MadSci Network: General Biology

Re: will observational science ever be able to explain the origin of life

Date: Sun May 27 19:44:10 2007
Posted By: Keith Jones, Faculty, Pharmacology and Cell Biophysics, University of Cincinnati
Area of science: General Biology
ID: 1178329357.Gb

Observational science DOES explain the origin of life from non-living
substances, in the form of hypothesis and theory (more on that later).  Now, if
the question were can observational science  PROVE that how life derived from
non-living substances, that is tougher.  Short of a time machine (never say
never) to actually go back and observe this may well be impossible.

THE THEORY  Many scientists have worked for decades and results support the
chemosynthetic theory of the origin of living cells from pre-biotic substances.
This theory states that under the right circumstances, non-organic molecules can
randomly, with addition of energy in the form of UV or electricity, form simple
organic molecules such as amino acids (the building blocks of proteins).
Experiments done in the lab by Stanley Miller and Harold Urey (Miller, 1959) 
demonstrated that this is indeed possible.  Under the right conditions, these
amino acids may combine to form simple peptides.  Some of these peptides do have
biochemical activity (this is the nature of peptides) and, it is thought, some
had a crude capacity to mediate copying of themselves.  Thus began pre-biotic
evolution.  You can see how such peptides would quickly predominate, and how
more efficient versions would be able to replace less efficient.  The details 
of pre-biotic evolution are still being worked out and only some of the proposed
"steps" have been replicated in the lab, hey but that's a good start! 
Gradually, nucleic acids, randomly formed from organic precursors that must have
been generated much like amino acids, gained from association with peptides and
with lipids, and primitive pre-biotic "cells", wherein the nucleic acids could
help the peptide synthesis and perhaps vice-versa became prominent.  Now, it is
just a short leap to life; these pre-biotic organized macromolecules had to
develop the ability to grow and convert energy or food into growth (metabolism),
the ability to adapt to acute changes in environment, the ability to reproduce
and the ability to adapt to chronic changes in environment by natural selection.
These abilities separate the living from the non-living, but the living likely 
"evolved" from the non-living via chemosynthesis.  

Now, can science prove this?  Even if we could duplicate every step in the lab,
some people would still not believe this is the proper explanation for the
origin of life.  Nevertheless, these theories seem the best explanation of the
HOW life formed that we have.  Science cannot and does not attempt to address
the WHO DONE IT aspect of the origin of life.  Leave that 
to your friend.

MILLER SL, UREY HC. Organic compound synthesis on the primitive earth.
Science. 1959 Jul 31;130(3370):245-51.

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