It all starts with amino acids. Amino acids can synthesize proteins, and proteins can make up the simplest of life, ieNon-cellular organisms(Viruses, for example, are such life structures).
In 1965, Chinese scientists achieved the first artificial synthesis of bovine insulin, which was the world's first total synthesis of protein. Know that protein is an important part of life. This great experiment revealedUnder certain conditions, amino acids can be used to synthesize proteins. In 1953, Miller's flask experiment revealed that in the primordial ocean, inorganic matter could be transformed into various amino acids, which are the raw materials of proteins
In other words, the formation of life needs to go through: inorganic matter - amino acids - proteins - non-cellular organisms
Can the primitive earth turn inorganic matter into organic matter?
1.Life is born out of lightning and thunder.
Let's turn the clock back to 4.6 billion years ago, when the Earth was just born. The newborn earth was silent, there was no sign of life at all, the land was more desert than the desert, and the ocean was more apocalyptic than the end of the world.
Many inorganic substances (primitive atmosphere, water, etc.) are constantly tumbling in the ocean, and with the blessing of lightning and thunder, the whole earth is equivalent to a super-large laboratory, and every minute and every second is carrying out "experiments" in billions of dollars, and the content of the experiment is how to synthesize inorganic matter into organic matter.
Finally, after hundreds of millions of years of efforts, by chance, a large number of organic matter (including amino acids) was born on the earth.
A large amount of organic matter comes together and, by chance, forms proteins. In the process of long-term symbiosis, a large number of proteins collide with virus-like non-cellular organisms. This non-cellular creature is amazing, it can live for two lifetimes without breaking and changing. It seems that our ancestors did not lie to us, and it was indeed "Tao begets one, one begets two, two begets three, and three begets all things".
The birth of non-cellular organisms marked the birth of life on Earth。But this life form is very rough, it doesn't even have a cell membrane, it needs to exist in places rich in nutrients such as amino acids, and sometimes even its own genes will be washed away, or die out or become someone else's genes.
So, it is still necessary to wait for the emergence of cellular organisms.
2.Huddles produce cells.
The genetic vector of non-cellular organisms is RNA, and reproduction is essentially RNA turning one into two. RNA is a single gene** that records genetic information, and is not as stable as the double helix structure of DNA, and is prone to deletion or misalignment when one is fissioned into two. This is also the reason why the new coronavirus, which is also a non-cellular organism, mutates so easily. When deletions or dislocations accumulate to a certain extent, new non-cellular organisms are created
As non-cellular organisms become more and more diverse, "everyone" finds that it is not much fun to always play life two, and it is better to live together. In the beginning, it may be a simple cooperation, working together to get more nutrients. With the deepening of cooperation, different non-cellular organisms form a whole, and everyone has different division of labor. For example, the mitochondria that provide power, the various enzymes that provide digestion, and the cell membranes that provide protection are all likely to be integrated in the process of long-term internal symbiosis.
From inorganic matter to organic matter to non-cellular organisms to prokaryotic cells (without a nucleus), the Earth took 1.2 billion years. Earth's first sophisticated life was finally born (3.4 billion years ago)!
One billion years ago, the first eukaryotic cells finally appeared on Earth, that is, eukaryotes. Eukaryotic cells are an upgraded version of the prokaryotic cell, with the nucleus as the general command, more complex enzymes and more organelles. Although the eukaryotic cell is small, it is already an extremely complex living organism. Complex to the point of being more complex than an aircraft carrier, human technology has not yet been able to create a eukaryotic cell.
With the flourishing of eukaryotic cells, the rate of biological evolution began to accelerate. Similar to the formation of prokaryotic cells, as eukaryotes become more and more involved, some "smart" eukaryotic cells begin to huddle together to absorb nutrients and hunt together, slowly forming various algae.
At this point, the Earth began to appearMulticellular organisms, life visible to the naked eye, are beginning to emerge. The abundance of algae began to change the Earth's environment on a large scale, especially the Earth's oxygen levels.
3.Animals are starting to appear
With the improvement of the marine ecological environment, in the successive genetic variations,In the past5.4.2 billion years ago, there was a biological explosion, and animals began to appear on the earth. In just a few million years, a wide variety of arthropods have been born in the oceans, and trilobites are the most prominent representative. These arthropods are so small that they are difficult to detect with the naked eye and as large as several meters long, and the ocean suddenly comes alive.
With the continuous mutation of marine arthropods and mass extinctions of species again and again, they make room for survival400 million years ago, the first fish on the earth, the Wenchang fish, was finally born。The ocean is about to become a world of fish.