Just what you always suspected about corvids ...
http://www.nature.com/nsu/040322/040322-6.html
Crows switch sides to use tools
Study suggests brain differences between making and using tools.
24 March 2004
LAURA NELSON
Crows use different sides of their beaks to make and use tools,
researchers have found. This suggests that different parts of the brain
may control making and using tools, and that the biology of handedness
- or beakedness - may be more complex than we thought.
Just like humans, New Caledonian crows are usually right 'handed' when
it comes to tasks such as making tools. But it turns out the birds use
their tools with left and right sides equally, although individual
crows prefer one side or the other.
"This has opened up Pandora's box," says William McGrew, who studies
chimpanzees' tool use at Miami University. "People always assumed
handedness would be the same for using and making tools." Scientists
will now be more wary of making this assumption, he adds.
Counting crows
New Caledonian crows ( Corvus moneduloides ) are proficient tool users,
extracting insects from holes and crevices using elegant hooks made
from leaves.
"Crows are more competent tool users than even chimpanzees," says
zoologist Alex Weir of the University of Oxford, who led the study
published in Proceedings of the Royal Society of London 1. They also
appear to have a different set of rules for handedness than people and
chimps, he says.
Previous research has shown that crows usually attack the left side of
a leaf, using their right eye and the right side of their beak.
Weir's team went one step further and watched ten birds using their
tools. Five leaned the tool to the left, and five to the right, they
found. Each crow almost always stuck to one side.
Making and using tools may require different sets of muscles and brain
signals, says McGrew.
About 90% of people prefer to use their right hand for writing and
other tasks; no one is sure why. Most researchers think the preference
depends on which side of the brain controls each job. There could also
be social reasons, such as being able to write without smudging ink.
Other animals, such as chimpanzees, have individual biases for
handedness without showing an overall bias for the species.
References
Alex, A. S., Weir, B. K., Chappell, J. & Kacelnik, A. B. A .
Proc. R. Soc. Lond. B , published online, doi:10.1098/rsbl.2004.0183
(2004). |Article|
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