eli5: Why can’t we make boron-based life forms?

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I saw a boron-based life form in a sci-fi show and it made me curious about how that works. I did some reading on it, and all I see is around the oxidation states and the ability to bond with atoms.

I vaguely grasp these concepts, but don’t get why, if it is possible for boron to build life, why can’t we/haven’t we done it?

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4 Answers

Anonymous 0 Comments

The way I saw this sort of question explained best (it was about silicon, but same answer) is this:

Life as we know it works because there are molecules that can encode information, store it, copy it, build new molecules off of it and then, most importantly, MODIFY it (aka evolution).

This is important, because without stored information, you have just your standard chemistry.

To have these sort of molecules, you have to have atoms that like to interact with themselves strongly enough to form a skeleton of that molecule, but not so strongly that it’s brittle and can’t be rearranged.

It also has to have enough bods to allow attaching other atoms, so that more complex molecules can be form. A pure monoatomic crystal doesn’t do chemistry.

This skeleton’s form also has to enable of encoding and decoding of information. Here again, a 3 dimensional crystal lattice is too closed for chemistry. So you need something like chains or sheets. It would be difficult to enforce reading off of a surface with chemistry like we do with an HDD. Chemistry is too random. Chains seems like the only viable choice to actually encode something, because there’s literally only one direction. It enforces structure.

There’s only two atoms that we know of which form chains. Carbon and Silicon.

Out of the two, carbon chains are more flexible and form almost spontaneously, while silicon loves forming either a crystal or reacting with oxygen to form silicon dioxide, so it’s more difficult for it to form chains. And when it does, they’re much more fragile than carbon ones, which means they break apart too easily. Meanwhile carbon chains are really durable, but not so much to prevent SOME rearranging.

Basically, if you wanted to purposefully design self-replicating, information carrying molecules, carbon would be the no-brainer choice, with silicon a fairly distant second.

So while it’s remarkable that life can exist, it was going to be made out of carbon, because chemistry is blind and carbois the exponentially more likely one to work, so basically probability wins.

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