Re: The young age of Earth

Kevin O'Brien (
Thu, 18 Mar 1999 20:44:39 -0700

>>What do you mean by "protein interface"? There is no proteinaceous
>>material present in the tRNA-amino acid complex.
>I'm sorry for my mistake. Is there anything which connects tRNA to the
>amino acid?

Yes, there are, and I suspected that they are what you meant. They are
enzymes called aminoacyl tRNA synthetases. They catalyze the reaction that
binds an amino acid to a tRNA; they also make sure that the correct amino
acid is matched to the correct tRNA. Though mismatches can occur (maybe one
time out of 100,000 or less), which can lead to point mutations in the
resulting protein, for the most part the specificity between enzyme, tRNA
and amino acid is excellent. Once the aminoacyl tRNA (tRNA-amino acid
complex) is formed, however, the synthetase plays no further role.

>>Unless you left out some details, by your own admission your friend
>>2.5 hours after he left, therefore Pim's comment is quite accurate. You
>>assume that it would take 12 hours to drive from San Francisco to Poland,
>>but if your friend actiually did it in 2.5 hours your assumption is
>Yes, he drove up, but there is another explanation. Bob flew here, and
>a rental. There is no way in today's world he could have driven here in
>the alloted time, unless you want to stipulate a special exclusion.

OK, I see what you're saying; I had confused myself. However, your analogy
is flawed. Your said it would take longer than 500 million years to evolve
a single celled organism from simple chemicals. Pim said that the data
suggests you are wrong, then added that abiogenesis only had 500 million
years to work. Your analogy is meant to respond by saying that unless we
know what the mechanism for abiogenesis was, we cannot know how long it
would have taken.

But in fact your analogy does not really support your original claim. We
know exactly how long it took your friend to reach you -- 2.5 hours. We
know (or at least can hypothesize about) what modes of transportation were
available to him. We can thus use his travel time, plus the geography
between San Francisco and Poland, to determine which are the most likely
modes he could have taken. (In this case, flying is the only mode that
could work.)

Similarly we know that the first living organisms appeared roughly 500
million years after the earth first solidified. We also know (or can
hypothesize about) what mechanisms were available at that time. We can then
use the time constraint, as well as our knowledge of environmental
conditions back then, to help us determine which mechanisms would have been
the most successful. That gives us about a dozen viable mechanisms that,
working simultaneously or sequentially, could have evolved unicellular
organisms from simple chemicals. In fact, some of these mechanisms could
have accomplished some of the earlier steps in only a few million years.

>If what has occured in the laboratory is what you claim took 500 million
>years, then I concede.

The mechanisms studied in laboratory research in fact could conceivably have
produced simple unicellular organisms within 500 million years.

>Let me say here, that I am not opposed to naturalistic abiogenesis as a
>theory, but then neither am I disposed towards it. Whatever the answer may
>be, as to how life arose on this planet, it will be supremely interesting.

On that we can agree wholeheartedly.

Kevin L. O'Brien