@krishnagopal --While it is true that the atmosphere was not conducive to our kind of life, that's never been a stumbling block for life in the past. Just look at the thousands of extant species of extremophiles, they're thriving in environments that were previously considered completely hostile to life(including some like the tardigrade who can survive over an hour in hard vacuum with all that that entails). If life is capable of that now, in a very oxygen rich environment, who's to say that it wasn't back then?
I agree with you that ‘lower organisms’ are capable of adaptation. The lower the organism in the phylogenetic rung the better is its adaptability.
In fact one of the hypotheses concerning abiogenesis is that it occurred near undersea vents, with the energy required being provided by the heat from the vent.
I myself think it possible that this point is right
Which assumes that early life, some three point nine billion years ago, worked in the way that modern life does today. A rather bold assumption to make in the face of evidence to the contrary.
Why should we assume that something very grossly different had occurred billions of years ago?
There is much unity in diversity. There is diversity (among various species) in procuring energy from the environment and its subsequent release into the surroundings. Some use minerals, some sunlight, some organic compounds etc. But there is considerable unity in intracellular mechanisms (the metabolic processes) which are ‘comparable’ in all the organisms – the intermediates used for the cellular metabolism are almost the same. The energy currency (ATP) is almost universal.
Almost all metabolic pathways across the biological world use ‘stereotyped’ substrates– same handed amino acids, same chiral sugars, same nucleic acids, similar metabolic pathways – what more evidence is needed to say that life’s processes were uniform all the time … from the start?
And sunlight wasn't the only energy source available to them, it was(and still is) simply the most abundant, hence why life has evolved since then to use it as a source of energy.
Because, We can see that sunlight is ubiquitous and reaches the earth continuously, whereas mineral sources deplete fast, and not so energy efficient
they may have just been organic compounds who had a tendency(due to their physical shape) to rearrange nearby chemicals into copies of themselves. In fact given what we know of life and the universe this seems to be an increasingly likely scenario.
If they were ‘just’ organic compounds with ‘a tendency to rearrange nearby chemicals into copies … without being aware of what they are doing?? This ‘molecular rearrangement’ would have happened repeatedly (and what more –much more randomly), and they were led by the forces of nature alone (and not by anything ‘self’).
In such a case of random rearrangement, the birth of an ‘organized life form’ would have been difficult. If this random rearrangement continued (without a direction) – we would have known a far more diverse ‘metabolic forms’ on the earth. But this is not the case with what we see now.
The marked ecological interdependence of various life forms from archaea to mammals also proves the point.
What we know of life is far more complex, than simple rearrangement.
Well sure, once the cell was around. However life didn't begin with the cell, that evolutionary innovation came later.
Of course life did not begin in a cell
Wrong. The primary requirement for life was replication and the primary requirement for evolution(other than life, obviously) is heredity(imperfect replication with a high fidelity rate). Nowhere in there is awareness or consciousness required.
But this is the snag today. A discussion of this ‘direction’ or ‘awareness’ or ‘what ever’ is a ‘dangerous proposition’ in the scientific elite. We are not used to discuss such abstract things in science. If pushed a little further all this sounds ‘philosophical’ or even spiritual or theological, and scientists shy away immediately. We feel comfortable with a ‘rational’ and lock-stepped approach to the problems in biology. Worst still is that if we do not recognize a problem or a paradox as such, and feel that we have already explained this and that and there is nothing more. I say that the mystery of life is also scientific