Re: Fw: Most popular/common dinosaur misconceptions

[Phillip Bigelow <bigelowp@juno.com>]

On Sat, 19 Aug 2006 20:16:57 +0200 "Andreas Johansson"
<andreasj@gmail.com> writes:
> On 8/19/06, Phillip Bigelow <bigelowp@juno.com> wrote:
> >
> > > If one
> > > > accepts that life could arise on other planets (ooops! 
> undefined
> > > and
> > > > controversial term alert!), then logically one must accept 
> that it
> > > _could_
> > > > have arisen more than once on Earth.
> >
> >
> > If polyphyletic life *easily* arises in primordial soups 
> throughout the
> > universe, then the monophyly of Earth life is indeed interesting.  
> The
> > situation on Earth may suggest that there is only one pathway to 
> life.
> > If true, then the corrolary would be that all life in the universe 
> would
> > look and act and taste roughly the same.  Genetic sequences in 
> organisms
> > that live on a planet in the Andromeda galaxy would be similar to 
> genetic
> > sequences in Earth life.
> >
> > All Earth life shares certain key genetic sequences, similar cell
> > membrane proteins, etc., and that is nearly incontrovertable proof 
> for
> > monophyletic Earth life.  But inherent in this thesis is the 
> assumption
> > that polyphyletic life would be recognizable in the first place.  
> That's
> > a big assumption.
> 
> There's also the possibility that life arose repeatedly on Earth, 
> but
> one lineage succeeded in competing the rest out of business quick
> enough that we have no evidence of them.


A very real possibility.  And it is possible that new Earth life is even
starting *today* as we speak.  But because the "starting recipe" is the
same as it was back in the Archaean, we don't recognise these new
lineages as separate from the rest of Earth's older lineages.

Because the above statement is inherently untestable, it cannot be
considered a valid hypothesis.  It falls into the category of wild
speculation.

<pb>
--