Text 755, 59 rader
Skriven 2004-11-10 21:40:00 av Christian A (1:278/230)
Ärende: Re: Evolution metrics?
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The argument you outline is almost impossible either mathematically or
statistically, since you would need to have some way of calculating the
probability of developing multicelularity, skeletons, lungs, brains, etc.,
and no such probabilities exist.

What you can do is examine genetic sequences. Some mutate quickly enough
that we can estimate their mutation rates from samples collected within one
lifetime (I hope that isn't too historic). Given that mutation rate for that
segment of DNA (or "locus"), and given that the locus is present in bacteria
and humans, it is then possible to calculate the probability of one sequence
changing sufficiently to account for the observed differences in 10,000
years. Needless to say, the odds are very, very small.

Most efforts to make evolutionary trees (the ones that say dolphins are
closely related to mammals, but sharks are most closely related to rays) use
a particulary sequence from the mitochondria called cytochrome b. There's a
big argument over how accurate it is to use just those particular 1025 base
pairs and not look at other loci, but that's what Carl Woese chose when he
started this whole mess, and its basically what people have done since then.
It can be shown using recent sequences that the average probability of one
base pair changing per year is 1 in 200 billion, or 2% per million years for
the whole gene. Since Archea and humans have about an 89% divergence at loci
that *can* change, it is highly unlikely that we derived from the same stock
in the past few thousand.

On the creationist side of things, there is a highly controversial, but
mathematically sound, article in last month's Nature magazine. The authors,
Rhode (MIT), Olson and Chang (Yale), claim that all humans could be related
to the same person who lived as recently as 3000 years ago. This is not the
same thing as giving a birthdate to Adam and Eve, but does shorten
timescales for human populations dramatically, if true.

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v431/n7008/abs/nature02842_fs.html


-Christian

"Tom Adams" <tadamsmar@yahoo.com> wrote in message
news:cmtdud$1fmr$1@darwin.ediacara.org...
> Is there a mathematical or statistical theory of evolution that allow
> the calculation or estimation of the amount of trial and error it
> takes to produce a particular organism.
>
> Suppose that you had to argue that humans did not evolve from
> single-celled organisms in 10,000 years without using historical data,
> but just based on the limited capabilities of the trial and error
> process that was available over that period.  Is there a developed
> mathematical or statistical theory that addresses this kind of
> question?
>
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