Origin of humans

Author: Yang Mingbo
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Publishing Date: 2003-08-01
Features: [Excerpt:] About 30 million years ago, the primitive forests in the tropics and subtropics of Asia, Africa, and Europe stretched as far as the eye could see, with dense tree canopies almost covering the sky. At that time, ancient apes lived in groups in the trees. They were covered in fur, with pointed ears, and their main diet consisted of fruits, tender leaves, roots, and small animals. The forelimbs of ancient apes had begun to specialize, allowing them to move skillfully through the forests using arm locomotion, pick fruits with their forelimbs, and use natural wooden sticks and stones. They built nests in branches using branches and leaves and occasionally came down to the ground, struggling to stand and walk on their hind legs. Later, the Earth underwent the changes of "sea and land," and the climate also varied. In Asia and Africa, large areas of forest were transformed into sparse grasslands. The ancient apes living in these areas, due to environmental changes and differences in adaptability, underwent divergence. Some ancient apes could not adapt to the changing environment and became extinct; others retreated to the depths of the forests, continuing to live in the trees. Their descendants became the modern apes—chimpanzees, gorillas, and bonobos, etc. Meanwhile, other ancient apes, as the natural environment changed, came in groups to the grasslands and began a long-term terrestrial life, developing in the direction of upright walking. These upright-walking ancient apes later evolved into humans. Moving from life in the trees to life on the ground, from climbing to upright walking, was a decisive step in the evolution of apes to humans. Naturally, ancient apes did not immediately start walking upright after coming down from the trees. When walking on the ground, they gradually shed the habit of using their forelimbs for support and gradually learned to walk with their hind legs. They must have passed through a semi-erect stage before reaching full erect walking. The time they spent walking upright was not uniform. Some came down from the trees earlier or later, and some started walking upright earlier or later, with varying degrees of readiness and speed. It took several hundred thousand years for ancient apes to gradually entrust the task of supporting their entire body and moving it to their hind legs, while their forelimbs gradually developed into hands and their hind legs specialized for walking. The division of labor between hands and feet created the conditions for upright walking, and in turn, upright walking further promoted the further development of hands and feet. Ancient apes gradually evolved from four-legged movement to two-legged upright walking, completing a decisive step in the evolution from apes to humans. After standing upright, the field of vision of ancient apes expanded, making it easier for them to observe their surroundings and adapt to the environment. Only after standing upright could their forelimbs be fully liberated and transformed into hands; only after standing upright could their lungs and vocal cords be freed, providing conditions for the development of the brain and vocal organs. However, ancient apes capable of walking upright were not yet humans. The fundamental marker that distinguished humans from apes was labor. No animal, including ancient apes, understood labor. Labor began with the creation of tools, which was a purposeful and conscious activity, meaning that people could not only utilize natural objects but also transform them. Although ancient apes could engage in rudimentary labor by utilizing natural objects, they could not manufacture tools and were merely passively adapting to nature. No ape ever made even a crude stone knife. When the ancestors of humans, through long struggles with nature, learned that striking one stone with another could create something useful, stone tools were born. From then on, ancient apes transformed into humans, and humans entered the early Stone Age. The discovery of bone needles indicated that people could already sew animal hides into clothing. The appearance of ornaments showed that people's aesthetic sense had emerged. The Upper Cave People polished, drilled, and strung materials such as seashells, animal teeth, pebbles, and bone fragments to wear on their chests. With the development of primitive society and population growth, the social organization of this period gradually transformed from primitive groups to clan societies. At that time, a system of exogamy was practiced, where members of one clan married members of another clan. Under this group marriage system, children only knew their mothers but not their fathers, and blood relationships could only be traced through the maternal line, forming an early matrilineal clan society. Simultaneously, during the same period as the Upper Cave People, archaic humans were distributed across the world. Due to differences in their environmental conditions, such as climate, humidity, and sunlight, they gradually formed the various races of the world today. The development from Homo habilis to Homo erectus and then to Homo sapiens was the process of primitive human evolution. Afterward, humans entered the stage of modern humans. Dividing the history of primitive human development into three stages for easier understanding is a simplification. In reality, human development is far more complex than the above description suggests, and the process is difficult to neatly divide into such stages. Instead, it is intricate, with twists and turns in evolution and varying stages in development. In other words, it is not a straight line from ancient apes to Homo habilis, Homo erectus, and Homo sapiens. Rather, it is more like branches, with many side branches in human evolution, and only one branch extended high enough to evolve into modern humans. The other side branches, due to different living environments and slightly different developmental directions, ceased to evolve at certain stages and became extinct. For example, after various ancient apes descended from the trees to the ground, they underwent significant divergence, forming different types of ancient apes. To date, we do not have sufficient evidence to prove which ancient ape is the direct ancestor of modern humans. We can only say that certain ancient apes were very close to the ancestors of modern humans. Similarly, the transition from Homo habilis to Homo erectus and from Homo erectus to Homo sapiens also involved many divergences, and we cannot definitively identify which species is the direct ancestor of modern humans. In fact, whether molecular anthropologists or archaeological anthropologists, when discussing the course of human origin, have rejected the rigid linear model of evolution in favor of an open tree-like model. During the late Miocene and early Pliocene in the geological era, various primates lived on the continents of Africa and southern Asia. At that time, the climate in this region was warm, with evergreen forests, dense trees, winding streams, and abundant fruits. Various animals gathered in the forests. They lived in groups, climbed trees to forage for fruits, and sometimes came down to the ground to dig plant roots and stems, hunt small animals for food, and use natural tools to defend against predators. They chased and played with each other, reproducing offspring. The favorable living environment made their population thrive, turning it into their paradise. However, good times did not last long. By the end of the Cenozoic and the beginning of the Quaternary, the areas where these primates lived underwent significant changes. The dramatic shifts in land and sea layouts caused climatic fluctuations between warmth and cold, as well as dry and wet conditions, making the primate habitats dry and cold. Consequently, large areas of forest became increasingly sparse. The collapse of trees reduced the availability of wild fruits for primates, and the small animals they hunted either died or scattered, leaving few survivors. The paradise of primates vanished. With the drastic changes in nature, primates were forced to come down to the ground. The terrestrial life of primates accustomed to living in the forests was extremely difficult. Nothing in nature develops in perfect balance. Primates belong to a family with many genera and species, and their development on trees was uneven. Therefore, there were significant differences in their physical structures, with some individuals being smaller or larger, some being highly skilled at brachiation or less so, some having smaller or larger brain sizes, some with exceptionally long forelimbs or shorter ones, and some with poor or semi-erect to fully erect postures. The original imbalance inevitably led to major divergence at this time. Faced with impending disaster, ancient apes went their separate ways. One group of ancient apes had long and thick forelimbs and slender hind legs, making them highly skilled at leaping in trees but poorly adapted to life on the ground. Their long and thick forelimbs and slender hind legs made it difficult to support their bodies, and with fewer trees and more dead branches, brachiation became impractical. On the ground, their slender hind legs made walking difficult, preventing them from traveling far or escaping predators. With no "feet" to walk and no "hands" to find food, they became extinct, vanishing from the stage of life. Another group of ancient apes remained in the forests, constantly migrating to escape hardship. Wherever the forests retreated, they fled. The tectonic and climatic changes were not global, affecting only certain regions, leaving some areas where primates could survive. These ancient apes, hidden in the forests for generations, became more specialized, with each generation less capable than the last. Consequently, their descendants—the modern apes—were forced to perform tricks in zoos for human entertainment. Yet another group of ancient apes was highly developed, with larger bodies, shorter forelimbs, longer hind legs, a well-developed thumb, and a semi-erect to fully erect posture. Their forelimbs and hind limbs were specialized, and their brain sizes were larger, allowing them to move on the ground, use branches and stones to obtain food, and defend against predators. In other words, this group of ancient apes had already met the internal conditions for developing into humans, making it easier for them to adapt to environmental changes. After coming down to the ground, they could survive and develop through struggles with nature, moving toward human evolution through labor. However, not all highly developed ancient apes evolved into humans. Some, once companions on the path to humanity, later took a different route, became specialized, and went extinct, becoming a side branch in the evolutionary path from apes to humans. The Gigantopithecus discovered in Guangxi and Hubei, China, may be an example. As mentioned earlier, in the 1970s, scientists widely believed that Australopithecus ramidus was the ancestor of humans. They hypothesized that the triangular region formed by the distribution area of Australopithecus ramidus—covering Yunnan, Hungary, and Kenya in China—was the area of human origin. However, most of this triangular region had already sunk to become the seabed of the Indian Ocean in the Cretaceous period, leaving only the marginal landmasses, some of which might have been the birthplace of humans. Meanwhile, with scientific progress, more and more new theories about the origin of humans emerged. Later, a scholar named Frobisher, wholy obtained an adult Asian ape, believed it to be a gibbon and studied it, only to find it was actually a langur. This meant that while studying chimpanzees, humans unexpectedly confirmed the existence of langurs. At the same time, Dutch naturalist Osmer and renowned anatomist Cuvier, upon receiving a "chimpanzee" sent to the Netherlands, published a paper on chimpanzees in 1779, explicitly stating that there was a true chimpanzee on the islands of Indonesia (then called the East Indies). However, many people still disagreed with his view. A few years later, a senior Dutch official in Indonesia, Rademacher, offered a reward of 100 ducats for locals to capture a chimpanzee standing 1.3–1.7 meters tall and accompany them into the mountains. Unable to capture a live one, they ended up killing one and handing it to a German at the Dutch East India Company, who studied it and identified it as a large Bornean orangutan. After completing his research, Frobisher's ship tragically sank, preventing the specimen from being transported to Europe. As a result, people remained skeptical of Frobisher's findings. By 1784, Huxley, while examining a complete skeletal specimen in the Orange Prince's Museum in Britain, saw that it was not the one Frobisher had lost. This specimen later arrived in France, attracting the attention of many scholars. Saint-Hilaire and Cuvier believed that this skeleton was neither a chimpanzee nor a gorilla but resembled a baboon. They published an article in 1798 expressing their views. However, by 1818, Cuvier changed his mind and agreed with another scholar, Blumenbach, that it was an adult chimpanzee. In 1824, another scholar, Rudolf, further studied the skeleton of this animal and concluded that it was at least a type of primate closely related to chimpanzees. At the same time, he clearly stated that this primate lived in Borneo and Sumatra in Asia.