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Handedness



I already deleted the exchange, but in the posts of today (3/25) I
brought up handedness in regards to asymmetries in birds.

This just in:

http://www.nature.com/nsu/040322/040322-6.html

Crows switch sides to use tools
Study suggests brain differences between making and using tools. 

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.
...
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.
...


(I kinda doubt that this would produce the kind of asymmetry mentioned
here, tho)