Mark stated (quite clearly, I thought) that all life on earth gan be
genetically linked to earth and it seems far more likely that it
began here where conditions are ideal than it being delivered here
by something else. ......
Rob McC
Hi Rob,
There is a fascinating site called "Cosmic Ancestry" that makes the
case for panspermia and more in a way that would appeal to the science
minded person.
http://www.panspermia.org/index.htm
The "What's New" link has refers to research and current findings
relevant to the panspermia question.
http://www.panspermia.org/index.htm
Mike Fowler
PS Following example from the current What's New, to give you an
example of the issues discussed. Much of this is too highly technical
for the average person, or meteorite collector, but interesting
nevertheless:
The gain and loss of exons has contributed to the evolution of new
features. Evidence for this surmise comes from Japanese and
Californian geneticists whose primary interest is slightly different:
domain shuffling in vertebrate genomes. The geneticists conclude that
domain shuffling is important, and they notice that domains are
frequently gained or lost during evolution. "These genes are likely to
have gained new functional roles by acquiring new domains, and are
likely to be involved in phenotypic evolution," they comment.
Exons are the coding portions of genes, separated by noncoding
portions called introns. Introns (and consequently, exons) were first
recognized more than thirty years ago, and their evolutionary purpose
has been a contentious subject ever since. How could interruptions in
genes be a good thing? A dozen years ago we suggested, "Introns make
more sense if evolution is a constructive process requiring the
assembly of blocks of instructions imported from outside the cell."
Evidence that exons encoding the studied domains were ever gradually
composed is not apparent in the new report. Rather, in the
reconstruction of the past, exons seem to simply show up, already
composed; or else they were present in the most ancient studied
species. This supports our prediction, "If a new genetic program
arrives by the strong panspermia process, intervening species should
possess either nearly identical versions of it ...or nothing similar..."
If the studied domains were not gradually composed by mutation-and-
natural-selection, how did they acquire their programming? Could they
be encoded by random, "junk" DNA that just happens to contain working
programs or subroutines? No. Simple math makes that hope forbiddingly
unlikely for any but trivially small domains of, say, fifteen or fewer
codons. Meanwhile, the studied domains appear to average about 150
codons in length, the largest one longer than 3,000 codons.
The geneticists' conclusion concerning domain shuffling also interests
us, because, "In the evolutionary mechanism we advocate, new genetic
programs are acquired whole or in a few large pieces and then
assembled by genetic software with rule-following, puzzle-solving
capabilities."
In cosmic ancestry, genetic programming is as old as life itself.
During evolution the program components need assembly and
optimization, but the essence is there already. We think the data
support this expectation.
Takeshi Kawashima et al., "Domain shuffling and the evolution of
vertebrates" [abstract], doi:10.1101/gr.087072.108, p1393-1403 v19,
Genome Res., Aug 2009.
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