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Chimp Brains Don’t Shrink with Age

Unlike human brains, chimpanzee brains don’t get smaller as they age, suggesting that pronounced neurological decline is a uniquely human byproduct of our oversized brains and extreme longevity.

By | July 25, 2011

Tanzanian chimpanzeeFLICKR, NILS RINALDI

The brains of chimpanzees don’t undergo a general reduction in volume as the animals age, a sign of general cognitive decline that humans experience. The finding, published today (July 25) in Proceedings of the National Academy of Sciences, suggests that extreme neurological degeneration is the price humans pay for having evolved big brains and long life spans.

“Human beings and chimpanzees follow a similar lifespan in absolute years until you get late in life, and then humans have somehow managed to extend our lifespan,” said anthropologist and neuroscientist Todd Preuss of the Yerkes National Primate Research Center in Atlanta, who was not involved in the study. This study shows that during those extra years, we experience a sharper downturn in brain function, he added.

Many species experience subtle brain decline as they age, but in humans the process of neuronal degeneration is so extreme that it leads to a 10 to 15 percent decline in brain volume over the lifetime, said study author Chet Sherwood, an anthropologist at George Washington University in Washington, D.C.

To see whether this brain shrinkage occurred in other animals, Sherwood and his colleagues looked to our closest living relatives, chimpanzees. The team used MRI to measure the volume of 87 human brains, ranging in age from 22 to 88 years, and 99 10- to 51-year-old chimpanzee brains.

Unlike the human organs, which started to shrink when the subjects were in their mid-40s and decrease in size more dramatically after 70, chimpanzee brains didn’t shrink at all with age. This suggests that the shrinkage humans experience is primarily attributable to the extra 40 years of life that humans enjoy beyond the average ape lifespan of 45, Sherwood said.

Furthermore, because human brains are 3.5 times bigger than chimpanzee’s, human brains use much more energy and generate a greater amount of damaging oxidizing chemicals as a result. The production of oxidizing chemicals and the longer timespan during which they can accumulate can explain the damage that causes the extreme cognitive decline in our old age, Sherwood said.

Elephants and whales can live as long as humans and also have much bigger brains than their close relatives, so it would be really interesting—if impractical—to see if they undergo similar brain shrinkage as they age, he added.

But the cognitive decline associated with living longer may have been balanced by the benefits of increased lifespan, such as providing a greater opportunity to transfer knowledge to the next generation or allowing grandparents to help rear their children’s offspring, Preuss said.

C. Sherwood, et. al, "Aging of the cerebral cortex differs between humans and chimpanzees," PNAS,  doi:10.1073/pnas.1016709108, 2011.

Correction: This story has been updated from its original version to correctly note that Chet Sherwood is at George Washington University, not Emory University. The Scientist regrets the error.

 

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Anonymous

July 26, 2011

Chet Sherwood is at GWU not Emory.

Avatar of: Robert Karl Stonjek

Anonymous

July 26, 2011

Chimp brains come pre-shrunk...

Avatar of: STRMcHugh

Anonymous

July 26, 2011

The piece notes that :

"This
suggests that the shrinkage humans experience is primarily attributable to the
extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said.

"...the
cognitive decline associated with living longer... ", Preuss said.

To fear that the gods will punish you if you do better than average is a common superstition dating back thousands of years as can be seen by looking it up in Frazier's The Golden Bough. Charming as it is as a folk practice, it is nothing short of gobsmacking to find this superstition surfacing in a scientific paper.

Avatar of: Gzpenguin

Anonymous

July 26, 2011

"Unlike the human organs, which started to shrink when the subjects were in their mid-40s . . . chimpanzee brains didn’t shrink at all with age. This suggests that the shrinkage humans experience is primarily attributable to the extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said."

If it starts in humans but not in chimps during a period that is considered comparable, then how is it caused by the later period that is not comparable?

Avatar of: janicej

Anonymous

July 26, 2011

Instead of blaming brain size, blame the environment.  The study looked at lab chimps that live in the required sterile surroundings for laboratory animals.  They are not exposed to the immune challenges, or diverse stresses and food additives that humans are. 

Avatar of:

Posts: 0

July 26, 2011

Chet Sherwood is at GWU not Emory.

Avatar of:

Posts: 0

July 26, 2011

Chimp brains come pre-shrunk...

Avatar of:

Posts: 0

July 26, 2011

The piece notes that :

"This
suggests that the shrinkage humans experience is primarily attributable to the
extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said.

"...the
cognitive decline associated with living longer... ", Preuss said.

To fear that the gods will punish you if you do better than average is a common superstition dating back thousands of years as can be seen by looking it up in Frazier's The Golden Bough. Charming as it is as a folk practice, it is nothing short of gobsmacking to find this superstition surfacing in a scientific paper.

Avatar of:

Posts: 0

July 26, 2011

"Unlike the human organs, which started to shrink when the subjects were in their mid-40s . . . chimpanzee brains didn’t shrink at all with age. This suggests that the shrinkage humans experience is primarily attributable to the extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said."

If it starts in humans but not in chimps during a period that is considered comparable, then how is it caused by the later period that is not comparable?

Avatar of:

Posts: 0

July 26, 2011

Instead of blaming brain size, blame the environment.  The study looked at lab chimps that live in the required sterile surroundings for laboratory animals.  They are not exposed to the immune challenges, or diverse stresses and food additives that humans are. 

Avatar of:

Posts: 0

July 26, 2011

Chet Sherwood is at GWU not Emory.

Avatar of:

Posts: 0

July 26, 2011

Chimp brains come pre-shrunk...

Avatar of:

Posts: 0

July 26, 2011

The piece notes that :

"This
suggests that the shrinkage humans experience is primarily attributable to the
extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said.

"...the
cognitive decline associated with living longer... ", Preuss said.

To fear that the gods will punish you if you do better than average is a common superstition dating back thousands of years as can be seen by looking it up in Frazier's The Golden Bough. Charming as it is as a folk practice, it is nothing short of gobsmacking to find this superstition surfacing in a scientific paper.

Avatar of:

Posts: 0

July 26, 2011

"Unlike the human organs, which started to shrink when the subjects were in their mid-40s . . . chimpanzee brains didn’t shrink at all with age. This suggests that the shrinkage humans experience is primarily attributable to the extra 40 years of life that humans enjoy beyond the average ape lifespan of 45", Sherwood said."

If it starts in humans but not in chimps during a period that is considered comparable, then how is it caused by the later period that is not comparable?

Avatar of:

Posts: 0

July 26, 2011

Instead of blaming brain size, blame the environment.  The study looked at lab chimps that live in the required sterile surroundings for laboratory animals.  They are not exposed to the immune challenges, or diverse stresses and food additives that humans are. 

Avatar of:

Posts: 0

July 27, 2011

I've read that chimps in the wild don't go through menopause, either, because they never get old enough.

Avatar of:

Posts: 0

July 27, 2011

The authors of this paper, and presumably the referees, seem to forget that in cross-sectional studies (i.e. taking samples from individuals in diverse age-groups) one must take account of secular changes in the population before drawing conclusions. The study of laboratory chimps from a colony maintained under standardised nutritional and other environmental conditions cannot be compared easily with a group of humans ranging from 22 to 88 years of age. The older humans were born around 1922 when, depending on their backgound, nutritional and disease patterns were very different. I seem to remember this was extensively discussed in papers in the 70s/80s, but there seemed to be quite solid data that human brain sizes were smaller in the late 19th and early 20th centuries when compared with individuals born in the later part of the 20th century.

Avatar of:

Posts: 0

July 27, 2011

Very interesting. One scientifically and peer-reviewed proven way to avoid decline is also to train your brain with free brain fitness program such as cognifit (www.cognifit.com).

Avatar of:

Posts: 0

July 27, 2011

An interesting study "but"...which chimp species (or subspecies) was considered; were they all laboratory/zoo "prisoners" and were any natural living individuals studied (chimos, not people since we have not lived "naturally" since Jimmy Carter introduced us to wool swaters again). There have been reports of very long lived "chimps" attaining lifespans of 65 years or more, and perhaps these would havemade for more reasonable comparisons.

Avatar of:

Posts: 0

July 27, 2011

On Evolution And Devolution

A.
Chimp Brains Don’t Shrink with Age
http://the-scientist.com/2011/...

Human brains are 3.5 times bigger than chimpanzee’s

B. What is evolution
http://dovhenis.wordpress.com/...

“ Evolution is energy temporarily constrained in a mass format to postpone reconversion of the mass to the energy fueling the cosmic expansionâ€쳌.

http://dovhenis.wordpress.com/...

“ It’s culture that modifies genetics, that changes gene’s expression. NOT vice versa.â€쳌

C. Reason and nature of devolution

When cultural evolution ceases, when circumstances become stale, there is no option for farther evolution, for energy constraint. At this state Earth’s primal organisms, the RNAs, initiate reverting the accumulated evolutionary steps, losing the constrained energy rungs, towards the organism’s starting
base status.

This applies, of course, to evolution and devolution of all types of organizations.

Dov Henis
(comments from 22nd century)
http://dovhenis.wordpress.com/...

Avatar of:

Posts: 0

July 27, 2011

I've read that chimps in the wild don't go through menopause, either, because they never get old enough.

Avatar of:

Posts: 0

July 27, 2011

The authors of this paper, and presumably the referees, seem to forget that in cross-sectional studies (i.e. taking samples from individuals in diverse age-groups) one must take account of secular changes in the population before drawing conclusions. The study of laboratory chimps from a colony maintained under standardised nutritional and other environmental conditions cannot be compared easily with a group of humans ranging from 22 to 88 years of age. The older humans were born around 1922 when, depending on their backgound, nutritional and disease patterns were very different. I seem to remember this was extensively discussed in papers in the 70s/80s, but there seemed to be quite solid data that human brain sizes were smaller in the late 19th and early 20th centuries when compared with individuals born in the later part of the 20th century.

Avatar of:

Posts: 0

July 27, 2011

Very interesting. One scientifically and peer-reviewed proven way to avoid decline is also to train your brain with free brain fitness program such as cognifit (www.cognifit.com).

Avatar of:

Posts: 0

July 27, 2011

An interesting study "but"...which chimp species (or subspecies) was considered; were they all laboratory/zoo "prisoners" and were any natural living individuals studied (chimos, not people since we have not lived "naturally" since Jimmy Carter introduced us to wool swaters again). There have been reports of very long lived "chimps" attaining lifespans of 65 years or more, and perhaps these would havemade for more reasonable comparisons.

Avatar of:

Posts: 0

July 27, 2011

On Evolution And Devolution

A.
Chimp Brains Don’t Shrink with Age
http://the-scientist.com/2011/...

Human brains are 3.5 times bigger than chimpanzee’s

B. What is evolution
http://dovhenis.wordpress.com/...

“ Evolution is energy temporarily constrained in a mass format to postpone reconversion of the mass to the energy fueling the cosmic expansionâ€쳌.

http://dovhenis.wordpress.com/...

“ It’s culture that modifies genetics, that changes gene’s expression. NOT vice versa.â€쳌

C. Reason and nature of devolution

When cultural evolution ceases, when circumstances become stale, there is no option for farther evolution, for energy constraint. At this state Earth’s primal organisms, the RNAs, initiate reverting the accumulated evolutionary steps, losing the constrained energy rungs, towards the organism’s starting
base status.

This applies, of course, to evolution and devolution of all types of organizations.

Dov Henis
(comments from 22nd century)
http://dovhenis.wordpress.com/...

Avatar of: Jacqui

Jacqui

Posts: 1

July 27, 2011

I've read that chimps in the wild don't go through menopause, either, because they never get old enough.

Avatar of: creigiau

creigiau

Posts: 1

July 27, 2011

The authors of this paper, and presumably the referees, seem to forget that in cross-sectional studies (i.e. taking samples from individuals in diverse age-groups) one must take account of secular changes in the population before drawing conclusions. The study of laboratory chimps from a colony maintained under standardised nutritional and other environmental conditions cannot be compared easily with a group of humans ranging from 22 to 88 years of age. The older humans were born around 1922 when, depending on their backgound, nutritional and disease patterns were very different. I seem to remember this was extensively discussed in papers in the 70s/80s, but there seemed to be quite solid data that human brain sizes were smaller in the late 19th and early 20th centuries when compared with individuals born in the later part of the 20th century.

Avatar of: Thomas Mann

Anonymous

July 27, 2011

Very interesting. One scientifically and peer-reviewed proven way to avoid decline is also to train your brain with free brain fitness program such as cognifit (www.cognifit.com).

Avatar of: Donald Wolberg

Anonymous

July 27, 2011

An interesting study "but"...which chimp species (or subspecies) was considered; were they all laboratory/zoo "prisoners" and were any natural living individuals studied (chimos, not people since we have not lived "naturally" since Jimmy Carter introduced us to wool swaters again). There have been reports of very long lived "chimps" attaining lifespans of 65 years or more, and perhaps these would havemade for more reasonable comparisons.

Avatar of: Dov

Dov

Posts: 1457

July 27, 2011

On Evolution And Devolution

A.
Chimp Brains Don’t Shrink with Age
http://the-scientist.com/2011/...

Human brains are 3.5 times bigger than chimpanzee’s

B. What is evolution
http://dovhenis.wordpress.com/...

“ Evolution is energy temporarily constrained in a mass format to postpone reconversion of the mass to the energy fueling the cosmic expansionâ€쳌.

http://dovhenis.wordpress.com/...

“ It’s culture that modifies genetics, that changes gene’s expression. NOT vice versa.â€쳌

C. Reason and nature of devolution

When cultural evolution ceases, when circumstances become stale, there is no option for farther evolution, for energy constraint. At this state Earth’s primal organisms, the RNAs, initiate reverting the accumulated evolutionary steps, losing the constrained energy rungs, towards the organism’s starting
base status.

This applies, of course, to evolution and devolution of all types of organizations.

Dov Henis
(comments from 22nd century)
http://dovhenis.wordpress.com/...

July 30, 2011

Awful and very funny.

Avatar of:

Posts: 0

July 30, 2011

Awful and very funny.

Avatar of:

Posts: 0

July 30, 2011

Awful and very funny.

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