Group 14 elements are in the unique position of having 4 valence electrons. Carbon is in the unique position of being able to hybridize its S and P electron shells making 4 electrons of equal energy level. Add to that that carbon has different bond types with single (sigma) bonds, double (pi) bonds, and triple bonds, plus its ability to bind ad nauseum in hydrocarbon chains and rings, and it becomes rapidly apparent that out of all the chemicals, carbon can create the most types of molecules. An infinite number possibly. So from a statistics perspective, all life is carbon based because carbon is the atom with the least limitations and the most possible structures. This may seem as though I'm saying "life is carbon based because its not 'not' carbon based", but the important thing is that carbon has the capacity to produce structures known as functional groups, allowing for molecules with multiple independent functions to be formed. Finally, consider the abundance of carbon in the universe ( 4,600 ppm in the universe) versus the next group 14 element silicon (650 ppm in the universe) and you see that carbon really was the only way for this to happen. To ask further would be to ask why the laws of physics are the way they are.

Becuse carbon is the main essential element in the organic compounds which all kinds of cells and their components and derivatives consist of. So you can find carbon in every thing which belongs to cells then which means belongs to life.

Group 14 elements are in the unique position of having 4 valence electrons. Carbon is in the unique position of being able to hybridize its S and P electron shells making 4 electrons of equal energy level. Add to that that carbon has different bond types with single (sigma) bonds, double (pi) bonds, and triple bonds, plus its ability to bind ad nauseum in hydrocarbon chains and rings, and it becomes rapidly apparent that out of all the chemicals, carbon can create the most types of molecules. An infinite number possibly. So from a statistics perspective, all life is carbon based because carbon is the atom with the least limitations and the most possible structures. This may seem as though I'm saying "life is carbon based because its not 'not' carbon based", but the important thing is that carbon has the capacity to produce structures known as functional groups, allowing for molecules with multiple independent functions to be formed. Finally, consider the abundance of carbon in the universe ( 4,600 ppm in the universe) versus the next group 14 element silicon (650 ppm in the universe) and you see that carbon really was the only way for this to happen. To ask further would be to ask why the laws of physics are the way they are.

I've heard that recent numerical modeling results predict that silicon compounds under very high pressure are even more abundant then carbon compounds at normal conditions (Artem R Oganov can say more). Also given that "normal" conditions are quite rare in the Universe, I would not be surprised if our carbon-based life is actually an exotic thing.

Igor Ostanin I would certainly be curious to see that study. My gut instinct says not likely considering simple statistics of how elements are formed through fusion, I doubt there are stars that are producing higher amounts of silicon out there than carbon. Maybe higher amounts of silicon compounds (that's a big maybe) but certainly not higher amounts of atomic silicon vs carbon. Such a discovery would throw nuclear physics on its head.

Sure, there's definitely more carbon in the universe than silicon, in terms of mass or absolute number of atoms. But my point was that the huge abundance of organic compounds of carbon, hydrogen, nitrogen etc are stable at the pressures around 100 kPa and temperatures around 300K, which are clearly extraordinary rare conditions in the Universe. Inorganic chemistry looks completely different even inside the Earth mantle (https://www.nature.com/articles/nature02701), not mentioning, say, interiors of giant planets.

Igor Ostanin Ah yeah that is a good point. I would be fascinated to see life in those alternate conditions. A fun thought experiment for sure.

I think, the answer depends on how we define life... So far everybody is talking about chemical life. Is it the only option?

Andrei L Tchougréeff That's a fair point. If/when we have achieved the generation of life in silica through artificial intelligence, we will need to revisit this argument.

Bobby Cox Very remarkable your "If/when". What is life? pieces of (genetic) information moving around, absorbing and dissipating energy and proliferating. But look around: computer viruses are pieces of information, moving around, dissipating energy in computers and proliferating... Future is now

Andrei L Tchougréeff Your argument only works if we consider prions, viruses, and lab PCR DNA amplification processes as life.

While as romantic as the idea of life being "pieces of information moving around, absorbing and dissipating energy and proliferating" is, it's not a very solid definition considering how many things can fall into the category.

Thanks a lot to all RG members for the given interesting and nice discussions to my question.

i would give a macroscopic answer. The body of the living creatures contains carbon for performing their functions well. Carbon and hydrogen are sources of energy. In the body carbon obtained from eating plants for example will be utilized to share in building cells and to release heart by oxidation. This occurs in the breathing process. Carbon is the element circulating between the animals and plants. So, it is not only necessary for animals but also for plants.

Best wishes

Preprint THE PHILOSOPHICAL STUDY OF INTELLECT EVOLUTION

So far we know for certain that life on Earth is carbon based. This and versatility of carbon are two indicators that may be (just may be) all/most of life forms are carbon based. But we do not have any proof, we do not even have proof that life exists somewhere beyond Earth. Science in its current state is unable of creating any solid predictions. Good field for Sci-Fi.

please visit wikipedia

https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

in my opinion

• Carbon is able to form both long, stable chain with itself (catenation) and/or bind with sufficient number of other heteroatoms to form complex chemical compound, and sufficiently abundant on universe
• the balance between kinetics of biochemical reaction and stability of complex biomolecules is only at this temperature, as far as knowledge of our conventional biochemistry goes.
• silicates as well as polyoxometalates are complex enough but still the huge data storage and hereditary transfer of data are yet to be observed by these molecules
• Boron can show three-center-two-electron bond, and Sulfur also shows six valency and can form complex compound, but still complexity of life in these molecules are yet to be observed.

Of course, our present understanding on chemical basis of life and abiogenesis is still incomplete. Best is to wait for the future.