Walking upright stimulates brain of monkey
alexs19 at hotmail.com
Wed Jan 9 10:02:30 EST 2002
This article was in a paper here in Japan that I thought it might fit the
The Daily Yomiuri
Tuesday, December 18, 2001
Jun Sugimori, Yomiuri Shimbun Staff Writer
Walking upright stimulates brain of monkey
Monkeys walking on two feet have long been an integral part of circus
acts. The way they waddle from side to side appeals to our sense of comedy.
Now, however, Prof. Shigemi Mori and other researchers at the National
Institute for Physiological Sciences have succeeded in training monkeys to
walk erect smoothly, as humans do, by working with them from the age of 2
Through this research, the scientists have learned that there is a
considerable difference in brain function when an animal walks bipedally and
when it walks on all fours.
The researchers expect their findings to provide clues as to the
influence of bipedalism on the evolution of the human brain.
At the beginning of the project, Mori's group helped the monkeys stand
up by having people support them with their hands.
Then the researchers tried to have the monkeys learn how to walk on a
treadmill in their laboratory. They walked for 30 minutes to an hour every
About two months later, the monkeys had achieved a rudimentary ability
to walk bipedally, although only very slowly at the beginning.
Seven months after the experiment began, the monkeys were able to walk
at much higher speeds.
When they walk, they skillfully use the joints of their knees and the
tips of their toes. The instability of their vertical axes that had caused
their bodies to waver from left to right decreased significantly. Their
posture came to resemble more that of young children, with straight spines,
and they developed more muscles along the inner thigh, also helping to
smooth out their gait.
After two years of training, the monkeys have developed S-shaped
backbones, very similar to human ones. Their weight is fully supported by
their two feet, showing that their bodies have adjusted to bipedalism.
As their bodies changed physically, the monkeys found ways to further
enhance their ability to walk. They have learned how to change the length of
their stride as well as how to adjust slightly their center of gravity in
relation to the steepness of slopes.
The monkeys even avoid obstacles in their way by raising their feet
higher. When they stumble against something, they are able to balance their
weight with their hands, recovering their equilibrium. In the case of
obstacles, the monkeys prepare for them by raising their legs higher than
usual. This anticipatory movement is believed to require a high level of
In the project, the researchers, in cooperation with instrument maker
Hamamatsu Photonics K.K., examined what part of the brain the monkeys mainly
used when they walked upright. As bipedalism increased, a certain area of
the brain that handles relatively sophisticated processing saw more action.
More activities were recorded in the motor area that gives instructions
for physical movement and in the visual area that handles visual information
in the cerebral cortex when the monkeys walked upright rather than on all
Researchers said this seems to show that bipedalism altered the way the
monkeys used their brains.
"They have been reluctant to walk on all fours, and they look more
lively when they walk on two legs," Mori said. "There might also have been
an increase in intelligence."
It is believed that human beings developed intelligence after the
cerebral cortex enlarged as bipedalism increased.
Mori said: "The brain controls movement of the hands and legs. But
physical movement also has an effect on the brain, enhancing development. By
chronologically examining changes in the function of the brain as the
ability to walk bipedally develops, we'll be able to understand how humans
developed intelligence upon receiving various stimuli during evolution."
The research on bipedalism in monkeys is believed to be helpful in the
study of the development of babies' brains and the prevention of falls in
It has been reported that about 5 percent of the elderly population have
experienced falls and nearly half of these falls have resulted in bone
fractures, some of which leave the patient bedridden.
To avoid fall, the ability to anticipate obstacles and balance one's
weight are necessary.
A decline in these abilities, in conjunction with failing eyesight and
lack of exercise, are believed to be the main cause of falls.
"By thoroughly examining the difference in the function of the brains of
monkeys who walk erect and monkeys who use all four limbs, I hope to fight
the decline of the power of memory or recognition among the elderly, as well
as work toward the prevention of falls," Mori said.
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