MadSci Network: Evolution
Query:

Re: Silicon Life forms in Hydrothermal Vents?

Date: Mon Mar 27 10:27:08 2000
Posted By: Joseph E. Armstrong, Faculty, Botany, Illinois State University
Area of science: Evolution
ID: 953920342.Ev
Message:

Sorry, but I have not heard of any silicon based, as opposed to 
carbon-based, life forms from deep ocean geothermal vents. You asked about 
silica, but that is silicon dioxide, and therein is part of the problem 
with silicon chemistry. A number of people have considered whether 
silicon-based life is possible, and the answer seems to be perhaps, but not 
without overcoming some pretty big problems. While the bonding of silicon 
makes it appear that it could make some interesting molecules, the problem 
arises in capturing, storing, and metabolizing energy from silicon based 
molecules.  Carbon dioxide is gas, diffusable and soluble in water; silicon 
dioxide, well, is sand!  So how would this life work?  I know of no 
scenario for silicon-based life.

The chemotrophic life forms from deep-sea vents have as you mentioned 
contributed tremedously to our understanding of diversity, although I would 
stop short of saying these discoveries have revolutionized evolutionary 
biology.  They haven't, but they have contributed to our understanding of 
how and where life arose.  Put very simply, the temperature and chemistry 
of these deep ocean vents makes certain synthetic reactions energetically 
easy, syntheses of certain molecules will take place here readily that 
would require enzymes, thus implying preexisting life, elsewhere.

If you are interested in this subject, a book by B. D. Dyer and R. A. Obar, 
Tracing the history of Eukaryotic cells: the enigmatic smile, provides a 
very good introduction for a knowledgeable reader.




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