In exploring the evolutionary history of humans, scientists generally agree that humans and chimpanzees share a common ancestor.
This view, based on fossil records, genetic data, and other biological evidence, reveals that humans and chimpanzees branched off from a common primate ancestor and embarked on separate evolutionary paths about 6 million to 8 million years ago.
Over time, changes in the environment have led to adaptive differentiation of biological populations. The different existential challenges and opportunities faced by humans and chimpanzees have led to significant differences in anatomy, physiological functions, and even behavioral habits. These differences gradually accumulated, eventually leading to the formation of two species. And this process is at the heart of what evolution describes as biodiversity and adaptation.
It is important to note that evolution does not presuppose a specific goal or direction. It is not a purposeful process, but the result of constant adaptation of living beings through natural selection in a changing environment. Therefore, the divergence between humans and chimpanzees is not a predetermined outcome, but a product of historical contingency.
Changes in the environment have had a profound impact on the evolution of organisms. In the history of the Earth, major changes in climate, geography and ecological conditions, such as the alternation of glacial and interglacial periods, continental drift, sea level rise and fall, etc., have greatly affected the living environment of biological populations. These changes have forced organisms to adapt to sustain populations and thrive.
Adaptive changes in organisms are usually achieved through genetic variation and natural selection. In the long course of evolution, genes that give organisms an advantage in their new environment will be more likely to be preserved and passed on. For example, during the transition from forest to grassland environment, the genetic variation of walking upright provided the advantage of moving and foraging in the open environment, and thus gradually became the mainstream of the population.
However, adaptive change does not always immediately manifest a clear survival advantage. Many times, genetic variation in an organism is neutral, and they neither increase nor decrease the adaptability of the organism. Changes in these neutrophil genes, accumulating over time, may also be an important factor in promoting the differentiation of biological populations and the formation of new species.
Walking upright is considered a major shift in human evolutionary history.
Scientists generally believe that our ancestors in Africa, about 5 million years ago, began to come down from trees and walk upright on the ground due to changes in the environment. This shift in behavior not only freed up the hands and created the conditions for the use of tools and complex social activities, but also had a profound impact on human anatomy.
As the genetic mutation for upright walking spreads in the population, structures such as the pelvis, spine, knees, and ankles of humans have gradually adapted to the new way of walking. For example, the hip bone narrows to accommodate changes in the center of gravity when standing upright, and the toes degenerate to increase the support of the arch of the foot. These anatomical changes allowed humans to move and hunt on land more efficiently, increasing survival rates.
However, walking upright is not an overnight process, but a gradual evolutionary process. In the process, many other related biological changes also occurred, such as an increase in the size of the brain and changes in the structure of the throat, which together laid the foundation for human evolution.
The randomness of the evolutionary process is a key concept in modern evolutionary theory. Genetic variations in populations of organisms usually occur randomly, and these variations do not predetermine the direction of future evolution of organisms. For example, the emergence of the upright walking gene may have initially been a random attempt to adapt to the environment for human ancestors. The retention and diffusion of such variations is achieved through the non-random process of natural selection, which depends on whether these variations give organisms an advantage in a given environment.
However, randomness does not mean that biological evolution is not inevitable. Under certain environmental conditions, certain more adaptable biological traits will appear more commonly in the population. For example, in a grassland environment, the ability to walk upright may be more advantageous than climbing on a tree, contributing to an increase in the frequency of the gene in the population. This inevitability of adaptation to the environment is achieved through a cycle of countless random variations and natural selection.
Therefore, even if time is turned back, the evolutionary path of humanity cannot be completely repeated. The future of living things is affected by too many unpredictable random factors, but the inevitability of adapting to the environment will lead evolution in a more conducive direction for survival.
Modern theory of evolution is a scientific theory based on Darwin's theory of evolution and formed after more than a century of supplementation, revision and improvement. It integrates the achievements of genetics, ecology, molecular biology and other disciplines to provide a more comprehensive and in-depth explanation of the origin, evolution and diversity of organisms. Especially on key issues such as genetic variation, natural selection, and speciation, modern evolutionary theory provides more abundant and precise evidence.
The credibility of a scientific theory is often closely related to the evidence on which it is based. The modern theory of evolution is widely accepted because of its ability to verify its main arguments through experiments and observations. For example, the fossil record provides direct evidence of the gradual evolution of organisms, while genetic data reveals a detailed map of the genetic relationships between organisms. Together, this evidence makes a strong case for the scientific validity of evolution.