# Shouldn't "intelligence" increase as we age? **URL:** \ **Category:** Factual Questions\ **Created:** [August 9, 2006, 7:50pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047 "2006-08-09T19:50:09Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [August 9, 2006, 7:50pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/1 "2006-08-09T19:50:09Z")
Without getting sidetracked by hair-splitting definitions of what constitutes “intelligence,” why don’t humans become more intelligent, as we age? Recent imagining studies conclusively demonstrate that brain activity stimulates the formation of new, denser, more efficient neural pathways. Generally accepted studies on human intelligence suggest that cognitive ability is strongly associated with efficient neural pathways and the unimpeded transmission of signals. Nowhere have I read that these neural pathways die off, in large amounts, as part of the natural aging process. What gives? ---
**Author:** ![Lissa](https://avatars.discourse-cdn.com/v4/letter/l/85f322/32.png) [@Lissa](https://boards.straightdope.com/u/Lissa)\ **Post date:** [August 10, 2006, 3:05am UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/2 "2006-08-10T03:05:33Z")
Evolution didn’t prepare us for medical advances that would keep us alive for nearly a century. We really weren’t built to last this long-- once you’re past breeding age, you’re pretty much redundant. Our organs, including the brain, sort of “burn out” because there was no incentive for evolution to make them regenerating. The goal is reproduction, not a long life. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [August 10, 2006, 9:08am UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/3 "2006-08-10T09:08:32Z")
We constantly lose brain cells, and therefore slowly lose intelligence as we age, compensated for by the fact that we learn about the world. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 10, 2006, 9:12am UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/4 "2006-08-10T09:12:59Z")
> [@Lissa](#): > > Evolution didn’t prepare us for medical advances that would keep us alive for nearly a century. We really weren’t built to last this long-- once you’re past breeding age, you’re pretty much redundant. Our organs, including the brain, sort of “burn out” because there was no incentive for evolution to make them regenerating. The goal is reproduction, not a long life. I sort of agree, but I think it would be reasonable to argue that from an evolutionary standpoint, _having successful grandchildren_ is as important as _having successful children of your own_. ---
**Author:** ![Otara](https://avatars.discourse-cdn.com/v4/letter/o/a88e4f/32.png) [@Otara](https://boards.straightdope.com/u/Otara)\ **Post date:** [August 10, 2006, 12:43pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/5 "2006-08-10T12:43:41Z")
We do, to a point. Its not huge though. > **[Yahoo | Mail, Weather, Search, Politics, News, Finance, Sports & Videos](https://www.yahoo.com/)** > > Latest news coverage, email, free stock quotes, live scores and video are just the beginning. Discover more every day at Yahoo! "Actually, certain mental functions increase slowly and slightly after the age of 16, peaking in the 20’s, with others remaining stable or even rising slightly up to the age of 60 or so. With some individuals, vocabulary may increase over time. " The important thing to remember is that an ‘IQ’ score is actually measuring how ‘intelligent’ you are _compared to other people in your age range_ - its a relative score, not an absolute one. The reason for this is that its intended to be a diagnostic tool, ie to tell us if a person is doing particularly well or badly on cognitive tasks compared to other people in the same age range. We need to account for age because people _do_ change over time and comparing a 40 year old to a 20 year old isnt very helpful usually - they have a 20 year head start after all. The difference isnt large but its enough to potentually interfere with what IQ tests are generally intended for. The thing is though, on average any age related change in intelligence will be similar for other people in your age range, so your score ends up as pretty much the same as it was at 20, even though your actual ‘intelligence’ does change over time to a certain extent. That is, if Tom was smarter than me in high school, theres a fair chance he’ll be smarter than me at 40, even though we’ve both got smarter since high school. I hope that makes some kind of sense, my head is starting to hurt. Otara ---
**Author:** ![psychloan](https://avatars.discourse-cdn.com/v4/letter/p/4bbf92/32.png) [@psychloan](https://boards.straightdope.com/u/psychloan)\ **Post date:** [August 10, 2006, 12:48pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/6 "2006-08-10T12:48:27Z")
> [@Carnac the Magnificent!](#): > > Without getting sidetracked by hair-splitting definitions of what constitutes “intelligence,” why don’t humans become more intelligent, as we age? > > Recent imagining studies conclusively demonstrate that brain activity stimulates the formation of new, denser, more efficient neural pathways. Generally accepted studies on human intelligence suggest that cognitive ability is strongly associated with efficient neural pathways and the unimpeded transmission of signals. Nowhere have I read that these neural pathways die off, in large amounts, as part of the natural aging process. > > What gives? Recent studies also show that exercising your leg muscles makes them stronger. So why is it that letter carriers don’t get stronger and stronger legs over the years until they retire? Or perhaps they do? I would think that a 20-year-old who joins the postal service would get stronger and stronger legs for the first few months, but eventually, down the road, the process would level off and then reverse itself as other factors (i.e. physiological limitations and aging) start to slow down the process and ultimately work against him. I think it’s same thing with your brain. Just guessing though. ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [August 10, 2006, 4:00pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/7 "2006-08-10T16:00:21Z")
> [@Mangetout](#): > > I sort of agree, but I think it would be reasonable to argue that from an evolutionary standpoint, _having successful grandchildren_ is as important as _having successful children of your own_. Sure, but the only genetic way to have grandchildren is to have children. After that, your gene production isn’t directly involved any more. Nurturing is useful, of course, but in social animals like man, it can be done by someone else just as easily. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [August 10, 2006, 4:20pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/8 "2006-08-10T16:20:30Z")
> [@Lissa](#): > > Our organs, including the brain, sort of “burn out” because there was no incentive for evolution to make them regenerating. The goal is reproduction, not a long life. Have you recent cites to corroborate your claims–claims that directly contradict recent imaging studies that show increased neural pathways? ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [August 10, 2006, 4:22pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/9 "2006-08-10T16:22:59Z")
> [@Mangetout](#): > > I sort of agree, but I think it would be reasonable to argue that from an evolutionary standpoint, _having successful grandchildren_ is as important as _having successful children of your own_. Sure, but in our environment of evolutionary adaptability (EEA) limited resources and the means to gather such resources may have put more of the pressure for upbringing on the parents rather than grandparents. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [August 10, 2006, 4:30pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/10 "2006-08-10T16:30:51Z")
Food for thought… A Decade of Discovery Yields a Shock About the Brain January 4, 2000 New York Times By SANDRA BLAKESLEE As scientists look back at all the discoveries made in the 1990’s, the so-called Decade of the Brain, one finding stands out as the most startling and, for many scientists, the most difficult to accept: people are not necessarily born with all the brain cells they will ever have. In fact, from birth through late adolescence, the brain appears to add billions of new cells, literally constructing its circuits out of freshly made neurons as children and teenagers interact with their environments. In adulthood, the process of adding new cells slows down but does not stop. Mature circuits appear to be maintained by new cell growth well into old age… Although the Congressionally mandated “Decade” produced many other discoveries, from ways to obtain images of fleeting thoughts inside a person’s head to new drugs for a wide variety of mental disorders, the finding that the brain develops and maintains itself by adding new cells is the most revolutionary. … Some researchers have begun isolating special cells that continue to divide and produce new brain tissue, with the hope of implanting such cells into areas of the brain that are damaged by disease or accidents. For decades, it was axiomatic that people were born with all the brain cells they would ever have. Unlike the bones, the skin, the blood vessels and other body parts, where cells divide throughout life to give rise to new cells, it was believed that the brain did not renew itself. Though the brain did add vast amounts of new connections early in life and could compensate somewhat for many injuries, it was thought that no one could be expected to grow more brain cells with age. Quite the opposite. People were told that the only thing they could look forward to was gradual mental deterioration as cells died off and were never replenished. These ideas were so firmly established that many scientists have a hard time believing the findings, reported in the last couple of years by a number of investigators, that the human brain makes new cells after birth, said Dr. Fred H. Gage, a neuroscientist at the Salk Institute in La Jolla, Calif. ---
**Author:** ![simster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/simster/32/1047_2.png) [@simster](https://boards.straightdope.com/u/simster)\ **Post date:** [August 10, 2006, 4:36pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/11 "2006-08-10T16:36:43Z")
Not sure… It seems to me that most teenagers I have encountered know \_everything, and I, the parent, know nothing. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [August 10, 2006, 9:16pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/12 "2006-08-10T21:16:37Z")
There is also the effect of decreased blood circulation to the brain reducing its effectiveness. I recall reading of a writer (Robert Heinlein?) who had surgery to fix constricted arteries that were restricting crainal blood flow. The surgery was successful, and besides the good effects on his health, critics noted that the books he wrote after this surgery were much better than recent ones before the surgery. The books were said to be as good as the ones he had written in his prime. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 10, 2006, 9:22pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/13 "2006-08-10T21:22:34Z")
I think that intelligence might be fairly defined as the ability to handle new things: Come up with new ideas, learn the new ideas others have come up with, etc. For this, having a lot of neuron connections wouldn’t be so important, as forming new ones. So even if new connections are always being formed, if they’re formed more slowly in older folks, then the older folks might be said to be less intelligent. ---
**Author:** ![LiveOnAPlane](https://avatars.discourse-cdn.com/v4/letter/l/3d9bf3/32.png) [@LiveOnAPlane](https://boards.straightdope.com/u/LiveOnAPlane)\ **Post date:** [August 11, 2006, 5:55am UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/14 "2006-08-11T05:55:36Z")
> [@simster](#): > > Not sure… > > It seems to me that most teenagers I have encountered know \_everything, and I, the parent, know nothing. Yes, this is true, but give them a few years. As they get older, you will be astonished at how much smarter YOU become! 😉 ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [August 11, 2006, 1:07pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/15 "2006-08-11T13:07:12Z")
> [@Chronos](#): > > I think that intelligence might be fairly defined as the ability to handle new things: Come up with new ideas, learn the new ideas others have come up with, etc. For this, having a lot of neuron connections wouldn’t be so important, as forming new ones. So even if new connections are always being formed, if they’re formed more slowly in older folks, then the older folks might be said to be less intelligent. Studies (and conventional wisdom) suggest that age and exceptional creative insight (aka brilliance) largely depends on the field of study. You may be correct in youth being an asset in theoretical physics, but for researchers in the humanities, or the social or behavioral sciences, the ability to brilliantly connect dots is largely dependent on the acquisition of a massive knowledge base–combined with intellectual rigor, of course. Someone above suggested arteriosclerosis in older brains as a major limiter. But this condition isn’t the norm in adults in their 30s and 40s. ---
**Author:** ![Lissa](https://avatars.discourse-cdn.com/v4/letter/l/85f322/32.png) [@Lissa](https://boards.straightdope.com/u/Lissa)\ **Post date:** [August 11, 2006, 2:15pm UTC](https://boards.straightdope.com/t/shouldnt-intelligence-increase-as-we-age/368047/16 "2006-08-11T14:15:21Z")
> [@Carnac the Magnificent!](#): > > Have you recent cites to corroborate your claims–claims that directly contradict recent imaging studies that show increased neural pathways? From what I’ve been reading, the problem isn’t necessarily neuron loss (though that happens with some people) but a change in the way the brain communicates as we get older. [This](http://web.sfn.org/skins/main/pdf/brainfacts/brainfacts.pdf) site says: (Warning PDF) > [@](#): > > All human behavior is determined by how well the brain’s > communication systems work. Often a failure in the cascade of > one of these systems results in a disturbance of normal function. > Such a failure may be caused by an abnormal biochemical process > or a loss of neurons. > > The cause of brain aging still remains a mystery. Dozens of > theories abound. One says that specific “aging genes” are switched > on at a certain time of life. Another points to genetic mutations > or deletions. Other theories implicate hormonal influences, an > immune system gone awry, and the accumulation of damage > caused by free radicals, cell byproducts that destroy fats and proteins > vital to normal cell function. There are also [physical changes in the brain:](http://www.usc.edu/hsc/info/pr/hmm/01spring/brain.html) > [@](#): > > Brain weight and volume decrease. On average, the brain loses 5-10 percent of its weight between the ages of 20 and 90. > > The grooves on the surface of the brain widen, while the swellings on the surface become smaller. > > So-called “neurofibriallary tangles,” decayed portions of the branch-like dentricles that extend from the neurons, increase. > > “Senile plaques,” or abnormally hard clusters of damaged or dying neurons, form. > > Along with realizing these physical changes in the brain, one of the big surprises in recent years is data that suggests cognitive decline like age-related memory loss is not due to neuron loss, as previously thought. Instead, scientists now believe changes in function as we age have more to do with complex chemical interactions in the brain that occur over time. > > \ > The genetic influence on the rate of brain aging is the focus of new research. Jeff Victoroff, M.D., associate professor of clinical neurology at the Keck School and director of neurobehavior at Rancho Los Amigos, suggests, “Genetic evolution may have even favored those who, once they hit the old age of 35, retained the capacity to teach and provide emotional support rather than those whose brains’ limited resources were devoted to new learning.” In evolution 100,000 years ago, he says, “It was probably rare for people to live past age 40 or 50, which means there was very little evolutionary selective pressure to make the brain work when we’re 60 or 70 or 80. That’s probably why all brains decline with aging.” [/quote]