The process of human development

studied the direct evidence of human origin from fossils. Anthropologists use the method of comparative anatomy to study all kinds of ancient ape fossils and human fossils, determine their relative and absolute ages, and thus determine the dating of human fossils, and roughly divide the evolution history of human beings into several stages. Geneticists, on the other hand, use the methods of biochemistry and molecular biology to study the difference and variation speed of protein and deoxyribonucleic acid (DNA) among modern humans, various apes and other higher primates, so as to calculate their respective origins and differentiation ages. At present, it is generally believed in academic circles that the time when the ancient ape turned into the ancestor of human beings was 7 million years ago.

judging from the discovered human fossils, the evolution of human beings can be roughly divided into the following four stages:

(1) Australopithecus stage. The discovered Australopithecus lived from 4.4 million years ago to 1 million years ago. According to the research on the anatomical characteristics of fossils, the most important feature of Australopithecus is that it can walk upright on both feet, which is different from apes.

(2) capable person stage. The first 2 million-the first 1.75 million years. Fossils of homo habilis have been discovered in Tanzania and Kenya in East Africa since 196. The earliest possible life existed 1.9 million years ago. Homo habilis is classified as homo habilis below hominid. Homo habilis has a larger brain than Australopithecus, and can make tools (stone tools) from stones, and then gradually evolved into Homo erectus.

(3) Homo erectus stage. Homo erectus belongs to homo erectus in classification, which is called Homo erectus for short, commonly known as Homo erectus. Homo erectus fossils were first discovered in Java, Indonesia in 1891. At that time, there was also a debate about whether it was a human or an ape. It was not until the 192s that the fossils and stone tools of Peking Man were discovered in Zhoukoudian, Beijing, that the position of Homo erectus in the history of human evolution was established. Homo erectus lived about 1.7 million years ago to more than 2 thousand years ago. So far, homo erectus fossils have been found in Asia, Africa and Europe.

(4) Homo sapiens stage. Homo sapiens is generally divided into early homo sapiens (ancient homo sapiens) and late homo sapiens (modern man). Early Homo sapiens lived from 2, years ago to more than 1, years ago. The survival age of late Homo sapiens began about 1, years ago. Its anatomical structure is basically similar to that of modern people, so it is also called modern people in anatomical structure.

According to the evidence of human fossils found so far, Australopithecus is the earliest known human.

(2) Dunn's skull

In p>1924, in a place called Dunn in azania, South Africa, a small skull fossil was blasted by quarry workers there while quarrying. This fossil of Towne's skull was quickly sent to the Medical College of the University of Witwatersrand in Johannesburg and handed over to Raymond Dart, a professor of anatomy. Dart, an Australian, had just returned from studying medicine, anatomy and anthropology in London, England. The skull fossils given to Dart by quarry workers, including most of the skull and a complete intracranial model, contain a full set of deciduous teeth and the first permanent molars that are erupting, belonging to young individuals (equivalent to modern children aged 3-6).

Dart found that this fossil has many ape-like characteristics. For example, this young individual's brain is about 5 ml like an adult gorilla, and it is estimated that it is only about 6 ml in adulthood. In addition, the upper and lower jaws protrude forward, similar to apes. At the same time, Dart noticed that the fossil also has human characteristics. Its teeth are very small, similar to human teeth. Most importantly, the foramen magnum is located in the center of the skull base, just like humans. The foramen magnum is the opening at the base of the skull, where the spinal cord is connected with the brain. Because humans walk upright with their feet, their heads are balanced at the top of the spine, and the foramen magnum is located in the center of the skull base. The ape's head leans forward, and the foramen magnum is located at the back of the skull base. The characteristics of the foramen magnum in Tonne's skull show that its individual can walk upright.

Based on these findings, Dart published a research report in 1925, pointing out that the individual to which this fossil belongs is a mixture of anthropoid and ape-like traits, and it is an extinct ape that has been found to be the closest to the human system. Because it was found in the southernmost part of Africa, the species of the individual to which Towne's skull belongs was named Australopithecus Africa. After the publication of Dart's article, it was ridiculed by many authorities in British anatomy and anthropology. They think this fossil is just an early ape fossil. In the following 1 years, this skull was rarely mentioned again because of the discovery of the high-profile Peking man fossil.

in p>1936, another batch of fossils were blasted in the stech Fontaine quarry in Transvaal. Among them, there is a complete skull that is very similar to the skull of Towne. Since then, similar fossils have been found in krom Delai, Macapansgate and Reims, Svatek. By the 195s, more than 7 Australopithecus fossils had been found in the above five sites. The academic circles classified the Australopithecus fossils found in South Africa into one genus and two species, namely Australopithecus africanus and Australopithecus robustus, or gracile australopithecine and robust australopithecine, and gradually established the status of Australopithecus as the ancestor of early humans.

it should be pointed out here that although Australopithecus is still called Australopithecus in name, it is actually a member of Hominidae. According to the international paleontological naming rules, once a species is named, its name cannot be changed casually. Therefore, the name of the ancient ape is still in use today.

(3) Discovery in East Africa

In the late 195s, the search for human fossils in Africa gradually moved to Ethiopia, Kenya and Tanzania in East Africa. The geological feature of East Africa is that there is a great rift valley from south to north, and its surface is a series of canyons and lakes. There are a lot of volcanic deposits caused by volcanic eruption in this area for millions of years, which provides good materials for isotopic dating. Therefore, the age of fossils buried in these volcanic layers can be accurately determined.

On July 17th, 1959, after 3 years' searching, paleoanthropologist Louis Leakey and his wife Mary Leakey finally found a nearly complete skull and a calf bone of a stout Australopithecus in Oduwei Canyon. The skull is particularly thick, with huge molars on the gums. Mr. and Mrs. Leakey named the species of the individual to which this skull belongs as Zinjanthropus boisei, and later changed it to Australopithecus boisei. In their opinion, Bauhinia species is an East African variety of robust species. The generic name Zinjanthropus means "people from East Africa", while the name boisei comes from Charles Boise. He once supported the work of the Leakey family in East Africa. The age of fossils was determined by potassium-argon method, and it was determined that "East Africans" lived 1.75 million years ago. In this excavation, broken bone fragments of stone tools and extinct animals (which seem to be caused by feeding on nutritious bone marrow) were also found. Have "East Africans" been able to make stone tools and even hunt animals? Judging from the skull, its brain is still too small to complete such complicated technical operations and labor. If these stone tools were not made by "East Africans", who made them?

In p>196, near the location where the skull of "East African" was found, Jonathan Leakey, the son of Louis Leakey, found part of the skull and mandible of a 1-11-year-old child, hand bones of people of different ages, an adult clavicle and nearly complete foot bones. In 1963, another skull and mandible with most teeth were found in the same place. The study of these fossils shows that this is a more progressive person than the "East African". Its brain is almost 5% larger than that of "East African", its skull shape is more progressive, and its teeth are smaller than that of "East African", living 1.78 million years ago. According to Dart's suggestion, Louis Leakey and others named it Homo habilis, as the first early member of the genus Homa. The name Homo habilis means "handy person" or "skilled person".

Louis Leakey believes that the stone tools found in the excavation of "East Africans" were made by "homo habilis" and the bone fragments were also broken by "homo habilis". He believes that although Australopithecus is a part of the early ancestors of human beings, only "homo habilis" can continue to evolve into the later stage of human beings and eventually produce modern people. The discovery of "East Africans" and "capable people" in East Africa is also the earliest evidence that members of the two types of human families live in the same area at the same time. Since then, a number of "homo habilis" fossils have been discovered in Ethiopia and Kenya. One of the most important is that in 1972, another son of Louis Leakey, Richard Leakey, found the skull numbered KNM－ER147 on the east bank of Lake Turkana.

since 196s, a large number of Australopithecus fossils, including hominid fossils from about 3.5 million years ago to 1.5 million years ago, have been found in Omo Valley in Ethiopia and Hadar in Afa region. Among them, two bones, the lower femur and the upper tibia, which constitute a knee joint, were found in Hadar in 1973, and have been shown to have the function of walking upright. These fossils date back to 3.5 million years ago. In 1974, Donald Johanson, an American paleoanthropologist, found most of the skeleton of a woman in the same area and named it "Lucy". According to the study of her pelvis, spine and kneecaps, it can be confirmed that she walked upright on two feet and lived for 3.4 million years ago.

In p>1976, mary leakey discovered a group of human footprints condensed in volcanic ash in Letori. This set of footprints left 3.7 million years ago is quite intact, and its dating is also quite reliable. According to the analysis of the arch shape and gait, it can be considered that it was left when walking upright. The above findings are the earliest evidence of human bipedal walking.

According to the comparative study of Hadar and Lettori fossils, Johansson and others think that the specimens from these two places are very similar, that is, they can walk completely upright on both feet, and both have small brains and big canine teeth, so they belong to a class and should be classified as a new species-Australopithecus afarensis. They believe that some characters of Afa species are between apes and humans, but their ape-like characters are obviously changing to humans. Therefore, the Afa species is not only the ancestor of the African species of Australopithecus Australopithecus, but also the ancestor of "homo habilis". On the one hand, the Afa species changed from Australopithecus africanus to Robinia species and eventually became extinct; on the other hand, it developed into homo habilis and Homo sapiens.

By the early 199s, there were five species of Australopithecus found in Africa, namely, African species, Afa species, Robinia species and Ethiopia species. These five species of Australopithecus are classified into the slender and stout Australopithecus described above. African species and Afa species belong to slender type. Among them, Afa was earlier, represented by "Lucy"; The African species is a little later and only found in South Africa. The other three species belong to the stout Australopithecus. The Ethiopian species is named after a mandible 2.5 million years ago. This fossil was discovered in southern Ethiopia in 1967. Many paleoanthropologists don't recognize this species and think it should be classified as Bowie species.

After 199s, the study of early human fossils in East Africa has made a new breakthrough. In 1994, American paleoanthropologist Tim White and others announced that they had discovered a large number of hominid fossils 4.4 million years ago in Afa Basin, Ethiopia, and named them Australopithecus ramidus. Ramid means "root" in Arabic, a local tribal language. Named after this fossil, it means that this is the oldest direct ancestor of human beings discovered so far. After that, Richard leakey's wife, Meave Leakey, and American paleoanthropologist, Alan Walker, discovered the Australopithecus anamensis 4.2 million years ago on the west bank of Lake Turkana. Because there are still different views on the anthropological status of the ancestor species in academic circles, it is generally believed that the lakeside species is the earliest anthropological member who can walk upright.

(4) Looking at human evolution from Australopithecus

Since Datt first discovered Australopithecus fossils in 1924, seven species of Australopithecus fossils have been discovered so far. In the past few decades, the continuous discovery of new Australopithecus fossils and the multidisciplinary research on the discovered fossils have enabled the academic community to have a new understanding of the process involving the origin and evolution of early humans. Firstly, the position of Australopithecus in the whole human evolution system was established. The discovery of Australopithecus fossils 4 million years ago in recent years makes the survival age of Australopithecus closer to the separation time of apes calculated by geneticists through DNA research; Secondly, the characteristics of various species in Australopithecus in fossil characteristics, survival age and evolutionary relationship with later hominids make anthropologists realize that the evolution process of human beings is much more complicated than originally thought. In the same time range, several species of Australopithecus existed at the same time, but only one population evolved in the direction of hominid, and the rest eventually became extinct. This shows that human evolution is carried out in a "bush" way, rather than in a traditional linear way. This is of great significance to enrich the theory of biological evolution. The discovery and research of Australopithecus deepened human's understanding of its origin and evolution, and promoted the development of paleoanthropology. It is worth mentioning that in the past decades, the Niche family has made great contributions to the discovery and research of ancient humans in East Africa.

(5) Stories in the East

Academics generally divide hominids into Australopithecus, Homo habilis, Homo erectus and Homo sapiens. Australopithecus is the earliest known hominid. So, what exactly prompted Australopithecus to expand its brain and gradually acquire the ability to walk upright and make tools, thus transforming into a human?

15 million years ago, Africa was covered with dense forests from west to east, inhabited by various primates, including many kinds of monkeys and ancient animals.