It is not surprising that human beings have more than one ancient ancestor, because the creatures of the earth have evolved step by step, and at each stage, human beings have different ancestors, and today we will have a good chat about what the ancestors of human beings are in different historical stages.
<h1 class= "pgc-h-arrow-right" > the ancient ancestor of mankind's oceans</h1>
The most primitive ancestors of human beings were bacteria that lived in the oceans. About 4 billion years ago, no specific organism was the ancestor of humans, because bacteria at that time could exchange genes at will. This may sound incredible, but at that time, life was just born, there was no complete form, and the genes in the body would wander at any time, so the ocean at that time was equivalent to a large genetic porridge.
We often say that life evolves like a tree, but the very bottom of this tree is not a trunk, but an intricate root system like a mangrove forest.
The last common ancestor of all living things was luca, and although it was not the first life on Earth, it was the only creature at that time that still had offspring. Luca appeared 3.8 billion years ago.
The earliest bacteria belong to prokaryotes, that is, unformed nuclei, organisms with molded nuclei are called eukaryotes, humans belong to eukaryotes, and the earliest eukaryotes appeared 1.4 billion years ago, so 1.4 billion years ago, the ancestors of human beings were a eukaryote.
Eukaryotes continued to evolve, sponge organisms began to appear on Earth, sponge organisms appeared 650 million years ago, at this time there is a lot of life in the earth's oceans, but the land is still lifeless, and even there are no large organisms in the oceans.
About 540 million years ago, there was a major event in the history of life: the Cambrian explosion of life. In just over 20 million years, a large number of new creatures have suddenly appeared on the earth, such as arthropods, brachiopods, demodexes, sponges and chordates. The ancient ancestors of human beings are the chordates, one of the most primitive chordates is the Pika worm, and the current Wenchang fish retains some of the characteristics of the Pika worm.
375 million years ago, the Titalik fish living in the late Devonian period had evolved the characteristics of tetrapods, and at this time there was a large amount of free oxygen on the land, and these free oxygen combined to form the ozone layer, which was isolated from a large amount of ultraviolet light, allowing marine life to crawl to land and explore the future on land.
<h1 class= "pgc-h-arrow-right" > the ancient ancestor of mankind</h1>
Although the earth's creatures had moved from the ocean to the land at this time, they could not be too far from the water source, but lived in shallow water habitats in shoals or swamps, closer to amphibians than land creatures, and they had to lay their eggs in the water, and they could not be too far from the water source.
By 320 million years ago, amniotic organisms began to appear, and one of the earliest amniotic animals was the forest lizard, which had a body shape characteristic somewhat similar to today's small lizards. Instead of laying their eggs in water, they lay "eggs" similar to today's, with amniotic membranes wrapped in the moisture and nutrients needed to hatch their pups. Because of this feature, they can come to arid areas to survive.
About 310 million years ago, amniozoans evolved into two branches, one is the current reptile, the other is the homophony, and the order Pylitosaurus under the order Zygosteensis is the earliest mammal-like order.
About 125 million years ago, placenta mammals appeared, and the placenta is one of the symbols of mammals.
About 95 million years ago, a common ancestor of humans and mice began to emerge. If you have a concept of time, you will know that dinosaurs have not yet gone extinct at this time, so mammals at this time are relatively weak and often hide in ecological niches that dinosaurs cannot see. For example: trees, underground or nocturnal.
Between 85 million and 65 million years ago, humans and rats began to separate, with rats going underground and humans being primates that lived in trees, nocturnal, and insect-fed.
<h1 class= "pgc-h-arrow-right" > primates</h1>
65 million years ago, there was a major accident on Earth, and an asteroid with a diameter of 10 kilometers was affected by Earth's gravity and crashed into Earth. The huge impact triggered changes in the Earth's environment, and the Earth's temperature dropped, leading to the extinction of the then Earth overlord Dinosaurs.
The extinction of the dinosaurs gave mammals a chance, and the primates of humanity's ancient ancestors also developed and grew at this time.
By 40 million years ago, primates began to appear two suborders: proto-monkey suborder and suborder Psyllodontis, and humans belong to the suborder Homogeneous Suborder, which lost the ability to synthesize vitamin C in evolution, so organisms under the suborder Homogeneous Must Obtain Vitamin C from food, which is why we humans need to eat fruits.
30 million years ago, the suborder Homonidae evolved two more branches: the broad-nosed suborder and the narrow-nosed suborder, and the narrow-nosed suborder later diverged into two branches: the monkey family and the ape family, and there is no doubt that humans are the descendants of the family Homopodidae.
<h1 class= "pgc-h-arrow-right" > the emergence of humans</h1>
The earliest living creatures to walk upright were the earth apes, which lived 4.4 million years ago, and due to the changing environment in Africa at that time, the forests were constantly decreasing, and the apes that originally lived in trees had to live on the ground.
3.5 million years ago, Australopithecus appeared, and what we often call "All Human Grandmother Lucy" belongs to the Australopithecus Alpha species. By studying Lucy's body structure, we can see that they have been able to habitually walk upright, but the pelvic bone size is between humans and chimpanzees, and the brain capacity is close to that between humans and chimpanzees, which is one of the species in the transition from ape to human.
Paleoanthropologists have defined the dividing line between humans and apes as a brain volume of more than 750 milliliters (some say 600 milliliters), and the earliest human race to meet this condition is the Noh. Although the brain capacity of the capable person exceeds 750 ml, the capable person does not use tools and fire, until the emergence of craftsmen, humans learn to use fire and simple tools.
About 1.9 million years ago, Homo erectus first appeared in Africa, and then they took advantage of environmental changes and moved out of Africa. These people who came out of Africa evolved into Homo erectus races around the world, including the Peking Ape Man. But at this time, human ancestors were still evolving in Africa.
Ancient Homo sapiens began to appear 200,000 years ago, but 65,000 years ago, Homo sapiens began to leave Africa. In the process of Homo sapiens out of Africa, many large animals were extinct, and some other races also lost in the competition of Homo sapiens and gradually went extinct, such as Neanderthals, Flores and so on.
12,000 years ago, with the death of the last Flores, Homo sapiens became the only surviving race in the world, and today we all belong to Homo sapiens.
From the history of human evolution, it can be seen that the emergence of human beings is the result of the continuous evolution of earthly organisms, so it is not surprising that apes, fish, insects, bacteria, etc. are the ancestors of human beings. But it should also be emphasized that the above ancient ancestors of these human beings are based on the information obtained from existing fossils, and if one day we can dig up more and more informative fossils, perhaps the above inferences will be overturned, which is not unusual in the history of science.