If there are countless unsolved mysteries in the vast universe, then the origin of humanity is the greatest and most perplexing enigma.
The legend of Adam and Eve creating humanity has long been regarded as an ancient story. In today's high-tech society, people rely on scientific methods to validate any hypothesis or reasoning. No one denies that Charles Darwin, the British naturalist born in the 19th century, was a groundbreaking figure. His monumental works, "On the Origin of Species" and "The Descent of Man," introduced the idea that humans evolved from lower forms of life, fundamentally altering traditional thinking. He further suggested that traits such as human intelligence, societal morals, and emotional foundations can also be traced back to lower animals, laying the groundwork for the scientific study of humanity. This was an unprecedented breakthrough in the conscious historical development of humankind.
After the birth of Marxism, Engels applied dialectical materialism and historical materialism to comprehensively analyze the process from ape to human, establishing the theory of "labor creates man," which fundamentally shattered the religious myth of divine creation. In the transformation from ape to human, labor played a decisive role. Whether through the division of labor, tool-making, the emergence of language, or the development of the brain and thought, all these phenomena arose from labor. Thus, Engels stated that labor is "the first fundamental condition of all human society... in a certain sense, one must say that labor created man himself."
1. Did humans evolve from monkeys?
Darwin and Engels' explanations liberated people from the constraints of religious ideology, prompting over a century of exploration into the mysteries of human origins within the realm of science.
Among the most accepted hypotheses regarding human origins are the following:
First, humans evolved from primates. In 1960, British anthropologist Sir Alister Hardy proposed a new hypothesis suggesting that the human ancestors from the fossil gap (a period 4 to 8 million years ago with almost no fossil records) did not live on land but in the sea. He posited that there existed a marine ape phase in human evolution lasting millions of years, leaving many anatomical and physiological traces in humans that are absent in other terrestrial primates but present in marine mammals like seals and dolphins. For instance, all primates have dense fur, except for humans, who, like aquatic mammals, have exposed skin. Primates lack subcutaneous fat, while humans possess thick subcutaneous fat. The fetal hair of human embryos is distinctly different from that of other primates and is closer to that of marine mammals. The physiological phenomenon of tear glands secreting tears to expel salt is also unique to humans among primates. Hardy pointed out that geological history indicates that 4 to 8 million years ago, large areas of East and North Africa were submerged by seawater, isolating ancient ape populations and forcing some to adapt to aquatic life, evolving into marine apes. Millions of years later, as the seas receded, these marine apes, now adapted to aquatic life, returned to land, becoming the ancestors of modern humans. These marine apes, having evolved skills like bipedalism and breath control during their time in the water, laid the foundation for significant evolutionary steps such as upright walking and the development of language.
Second, humans evolved from marine organisms. By comparing the physiological characteristics of different animals, scientists can discern their evolutionary relationships. Professor A.P. Danton from the University of Melbourne concluded through research that humans are more similar to marine mammals.
Experts have also noted that humans possess exceptional diving physiology. In ancient ape habitats, archaeological sites of famous prehistoric shell middens have been discovered, indicating that early humans had to master breath-holding diving techniques to collect these shellfish. Clearly, these early humans had remarkable diving abilities, unique among primates. Humans are natural divers, able to hold their breath underwater for much longer than other terrestrial animals. When diving, humans exhibit a diving reflex: muscle contraction, reduced blood flow to the arteries, breath cessation, and slowed heart rate. This reflex is strikingly similar to that of marine mammals like seals and diving ducks. The diving reflex is not a conditioned response but is controlled by higher brain centers, which also consciously regulate breathing. This precise control of breath is fundamental to the development of language; without the breath control developed during the marine ape phase, humans could not have evolved such complex vocalizations.
Third, humans may have extraterrestrial origins. In recent years, a series of discoveries have rekindled interest in the theory of life originating from beyond Earth. Observations reveal that despite the vast diversity of life on Earth, it shares a common pattern with similar cellular structures and genetic material composed of the same nucleic acids and proteins. This raises questions: if life truly evolved from inorganic matter on Earth, why aren't there multiple life forms? Additionally, the rare element molybdenum plays a crucial role in biological processes, yet its abundance in Earth's crust is only 0.002%, prompting speculation about whether life on Earth originated from molybdenum-rich celestial bodies. Furthermore, organic compounds originating from interstellar space have been found in meteorites, including all the essential elements for life on Earth. Organic molecular clouds have also been detected in various regions of the universe, leading many to believe that life is not solely confined to Earth. Some have even noted that certain infectious diseases, such as influenza, exhibit periodic global outbreaks that coincide with the return cycles of certain comets, raising the possibility that some pathogens may have extraterrestrial origins. If so, could humans be extraterrestrial visitors?
The origin of humanity is a topic of longstanding fascination, ranking alongside the origins of the universe and Earth as one of the three great mysteries of origin.
So, are humans derived from primates, marine organisms, or extraterrestrial origins? To this day, no scientist has been able to definitively confirm or deny any of these theories, leaving this question as one of humanity's greatest challenges.
2. How old is humanity?
Mao Zedong mentioned in his essay "On the Chongqing Negotiations" that humanity has existed for 500,000 years. Chinese historians, based on archaeological findings of "Peking Man," also estimate that humans have existed for 500,000 years. Foreign historians, using fossils of "Java Man" and "East African Man" from Tanzania, suggest that humanity has been around for 3 to 5 million years. So how old is humanity?
Since 1973, a large number of human fossils have been unearthed from layers dating back 3.3 to 2.9 million years in the Hadar region of Ethiopia. Scholars believe that some of these fossils can be considered as "hominid ancestors." The famous "Lucy" fossil, dating back approximately 3.5 million years, was also discovered in this region. In 1974, 13 pieces of human or hominid fossils were found about 40 kilometers from the Olduvai Gorge, one of which was identified as belonging to the genus Homo and dated to be between 3.35 and 3.75 million years old. In 1965, B. Patterson discovered a humerus fossil in Kenya's Turkana Lake area, dated to be over 4 million years old and resembling modern human humeri. From 1932 to 1967, international scientific expeditions discovered human fossils at 70 sites in Ethiopia's Omo Valley, with the oldest dating back to 4 million years. In 1982, scholars from the University of California found a remarkably complete "primitive human fossil" ("Lucy") in the Awash Valley of Ethiopia, also dated to be over 4 million years old. In 1984, experts from Kenya and the United States discovered a jawbone fossil of an ancient human dating back 5 million years. Harvard University anthropologist D. Pilbeam, who participated in the excavation, stated that previous findings indicated the presence of humans in East Africa 3 to 4 million years ago, and this jawbone pushed the timeline of human existence back by another million years.
Despite the lack of stone tools associated with these fossils and ongoing debates, the overall evidence suggests that these fossils belong to the genus Homo. If we follow the "pre-tool theory," they may represent a transition from tool-making to humanity. Therefore, humanity's age is not merely 2 to 3 million years but at least 3 million years or even longer.
In summary, while there are assertions of humanity being 500,000 years, 1 million years, 2 to 3 million years, 3 million years, and 4 million years old (according to the pre-tool theory), none of these claims can be definitively concluded. The evidence for 3 million years and 4 million years is still insufficient, and even the validity of the "pre-tool theory" remains debated. Currently, the consensus leans towards the idea that humanity is over 3 million years old, or even longer. However, how much longer remains uncertain.
3. What were the ancestors of humans?
The origin of humanity is a perplexing question, and the location of that origin is equally uncertain for contemporary scientists.
The hypotheses regarding human origins are primarily based on discovered human fossils. Most ancient human fossils have been found in Asia and Africa. In the late 19th century, fossils of Homo erectus were discovered in Indonesia, and in the 1920s, fossils of Peking Man were found in Zhoukoudian, Beijing. These two significant discoveries pushed the timeline of human existence back to 1 million years, leading many to believe that humanity originated in Asia, making Asians the ancestral lineage of modern humans. However, in the 1960s, scientists began to shift their perspective based on new archaeological findings of "East African Man," suggesting that Africa is the birthplace of humanity, with Africans being the most likely ancestors of modern humans.
In the Olduvai Gorge region of Tanzania, numerous stone tools have been found alongside ancient animal fossils. As early as 1911, German biologist Karl Weidenreich discovered animal fossils while collecting insect specimens in the area, drawing attention to its significance. In 1931, British anthropologist Louis Leakey and his wife chose Olduvai Gorge as their excavation site to search for early human fossils. This gorge, part of the East African Rift, stretches over 20 kilometers and is over 900 meters deep, displaying clear geological layers dating from over 2 million years to 500,000 years ago. It was once a lake, and over the ages, thick layers of sediment accumulated, providing excellent conditions for the preservation of human fossils. Indeed, the Leakeys were successful in their efforts. In the first two years, they found some extinct animal fossils and crude stone tools from the Old Stone Age, but they had not yet discovered any associated human remains. It wasn't until July 17, 1959, after 30 days of arduous work, that they made a breakthrough by discovering a prehistoric human skull, named "East African Man." This discovery sent shockwaves around the world. Subsequently, a series of new discoveries followed. In 1963, Louis Leakey's son, Jonathan Leakey, discovered another human fossil in the same layer, dating back 1.85 million years, named "Homo habilis." In the early 1970s, Louis Leakey asserted in his works "The Origins of Man" and "Lake Dwellers" that "Homo habilis" directly evolved into "Homo erectus," becoming the direct ancestor of modern humans. Other anthropologists later discovered additional "Homo habilis" fossils and footprints, dating back significantly earlier than Leakey's findings. Notably, in 1975, anthropologist Mary Leakey and her team discovered footprints of "Homo habilis" in Laetoli, Tanzania, which she reported in National Geographic, dating back 2.6 million years. Furthermore, a wealth of fossils belonging to "Homo erectus" has also been discovered in East Africa. In 1965, Dr. Leakey found fossils of "Homo erectus" in the second layer of the Olduvai deposits, naming them "Leakey Man." In 1969, a femur of "Homo erectus" was unearthed in Tanzania. In 1976, a nearly complete skull of "Homo erectus" was found near Lake Turkana in Kenya, dated to be 1.5 million years old. Scholars unanimously agree that "Homo erectus" is the direct ancestor of modern humans.
As early as the late 19th century, Darwin proposed that humanity originated in Africa. In his famous work "The Descent of Man and Selection in Relation to Sex," he stated, "In all parts of the world, existing mammalian species and their extinct counterparts are closely related. Therefore, the ape species closely related to gorillas and chimpanzees likely inhabited Africa in the past. Given that these two species have the closest genetic relationship to humans, it seems increasingly probable that the early ancestors of humans lived on the African continent rather than elsewhere." When Darwin proposed this theory, human fossils were scarce, and related sciences were not well developed, so it remained a hypothesis. Darwin's theory was temporarily challenged by the discoveries of "Peking Man" and "Java Man," but with the subsequent discoveries of East African human fossils, most anthropologists have come to affirm Darwin's hypothesis. Their reasoning is based on three points: first, only in Africa have fossils representing all stages of human evolution been discovered, from ancient apes to Australopithecus, Homo habilis, Homo erectus, Homo sapiens, and modern humans. The earliest known fully formed human fossils have also been found on the African continent; second, Africa's vast and diverse geography, with its tropical rainforests, expansive grasslands, towering mountains, deep rifts, and numerous lakes, provides crucial external conditions for the evolution of apes; third, molecular biology research indicates that African gorillas and chimpanzees share the closest genetic relationship with humans, providing strong scientific support for Darwin's hypothesis. The mystery of humanity's origins is gradually being unraveled.
4. Why are there four skin colors?
Based on existing archaeological data, scientists can only infer that Africa is the earliest cradle of humanity. But why do modern humans exhibit different skin colors? Scientists have embarked on endless research to explore the differences in skin color among modern humans.
Dr. Brown from the United States extracted mitochondrial genes from cells of 13 white individuals, 4 Chinese individuals, and 4 black individuals. He was astonished to find that the genotypes of different racial groups were remarkably similar. His groundbreaking discovery suggests that the differences in human skin color are merely superficial variations that developed over a long evolutionary process; in short, while there are different skin colors, the genetic makeup of humanity is closely related, indicating a common ancestry.
Scientists increasingly believe that yellow-skinned people are the ancestors of both white and black people. American researchers used baboon virus genes as a standard and found that modern humans' genes closely resemble those of Asian monkeys, suggesting that modern humans originated in Asia.
Throughout their development, humans have faced countless hardships and challenges. Environmental changes, predatory threats, and conflicts with one another have led to the extinction and rebirth of human races, resulting in the current distribution of races: predominantly yellow-skinned in Asia, white-skinned in Europe and America, and black-skinned in Africa. However, regardless of skin color, the common ancestry of modern humans is hypothesized to be yellow-skinned. The discovery of a 200,000-year-old early Homo sapiens skull in Dali County, Shaanxi, has led many scientists to believe that both black and white people evolved from the Peking Man, leading to the modern human lineage.
Dr. Brown has confidently stated that "the Dali people of Asia are not only yellow-skinned but also the common ancestors of both white and black people."
Although we can accept that yellow-skinned people are the ancestors of white and black people, the question remains: how did yellow-skinned individuals evolve into different skin colors, and when did these variations occur? This remains a mystery.
