Why do other animals have different species, but humans have only one?

2020-01-08 | Animal Expo original |

We human beings are the primates of all things, but they are also one of the most "lonely" creatures on the planet. Most animals have their own close relatives, such as 7 species of canine including wolf, jackal, etc., and bovineIncluding 5 species of domestic cattle, white-legged bison, and yak, there are nearly 40 species of Mus musculus, and more than 60 species of rat. We modern humans, biologically called Homo sapiens, are the only species of human genus, and we existThe nearest relative, the chimpanzee, has been separated from us for 7 million years.

We Homo sapiens were not born so lonely. In ancient times, there were many human races such as sapients, erects, Neanderthals, and Flores. Later they became extinct, and new races did not appear.That makes us the only kind of person on earth. So why is this so?

Schematic representation of human species evolution

Humans conquer every corner of the world

The evolution of modern humans has gone through four stages: the southern ancient ape → capable human → erect human → sapiens. Humans originated in the African savannah. Later, as humans' ability to adapt to the environment increased, the number of people increased.Drove humans to spread outwards and open up new living spaces. At least four "out of Africa" ​​events have occurred in the history of human evolution.

The first person out of Africa was a capable person. Ancient ape-man fossils have been found in Africa, China and Australia. The earliest human fossils in China can be traced back 2.1 million years ago. About 1.8 million years ago, it is knownThe earliest Homo erectus appeared in the Caucasus and Africa, and later the Homo erectus quickly occupied southern Eurasia and Africa. Our Yuanmou, Lantian, and Beijingers belonged to Homo erectus. Homo erectus lived about 200,000 years ago.The Homo erectus in Eurasia eventually became extinct because they could not adapt to the environment. The Homo erectus hiding in Africa later evolved into Heidelberg and Homo sapiens.

Evolution of humans: Primitive ancient apes → Southern ancient apes → Noble people → Homo erectus → Neanderthals, Homo sapiens

800,000 years ago, the Heidelbergs crossed the Strait of Gibraltar to southern Europe, and the descendants of the Heidelbergs were the famous Neanderthals. The Nepalese later expanded to Western and Central Asia, and their rule in these regions has beenIt lasted about 40,000 years ago.

135,000 years ago, the early Homo sapiens went out of Africa. They followed the "Northern Route", entered the Middle East from the Sinai Peninsula, and then advanced to Central and East Asia. Our Liujiang people may belong to this group of descendants..Because early Homo sapiens's ability to adapt to the environment was not strong enough to cope with the cold environment in the northern part of the glacial period, they could all be extinct or returned to Africa no later than 70,000 years ago.

70,000 years ago, the late Homo sapiens embarked on a journey to conquer the world. This time they chose the "Southern Route", that is, crossing the Strait of Mander into the Arabian Peninsula, and the level of the Red Sea dropped by 70 meters during the glacial period.The strait is much narrower than today, allowing humans to pass by rafts. From 6.5 to 50,000 years ago, these people crossed the southern coastal areas of Iran to India, where settlements were established and then expanded to Southeast Asia and Australia..

Homo sapiens conquers the world, the figure is the occupation year unit is thousands of years ago

The late Homo sapiens who came out this time are relatively mature in technology and culture, and are already the strongest in nature, so this expansion has achieved ultimate success. Since about 50,000 years ago, it has developed to a certain extentHumans of population size began to "go north and east", replaced Neanderthals to occupy Europe 40,000 years ago, occupied North and East Asia 25,000 years ago, and entered the American continent on the Bering Land Bridge 15,000 years ago, completing the globalThe conquest of these people is our immediate ancestor.

The above is the process of human beings out of Africa to dominate the world. Rather than the only modern humans on the planet, it is better to say that only our ancestors have completed the conquest of the earth.

Zhoukoudian Ruins, where people who lived upright—Beijing, Homo sapiens, and cave dwellers

Two people can't be accommodated anywhere

Before the modern people, Homo erectus also used to spread across the three continents of Eurasia, Africa. If the Homo erectus in each place evolved into modern people in parallel-this is the "parallel chemistry theory", then there will be many people on the planet today. However, the currentBoth genetics and fossil evidence support the "replacement doctrine", that is, Homo erectus in Africa evolved into Homo sapiens, and Homo sapiens went out of Africa, replacing early humans already living throughout Eurasia, becoming the only person on earth today.

Ecologist Gauss proposed the principle of competitive exclusion, that is, two species with the same niche cannot coexist in the same area, they either completely replace the other, or the niche feeding habits, habitat and activity time, etc. separate.Here human beings are very special. Their competitive inhibition is too strong, because human beings can not only use nature, but also transform nature. There can be two kinds of antelopes on the same grassland, but if there are two kinds of people, you must fight for your life.No. You can only call it a human being as a ruler of the earth as a highly intelligent creature, otherwise it is just an ape.

Homo sapiens dark cannibalizing Neandertal territory shallow

One of the most famous examples of "replacement doctrine" is Homo sapiens replacing Neanderthals in Europe and West Asia. Homo sapiens have larger tribes, are more densely populated, and have mastered spoken language, forming a social network that is beginning to take shape; Stone technology is ahead of the Nine generations, inventing weapons that can be thrown remotely; and wearing clothes and building a house. Because of these advantages, Homo sapiens finally defeated the Nine. About 60,000 years ago, two races inThis is the first time that Israel and Iraq have confronted each other. By 40,000 years ago, Homo sapiens occupied the whole territory of Europe, and the species of the genus Nissan disappeared forever.

None skeletons killed by Homo sapiens have been found in Iraq and France. Our ancestors can say that their hands were stained with blood during the expansion of their living space. I do n’t know how many early humans were destroyed by us. Maybe, each of usEveryone has a cannibalism.

Neandertal film and television image

Human beings can enter any corner of the earth, and there is no place that can accommodate two kinds of human beings, which is destined to have only one kind of person in the world. As the saying goes, one mountain cannot tolerate two tigers, human beings are more exclusive than tigers, and one planet cannot tolerateTwo humans.

Communication eliminates differences

The "replacement model" does not exclude that Homo sapiens and other races have had mixed blood. In fact, intermarriage is the last straw that led to the demise of some early races. Today, people in all parts of the world except those who stay in black AfricaThe DNA contains a small amount of Neanderthal and Denisova genes, which is evidence that our ancestors had mixed blood with them.

Because individuals located at both ends of the distribution area cannot communicate with each other, after a long evolution of the widely distributed species, intra-species differences will inevitably occur. This is the origin of modern race and ethnicity. There are now four people in the world.Race: yellow, white, black, and brown, with more than 2,000 ethnic groups.

Ancient minority in China: Khitan

However, with the advancement of science and technology, the population's ability to migrate is getting stronger and stronger. Today human beings can reach any corner on the ground in a short time, and the earth has also become a "global village." The interracial race and cultural exchanges are advancingGlobal integration. Although some rulers in ancient and modern times have implemented policies that hinder integration, such as apartheid, today, as society becomes more and more civilized, these obstacles are becoming fewer and fewer, and integration is the general direction.

Like some ancient Chinese Khitans and Xianbei people, they have completely disappeared in the process of ethnic integration. It is no longer possible to create new races and nationalities in the future, and the boundaries between existing races and nationalities are gradually gradual.blurry.

Mixed Family

In the evolution of species, isolation leads to differences, while communication eliminates differences and promotes normalization. Tiger subspecies have been formed in the past tens of thousands of years, because different subspecies such as Siberian tiger and Sumatran tiger cannot be carried out due to geographical isolation.Gene communication, different breeds of dogs are the result of human-oriented breeding. However, modern people and foreigners are completely personally free to marry, there is no obstacle to gene communication, and the obstacles will become smaller and smaller in the future. So the ultimate trend of human development is raceWith the demise of the nation, this is good for the peaceful development of the world and the common prosperity of all mankind.

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