Navigation Links
The secret to chimp strength
Date:3/30/2009

February's brutal chimpanzee attack, during which a pet chimp inflicted devastating injuries on a Connecticut woman, was a stark reminder that chimps are much stronger than humansas much as four-times stronger, some researchers believe. But what is it that makes our closest primate cousins so much stronger than we are? One possible explanation is that great apes simply have more powerful muscles. Indeed, biologists have uncovered differences in muscle architecture between chimpanzees and humans. But evolutionary biologist Alan Walker, a professor at Penn State University, thinks muscles may only be part of the story.

In an article to be published in the April issue of Current Anthropology, Walker argues that humans may lack the strength of chimps because our nervous systems exert more control over our muscles. Our fine motor control prevents great feats of strength, but allows us to perform delicate and uniquely human tasks.

Walker's hypothesis stems partly from a finding by primatologist Ann MacLarnon. MacLarnon showed that, relative to body mass, chimps have much less grey matter in their spinal cords than humans have. Spinal grey matter contains large numbers of motor neuronsnerves cells that connect to muscle fibers and regulate muscle movement.

More grey matter in humans means more motor neurons, Walker proposes. And having more motor neurons means more muscle control.

Our surplus motor neurons allow us to engage smaller portions of our muscles at any given time. We can engage just a few muscle fibers for delicate tasks like threading a needle, and progressively more for tasks that require more force. Conversely, since chimps have fewer motor neurons, each neuron triggers a higher number of muscle fibers. So using a muscle becomes more of an all-or-nothing proposition for chimps. As a result, chimps often end up using more muscle than they need.

"[A]nd that is the reason apes seem so strong relative to humans," Walker writes.

Our finely-tuned motor system makes a wide variety of human tasks possible. Without it we couldn't manipulate small objects, make complex tools or throw accurately. And because we can conserve energy by using muscle gradually, we have more physical endurancemaking us great distance runners.

Great apes, with their all-or-nothing muscle usage, are explosive sprinters, climbers and fighters, but not nearly as good at complex motor tasks. In other words, chimps make lousy guests in china shops.

In addition to fine motor control, Walker suspects that humans also may have a neural limit to how much muscle we use at one time. Only under very rare circumstances are these limits bypassedas in the anecdotal reports of people able to lift cars to free trapped crash victims.

"Add to this the effect of severe electric shock, where people are often thrown violently by their own extreme muscle contraction, and it is clear that we do not contract all our muscle fibers at once," Walker writes. "So there might be a degree of cerebral inhibition in people that prevents them from damaging their muscular system that is not present, or not present to the same degree, in great apes."

Walker says that testing his hypothesis that humans have more motor neurons would be fairly straightforward. However, he concedes that testing whether humans have increased muscle inhibition could be a bit more problematic.


'/>"/>

Contact: Kevin Stacey
kstacey@press.uchicago.edu
773-834-0386
University of Chicago Press Journals
Source:Eurekalert

Related biology news :

1. Scientists discover important beauty secret for balanced skin color and tone
2. MIT unraveling secrets of red tide
3. Scientists eye secrets of retinal regeneration
4. NMR researchers unlock hydrogens secrets to spot polymorphism in pharmaceuticals
5. Scientists gather in New Zealand to share oceans secrets
6. New study uncovers secrets behind butterfly wing patterns
7. The key to unlocking the secret of highly specific DNAzyme catalysis
8. Eat chocolate, drink wine, add fun to life: SLU geriatrician shares secrets of staying young
9. Ripening secrets of the vine revealed
10. New research to decode the genetic secrets of prolific potato pest
11. Research reveals secrets of alcohols effect on brain cells
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/14/2017)... June 15, 2017  IBM (NYSE: IBM ) is introducing ... event dedicated to developing collaboration between startups and global businesses, ... 15-17. During the event, nine startups will showcase the solutions ... various industries. France ... market, with a 30 percent increase in the number of ...
(Date:5/16/2017)... DALLAS , May 16, 2017   ... for health organizations, and MD EMR Systems ... certified development partner for GE, have established a ... Patient Portal product and the GE Centricity™ products, ... Centricity EMR. These new integrations ...
(Date:4/19/2017)... April 19, 2017 The global ... landscape is marked by the presence of several large ... held by five major players - 3M Cogent, NEC ... accounted for nearly 61% of the global military biometric ... in the global military biometrics market boast global presence, ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... , ... October 11, 2017 , ... Disappearing forests and ... lives of over 5.5 million people each year. Especially those living in larger cities ... Treepex - based in one of the most pollution-affected countries globally - decided to ...
(Date:10/10/2017)... ... October 10, 2017 , ... For the second ... a US2020 STEM Mentoring Award. Representatives of the FirstHand program travelled to Washington, ... from US2020. , US2020’s mission is to change the trajectory of STEM education ...
(Date:10/10/2017)... ... October 10, 2017 , ... The Pittcon Program ... honoring scientists who have made outstanding contributions to analytical chemistry and ... 2018, the world’s leading conference and exposition for laboratory science, which will be ...
(Date:10/9/2017)... ... October 09, 2017 , ... ... journal, Epilepsia, Brain Sentinel’s SPEAC® System which uses the surface electromyography (sEMG) ... tonic-clonic seizures (GTCS) using surface electromyography (sEMG). The prospective multicenter phase III ...
Breaking Biology Technology: