Why are there people on earth?

Is developed from single-celled organisms. Fish-two species-reptiles-birds-mammals are arranged in turn. The evolution of human beings has found humans with the same ancestors in Europe and Asia, which proves that Eurasian humans are related. In terms of time, European Homo erectus was earlier than Asian Homo erectus and was a descendant of African Homo erectus. From 1.2 million years ago to 800,000 years ago, Homo erectus from Africa spread all over non-Eurasia. Some experts believe that 800,000 years ago, Homo erectus became the first human to come to Europe and enter the Iberian Peninsula. At the same time, Homo erectus in East Asia, represented by Beijingers, began the road of independent evolution. Their brains began to get bigger. Finally, 200,000 years ago, a homo erectus named Neanderthal had almost the same brain as modern people. Neanderthals were kings of the Ice Age. They cooperate with each other and live together, perfectly adapting to this harsh world. According to the theory of polycentric origin, Neanderthals in Europe evolved into advanced races, and Homo erectus in Asia also expanded its brain capacity and evolved into modern humans together with primitive people in Africa. But according to this theory, modern people should evolve three different forms of species. However, from a genetic point of view, the differences in skin color and hair of modern people are very small changes. Biologically, we all belong to the same species. How do you explain this? Some experts believe that in the process of evolution, the genes of people in various regions have become closer and closer through 500,000 years of communication. If this theory holds, it means that these independent people meet and mate through mobility, thus exchanging genes. Can this theory be confirmed by genetic science? ? The earliest evidence of African Eve theory or single origin hypothesis comes from genetic research. Professor Wilson of the University of California, Berkeley, is interested in genetic variation between people. Wilson and others believe that genetic variation can explain the evolutionary history of all animals. For example, chimpanzees that look the same may have great differences in gene types, because there will be a lot of genetic changes in their 3 million-year development history. Moreover, there should be more than 6.5438+0 million years of genetic differences between races. From 65438 to 0987, Rebecca Kahn of the University of Hawaii purified DNA samples from women all over the world to find a unique substance called mitochondria. Mitochondria exist in cytoplasm and are called energy supply stations of cells. It has its own DNA and can replicate independently. The next generation of mitochondrial DNA generally comes only from the mother and is passed down from generation to generation, so it is a good genetic marker. The result of the experiment is surprising. The results show that all the genes of modern women come from a woman who lived about 148000 years ago, and the difference between Africans and Asians is only about 65438+ million years ago. In this case, multi-regional origin becomes impossible. Subsequently, geneticists successfully deciphered the Y chromosome code of male genes again. They come to the conclusion through research that all modern people have a father like him, and he should have lived 6.5438+0.5 million years ago. This is well-deserved Adam and Eve, the ancestors of mankind. * * * Homologous If the evolution of human beings is compared to a tree, the process of searching for Adam and Eve by geneticists is like searching for roots through fruits, and the roots have the greatest genetic variation because of their age. So geneticists judge that Africans are the source of modern human evolution. The discovery of Indonesian dwarfs proves that Asians and Europeans are the same race and share a common ancestor. They come from the African continent. Homo erectus once spread all over the world, but why did African Homo erectus finally stand out? 1997, paleoanthropologists discovered three ancient human skulls160,000 years ago in Ethiopia, no different from modern people. They were named Old Homo sapiens. They lived in an era similar to Eve, and they are probably our immediate ancestors. At that time, the earth was in the ice age and Africa was facing severe drought. The expanding desert divides human beings into isolated small communities and lives independently in the small forests around the coastline. A new genetic mutation changed all this. There are new human beings on the earth, that is, our ancestors, who have brand-new thinking. If we compare the 5 million years of human evolution to a day, in the last few minutes of this day, the earliest intelligent human caveman stood out from the apes. Homo sapiens is not alone. In Europe, Neanderthals were still fighting for life and death during the Ice Age, and in Asia, Homo erectus gradually became stronger. There is not only one kind of human beings, and soon they will be close to each other, which will be an encounter that will determine the fate of our species.