Travel Reference
In-Depth Information
our own bilateral body plan, their left and right sides were sometimes mirror
images of each other. Convergence on this body plan happened repeatedly,
even though the cyber-creatures' ancestors had started out as dif erent ran-
dom and inef ectual collections of parts.
It is perhaps not coincidental that one of the earliest events in the evolu-
tion of animals, an event that happened long before the Cambrian, was the
emergence of bilateral symmetry from ancestors that had previously been
round or irregular in shape and that lacked a head or a tail. Bilateral symme-
try gives organisms the ability to move directionally through the environ-
ment. It seems to be a highly favored evolutionary path, both in Precambrian
organisms crawling across a mud sea bottom and in virtual organisms that
must make their way across a computer-generated surface.
Lipson and Pollack's experiment provides us with some guidance on
how to design our
Caenorhabditis
experiments. Because this worm is already
bilaterally symmetrical, we will have to select for other types of body-plan
changes. Perhaps collections of mutated
Caenorhabditis
could be selected for
the ability to wriggle quickly across a smooth surface, while at the same
time they are being buf eted by a current of water fl owing in the opposite
direction. Would we select for worms that can adhere to the surface, so that
they can wriggle forward despite the current? Or would we select for worms
with sail-like structures that would allow them to tack against the current?
The possibilities are endless. Perhaps we could create a world like the Pre-
cambrian one, in which it is possible to select for many dif erent body plans
simultaneously.
Closing the gap between scuba divers and cuttlefi sh
As I roamed the fl oor of the Lembeh Strait I met many radially and bilater-
ally symmetrical creatures that are the remote descendants of Precambrian
developmental mutants. When I locked gazes with my inconceivably distant
relative, the fl amboyant cuttlefi sh, I felt a kinship that reached across the 600
million years of accumulated genetic dif erences that separate us.
