Re: [asa] How far back can we see?

On Sat, 28 Jun 2008 13:43:21 -0400 "Alexanian, Moorad"
<alexanian@uncw.edu> writes:
> In cosmology, the cosmic background radiation (the remnant of the Big
> Bang) allows us to see back in time to the time when the
> electromagnetic radiation decoupled from the existing matter. In
> evolutionary biology, how far back can we see with genome evolution?
> How far back can we see, say, with protein evolution?
>
>
>
> Moorad
>
Though I'm neither a physicist nor a biologist, it looks to me as though
you're not even comparing apples and oranges, but more like cannon balls
and eggs. The remanent microwave radiation involves a simple Doppler
shift of what is essentially unchanging. What changes is our view.
Redsifted radiation retains, barring absorption en route, all the
spectral peaks or lack thereof with which it started. In contrast, there
is nothing unchanging about fossil genetic material and protein. There is
mighty little that anyone can examine. What can be compared is current
genes and other genetic structures, all of which have been changing
during the existence of the organisms. However, comparing the current
function, the number of duplications, the base changes, the insertions
from various sources, and whatever other elements the experts can devise,
allow a reasonable determination of the history and timing of the several
genes and the organisms. I recall a comparison of a gene from two yeast
species with those of a number of other organisms. There will be more and
more complex comparisons as more creatures are sequenced, and also as we
learn more about how genomes function. It's no longer "one gene, one
protein." Such measurements cannot be as precise as the single
measurement of radiation, but they can produce relevant comparisons. Of
course, I might challenge you to predict the timing of a radon nucleus
kicking out an alpha particle. Can you even identify the individual
atoms? Statistical measures are often the best we can get.

May I note that Galileo could get a mathematical representation of
acceleration with no better than a relative measurement of time. The most
accurate measurement he had was of weight, with length coming in second.
Physics has come a long way with atomic clocks and interferometers.
Dave (ASA)
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Received on Sat Jun 28 18:26:48 2008