Self And The Phenomenon Of Life: A Biologist Examines Life From Molecules To Humanity

Self and the Beginning of Life 57

“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity

temperatures and pressures. He could have spent a lifetime on the prob-
lem and gotten nowhere. No one else seemed to have any good ideas
either. ”^69 Kauffman himself also conceded, “Central to this is a missing
theory of organization...My difficulty in constructing such a theory is, at
least, that I cannot see how to begin...Yet the biosphere, for 4.8 billion
years, has been doing just this.”^67 A verifiable law for naturally occurring
complexity is yet to be found.

3.20 An Aside: A Model for Molecular Self-assembly
using Synthetic “Organic Bricks”

In an experiment unrelated to genetics, a model for self-assembly
has been demonstrated using single-stranded DNA as construction
“bricks”. DNA strands of 32 nucleotides long, containing four regions
that can hybridize (by Watson-Crick base pairing) to four neighboring
DNA strands, were synthesized and used like LEGO bricks. Arbitrarily
prescribed 3-D structures were formed by selecting different subsets
of strands from the same pool of DNA sequences. The generality and
diversity of the method was demonstrated by creating 102 different
structures out of a subset of 10 × 10 × 10 voxel cuboid. Each voxel cor-
responds to 8-base pair interaction between bricks or the equivalent of
a one-stud LEGO brick.^70 This interesting model shows that complexity
can come from simple principles. Nevertheless, the model falls short of
being spontaneous, as it was designed by human intelligence.

3.21 What have we Learned about the Origin of Life?

Over the last fifty years, substantial progress has been made on formu-
lating hypotheses on the beginning of life on Earth. However, we are far
from putting the pieces together to arrive at a coherent picture. Deep
gaps still exist, preventing us from making sensible connections among
isolated clues. Obviously it would be impossible to re-enact the entire
process in the laboratory. Even if we are lucky enough to witness the