(JP)Walking upright stimulates brain of monkey

[Guest guest]

Walking upright stimulates brain of monkey

 

Dec 18, 2001

Jun Sugimori Yomiuri Shimbun Staff Writer

 

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 2-1/2 years.

 

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 day.

 

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

intelligence.

 

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 fours.

 

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 the elderly.

 

It has been reported that about 5 percent of the

elderly population have experienced falls and nearly

half of the these falls have resulted in bone

fractures, some of which leave the patient bedridden.

 

To avoid falls, 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 causes 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.

 

Copyright 2001 The Yomiuri Shimbun

 

 

 

 

 

 

 

Check out Shopping and Auctions for all of

your unique holiday gifts! Buy at

or bid at http://auctions.