Bit by Bit:
The Darwinian Basis of Life
All known
examples of life belong to the same biology, but there is increasing enthusiasm
among astronomers, astrobiologists, and synthetic biologists that other forms
of life may soon be discovered or synthesized. This enthusiasm should be
tempered by the fact that the probability for life to originate is not known.
As a guiding principle in parsing potential examples of alternative life, one
should ask: How many heritable “bits” of information are involved, and where
did they come from? A genetic system that contains more bits than the number
that were required to initiate its operation might reasonably be considered a
new form of life.
Thanks to a
combination of ground- and space-based astronomical observations, the number of
confirmed extrasolar planets will soon exceed 1,000. An increasing number of
these will be said to lie within the “habitable zone” and even be pronounced as
“Earth-like.” Within a decade there will be observational data regarding the
atmospheric composition of some of those planets, and just maybe those data
will indicate something funny going on—something well outside the state of
chemical equilibrium—on a potentially hospitable planet. Perhaps our astronomy
colleagues should be forgiven for their enthusiasm in declaring that humanity
is on the brink of discovering alien life.