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Wow! These things will become really sentient next! Fascinating!
Subject: Artificial life forms evolve and ouwit experimenter
If you want to find alien life-forms, hold off on booking that trip to the
moons of Saturn. You may only need to catch a plane to East Lansing,
Michigan.
The aliens of East Lansing are not made of carbon and water. They have no
DNA. Billions of them are quietly colonizing a cluster of 200computers in
the basement of the Plant and Soil Sciences building at Michigan State
University. To peer into their world, however, you have to walk a few blocks
west on Wilson Road to the engineering department and visit the Digital
Evolution Laboratory. Here you'll find a crew of computer scientists,
biologists, and even a philosopher or two gazing at computer monitors,
watching the evolution of bizarre new life-forms.
These are digital organisms-strings of commands-akin to computer viruses.
Each organism can produce tens of thousands of copies of itself within a
matter of minutes. Unlike computer viruses, however, they are made up of
digital bits that can mutate in much the same way DNA mutates. A software
program called Avida allows researchers to track the birth, life, and death
of generation after generation of the digital organisms by scanning columns
of numbers that pour down a computer screen like waterfalls.
After more than a decade of development, Avida's digital organisms are now
getting close to fulfilling the definition of biological life. "More and
more of the features that biologists have said were necessary for life we
can check off," says Robert Pennock, a philosopher at Michigan State and a
member of the Avida team. "Does this, does that, does this. Metabolism?
Maybe not quite yet, but getting pretty close."
One thing the digital organisms do particularly well is evolve." Avida is
not a simulation of evolution; it is an instance of it," Pennock says. "All
the core parts of the Darwinian process are there. These things replicate,
they mutate, they are competing with one another. The very process of
natural selection is happening there. If that's central to the definition of
life, then these things count."
It may seem strange to talk about a chunk of computer code in the same way
you talk about a cherry tree or a dolphin. But the more biologists think
about life, the more compelling the equation becomes. Computer programs and
DNA are both sets of instructions. Computer programs tell a computer how to
process information, while DNA instructs a cell how to assemble proteins.
The ultimate goal of the instructions in DNA is to make new organisms that
contain the same genetic instructions. "You could consider a living organism
as nothing more than an information channel, where it's transmitting its
genome to its offspring," says Charles Ofria, director of the Digital
Evolution Laboratory. "And the information stored in the channel is how to
build a new channel." So a computer program that contains instructions for
making new copies of itself has taken a significant step toward life.
A cherry tree absorbs raw materials and turns them into useful things. In
goes carbon dioxide, water, and nutrients. Out comes wood, cherries, and
toxins to ward off insects. A computer program works the same way. Consider
a program that adds two numbers. The numbers go in like carbon dioxide and
water, and the sum comes out like a cherry tree.
In the late 1990s Ofria's former adviser, physicist Chris Adami of Caltech,
set out to create the conditions in which a computer program could evolve
the ability to do addition. He created some primitive digital organisms and
at regular intervals presented numbers to them. At first they could do
nothing. But each time a digital organism replicated, there was a small
chance that one of its command lines might mutate. On a rare occasion, these
mutations allowed an organism to process one of the numbers in a simple way.
An organism might acquire the ability simply to read a number, for example,
and then produce an identical output.
Adami rewarded the digital organisms by speeding up the time it took them to
reproduce. If an organism could read two numbers at once, he would speed up
its reproduction even more. And if they could add the numbers, he would give
them an even bigger reward. Within six months, Adami's organisms were
addition whizzes. "We were able to get them to evolve without fail," he
says. But when he stopped to look at exactly how the organisms were adding
numbers, he was more surprised. "Some of the ways were obvious, but with
others I'd say, 'What the hell is happening?' It seemed completely insane."
On a trip to Michigan State, Adami met microbiologist Richard Lenski, who
studies the evolution of bacteria. Adami later sent Lenski a copy of the
Avida software so he could try it out for hims
