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Re: exobiology possibilities

On 03/12/2015 07:55 AM, Thomas R. Holtz, Jr. wrote:
> On the contrary: we have every reason to think that all life on Earth studied 
> so far are descendants of a single instance of life, and every reason to 
> dismiss the possibility that any known terrestrial life is of independent 
> origin. A good reason for this is the fact that A, T, C & G are NOT the only 
> possible nucleotides.  Furthermore people have synthesized nucleic acid 
> analogues in the lab that work essentially like DNA and RNA but which have 
> different backbones. The fact that all living things use only the one system 
> when there are numerous alternatives which are seemingly just as likely 
> points to a common origin. Statistically, we would expect alien life will  
> like have DNA/RNA analogues using other nucleotides and/or backbones, if 
> indeed they used these forms of molecules as the carrier of genetic 
> information.
> The Lost City microbes fall within the family tree of other life, and use the 
> same genetic carriers in the same fashion the rest of Earth life does.

Thank you

Do you have a reference for any nucleotide pairs outside of the ones in
DNA and RNA which can form a double helix and be injected into a life
form?  Or nucleotides that have properties of DNA or RNA.


> Thomas R. Holtz, Jr.
> Email: tholtz@umd.edu Phone: 301-405-4084
> Office: Centreville 1216                      
> Senior Lecturer, Vertebrate Paleontology
> Dept. of Geology, University of Maryland
> http://www.geol.umd.edu/~tholtz/
> Fax: 301-314-9661             
> Faculty Director, Science & Global Change Program, College Park Scholars
> http://www.geol.umd.edu/sgc
> Fax: 301-314-9843
> Mailing Address:      Thomas R. Holtz, Jr.
>                       Department of Geology
>                       Building 237, Room 1117
>                       University of Maryland
>                       College Park, MD 20742 USA
>> -----Original Message-----
>> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of 
>> Ruben Safir
>> Sent: Thursday, March 12, 2015 4:17 AM
>> To: dinosaur@usc.edu
>> Subject: exobiology possibilities
>> http://finance.yahoo.com/news/discovery-one-saturns-moons-just-182029759.html
>> This article is worth reading only because it point to the possibility of an 
>> independent evolution of life, which brings up a question I
>> have long had.
>> We really don't know if all life on this planet comes from a single 
>> continuous linage.  The organism that exist in the lost city might not
>> be related to anything on the planet.  And similarly, is possible that 
>> flowering plants, as an example, some from several branches of
>> plant life, in a form of convergence where closely related specifies 
>> simultaneously develop like features, even controlled by similar
>> haplans and control genes?
>> Why should the course of evolution be simple?
>> Ruben
> .