Dr. Thompson peered inside his perfect offspring to gain insight into
its methods, but what he found inside was baffling.  The plucky chip
was utilizing only thirty-seven of its one hundred logic gates, and most
of them were arranged in a curious collection of feedback loops.  Five
individual logic cells were functionally disconnected from the rest—
with no pathways that would allow them to influence the output— yet when
the researcher disabled any one of them the chip lost its ability to
discriminate the tones.  Furthermore, the final program did not work
reliably when it was loaded onto other FPGAs of the same type.

It seems that evolution had not merely selected the best code for the
task, it had also advocated those programs which took advantage of the
electromagnetic quirks of that specific microchip environment.  The five
separate logic cells were clearly crucial to the chip’s operation, but
they were interacting with the main circuitry through some unorthodox
method— most likely via the subtle magnetic fields that are created when
electrons flow through circuitry, an effect known as magnetic flux.
 There was also evidence that the circuit was not relying solely on the
transistors’ absolute ON and OFF positions like a typical chip; it was
capitalizing upon analogue shades of gray along with the digital black
and white.