Expansionary Institute

Michael Zey
futurist3000@aol.com

Virtual natural selection

Scientists have built a virtual world inside a computer and filled it with
"digital bugs". They think their special program can be used as a test bed
for theories in evolutionary biology.

In what has become a popular line of research, the digital bugs are
allowed to reproduce, mutate and compete for computer processing time, in
much the same way that real, living organisms compete for nutrients and
the energy that gives them.

Changes that might take millions of years to observe in the real world can
now be seen on a more useful time scale, according to the program's
creators, Richard Lenski and colleagues from the Michigan State University
in the US.

Another advantage over similar experiments involving fast-breeding
organisms like bacteria is that each minute step of evolution in each
digital bug can be recorded, so that a complete evolutionary history is
available.

Primordial soup

"This artificial world yields some of the same complexities we see in the
real living world, but we have trouble studying these complexities in
detail with the real organisms because the genetic experiments get too
complicated," Lenski said.
Inman Harvey of the University of Sussex in southern England has reviewed
the research, which appears in the journal Nature, and said the artificial
world is like a primordial soup.

"You've got these digital organisms evolving away and you can just pick
one out and measure how well it replicates. You can then take a clone and
put a mutation in."

Lenski said the marriage of computer science and biology allowed the
researchers to study what happened when organisms were exposed to more
than one genetic mutation.

Additive effects

"One of the questions, we wanted to ask...is whether the effects of
mutations can be understood in isolation or whether, if you have two
mutations, the combined effect might be different from the sum of the
two," Lenski said.

His team found that multiple 'mutations' occurring at random in the
digital organisms did not necessarily have simple additive effects on the
organisms' ability to multiply and carry out simple 'functions'.
Instead, as in real-life organisms, the different mutations interacted
with each other to affect performance in more unexpected ways.

They also found that the more complex digital bugs tended to show a
greater resistance to multiple mutations.

Different effects

"Simple bugs just got sicker and sicker. For the more complex ones, the
rate at which they got sicker began to slow down. The effects of combining
two mutations did have a different effect," Lenski said.

"Our results suggest that there might be some relation between sensitivity
to multiple mutations and genome size."

Some scientists remain to be convinced of the value of such virtual
worlds, doubting whether digital bugs are sufficiently sophisticated to
tell us anything useful about real-world evolution.
"If you can trust it to be valid, then you are laughing. However that is a
big if," said Inman Harvey. "Without a doubt, digital organisms mirror
living organisms in particular ways but the question is how far you can
push that.

"Some would say the experiments are useless...but I think that's too
extreme a view."

Virtual Evolution