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Asked by hahex12 to Sam, Katie, Ed, Steve, Vera on 19 Jun 2011. This question was also asked by adotxdii, courteney.
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Sam Tazzyman answered on 14 Jun 2011:
This is an active field in science – people are still researching this. Amino acids, which are a type of chemical crucial to life, can be formed in the laboratory by experiments that try to reproduce what it was probably like back on Earth in the superdistant past. But I don’t know for sure what the current best theory is as to how these gave rise to life itself. But it must have been a very simple form of single-celled life to start with. Then evolution got going, and look at the wide variety of things that came about!
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Katie Marriott answered on 14 Jun 2011:
Sorry this is copied from a question I answered previously but hope this helps:
Things always have to start off with something simple that can be get more complicated. So:
Firstly, there would have been simple chemicals like that in the air, so Oxygen, Nitrogen and other chemicals that are more reactive (for example, formaldehyde and compounds that contain nitrogen and oxygen – do you understand what I mean by a compound?).
These simple chemicals would have reacted together to make larger compounds – for example, formaldehyde can react with more formaldehyde to make a sugar like glucose.
It is possible that these larger compounds could start interacting with one another but not necessarily reacting. In our bodies lots of chemicals interact with one another like enzymes breaking down a substrate but they do not necessarily form bonds so they are not reacting.
From here all you need to add is a cell membrane to keep all the interacting chemicals together, and this would be a simple organism, like a bacteria.
It all sounds very simple really, but it’s actually very complicated! This process would have taken millions of years. It is still very unclear how the simple molecules formed the complicated molecules that we find in our biology today. The fact that nature had billions of years makes this research very difficult as well as scientists do not have this time span! The reactions I do are on for days to weeks to even months, which is a very long time in chemistry!
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Ed Morrison answered on 15 Jun 2011:
We don’t really know, but it must have involved some kind of molecules replicating each other. Once they start replicating, evolution can happen and life can become more complex.
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Steven Daly answered on 17 Jun 2011:
What Katie said, pretty much. Although it is possible that some of the molecules we are made from came from space via comets.
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Comments
Sam commented on :
Katie’s answer is great – it’s cool to learn new stuff!
optimusgrime786 commented on :
there was nothing and nothing happened to nothing and then nothing magically exploded into nothing creating everything and then a bunch of nothing magically rearranged for no reason whatsoever into self replicating bits that then turned into dinosaurs.
Ed commented on :
Yes, I’ve seen this one before. Although it’s true that we don’t know what caused the big bang (or even if “cause” is the right word), I must take issue with “a bunch of nothing magically rearranged for no reason whatsoever into self replicating bits that then turned into dinosaurs.”
Scientists are quite confident that once chemicals were arranged, by chance, into self-replicating molecules they would by definition repdrouce themselves. This means that evolution can and must happen, making it more or less inevitable that they would become more complex and produce a vast array of different lifeforms.