[ExI] Discovery Suggests All Complex Life Came From Archaea

[BillK]

On 18 February 2017 at 21:46, Ben  wrote:
> I've had this discussion before, and am not convinced that all life on earth
> had to originate from a single cell. In fact it seems highly unlikely.
>
> It seems much more likely to me that all life originated from a /population/
> of similar cells. This is how evolution works, variation in a population,
> some members are more successful than others at reproducing, some are not
> successful at all.
>
> It doesn't tend to happen that only a single individual is the least bit
> successful at reproducing, and all the others die. I don't see why this
> wouldn't be just as true 3.8 bn years ago as it is today.
>
> Does anyone have a convincing counter-argument?
>

Yes. Every earth species uses the same DNA proteins.  Multiple origins
are far more unlikely than everything coming from one origin.

<https://en.wikipedia.org/wiki/Common_descent>
Quote:

Common biochemistry and genetic code

All known forms of life are based on the same fundamental biochemical
organization: genetic information encoded in DNA, transcribed into
RNA, through the effect of protein- and RNA-enzymes, then translated
into proteins by (highly similar) ribosomes, with ATP, NADPH and
others as energy sources, etc. Furthermore, the genetic code (the
"translation table" according to which DNA information is translated
into proteins) is nearly identical for all known lifeforms, from
bacteria and archaea to animals and plants. The universality of this
code is generally regarded by biologists as definitive evidence in
favor of the theory of universal common descent. Analysis of the small
differences in the genetic code has also provided support for
universal common descent. An example would be Cytochrome c which most
organisms actually share. A statistical comparison of various
alternative hypotheses has shown that universal common ancestry is
significantly more probable than models involving multiple origins.
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BillK