Human evolution is a theory that indicates that the evolutionary process began with the first life forms until reaching the current stage of human development, homo sapiens sapiens.
Biology estimates that life on Earth arose 3.8 billion years ago in the form of unicellular organisms called prokaryotes. Millions of years later, with the changes related to oxygen and the evolution of photosynthesis, the first eukaryotes (with complex cells containing organelles) appeared.
The mutations continued over time and about 530 million years ago, the first fish appeared, which then gave rise to amphibians (340 million years ago), reptiles (310 million years ago) and eventually mammals 100 million years ago). Finally, the earliest primitive mammals on Earth gave birth to hominids.
It is important to clarify that the meaning of “hominid” has been revised several times over time. For this reason, it is still very common that the term is used to refer exclusively to humans (genus homo), although it also includes chimpanzees, gorillas and orangutans.
These four species, also known as Great Primates, had a common ancestor 14 million years ago and, over time, subdivided into different species as physical attributes diverged with new mutations. Eventually, the primates gave birth to the first forms of human life, about 3.5 million years ago.
Stages of Human Evolution
In the study of human evolution, it is important to look at the fact that the appearance of a new species does not imply the immediate extinction of another species. The timeline above shows that less evolved species cohabited with their successors for thousands of years until their eventual extinction.
Science believed that this species was, in fact, an ancestor close to humans. This classification came to be questioned after the discovery of older Australopithecus fossils with characteristics very similar to the members of the homo genus. Nowadays, although there is no consensus, similarities with humans keep the Australopithecus species closely related to the onset of human life on Earth.
The australopithecines were bipedal beings of short stature (not exceeding 1.4 meters) and had their bodies covered with hairs. The species lived in tropical areas of Africa feeding on fruits and leaves, and was the first to use the opposing thumb to hold and handle instruments.
The term australopithecus comes from the Latin “australis”, which means southern and from the Greek “pithekos”, which means primate.
From the Latin “skilful man”, the species lived on Earth about 2.4 and 1.6 million years ago. In physical terms, it is the member of the homo genus that is most different from humans today. The homo habilis were named after being the first hominids to use their hands to make rudimentary instruments made of stone. Their brains were 50% larger than those of the australopithecines and had a mean height of 1.3 meters.
With their hands for the handling of instruments, homo habilis learned to balance on both legs and, over time, gave birth to homo erectus. It is estimated that the species has lived between 2 million years and 400,000 years ago.
The homo erectus were the first to control the fire. In addition to contributing to survival in the nightlife, the discovery has brought drastic changes in the species’ diet and habits, making it possible to migrate to colder places. For this reason, the homo erectus were the first to leave Africa and spread around the world, about 1.8 million years ago.
Better known as Neanderthal Man, he is considered the closest ancestor of the modern human. They lived in Europe and Asia between 2.5 million and 12 thousand years ago. Although smaller in stature than the present humans, the Neanderthals had a much stronger physical constitution, which, together with the domain of weapons and fire, made them great hunters.
As they lived in colder regions, the Neanderthals learned to make clothes to keep warm. Moreover, it is believed that the cold has a direct link to the sense of socialization developed by the Neanderthals, who spent a lot of time gathering around campfires or in caves.
Neanderthals are considered the most carnivorous members of the homofamily. This feature was decisive, since when climatic changes eliminate most of the animals hunted by them, the Neanderthals failed to feed and eventually extinct.
From the Latin “wise man”, he is the member of the homo family with the most developed brain. It is estimated that the first homo sapiens arose about 300 thousand years ago.
With the capacity for accurate reasoning, homo sapiens were able to interpret the environment around them, solve problems and thus continue in the process of adaptation to the present day. Science classifies the modern human being as homo sapiens sapiens, which means “man who knows that he knows”. This means that the present human being has developed awareness of their knowledge and learned to use them in the search for new ones.
Theories of Human Evolution
In opposition to Creationism, a theory that explains human origin through a divine entity, evolutionary theory draws heavily on the studies developed by Chales Darwin.
Darwinism, as evolutionary theory is also known, believes that the human being, like other species, has evolved gradually over time as they undergo minor changes as a way of adapting to the environment.