"JoVe" <send_ikke_hertil@hotmail.com> skrev i en meddelelse
news:416278d0$0$297$edfadb0f@dread11.news.tele.dk...
>
http://www.berlingske.dk/indland/artikel:aid=489944/
>
> "Alle nulevende mennesker kan spore slægt og oprindelse tilbage til en
> enkelt person, der levede for omkring 3.500 år siden i Asien. Det hævder
> amerikanske forskere på baggrund af computermodeller."
>
> ...bortset fra at der i computermodellerne åbenbart er en lille regnefejl
> i
> årstalsangivelsen!
>
>
>
))))
>
> Mvh
> Jørgen Vestrergaard
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I forlængelse heraf er det interessant at notere sig evolutionsteoretikernes
"skjulte" problemer:
The nature of the last universal common ancestor
David Penny* and Anthony Poole?
Introduction
The last universal common ancestor (LUCA) is the organism
at the root of the 'tree of life' the ancestor of all organisms
alive today [1..]. Estimating its properties helps understand
even earlier steps in the origin of life - it is a window further
back into time. Indeed, the usefulness of models of the
LUCA are judged by their ability to improve understanding
of these earlier steps, and models that make the origin of life
more difficult to resolve require reconsideration.
Conclusions
An interesting picture of the LUCA is emerging. It was a
fully DNA and protein-based organism with extensive processing
of RNA transcripts by RNPs (Figure 3). It had an
extensive set of proteins for DNA, RNA and protein synthesis,
DNA repair, recombination, control systems for
regulation of genes and cell division, chaperone proteins,
and probably lacked operons. Biochemistry favours a
mesophilic LUCA with eukaryote-like RNA processing,
though it is still possible to fit the data to several different
trees (Figure 4). A eukaryote-like LUCA is not a new idea
and can be traced back to Reanney [40].
Details of energy source(s) are unclear, partly because
operational genes apparently undergo frequent horizontal
transfers. Comparative genomics promises a clearer picture
but apparent intermingling of lineages via horizontal transfer
is a major obstacle [38..]. Increasingly, models need to
fit our understanding of evolutionary theory and population
genetics -it is essential to have plausible mechanisms
and selective forces.
Altså ville evolutionsteoretikerne gerne se nogle forstadier til RNA
udmøntende sig i protoformer opdelt i planlægningsfragmenter og udøvende
cellefragmenter. Men de finder fiks og færdige udgaver af de mindste
celledele med alle funktioner færdigindbygget. De tyder på intelligent
design snarere end udvikling!
Det engelske klippet fra :
http://www.icb.ufmg.br/~lbem/aulas/grad/tge/evol/pdf/penny-genevol-99.pdf
Hilsen
Jens