Why is all life on Earth carbon based?

[Chaupoline]

Does anyone know why this is? Is it because of the type of Sun we have?

[premjan]

Only carbon has the diversity of chemical reactions needed to produce the flexible evolutionary manifestations we term as life.

[Professor Mayhem]

Carbon reacts abundantly and relatively quickly. It's great at forming long-chain organic compounds with the potential for replication. Carbon is great little engine for chemical affinity.

There are other elements that can conceivably produce long chain compounds that could preclude some form of biological life, but they take an extraordinarily long time to react in comparison to carbon.

[Alludium Fozdex]

Carbon reacts abundantly and relatively quickly. It's great at forming long-chain organic compounds with the potential for replication. Carbon is great little engine for chemical affinity.

There are other elements that can conceivably produce long chain compounds that could preclude some form of biological life, but they take an extraordinarily long time to react in comparison to carbon.IIRC, silicon is second fiddle to carbon, and a distant second at that.

[Lavis Knight]

This is a fascinating question. I have heard speculation about how silicon based lifeforms are possible; although, it had its share of problems.

I found this wikipedia article particularly interesting:

http://en.wikipedia.org/wiki/Silicon_based_life

The Earth, as well as other terrestrial planets, is exceptionally silicon-rich and carbon-poor. However, terrestrial life is carbon-based. The fact that carbon, though rare, has proven to be much more successful as a life base than the much more abundant silicon may be evidence that silicon is poorly suited for biochemistry on Earth-like planets.

[Chaupoline]

Is there a relationship between the energy produced by our Sun, carbon and life? What little I know of the carbon cycle, it seems that plants absorb sunlight and carbon dioxide. They then absorb the carbon and release the oxygen. Animals inhale the oxygen, exhale carbon dioxide and eat the plants as well as other animals that have eaten plants. The amount of energy they get from eating plants or animals varies. Coal, shale, and oil are former organic life that was buried long ago, the earth compressed it into its current form and it is concentrated energy which we use to power machinery. When it seeps into the ocean it assists in promoting more life. When burned it releases energy and carbon dioxide.

If I am wrong with my assumptions, please let me know. These are not loaded questions and I am not trying to promote any beliefs.

[premjan]

In addition to C-C-C and Si-Si-Si chains, there are also C-O-C-O-C and other alternating chains. I'm not sure, but a planet richer in oxygen might cause a Carbon-Oxygen chain to be preferred, and that would perhaps generate a totally different biochemistry.

[Loren Pechtel]

Carbon reacts abundantly and relatively quickly. It's great at forming long-chain organic compounds with the potential for replication. Carbon is great little engine for chemical affinity.

There are other elements that can conceivably produce long chain compounds that could preclude some form of biological life, but they take an extraordinarily long time to react in comparison to carbon.

Yeah--there might be some cold biochemistries out there but there are no intelligent beings based on them--there simply hasn't been enough time for them to evolve intelligence.

In addition to C-C-C and Si-Si-Si chains, there are also C-O-C-O-C and other alternating chains. I'm not sure, but a planet richer in oxygen might cause a Carbon-Oxygen chain to be preferred, and that would perhaps generate a totally different biochemistry.

Note that C-O-C-O-C is *NOT* a viable biochemistry. It suffers from the same problem that Si-O-Si-O-Si does: Look at the rest of the molecule. Most of the rest of the C bonds have hydrogens on them.

Consider the reaction sequence of removing one O and 1 H from the two adjacent C's. This leaves a double bond between the two C's, releases a water molecule and some energy.

In general molecules that can decompose and release energy in the process are known as explosives.

[premjan]

Most explosives seem to contain Nitrogen as far as I can tell.

[Kharakov]

Does anyone know why this is? Is it because of the type of Sun we have?
The most common form is of the atomic arrangement 6 6 6. :devil1: It's to mess with xians.

[itsamysteryhuh]

Does anyone know why this is? Is it because of the type of Sun we have?

Carbon is unique among the elements in both the number and the variety of compounds which it can form. One of its most significant properties is the ability to form chains very easily by lining atoms up one after another... the shortest chain being made up of two carbon atoms. The reason for this ability to form chains with so many links is because its chains are not exclusively linear (chains may be branched and may also form polygons).

[Starr]

The Wikipedia entry gives a fairly good rundown of why Silicon based biochemistry isn't terribly viable:


But silicon has a number of handicaps as a carbon alternative. Because silicon atoms are much bigger, having a larger mass and atomic radius, they have difficulty forming double or triple covalent bonds, which are important for a biochemical system. Silanes, which are chemical compounds of hydrogen and silicon that are analogous to the alkane hydrocarbons, are highly reactive with water, and long-chain silanes spontaneously decompose. Molecules incorporating polymers of alternating silicon and oxygen atoms instead of direct bonds between silicon, known collectively as silicones, are much more stable. It has been suggested that silicone-based chemicals would be more stable than equivalent hydrocarbons in a sulfuric-acid-rich environment, as is found in some extraterrestrial locations.[1] In general, however, complex long-chain silicone molecules are still more unstable than their carbon counterparts.

I really expect that if we do find complex life somewhere else in the Universe, it is going to be Carbon based, much like us. The alternative chemistries just seem to have too many hurdles to a viable biochemistry.

However, it might be more viable to have non-water based life. It would be so cool to find Ammonia based life on Titan for instance.

[Ezkerraldean]

because carbon is really common and, unlike other really common elements, does loads of neat chemical stuff.

[Dirge]

It helps that carbon isn't brittle, like silicon, as an example.