Enter your name and a friend's email address in the fields below and click "Submit" to email this Press Release to a friend.
Your message will look like this:
[YOUR NAME HERE] thought you might be interested in this story from the University of Rochester.
MEDIA CONTACT: Tom Rickey, (585) 275-7954, or Eldridge Adams, (585) 275-3007
September 25, 1995
Do Animals "Lie"? Yes, Even to Their Own Kind, Biologist Says
When in a tight spot, animals "lie" to their own kind to get
what they want, a University of Rochester biologist has found. In
work described in the current issue of the Journal of Theoretical
Biology, Eldridge Adams shows that within a single species, it is
possible for some members to deceive others.
By proving that the weaker are able to deceive the stronger
to survive, Adams' findings runs counter to a common belief by
biologists that communication within a species must always be
reliable and honest.
"We've shown that the communication is not always reliable,
and that in theory, you shouldn't expect it to be," says Adams,
who began the work as a graduate student at the University of
California at Berkeley.
Biologists have long recognized that deception is
commonplace in communication between different species. But most
believed bluffing among animals of a single species should be
rare or impossible.
To demonstrate how widespread deception between members of
the same species could be, Adams watched hundreds of
confrontations between two-inch, crayfish-like stomatopod
crustaceans, whose bluffing was originally observed by behavioral
ecologists Roy Caldwell and Rick Steger. Working with co-author
Michael Mesterton-Gibbons of Florida State University, Adams
modeled a confrontation mathematically and proves in a game
theory model that bluffing is possible in a stable communication
Adams studied one species of stomatopod crustacean,
Gonodactylus bredini, in Panama while doing graduate work under
Caldwell. The creatures, known to sushi connoisseurs as mantis
shrimp, live in cavities in shallow, tropical waters.
Stomatopods typically compete over these cavities, and when
a confrontation looms, they can either flee or fight. If the
creature chooses to fight, it often invokes a threat display,
holding its appendages out to the side and lifting its head
aggressively. If the opponent chooses to fight, the creatures use
their appendages to whack each other with considerable force.
(Stomatopods are good at this: They regularly beat senseless
crabs and other hard sea creatures before cracking the shells
open and gulping them down; their striking force is so great that
marine biologists have nicknamed them "thumb busters.")
If threats were always honest, or reliable, only the
strongest creatures -- those able to back up a threat with deadly
force -- would menace others. But both the strongest and the
weakest stomatopods threaten. In fact, creatures rely on threats
most when they are weakest: immediately after molting, when their
new skeleton is still hardening up and they don't even have hard
appendages capable of crushing an opponent. "These threats often
drive off opponents," says Adams, "yet they're certainly not
reliable. These animals are bluffing, and they would be readily
killed in a fight."
Biologists have long thought that such widespread bluffing
wasn't possible in a stable communication system. If weak animals
use threats deceptively, they reasoned, threats would become so
common that the communication system would quickly break down
because other animals wouldn't pay attention to any threats,
whether real or deceptive. Adams and Mesterton-Gibbons have shown
that a system can remain stable even though some members bluff
Adams likens the phenomenon to a game of draw poker between
two people. "Each person knows his or her own strength, but not
the strength of the opponent. Sometimes the optimal strategy is
to threaten the opponent by raising the stakes, even though you
have a weak hand."
This work was funded by the Smithsonian Institution and the
About the University of Rochester
The University of Rochester (www.rochester.edu) is one of the nation's leading private universities. Located in Rochester, N.Y., the University gives students exceptional opportunities for interdisciplinary study and close collaboration with faculty through its unique cluster-based curriculum. Its College of Arts, Sciences, and Engineering is complemented by the Eastman School of Music, Simon School of Business, Warner School of Education, Laboratory for Laser Energetics, Schools of Medicine and Nursing, and the Memorial Art Gallery.