysteries of nature are easily revealed to people. In order to unravel the mystery of human origins, scientists around the world are working hard to find new evidence. Like detectives, they miss no clues and constantly search for human ancestors and their footprints. It's like big pieces of a puzzle, but most of the pieces are lost forever. People want to get a complete picture of human evolution, but now we know only fragmentary fragments, and the story of human origins still feels like smoke and mirrors.

The search for human origins has spanned more than a century. Before the 20th century, humans knew very little about their origins. But now, scientific research results in the fields of anthropology, archaeology, biology, and geology have given us more and more knowledge about our early ancestors. The richer. This knowledge tells us that humans, like other animals, are products of natural selection and evolved from a Pleistocene primate. It is generally believed that this primate first appeared in the savannahs of eastern and southern Africa more than 4 million years ago. In the 1990s, a group of American scientists discovered fossils about 4.4 million years ago in Ethiopia. This is considered to be the ancestral species of Australopithecus and is the earliest human fossil discovered. Therefore, people came to the conclusion that human ancestors appeared more than 4 million years ago. However, in 2000, French scientists discovered some fossils in Africa that may be earlier human ancestors. The thigh bones in these fossils suggest that this species may have been able to walk upright on two legs. These fossils are very old, about six to seven million years ago. Therefore, our ancestors have experienced a long period of millions of years. It was on this long evolutionary road that our ancestors gradually evolved into modern humans.

In the vast universe, the earth itself is like an inconspicuous speck of dust. Scientists tell us that the earth is about 4.6 billion years old. Life on earth was born about 4 billion years ago and began to develop from the ocean to land about 300 million years ago. Starting 60 million years ago, mammals occupy a dominant position in the biological world. Scientists believe that humans belong to the order of primates in the class Mammalia in the animal kingdom. Primates also include animals such as lemurs, tarsiers, monkeys and great apes (including orangutans, gorillas, chimpanzees, etc.). Anthropologists' research on human fossils shows that humans gradually evolved from ordinary apes. These fossils can continuously show the evolutionary process of humans.

In the early 20th century, the scientific community believed that the cradle of human origins was in Asia, but subsequent discoveries changed this view. Now, the generally accepted view in the scientific community is that human beings originated in Africa. This is the early "African origin" theory. This theory holds that the earliest humans originated in Africa and then migrated to the continents of Asia, Europe, America and Oceania.

It is generally believed that the earliest ancestors of humans lived on the savannahs of eastern and southern Africa. The study of human fossils is an important and direct way for anthropologists to reveal the mysteries of human origins, while molecular biologists use test tubes and other instruments in the laboratory to infer the specific age of human evolution.

Analysis provided by molecular biologists shows that humans originated from apes that lived in Africa millions of years ago and have the same ancestors as orangutans, gorillas and chimpanzees; the line that developed into orangutans was 15 million years old. The branch that separated from the branch that evolved into humans before; the next separation occurred five million years ago, which is the branch of gorillas; the closest relationship to humans is chimpanzees, and chimpanzees and humans may not have existed until four to five million years ago. Separation and evolution began only a few years ago.

Therefore, more than 4 million years ago, human ancestors appeared on the savannahs of eastern and southern Africa, and they belonged to the primates of that period. After roaming on the African plains for more than 2 million years, this primate began to spread from Africa to other continents. It is generally believed that the earliest time human ancestors left Africa was about 2 million years ago, and at this time Homo erectus appeared. Anthropologists' speculations about these dates are based on the fact that human fossils from 2 million years ago have been found only in Africa, while human fossils from 2 million years later have appeared on other continents. The early "African Origin" theory believed that the earliest humans originated in Africa and then migrated from here to the continents of Asia, Europe, America and Oceania. By now it is generally accepted that the earliest humans originated in Africa. Therefore, it is believed that Homo erectus, which is distributed in Asia, Europe and Oceania, originated in Africa. Their ancestors left Africa about 2 million years ago and migrated to other continents. Later, some of these Homo erectus may have evolved locally until early intelligence. human stage.

At present, people are not very clear about the migration of early humans, but anthropologists have discovered the fact that human fossils from 2 million years ago are currently only found in Africa, and after 2 million years ago Human fossils have appeared on other continents. Human fossils dating back 2 million years have been found in many places outside the African continent. For example, the "Peking Man (Peking subspecies of Homo erectus)" fossil was discovered in Zhoukoudian, Beijing (about 50 kilometers southwest of Beijing) in the 1920s. Peking Man lived about 500,000 years ago and belonged to Homo erectus. Although it is generally believed that Peking Man is a side branch in the process of human evolution and eventually became extinct, and is not a direct ancestor of modern humans, in anthropology, Peking Man is generally considered to belong to the human category.

So, how did modern humans develop? Did those early humans who migrated from Africa 2 million years ago and evolved there eventually evolved into modern humans?

Although modern humans have racial differences (yellow race, white race, black race), that is, each has significant characteristics in skin color, hairstyle and facial shape, in fact, racial differences The emergence of occurred very late. It is generally believed that the formation of racial differences is mainly due to different races adapting to different environments during migration. Therefore, the emergence of race occurred after the formation of human beings in the full sense, which means that modern humans originated from the same ancestor very late in time. It is precisely because of this that different races in the world can intermarry; there is no big difference in innate intelligence between races. In fact, anthropologists generally agree that "upper Paleolithic hominids or contemporary Australian Aboriginals were just as likely to graduate from university as any other race if they had access to education."

In recent decades, the intervention of molecular biology has injected fresh vitality into the study of human origins. In 1987, American geneticist Rebecca Cann and others studied mitochondrial DNA extracted from the placenta of 147 women of different races from around the world and found that the mitochondrial DNA from African women had particularly large variations. It is the oldest human race, so it is proposed that all modern human races originated from the same ancestor in Africa. Based on the mutation rate of mitochondrial DNA, they calculated that the African female ancestor lived about 140,000 to 290,000 years ago, with an average of 200,000 years ago. Her descendants left Africa about 130,000 years ago and dispersed throughout the world. , completely replacing the people who originally lived in the local area. This is the so-called "Eve hypothesis". The Eve hypothesis is the beginning of using genetic methods to explore the origin and evolution of humans.

As for the origin of modern humans, the Eve hypothesis and some other genetic analysis results support the "African origin hypothesis." The African origin hypothesis (or single regional origin theory) holds that humans with the anatomical characteristics of modern humans first appeared in Africa, and then spread to all parts of the world and replaced the local Homo erectus or early Homo sapiens, with almost no interaction with the local residents during the diffusion process Fusion or genetic exchange, no anatomical or genetic continuity. For example, the white race in Europe was formed by invading from Africa and wiping out the indigenous Nepalese people; the same goes for those who invaded Asia, replacing the early humans in the area and evolving into the modern yellow race. The research results of molecular biology do provide more support for the African origin hypothesis, which encourages the supporters of this hypothesis. They believe that molecular biology provides genetic evidence for the single regional origin of modern humans.

However, in general, the origin of modern humans is controversial. Regarding this issue, the view that is diametrically opposed to the African origin hypothesis is the "multi-regional origin theory" (or direct evolution theory).

This hypothesis holds that modern humans evolved from local early Homo sapiens and even ape humans. There is anatomical or genetic continuity between them, but there is genetic exchange between different regions. For example, the white people in Europe gradually evolved from the local Neanderthals, and the yellow people in Asia evolved from the local early Homo sapiens and ape people. Support for the multi-regional origin theory mainly comes from archaeologists and paleoanthropologists. The continuity and widespread geographical distribution of unearthed human fossils make them believe that "Homo erectus → early Homo sapiens →" existed in Asia and Africa. The evolutionary history of "modern man" means that the origin of modern human beings is multi-regional.

In addition to the above two theories, some people have proposed a new theory of the origin of modern humans called "regional continuity". This theory holds that Homo erectus, which originated in Africa, has continuously migrated to other areas outside Africa over the past 1.5 million years and formed different branches. These branches reproduced through interbreeding and developed in Africa, Europe, and East Asia 100,000 to 150,000 years ago. and West Asia and other places evolved into modern humans.

Scientists are still exploring the question of "who are our ancestors?" Among the various current views, the African origin hypothesis about the origin of modern humans seems to be more accepted. This hypothesis was proposed by molecular biologists and geneticists. They believe that modern humans are a single species, but the early apes found in various places are very different and belong to different species. Not all of them evolved into modern humans. Only the apes in East Africa embarked on the path of evolving into modern humans. Specifically, the theory of African origins believes that modern humans originated in Africa about 250,000 to 200,000 years ago (most likely in East Africa), and then about 100,000 years ago, some modern humans left Africa and migrated to Asia and Europe. And completely replaced other local ancient groups. According to this hypothesis, all early humans in China (including Peking Man) that were older than 100,000 years ago are considered to have suffered the fate of extinction, leaving no descendants and not belonging to the ranks of the ancestors of the Chinese people. However, all current Chinese people are They are the descendants of the African woman "Eve".

At the end of the last century, some Chinese geneticists cooperated with foreign scholars. Through research on the DNA of living human groups in my country, they proposed that the Eve theory is applicable to China's historical conditions. They further proposed that African immigrants were It arrived in southern China about 60,000 years ago, then expanded to northern China and completely replaced the humans who lived on this land at that time. So now we can summarize the evolution of humans. Humans evolved from Pleistocene primates and first appeared in Africa more than 4 million years ago or earlier. About 2 million years ago, human ancestors first left Africa, and at this time Homo erectus appeared. Some of the Homo erectus who spread from Africa to Asia, Europe and Oceania evolved into the early Homo sapiens stage there, but they did not evolve into modern humans. Modern humans originated in Africa about 200,000 years ago, and spread to Europe and Asia about 100,000 years ago. About 40,000 years ago, Homo sapiens with the ability to think finally appeared. About 10,000 years ago, after the glaciers of the last ice age receded, the distribution of various human races was basically formed. The distribution of various races on the earth has been roughly the same as it is now.