Humanity is believed to have descended from primates 50 million years ago. Humans inherited life from primates. Biologically, humans are considered to be members of the primate order, a species of ape. The ancestors of modern humans first appeared on Earth approximately 200,000 years ago. Our ancestors, who lived in the trees of forests, originated in Africa approximately 200,000 years ago and left Africa approximately 60,000 years ago. Living in the trees ensured safety. 50,000-70,000 years ago, humans (Homo sapiens) left Africa and spread throughout the world. As humans spread, their regions were unique to their environments. In areas with strong ultraviolet rays, they developed an increased ability to produce melanin pigment to protect their skin. In Europe and the United States, where ultraviolet rays were weaker, they lost this ability, becoming what is known as the Caucasian race. From an epidemiological perspective, humans have adapted to their environments by devising ways to block bacterial and viral infection routes, weaken the toxicity of bacteria, and increase the host’s resistance (immunity).
When examining human DNA, we arrive at fish. Approximately 500 million years ago, animals, primarily fish, underwent explosive evolution in the oceans, resulting in the emergence of a wide variety of creatures. Amphibians moved into the water 400 million years ago. Amphibians began living on land and remained at the top of the ecosystem for a while. Amphibians must live in freshwater, so their success did not last long. Reptiles were the next to flourish after amphibians. Unlike amphibians, reptiles moved from the water to the land. Approximately 300 million years ago, reptiles evolved their bodies to withstand ultraviolet rays and high oxygen concentrations, and moved onto land. Once the constraints of water were removed, it was easy to expand their living territory, and they pioneered new territories on a global scale. As reptiles made their way to new territories, they rapidly evolved, acquiring limbs suited to walking. This marked the dawn of the so-called Age of Dinosaurs. Our mammalian ancestors also appeared approximately 200 million years ago. However, they were targeted by dinosaurs. Humans appear to possess DNA that allowed them to adapt to environmental changes.
Human prosperity may be a consequence of humanity leaving Africa, which was once a safe haven. It has been 50,000 to 70,000 years since humans left. The number of humans who left Africa was relatively small, estimated at around 5,000. This group developed the use of stone tools and fire, as well as abilities such as curiosity and imagination. The people who left Africa brought significant diversity to regions outside of Africa. Cro-Magnons (Homo sapiens), a species of human that arrived in Europe 40,000 years ago, encountered Neanderthals, and the two species shared habitats for several thousand years. Recent genome research has estimated that a few percent of human DNA comes from Neanderthals. Modern humans, Homo sapiens, are the only surviving species, and their origins are shrouded in mystery.
A discovery that brings us closer to this mystery has been made by the Max Planck Institute for Evolutionary Anthropology in Germany. It involves the discovery of a fossil of the common ancestor of modern humans and archaic humans. The fossil dates back 773,000 years. A distinctive feature of this fossil is the rounded tip of the jaw, similar to that of the early human Homo erectus. The tendency for wisdom teeth to shrink and degenerate is traced back to Neanderthals, who were distributed in Europe and other areas. This tendency for degeneration is similar to the characteristics of archaic humans, Denisovans and Homo sapiens, who spread into Asia. As humans become more modern, wisdom teeth tend to shrink and degenerate. As this degeneration occurred, Neanderthals, who represented Eurasian people, became extinct tens of thousands of years ago. Meanwhile, we, Homo sapiens, survived. The emergence of fossils that allow us to trace our human ancestors back and understand why we became extinct may be a test of our human potential.
