Scientists believe competing theories about the origins of the building blocks of life on Earth may fit together.
Of all the questions that science tries to answer, one of the most important is how life began on Earth. Now there are three main theories that explain this, and based on these theories, scientists believe that they are closer to solving one of the main mysteries of our planet, writes the Daily Mail.
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Three main theories of the origin of life on Earth:
- The first theory is called the primordial soup theory and proposes that the chemical building blocks of life formed in shallow bodies of water on the early Earth from basic gases and metals;
- The second theory, called the panspermia theory, suggests that meteorites brought living microbes to Earth, which spread across the planet;
- The third theory is called the pseudopanspermia theory and suggests that meteorites or comets brought the basic building blocks of life to Earth, rather than living things themselves. These molecules settled in the early seas and gave rise to single-celled organisms.
Experts in the field of astrobiology and chemistry believe that the most likely explanation for the emergence of life on Earth is a combination of the first and third theories.
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According to Graham Cooks of Purdue University, USA, the molecules of life on Earth include proteins and nucleic acids (RNA and DNA). Regardless of whether these molecules were created on Earth or somewhere else, the chemical reactions that lead to their formation will be the same.
Cooks believes that the building blocks of life may have arisen from a combination of the pseudopanspermia theory and the primordial soup theory. Meteorites carrying the building blocks of life crashed into deposited amino acids and other molecules in ancient bodies of water on Earth and thus began to form the basis for life on the planet as proteins. At least this is what laboratory experiments indicate. But whether this was actually the case is not completely certain.
At the same time, Yasuhiro Oba from Hokkaido University, Japan, considers the pseudopanspermia theory more likely, although he acknowledges its shortcomings. Creating amino acids in laboratory conditions that mimic early Earth is one thing, Oba said. But it is quite another thing to give rise to real living beings. Another problem is that scientists don’t know exactly what the actual environment on early Earth was like.
Oba and his colleagues discovered that basic organic molecules can form in space. These molecules, called nucleosomes, combine with phosphates and sugars to form the nucleotides that make up DNA, so they are far from real living things. However, they are necessary for life.
According to Oba, the processes that were created in the laboratory can lead to the formation of molecular precursors to life and this improves understanding of the early stages of chemical evolution in space.
Scientists have also discovered that amino acids can be formed in space, but it is difficult to say for sure that the pseudopanspermia theory better explains the emergence of life on Earth than the primordial soup theory. However, Oba does not exclude the possibility of a combination of these theories.
As for the theory of panspermia, it is much simpler than the other two theories and with its help it is easiest to explain the emergence of life on Earth. According to Japanese atrobiologist Yuko Kawagushi, according to this theory, a meteorite (or meteorites) broke off from some planet, flew through space and landed on Earth. Scientists have already found that the transfer of bacteria through space is possible in such a way that they can survive for 2-8 years. However, such bacteria could remain undamaged. But where exactly these microbes came from in this case is not yet clear.
Scientists agree that the building blocks of life existed on Earth before life itself arose. And these components came to Earth from space or already existed on Earth. Future extensive research into the origins of life on our planet should answer this question, the researchers say.
As I already wrote Focusa British architect has presented a futuristic concept for a future space elevator that could be used to get into orbit.