At the dawn of human civilization, the search for its origins began. In the era when scientific knowledge was not yet widespread, people often resorted to religious myths for the question of how did the first man come about.
The Western world believes that human beings were created by God according to the Bible, while Eastern cultures, such as Chinese myths and legends, have stories of Pangu opening the world and Nuwa creating man from the earth. These religious interpretations cast a veil of mystery over human origins, but over time they gradually failed to satisfy the thirst for knowledge.
However, the light of science gradually dispelled the fog of myth. The theory of evolution provides a new, empirically based explanation for the origin of human beings. Through in-depth study of the fossil record, scientists have gradually sketched a picture of the evolution from Australopithecus to modern humans. Although this scientific explanation does not have a mythical and shocking storyline, it opens the door for humanity to understand its own history and leads us to deeper truths.
According to the fossil record and scientific research, the distant ancestors of humans can be traced back to mammals about 65 million years ago. At that time, dinosaurs ruled the earth, and mammals did not have much room to develop. However, when the dinosaurs became extinct, a large number of ecological niches were vacated, and mammals began to multiply and differentiate rapidly, including the primates, the ancient ancestors of humans.
These primates originally lived in forests and fed on fruits and leaves. But over time, Africa's climate and landforms have changed dramatically. The forests gradually receded, replaced by vast grasslands. Primates had to adapt to their new living environment, living from the trees to the ground. In such an environment, walking upright becomes an advantage.
Scientists have proposed several reasons for humans to walk upright: the energy-saving hypothesis suggests that walking upright saves energy; The lookout hypothesis suggests that walking upright helps to observe the surrounding environment and warn of danger; The child-holding hypothesis suggests that walking upright frees up hands and makes it easier to care for the young. Either hypothesis, it is shown that walking upright is the result of human adaptation to changes in the environment.
However, walking upright does not come without a price. In the early days, walking upright was not very fast, making humans easy targets for predators. As a result, some of the apes that walked upright returned to the trees. The apes, on the other hand, continued to evolve and gradually developed the habit of eating meat. Humans at this time, although their teeth and claws were not sharp, had begun to consume meat, mainly carrion left by other animals. The high protein content of meat provides more energy for human beings and promotes the further evolution of human beings.
The development of the brain was a key turning point in the history of human evolution. When Australopithecus began to consume meat, especially protein-rich bone marrow, their energy gain increased dramatically. At the same time, because meat is easier to digest, the human intestine is gradually shortened, and the energy saved is used for the development of other organs, especially the brain.
The brain is extremely energy-intensive, making up 2% of the body's weight but using 20% of its energy, but in the course of evolution, the capacity of the human brain has continued to grow, which sets humans apart from other primates.
The increase in brain capacity has led to a leap in cognitive ability. Paleoanthropologists have set a brain volume of more than 650 milliliters as the criterion for the dividing line between humans and apes, and Homo sapiens was the first human species to meet this criterion. Although the increase in brain volume does not directly equate to an increase in intelligence, it provides the necessary physical basis for the development of intelligence. As the brain continued to evolve, humans began to exhibit more complex social behaviors and cultural abilities, which eventually led to the birth of the modern human race.
Human reproduction and population growth are achieved through sexual reproduction. Sexual reproduction not only ensures the transmission of genes, but more importantly, it increases the diversity of genes through the combination of genes from the father and the mother. This diversity is essential for species to adapt to changing environments. In the course of human evolution, sexual reproduction allows offspring to inherit the genetic traits of both parents, thereby improving the adaptability and survival of the population as a whole.
Although it is impossible to accurately determine the identities of the first two people who appeared on Earth, we can be sure that the mechanism of sexual reproduction existed in early human history and provided a solid foundation for later human evolution and reproduction. It is this mode of reproduction that has contributed to the growth and distribution of human populations, which have led to the diverse human societies we have today.
The origin and reproduction of human beings is a complex and long process, and our understanding of our own history has changed dramatically, from creationist myths to scientific evolutionary explanations. Environmental changes prompted Australopithecus to live in the ground, walk upright and eat meat as key evolutionary steps. As the brain continues to evolve, humans are finally distinguished from other primates and embark on a unique evolutionary journey. The mechanism of sexual reproduction provides genetic diversity for our reproduction and promotes the flourishing of human populations. This journey not only reveals the biological origins of humanity, but also lays the foundation for our understanding of the development of human culture and society.