Japanese engineer mice that don't fear cats
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could be a thing of the past with genetically modified "fearless" mice
that Japanese scientists say shed light on mammal behavior.
Using genetic engineering, scientists at Tokyo University say they
have successfully switched off the rodents' instinct to cower at the
smell or presence of cats -- showing that fear is genetically
hardwired and not learned through experience, as commonly believed.
"Mice are naturally terrified of cats, and usually panic or flee at
the smell of one. But mice with certain nasal cells removed through
genetic engineering didn't display any fear," said research team
leader Ko Kobayakawa.
"The mice approached the cat, even snuggled up to it and played with
it," Kobayakawa said. "The discovery that fear is genetically
determined and not learned after birth is very interesting, and goes
against what was previously thought."
The findings suggest that human aversion to dangerous smells like that
of rotten food, for example, could also be genetically predetermined,
he said.
Kobayakawa said his findings, published in the science magazine Nature
last month, should help researchers shed further light on how the
brain processes information about the outside world.