Re: Issues


"Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxxx> wrote in message news:daj87b$2st$1@xxxxxxxxxxxxxxxxxxxxxx
>
> "g" <gillawton@xxxxxxxxxxxxx> wrote in message news:daghdu$2407$1@xxxxxxxxxxxxxxxxxxxxxx
> > The following article is from current ed. of Science.
> > What Don't We Know?
> > ... For this
> > anniversary issue, we decided to shift our frame of reference, to look
> > instead at what we don't know: the scientific puzzles that are driving basic
> > scientific research.
> >
> > We selected 25 of the 125 questions to highlight based on several criteria:
> > how fundamental they are, how broad-ranging, and whether their solutions
> > will impact other scientific disciplines.
[snip]
> I am pleased that my favorite topic made the list - "How and Where Did
> Life on Earth Arise?".

The 100 issues on the "second tier" are listed here:
http://www.sciencemag.org/cgi/content/full/309/5731/78b

I am particularly interested in these two:

What enables cellular components to copy themselves independent
of DNA? Centrosomes, which help pull apart paired chromosomes,
and other organelles replicate on their own time, without DNA's
guidance. This independence still defies explanation.

Who was LUCA (the last universal common ancestor)?
Ideas about the origin of the 1.5-billion-year-old "mother" of all
complex organisms abound. The continued discovery of primitive
microbes, along with comparative genomics, should help resolve
life's deep past.

Does anyone know know where that number 1.5-billion came from?
I would have guessed at least a billion years earlier. They can't
be restricting the U of the term LUCA to the eukaryotes, can they?


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