I know That various factors on earth caused the formation of some complex compounds.These compounds then got better and better in pursuit of survival.My question is why the compounds were trying to survive in the first place?
In: Biology
That’s the big question for biology, and very much still an active field of study.
Something you need to understand to understand biology though is that life doesn’t *try* to do *anything*. It just coincidentally happens to do it. The process of evolution means that things that happen to do beneficial things will end up propagating, and things that don’t happen to do beneficial things will end up disappearing.
The beneficial thing evolution acts upon is self-replication – the ability for a molecule to create identical copies of itself. This makes intuitive sense: If a molecule makes copies of itself simply by existing, and those copies are identical to the original, then they’ll also make copies of themselves, and those copies will make copies, and so on, thus increasing the number of copies of the molecule. If this process happens faster than the process of the molecule disintegrating, then the molecule naturally survives as a byproduct of what it does (self-replicate), without ever *trying* to do so. Remember, there is no active *intention* in biology, but the accumulation of many, many coincidences and chemical reactions can *look* like intention to our human brains, and unhelpfully, the easiest way to describe evolution is by *pretending* that it’s conscious and capable of making decisions.
Now, evolution is the result of slight variations in the self-replicated product. If after self-replication, one of the copies is slightly different as the result of imperfect replication, and that difference makes the molecule better at self-replication in future, that molecule has now increased its chance of reproducing – it has evolved.
Eventually, cellular life comes about, as molecules randomly evolve that can interact with one another. Once molecules can interact with other molecules, their chance of reproducing becomes tied to those other molecules, and the molecules begin to evolve simultaneously and symbiotically. If one of the things molecule A does is increase the chance of molecule B reproducing, and one of the things molecule B does is increase the chance of molecule A reproducing, then both molecules will end up working together and evolving together. Trap molecule A and molecule B inside a cell membrane (which naturally occur and don’t need to evolve) and you’ve got a very simple cell, and now the “unit of reproduction” is not the molecule, but the cell – if the cell reproduces, everything inside the cell also reproduces, so now every molecule’s evolutionary goal is to increase the chance of the cell reproducing which will in turn increase the chance of themselves reproducing. This shared workload creates an environment in which molecules can begin to specialise. If one molecule can evolve to be able to reproduce *multiple* molecules, then those other molecules no longer need to reproduce by themselves, and can evolve to perform specific functions that will assist the other molecules better.
Over billions of years, this has caused the creation of an interacting trio of molecules: DNA, Ribosomes and Transcription proteins. At some point, a cell occurred that contained all three of these things. The three work together, and without one of them, none of them can replicate. The DNA contains the instructions to create new ribosomes and transcription proteins. The transcription proteins replicate the DNA and translate the DNA into instructions the ribosomes can read. The ribosomes replicate the transcription proteins. All three molecules get replicated, and whenever they’re not replicating, they cooperate to create all the other proteins and cellular structures that increase their own chance of reproduction. Every single cell alive on Earth today is the direct descendant of that cell, and uses mutated copies of that trio of molecules that replicate one-another.
There is no *intention* in nature. But by sheer coincidence, three molecules found themselves in a cell together, and through the inevitable process of natural selection and survival of the fittest, their descendants mutated into forms that were so good at working together they became entirely reliant upon one another.
The great mystery of the origin of life isn’t about how these complex compounds first appeared, or about how they replicated or survived – that’s all quite straight-forward. The mystery is what it looked like when multiple molecules first started directly working together and evolving side-by-side for the good of all of them, not just themselves.
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