Right, I'm hoping there's some anthropological/ science/ evolution genius out there who can answer a question for me.

I spent hours last night/ this morning "discussing" evolution with my partner. The basis of this discussion stemmed from the fact that while I understand evolution and I believe that's how we all came to be, what I can't understand is where exactly we all came from.

As far as I know, after the "Big Bang" the earth was created and there were a bunch of volcanoes which gradually gave birth to our atmosphere, which resulted in a world where life could survive... then there's a big gap, and suddenly from volcanoes and atmosphere we have single celled organisms which later evolved into sea life, which eventually evolved into air-breathing land life, and so on until you get human life. But, where did those single celled organisms come from? They can't just have appeared from nowhere. Volcanoes... and suddenly you have life? Am I missing something?

I'd like to point out that the last time I studied evolution was at GCSE level and as such I may just be having a major memory lapse, but if someone could explain this to me I'd be extremely appreciative.

Where did life come from? How did it come to be? Big questions I know...

Hi Jimkim65

Although i'm no evolutionary biologist, I am a biologist and may be able to shed some light upon an intrigueing question.

It is thought that when the earth was young (I use the term relatively) our atmosphere may have been somewhat different, in that it was, we think, rich in ammonia, methane, and hydrogen. In the presence of water, and a spark (Lightening) it was found that amino acids, the building blocks of life can be created.

When re-created in a laboratory by Stanley Miller in the 1950's, it was found that these conditions created the building blocks of life, namely amino acids. (Johnson AP, Cleaves HJ, Dworkin JP, Glavin DP, Lazcano A, Bada JL (2008). "The Miller Volcanic Spark Discharge Experiment". Science 322 (5900): 404).

Hence the chemical building blocks of life are present, but, where does it all start, was it the chicken or the egg? (or protein or nucleotide for the biologists) etc. My best guess is that these early reactions were somehow able to generate nucleotides of some sort in a sequence, possibly catalytic mRNA or ribozymes, from which basic proteins may have been created given the availability of amino acids (there is some ev idence for catalytic RNA). Then it would seem that over millions of years, natural selection etc did the rest.

The fact that prokaryotes, the simplest life forms do not have a distinct nucleus containing genetic material would support this notion loosely as it would seem that genetic material was originally quite a crude thing, i.e a few nucleotides strung together.

I appreciate some of this may not make perfect sense to a GCSE biologist, feel free to PM me about any of this stuff, or disagree, it's just a theory I happen to believe in.

I don't know enough about this, either. Is there a biochemist in the house?

I think that when people refer to the 'primordial soup', they mean a bunch of chemicals that were there at the time and might have been responsible for the beginning of life. Everything's made of carbon, isn't it? And you'd need water too...

I think there was also a famous experiment where they might have put some candidate chemicals in a flask to see if life began growing, but I don't remember what the results were.

Coo, this is like Conversations With The Ill-Informed Part 17...

Good Luck with your quest, Jinkim!

That does make sense.

Y'see I was under the impression that all living cells needed a nucleus, and this is where I was baffled. If there are life forms that survive with no nucleus then I suppose it's wholly probable that we evolved from this type of life form!

Thanks for clearing that up for me! I was on the verge of declaring the existence of a "higher power" who may or may not have carefully placed adam and eve in a beautiful garden including sacred apple tree, and a serpent for good measure. ;-)

Cakeman I'm relieved you turned up!

(up)

Of course, we could in fact be aliens in the true sense of the word. Current thinking also suggests that many of the chemicals that make us up could be contained within meteorites that crashed down to Earth when it was a young 'un. I used to do biology when I was a youngster and found this kind of stuff fascinating...

Read this link...

http://news.bbc.co.uk/1/hi/sci/tech/6197228.stm

yea, there seems to be a lot of support for the Panspermia theory (that life first blasted its way to Earth millions of years ago in meteorites etc, not a bad idea actually...), and the other big theory is of course the Primordial soup theory. I think it's also a good one, as it is highly possible that cells could develop in this way, that is, molecules forming nucleic acids, forming nucleus-free prokaryotes, forming prokaryotes with nuclei, in turn forming plant cells and allowing the atmosphere to change to allow other forms of life to emerge. Incidentally, my own research is on cyanobacteria, which are thought to have been one of the most important factors in the formation of plant cells and photosynthesis
However, I recently read about another theory, where living systems originated from inorganic incubators - small compartments in iron sulphide rocks. The idea is that inorganic cells first originated in the deep ocean due to the chemicals contained within hydrothermal vents, that gave a perfect environment for chemical reactions to take place, and kept the resulting molecules in close contact (a problem for cells originating the in atmosphere is that any reactions that occurred would disperse their molecules, which would have an unlikely chance of meeting together to form new life )
So while there are many theories, we don't have the answer yet, but it's out there! :) and much more fun than adam and eve! ;-):-):-)