How do genetic systems gain information by evolutionary processes?
Answering this question precisely requires a robust, quantitative
measure of information.
Fortunately, fifty years ago Claude Shannon defined information
as a decrease in the uncertainty of a
receiver.
For molecular systems,
uncertainty is closely related to entropy
and hence has clear connections to the Second Law
of Thermodynamics.
These aspects of information theory have allowed
the development of a straightforward and practical
method of measuring information in genetic control
systems.
Here this method
is used to observe information gain in the binding sites
for an artificial `protein' in a computer simulation of evolution.
The simulation begins with zero information and,
as in naturally occurring genetic systems,
the information measured in the fully evolved binding sites is close
to that needed to locate the sites in the genome.
The transition is rapid, demonstrating that
information gain can occur by punctuated equilibrium.