[meteorite-list] Bugs In Space!

[Michael Fowler]

>
> 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.