Brain differences between humans and chimpanzees linked to aging

July 25, 2011, George Washington University

Chimpanzees, the closest living relatives to humans, do not experience a decrease in brain volume as they age like humans do, according to a study by George Washington University researcher Chet Sherwood and his colleagues. There are many similarities between the species, but this discovery reveals an important distinction, demonstrating how humans are unique from other animals. The study "Aging of the Cerebral Cortex Differs Between Humans and Chimpanzees" is the first study of its kind in this field and will be published in the Proceedings of the National Academy of Sciences on July 25, 2011.

“Although other animals experience some cognitive impairment and brain atrophy as they age, it appears that human aging is marked by more dramatic degeneration,” said Dr. Sherwood, associate professor of anthropology in GW’s Columbian College of Arts and Sciences.
The researchers used magnetic resonance imaging (MRI) to measure the volume of the whole brain and numerous specific internal structures using a sample of 99 chimpanzee brains ranging from 10-51 years of age. This data were compared to brain structure volumes measured in 87 humans ranging from 22-88 years of age.

Measurements of the neocortical gray and white matter, frontal lobe gray and white matter and the hippocampus were performed. In contrast to humans, who showed a decrease in the volume of all brain structures over the lifespan, did not display significant age-related changes. Furthermore, the effects of aging in humans were only evident after the maximum age of chimpanzees. As a result, the researchers concluded that the brain shrinkage seen in human aging is evolutionarily novel and is the result of an extended lifespan.

The hippocampus, the area of the brain responsible for encoding new memories and maintaining spatial navigation, was of specific interest to the researchers, as this area is especially vulnerable to age-associated atrophy in humans. In addition, the hippocampus is the region of the brain most prominently affected by Alzheimer’s disease (AD), an illness that is only seen in primarily older humans. AD is a form of dementia that is associated with a loss of brain function, impacting memory, thinking and behavior. AD is a result of neurodegeneration, which is the progressive loss of structure or function of neurons, including the death of neurons. The unique vulnerability seen in humans to develop AD may be in part due to the human tendency to show more pronounced brain atrophy than any other species, even in normal, healthy aging.
“What’s really unusual for humans is the combination of an extremely long life and a large ,” said Dr. Sherwood. “While there are certainly benefits to both of these adaptations, it seems that more intense decline in in the elderly of our species is a cost.”

Established in 1821 in the heart of the nation’s capital, the George Washington University Columbian College of Arts and Sciences is the largest of GW’s academic units. It encompasses the School of Media and Public Affairs, the Trachtenberg School of Public Policy and Public Administration and more than 40 departments and programs for undergraduate, graduate and professional studies. The Columbian College provides the foundation for GW’s commitment to the liberal arts and a broad education for all students. An internationally recognized faculty and active partnerships with prestigious research institutions place Columbian College at the forefront in advancing policy, enhancing culture and transforming lives through research and discovery.

In the heart of the nation's capital with additional programs in Virginia, the George Washington University was created by an Act of Congress in 1821. Today, GW is the largest institution of higher education in the District of Columbia. The university offers comprehensive programs of undergraduate and graduate liberal arts study, as well as degree programs in medicine, public health, law, engineering, education, business and international affairs. Each year, GW enrolls a diverse population of undergraduate, graduate and professional students from all 50 states, the District of Columbia and more than 130 countries.

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More information: "Aging of the cerebral cortex differs between humans and chimpanzees," by Chet C. Sherwood et al.

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6 comments

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TheGhostofOtto1923
1.2 / 5 (6) Jul 25, 2011
This is because the human brain is not natural. It is the result of chronic tribal warfare brought about by the elimination of one natural attritive element after another. Humans became their own greatest enemy due to the resultant pop pressure.

The tribes which prevailed were the ones which could out-strategize the enemy, the ones which could best anticipate an enemys movements and perceive its weaknesses, and take advantage of them.

These superior thinkers got to absorb the females of the vanquished tribes and propagate their kind.

This forced evolution produced oversized brains which are energy-hungry, prone to damage and defect, and which begin to deteriorate shortly after adolescence. Humans also have the greatest intelligence spread of any species, due in part to the absence of natural selective elements which preyed upon the weak and the dim.

But defect and damage are the norm. This 'disease' of evolution can explain the bulk of crime. greed, psychosis, and religion.
ziphead
5 / 5 (1) Jul 25, 2011

This is because the human brain is not natural. It is the result of chronic tribal warfare brought about by the elimination of one natural attritive element after another.
The tribes which prevailed were the ones which could out-strategize the enemy, the ones which could best anticipate an enemys movements and perceive its weaknesses, and take advantage of them.

These superior thinkers got to absorb the females of the vanquished tribes and propagate their kind...blah, blah...


... Which (if true in its entirety) would have begged the question: under which rock did your "kind of the kind" managed to survive this evolutionary armageddon.
And more importantly, what makes you sure that it is safe to now crawl out?
RobertKarlStonjek
5 / 5 (2) Jul 26, 2011
Chimp brains come pre-shrunk...
TheGhostofOtto1923
1 / 5 (5) Jul 26, 2011
... Which (if true in its entirety) would have begged the question: under which rock did your "kind of the kind" managed to survive this evolutionary armageddon.
And more importantly, what makes you sure that it is safe to now crawl out?
I assume you take issue with something in my posting ziphead. Exactly what might that be? Maybe you need to borrow a less damaged brain in order to properly formulate a response? Maybe?

You may not like what I posted but I assure you it is all, unfortunately, TRUE. Ziphead.
ziphead
5 / 5 (1) Jul 27, 2011
... Which (if true in its entirety) would have begged the question: under which rock did your "kind of the kind" managed to survive this evolutionary armageddon.
And more importantly, what makes you sure that it is safe to now crawl out?
I assume you take issue with something in my posting ziphead. Exactly what might that be? Maybe you need to borrow a less damaged brain in order to properly formulate a response? Maybe?

You may not like what I posted but I assure you it is all, unfortunately, TRUE. Ziphead.


Ouch, TRUTH hurts, especially with caps in it.
You spewed out initial 1000 char rant, and now you wanna analyze me?

VOR
not rated yet Aug 02, 2011
Civilization has obviously removed many evolutionary pressures on humans (and perhaps added a few). I recently heard (think it was NPR) also that in absense of that pressure, random mutations are left to actually very slowly de-evlove us, and are increased by modern enviromental exposures.

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