Posted December 10, 2022 / Nature
The origin of life on Earth is still a mystery to scientists. According to the most common hypothesis, life on Earth appeared about 3.8 billion years ago.
The most likely cause of the emergence of life is considered to be biochemical evolution. However, scientists do not exclude the hypothesis of an extraterrestrial origin of life. The classic question "Which came first, the chicken or the egg?" shows us the complexity of the problem faced by theories of the origin of life on Earth.
Biomolecules are the basis for the emergence of life
What can be considered the beginning of life? Most modern scientists believe that the impetus for the emergence of life on Earth was given by chemical evolution, during which inorganic molecules on Earth began to turn into organic ones under the influence of water and air. At first, these were organic alcohols and acids, then the so-called “biomolecules” (amino acids, fatty acids and polysaccharides) gradually began to appear. And finally, the direct harbinger of the appearance of life on Earth was protein, which became the "building material" for all living organisms.
Bacteria were the first living organisms
The oldest living organisms we know of are cyanobacteria. These are blue-green algae that scientists believe were the first to develop the ability to photosynthesize. The first living organisms on Earth were primitive and lived in water. Scientists consider the presence of liquid water on Earth one of the most important conditions for the emergence of life.
Evolution is the way of development of life on Earth
Over time, living organisms became more and more complex, trying to adapt to earthly conditions and survive in the competitive struggle with relatives. This is how multicellular organisms appeared from bacteria and algae, then they slowly turned into fish and reptiles, came to land and eventually formed that incredibly rich animal world, of which we are a part.