256
The Body Electric
years after the world itself was born. The atmosphere then was com-
pletely different, much like Jupiter's today, mostly ammonia and meth-
ane. Into that atmosphere some source of energy—lightning, heat, and
ultraviolet radiation have all been suggested—led to the spontaneous
formation of simple organic compounds. Sifting into the oceans for mil-
lions of centuries, these compounds would have coalesced by chance into
ever more elaborate patterns. According to the theory, this process
culminated in closed "protocells" able to resist the reactivity of other
structures while growing through incorporation of similar compounds.
This idea owes its dominance largely to an important experiment made
by S. L. Miller in 1953. Miller pumped a facsimile of the presumed early
atmosphere—ammonia, methane, and water vapor—continuously past an
electric spark. After several days he had some amino acids. Since these are
the bricks of DNA, RNA, and all proteins, the evidence seemed very good.
Later runs yielded even more sophisticated molecules. In water they co-
alesced into globules with a sort of membrane around them—called
"coacervates" by A. I. Oparin and "proteinoids" by Sidney Fox, two of the
most assiduous students of biogenesis.
Nothing came close to being alive in any of these spark chambers,
however. More important, the experiments raised two difficulties, one
theoretical, one practical. The soup theory needed to come up with a
very sophisticated entity, a living cell with some genetic system using
DNA or RNA, right off the bat. According to our notions of biology,
nothing could be alive before that point, yet it seemed incredible that
chance associations of the building blocks could form a palace of such
complexity without passing through a mud-hut stage.
When the warm soup theory was first advanced, the mechanistic per-
suasion was at its height. Living things were complicated machines, but
molecular machinery they were. However, the concept of a cell was
much simpler than it is today. No longer is it considered a mere baglet
of jelly with a few master molecules telling it what to do. Even the
membrane of the simplest bacterium responds in intricate ways to infor-
mation from outside, yet our best electron microscopes haven't yet re-
vealed a complexity of structure adequate to explain its work.
There was a basic chemical problem as well. All organic compounds
exist in two forms, or isomers. Each contains the same number and type
of atoms, but in one they're arranged as a mirror image of the other.
One is "right-handed" and the other is "left-handed." They're identified
by the way they bend light in solution. The dextrorotatory (D) forms
rotate it to the right, while levorotatory (L) isomers refract it to the left.
All artificial methods of synthesizing organic compounds - including