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Re: Ceratopsian frill size (was Re: DINOSAUR digest 71)



[This thread has drifted pretty far -- I'm not likely to accept
 anything else on the topic if you can't relate it more directly to
 dinosaurs.  Anyhoo, I suspect Achut already knew the following.  I
 did, and I still concur that the idea is mainly a buck-passing
 argument. -- MR ]

In a message dated 96-10-06 18:18:56 EDT, achut@troodon.isp.net (Achut Reddy)
writes:

> Yes, Hoyle's theory is essentially a buck-passing argument.

Not quite. The argument is that the evolution of even the simplest life-forms
requires far more time than the earth has been in existence. Hoyle's
steady-state theory of the universe provides all the time you want for such
life-forms to evolve elsewhere and to spread throughout the universe. Then,
as new stars form, it's there in "bacterial spore form" to seed any congenial
host planets that might be created alongside the new stars. (But if the Big
Bang happened long-enough ago, this could still hold true; it's not
inseparably wedded to steady-state.)

One thing about the origin of life on earth that is not readily explainable
is the short amount of time between the termination of the "bombardment
phase" of earth's creation (Hadean) and the appearance of traces of life in
the fossil record (Archaean): a few hundred million years, at last count. Not
enough time, some say, for organized cellular life to appear from the
prebiotic soup. If the "seeds of life" arrived in the solar system from
elsewhere and kept landing on earth more or less constantly during its
formative phases, this could explain the rapid appearance of life on earth
following earth's formation.

This is not to defend Hoyle's thesis, just to show that it is not entirely
arrant nonsense as some would have it. Hoyle's theory (which has its roots in
Arrhenius's panspermia idea) predicts that all life forms throughout the
universe will be based on the same RNA and proteins--of the same
"handedness"--as on earth, and it would be falsified if life forms on other
planets are found to be based on radically different biochemistries. Onthe
other hand, if life on Mars is confirmed and is found to be similar to life
on earth, this would support the "panspermia" theories and would count
_against_ a terrestrial origin for life.