The brain and intelligence

brainsizeiq.jpg

You know what they say about people with big brains ... Or, actually, maybe you don't.

Despite being a major concept underlying of the neurobiology of intelligence for the last 150 years or so, the connection between brain size and smarts isn't well-understood by Joe and Jane Average. Does it mean smaller people—including women—are less intelligent? What about animals, like elephants, that have much larger brains than ours? Are our academic destinies really written in our hat size?

It's complicated. We know that brain size and intelligence are correlated, but that simple fact is only a starting point for a much more intricate story—one that science is only beginning to understand.

First off, yes, bigger brains really do seem to be smarter brains. That correlation has been pretty solidly proven, experts say, and the connection gets stronger when you calculate total brain volume via MRI technology or post-mortem analysis, rather than simply running a tape measure around somebody's head. Basically, the more accurate and precise the brain measurement, the more size and smarts are connected.

How connected varies a bit, depending on the methodology, but an analysis of previous research, published in 2005 in the journal Intelligence, found a .33 correlation at the population level. Which means, if you look at humans as a whole, a little more than 10% of the difference in intelligence from person to person can be accounted for by brain size.

That's statistically significant. But it also means overall brain size isn't the only thing affecting intelligence. Case in point: Gender.

"It is true that women have smaller brains than men," said Sandra Witelson, Ph.D, professor of psychiatry and behavioral neurosciences at the Michael G. DeGroote School of Medicine at McMaster University in Canada. "But numerous studies have shown that women aren't any less intelligent overall than men."

That works because male and female brains are built differently, according to Witelson and other researchers.

"If you look at the brain areas related to intelligence in men, they're different than the brain areas associated with intelligence in women. It implies at least two different brain architectures that lead to the same level of intelligence," said Richard Haier, Ph.D., a neuroscience consultant and professor emeritus at the University of California, Irvine.

Something about the way women's brains are built allows us to do the same thinking in a smaller space.

This difference helped tip researchers off to other factors that we now know are also correlated with variations in overall intelligence—and with variations in particular types of intelligence, such as verbal and spatial. Small differences in the placement and size of patches of grey matter (the stuff that does the thinking) and white matter (the stuff that helps the thinking get done more efficiently) can make a big difference in IQ.

Take Einstein. In 1999, Witelson's laboratory studied the great thinker's preserved brain.

" His brain was smack within normal brain size for his age," she said. "But he had a region in the parietal lobe that is crucial for visual imagery and mathematical thinking that was exceptionally large in his case. We suggest that it was the expansion of that region that gave him this extraordinary ability."

This also might help explain why some animals with larger brains are less intelligent than animals with smaller brains—the inner architecture and wiring of their brains are different.

Basically, "bigger brain = smarter" is a good rule of thumb, but it comes with a lot of "buts". Brain size can give you a general idea, but to make a really accurate prediction of any individual's intelligence, you'd need to look at multiple factors—from whether the person was right- or left-handed, to their gender, to their grey matter. Some answers are there, researchers say, but they don't fit easily into a sound byte.

Lars Chittka, Ph.D., professor of sensory and behavioral ecology at Queen Mary, University of London, and Jeremy Gray, Ph.D., associate professor in the department of psychology at Yale University, were also interviewed for this story. Their help was invaluable in piecing together the big picture of brain size and intelligence.

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  1. “the connection between brain size and smarts isn’t well-understood by Joe and Jane Average.”

    Joe and Jane Scientist are none too clear on that either. Defining and measuring intelligence has always been a political minefield. Even measures of brain size can be controversial (eg., include the complete brain stem or not?). 19th-century and 20th-century scientists who supposedly knew better were certainly sucked into some horrendous cultural biases as a result.

    http://en.wikipedia.org/wiki/Scientific_racism

    http://drvitelli.typepad.com/providentia/2009/10/saving-civilization.html

  2. Huh. My mother, a research biologist, always taught me that it was much more dependent on the number of convolutions and total surface area of the brain than the size. For instance, most cats are smarter than most dogs. Cat brains are smaller, but contain more convolutions, and thus more surface area, resulting in a higher overall intelligence.

    1. Thank you. I feel like this article missed the point about surface area. What’s interesting is that dolphins brains are even more convoluted than ours

  3. You raised an interesting point about the size of elephant brains, but didn’t take it anywhere. One should note that brain matter is terribly expensive, energy-wise (20% of a human’s energy goes into powering the brain, only 2% of body mass) so if an elephant could get by with a smaller brain then it almost certainly would. So why is an elephant with a brain around 4 times the size of a human’s not 4 times as smart? Presumably because a brain is not just an intelligence-generating engine, but is also required to do stuff that makes it necessary to scale it with the body size.

    So the observation that women’s brains tend to be smaller than men’s brains shouldn’t stand in isolation from the fact that women’s bodies also tend to be smaller than men’s bodies. If one scales appropriately for body size, are women’s brains actually smaller in comparison with men’s?

    1. “So why is an elephant with a brain around 4 times the size of a human’s not 4 times as smart?”

      Who says they are not? They don’t speak human language, so we can’t really find out for sure. Just because an animal doesn’t live in a house, wear clothes, and destroy its own environment by filling it up with fumes from vehicals doesn’t mean it’s not intelligent.

      1. Well, that brings up the question of what intelligence actually is, which is a whole other can of worms. But if an elephant is four times smarter than a human, you’d imagine that there would be some indication of it, if only organization into herds much larger than the 150 that our intelligence allows us to handle without artificial aids such as name badges. Can an intelligence that has no notable effect on behaviour be said to be intelligence at all?

  4. Carl Sagan wrote about this in The Dragons of Eden (1977).

    His central point is that intelligence correlates, not with absolute brain mass, but rather with the ratio of brain mass to body mass. Women have, on average, smaller brains than men; but they also have smaller bodies.

    1. Why DO women have smaller brains? What evolutionary pressure would there be to not evolve a brain that’s the same size? I know women are smaller overall but what’s wrong with having a head’s proportionally bigger? Women have proportionally longer legs and wider hips so why must women have proportional head as well?

      Also, on average are bigger people smarter? Have they done tests into that? In theory a larger body would allow for a larger brain, which is correlated with intelligence.

  5. I was going to say the same thing as Karl above, except that I had always remembered it as the ratio of brain size to heart size. I could have read that elsewhere though (and in either case, it pretty much comes to the same thing).

    The question remains, then: why does the bigger brain of a larger animal not correlate to more intelligence? Is it really because all the rest of that brain is “wasted” regulating that larger body? Or is it possible that the correlation in these ratios isn’t causal? That is, great big dinosaurs may have had big brains (and a tiny brain/body mass ratio), but maybe they were dumb just because they were dumb reptiles, not because of this ratio. And cats may have a larger brain/body mass ratio than crocodiles, but maybe the reason they are smarter is because they are mammals, which had evolved better brain structures for higher-order thought. What I’m saying is that maybe all the smart animals just happen to be the smaller ones (mammals and birds), which automatically give them a larger brain/mass ratio because of their smaller mass.

    Anyway, the line about Einstein’s brain had me remembering the book “Driving Mr Albert,” a funny (and true!) roadtrip book about driving across America with Einstein’s brain in the trunk.

  6. The journal ‘Intelligence’ is a pretty problematic source. It’s closely tied to both ‘The Bell Curve’ and eugenics nonprofit the Pioneer Fund. After the ‘Intelligence’ people whipped up the controversial document “Mainstream Science on Intelligence” for the Wall Street Journal, a more balanced statement called “Intelligence: Knowns and Unknowns” had to be put together by the APA.

    ‘The Mismeasure of Man’ does a good job covering a lot of the problems with attempts to define “intelligence,” which is necessary before making any scientific assertions about it. I am especially troubled by the uncritical assertions regarding “brain sex”-type theories Witelson and others have been feeding to the press for a long time. I discussed this kind of problematic “sex science” in some of my guest posts. The same “scientists” who make assertions about race and intelligence are the ones making these assertions about sex and intelligence. I really wish this article presented other scientific viewpoints, or at least acknowledged that there was one besides the evolutionary psychology POV of the people with whom you talked.

  7. To the “ratio of brain size to body size” comments: this is an unsatisfying conclusion, too.

    Yes, we need more brain mass to run bigger bodies- fine. But as far as intelligence goes, I would have thought that correlated with the amount of brain mass above the amount strictly needed, not the percent.

    Consider a computer used by one person, and another computer with twice the cores, ram, storage, input/output speed, etc. used by 2 people. If I double the first computer’s resources or add 50% to the second computer’s resources, I would seem to have added the same capacity for additional intelligence, have I not? In this sense it should be very easy for a whale, with an already large brain, to add an additional 2 kg of brain mass (the extra 20 watts of food is insignificant to a whale) and be as smart as a human. Obviously I must be wrong, but I don’t know where.

    1. The brain-as-computer model is useful in many ways, but is limited. My first computer operated at one five-hundredth the speed of my current desktop machine, so I should be producing five hundred times the amount of work now, right?

      Whatever intelligence is, it’s more than a simple quantity theory of computation would account for.

    2. In this sense it should be very easy for a whale, with an already large brain, to add an additional 2 kg of brain mass (the extra 20 watts of food is insignificant to a whale) and be as smart as a human. Obviously I must be wrong, but I don’t know where.

      Well, you’re making the assumption that it would be useful for a whale to have human-level intelligence. But would it? It’s not as if they’ve got tool-using hands to let them make use of a big problem-solving brain.

      There are uncountable thousands of species in the world that have the power of flight; it’s clearly pretty useful. There’s only one species in the world that’s known to have human-level intelligence, and that species has only been around for maybe 200,000 years or so. It remains to be seen whether this trait is viable in the long run.

  8. The Einstein example in the article overlooks that correlation != causation.

    Is the bigger parietal part the cause of his mathematical knowledge or DUE to his mathematical knowledge?
    THAT is the question..

    As for the IQ and difference between men and women. There are just so many variables, not least in testing peoples performance.
    We can easily show large differences in IQ, Einstein definitely was smarter than someone with downs, but when people are comparing IQ 115 against 125 that is just nonsense.

    But from these large differences we can easily see the difference to many other animals. Intelligence is a real term and IQ has a usable definition which lets us say that an elephant is not as intelligent as a human, and does not have as high an IQ. This is all classified from problem solving skills, which are very important to OUR survival and thus an important trait for humans. It may not be important to elephants, but we can still say that elephants are bad at those problem solving skills which constitute intelligence. It doesn’t make us better or worse than elephants, just more intelligent.

    Women vs men.
    Different but equal.
    Different connections giving rise to some small but measurable differences. This is all on a population level, meaning that individuals can fall far outside this. Women are better at retrieving from long term memory (more efficient memory retrieval) and men are better at mental rotations. Both these traits are important for intelligence.

    Women’s smaller brain:
    Energy efficiency!
    Our bodies are exercises in trade-offs. Men can’t give birth (and are thus reduced to the role of dna donor) while women can. Pregnancy has a huge energy cost which leads to some (minor) shrinking of the brain. That shrinking may be kept to a minimum by more efficient wiring. Sacrificing raw power (being able to use all the energy the brain wants) for efficiency seems like a good trade-off here. Anyone who has been around pregnant women will attest to their somewhat degraded cognitive performance at some points of the pregnancy.
    There are probably some undiscovered issues here which will be staggeringly interesting to see.

    1. The question about whether the morphology of Einstein’s brain was cause or effect is a valid one. A study of London taxi drivers – who are required to have a very detailed knowledge of the city’s streets – showed that the posterior hippocampus grew measurably, with greater growth seen in drivers who had been driving for longer. See http://news.bbc.co.uk/2/hi/677048.stm

      It’s also possible -even plausible – that a given brain structure could be both cause and effect. Maybe the unusual development of Einstein’s parietal lobe could have been both an innate condition that predisposed him to have superior imagination and mathematical ability, and the result of exercising those particular faculties.

  9. The article says that Einstein possessed a larger brain volume for visual imagery and mathematical thinking. Am I right in thinking that neuroplasticity may account for this, rather than a genetic disposition? Since the guy spent his whole life working in that area one imagines the brain may have recruited other parts to assist…

  10. If brain size is an intelligence predictor, the news for America and South Korea is not so good. We’ve never been able to reliably predict intelligence by brain size, however.

    Proper nutrition and healthcare has a huge impact on height. America, once the leader prior to WWII, stopped gaining in average height at the same time and is now surpassed by many European nations – even Japan is set to overtake America soon. (http://abcnews.go.com/WNT/Health/story?id=2998245&page=1)

    Meanwhile, North Koreans are 3 inches shorter on average than South Koreans.

  11. It’d be useful not to mix up intelligence and IQ. IQ tests measure performance along several unrelated axes of intelligence, and fold them into a single value. You might have more points on the spatial awareness part of it and less on the language part of it than someone else, but the exact same IQ (full IQ test results will indicate this, but the IQ value won’t).

    Given that IQ is the only semi-standardized (IQ tests in US vs. Europe differ substantially) measure by which we can measure intelligence, it becomes pretty clear that what we measure isn’t necessarily a good reflection of the person’s capabilities.

    Then there’s the controversial theory of multiple intelligences, that tries to account for those different types of intelligence, but – controversy aside – there’s no method in place (yet?) for measuring each axis of intelligence properly.

    The point?

    Don’t bother thinking about a correlation between brain size and intelligence when there’s no definition of intelligence that’s not very flawed.

  12. That’s really the big thing, would this advanced (and abstract) problem solving ability be good for other species. (another question is whether it’s good for us, but I’ll leave that one for posterity to answer)

    NelsonC and AnthonyC, brain as a computer analogies IS flawed, but the most accurate that we have at the moment. Situated cognition viewpoints are rising and are very interesting but don’t yet provide the same interesting possibilities for making artificial agents. That said, most of the current approaches to building artificial lifeforms have started taking more aspects into account than just the brain, and have thus moved to a more Situated viewpoint. These aspects include (but are not limited to) locomotion, sensing and manipulation in and through the environment. Taking these aspects into account as a PART of the mental processes, instead of seeing the environment as an obstacle to cognize seems to give quite interesting results. I could give a few references but can’t be bothered to look them up right now.. tired and lazy

  13. Female brainsize is usually samller in actual and relative size, but has more surface. Females are on average better at verbal skills, and males in mathematical skills. Male performance is more wider, so there are more lowIQ and highIQ in males, than in females. Females performance is more closer to the average. Female hip is also wider, because they need to give birth to the big headed babies.

    Dolphins have also big brains, but they need more fat in brains as insulator. This maybe true also for elephants, as they were half marine mammals earlier in evolution. Now they have big ears to cool the brain.

  14. So like, if I drop the beer belly, I’ll become more intelligent since my brain mass to body mass index has risen? Sounds good to me.

  15. This reporting is not very comprehensive. Don’t call the article “The brain and intelligence” if you’re only talking about brain size and focus on sex differences. Teufelaffe • #2 points out that it has more to do with folds and others point out is has more to do with total surface area (after unfolding). Size/volume is a bad metric. If you’re really interested in intelligence, read: On Intelligence by Jeff Hawkins. He has a good start on a real explanation (with only a few inaccuracies).

  16. In regardless of what it is. No matter how big nor small is the brains of the person , it always rooted from the origin meaning from one’s genes.If the origin mostly commonly has big brain definitely , a person will going to have big brain and vice versa. Thanks for that extravagant ideas of yourself.

  17. I just finished an article on cloning neanderthals in the most recent issue of Archaeology mag. Neanderthals had bigger brains than homo sapiens. That didn’t surprise me since I’m familiar with those mini documentaries that Geico puts out.
    —mac

  18. Okay, the first draft I wrote of this comment was pretty cranky, but after reading the post a few more times, I feel like it’s mostly redeemed in the end precisely because the story about Einstein’s brain undermines the “bigger = smarter” formulation. So I’m going to turn the crankiness down and just make a few remarks:

    A discussion of intelligence as a function of brain size needs to *begin* with some kind of working definition of “intelligence” and “brain size.” Intelligence, even “general” or “fluid” intelligence, is a concept that still brings mild-mannered academics to the point of screaming matches. Does “brain size” here mean brain mass or brain volume? Relative or absolute?

    And exactly how broad a comparison are we making? The post begins with talk about elephant vs. human brains, and leads into gender differences and from there into inter-regional differences in the same brain. But comparing intelligence and brain-volume differences within vs. across species are apples and oranges.

    Further, I realize this is a blog and not an academic journal, but statements like “That correlation has been pretty solidly proven, experts say” and especially, “the more accurate and precise the brain measurement, the more size and smarts are connected” really call for some kind of reference. Who are these experts, and is there really no disagreement among them? And is there actually a study that compares accuracy and precision in brain volume estimation to correlation values for intelligence:volume? (not that I’m aware of) How one measures brain volume is important – most MRI studies now use complicated spatial transformation algorithms for this, and whether they do and which ones they use *do affect* relationships between volume and subject groups.

    Does the 2005 meta-analysis cited take into consideration these measurement variables in its methods? (I know the answer to this one: it doesn’t). I don’t know anything about the reputation of the journal Intelligence, and the paper deserves to be evaluated on its own merits, but anyone armed with the author’s name and Google can find some legitimate reasons to approach this paper with heightened skepticism.

    Again, I realize this isn’t a science journal, and the point that needs to be made is made in the end, but the “bigger brain = smarter” rule of thumb comes with *so many* “buts” that I can’t agree with calling it a good one.

  19. And before I get back to work, a couple of wtf’s:

    “Cat brains are smaller, but contain more convolutions, and thus more surface area, resulting in a higher overall intelligence.”

    Here’s a cat brain: http://brainmuseum.org/specimens/carnivora/cat/brain/Cat6clr.jpg
    Here’s a dog brain: http://brainmuseum.org/Specimens/carnivora/beagle/brain/Beagle6clr.jpg

    So I don’t know what you’re talking about.

    And this one: “Dolphins have also big brains, but they need more fat in brains as insulator.”

    No. I don’t know if you meant an electrical insulator around the axons, or a thermal insulator because dolphins are aquatic mammals, but either way, it doesn’t make any sense.

    1. Not to mention that cats aren’t always smarter. Or if they are, they’re not in such an obvious way that all biologists agree on it, because I’ve heard some reports that the intelligence required to be a successful pack hunter is higher than that of an ambush one, with dogs and cats used as examples.

  20. Size seems like such a crude measure. Wouldn’t a better measure consider the metabolic rate of the brain tissue. i.e. People or animals with harder working brains should be smarter.

    1. I wonder how much the metabolic rate would vary. Clearly there’ll be a difference between average exothermic and endothermic species’ rates, and possibly between exothermic species in cold environments and warm environments. But I wonder whether, say, all mammals wouldn’t have very similar metabolic rates.

    2. I’m pretty sure the debate is going to come down to having mapped the human genome. I mean, what we should be asking is what percent of the genetic code relating to the brain is actually related to brain size? Further, do the number of sequences vary from a person who is intelligent to a person who is not intelligent? And finally what environmental factors affect these DNA sequences to explain variation in person to person.

      Examining this question any other way seems irrelevant, now that we have the tools to gather meaningful data.

    1. Kudos for turning up a reference, and my sincere apology for suspecting that you were just making shit up. Having said that, and I’m honestly not gunning for a fight here, I checked out your citation, and over to the right, another one got my attention:

      A claim in search of evidence: reply to Manger’s thermogenesis hypothesis of cetacean brain structure.

      http://www.ncbi.nlm.nih.gov/pubmed/18783363

      In which a whole posse of cetacean scientists pile on the author to tell him what a dumbass he is. Regardless of the issue, there is a special joy in these kinds of scientific slapfights. M.D.’s, in particular, seem prone to deciding suddenly that they’ve got the brain all figured out, and after they’ve committed their folly to publication, 700 annoyed specialists coalesce like a mongol horde to channel all their pent-up frustrations into the academic journal equivalent of a “fisking.” I don’t have a dog in this particular fight, and dissenters in a field are sometimes absolutely right, but I will note that the first author on this paper (of 17) is Laurie Marino, who has pretty much built a career on being The Cetacean Neuroanatomist, and that the journal editor gave the group over 20 pages to pound on Manger, which is serious real estate for such a thing in most journals. For anybody who can handle the scientific jargon, these things can be genuinely interesting examples of reasoning and rhetoric, and wicked fun to read for the teeth-clenched contempt collegially tucked between the lines.

  21. “First off, yes, bigger brains really do seem to be smarter brains.”

    Well. There is a flaw with this statment. The major issue with this is that there is no scientific definition of “Smart”

    What does smart mean? Is it the ability to solve problems? And if yes then what type of problems?

    If you give humans a series of problems that are made for cat I guarantee you that humans are going to suck at it.

    The problem with IQ tests is that they are very anthropomorphic and represent human values useful to humans only. More problematic is the fact that these test don’t measure any hypothetical “Intelligence” at all but just a level of conformity to a given culture.

    So of course if you test a Chimp with a test made for humans he is not going to do well.

    In this regard IQ test are even questionable for comparing humans.

    By confining people within a certain culture and measuring how close a given person is to a given particular cultural standard, IQ tests are creating confusion. None of these has anything to do with intelligence or level of consciousness.

    Because of that most discussions about brain size and “intelligence” including this one look very naive to me.

    My felling about this is that the level of perceived constiousness and the ability to solve problems might not change unless the brain size vary by at least several time in accordance to the body weigh.

    For example I am not convinced that a cat or a dog shall qualify as less “Intelligent” or less sentient than a human. Those who live with pets like I do and really pay attention to them probably know what I am talking about.

    (See ‘Encephalization quotients” http://www.beyondveg.com/billings-t/comp-anat/comp-anat-appx2.shtml)

  22. So I’m going to turn the crankiness down and just make a few remarks

    BoingBoing welcomes careful drivers.

    1. :) What goes for driving often goes for posting – don’t drive angry, don’t comment drunk, etc.

  23. “”How connected varies a bit, depending on the methodology, but an analysis of previous research, published in 2005 in the journal Intelligence, found a .33 correlation at the population level. Which means, if you look at humans as a whole, a little more than 10% of the difference in intelligence from person to person can be accounted for by brain size.

    That’s statistically significant. “”

    I’m not real up on my stats, but I’m pretty sure there is nothing in the first paragraph that demonstrates statistical significance.

  24. hi alls,

    I think that everyone can, everyone is smart, not big on the small value of his own brain on. that distinguishes it is, who diligently and who are lazy.

  25. Having a quite big head myself, I have to disregard the research (I’m not saying that there isn’t any truth in it).

    “It’s not what you have, it’s what you do with what you have.”
    The single truth about brain is that regardless of its size, a proper attitude and beliefs can unlock it’s full potential. My observations suggest most people have failed to do just that (That includes people with big brains.)
    e.g. Kids — smaller brains, no? — have outsmart some adults in countless occasions. Enough said ;) Also, Ingvar Kamprad of IKEA, Richard Branson (Take his hair off and you’ll find an old wrinkled peanut) – by the way, I dare you argue otherwise that he’s both intelligent and cunning man, etc. On the other hand, Bush – with reasonable brain size – is partially retarded. YESSS!

    One thing that bothers me about some researches is this: They find the correlation between two variables; find a pattern; and concludes that one causes another. What some of them have missed is that the two variables may just be an aftermath of other bigger variables e.g. For this particular research, it is more important to sample their habits. The fact that some part of Einstein’s brain is bigger than other people may be an aftermath of his habits of challenging himself in a particular kind of challenges. Even rat’s brains evolve, don’t they?

  26. I’m stretching my memory back to my undergrad biology classes, in other words a long time ago, but the example we were given was brain weight as a proportion of body size.

    Humans were the largest positive outlier from the average, followed by dolphins and then chimps etc.

    it is a pretty crude reduction of a complex issue but one of the interesting things was that animals that existed in social groups usually had a higher brain/body weight ratio than those that don’t.

  27. I have to say that of all the comments, this is my favorite:

    “If the origin mostly commonly has big brain definitely , a person will going to have big brain and vice versa. Thanks for that extravagant ideas of yourself.”

    I believe it was Aristotle who said, “The proper study of man is big-brained extravagant egoism.”

  28. I’ve known several people who were brilliant in certain subjects, but not so bright at others which required a different type of thinking. I am not bashing IQ tests, but it’s patently obvious that IQ tests only measure certain aspects of intelligence. The nature of intelligence is more complicated than an IQ test is able to reflect. This means that a fundamental measurement in the entire debate is an inadequate instrument and is giving only partial data. The prejudices enter the debate when certain aspects of intelligence are highly valued by science–therefore, they get the main focus of attention.

    Every seen an IQ test that measures artistic talent? Didn’t think so.

  29. “One thing that bothers me about some researches is this: They find the correlation between two variables; find a pattern; and concludes that one causes another.”

    I would say that only poor scientists would do that because this is not what they learned.

    What they learned to do with statistics is to find correlations and them to make more studies to explain it first before concluding that A is causing B.

  30. Well, interesting theories but I think you have to look at nutrition, environmental risks on top of Brain sizes. There are people with smaller brains but with more ‘BRAIN DENSITY’ than a larger brain human. The question becomes, why is that possible? Well, nutrition, exposure to academic/artistic stimulation lends a hand to higher brain densities. It would also not be out of the possibility to realize that Metabolic rates can alter the way the brain is functioning. Kind of a way to act as the CPU speed of the Brain processing unit. That in itself needs to be accounted for, which is brain speed. Then there are racial and ethnic differences regarding how brains are built.

    I remember that in a John Stuart Mills paper, he noticed that African Slaves working on his ship had much greater vision on the seas than the caucasian hand-men. Even, Mills himself said that there was quite a possibility that the black specie excel at different aspects of intelligence or sensory abilities, that being of Vision.

    When you take into account, gender, ethnic, metabolic, nutritional/environmental factors into an equation, obviously, things will get very complicated. But if you distill the process of observing Intelligence with all factors, outside Brain Size, being in the control group, then most likely Human Brain size will be a major decider regarding human intelligence or creativity.

  31. Read Broca, and then read about the autopsy of his remains. He lost his wager.

    I have a Stanford-Binet (version 3, SBL-M) test score of 180, and I believe intelligence testing is mostly humbug. What the SB measures is not how smart you are, it’s how well you have learned a particular method of problem-solving that works extremely well for people with a particular set of traits in a particular problem space. It would be an extremely valuable measurement if it weren’t wrongly believed to be applicable to all situations – it’s really a measure of how much you resemble certain other people.

    If a situation can be identified as best handled by someone who strongly represents the group that scores well on a particular intelligence test, one may use the results of that test to select a person to deal with the aforementioned situation. However, most people want to skip the part about analyzing the needs of the moment, preferring to irrationally believe that high test scores are magically and inherently “better” when dealing with any situation, even situations that have no resemblance to the test conditions.

  32. @ Anon, #51

    Perhaps your view of IQ tests was skewed by the one you took. The L-M test is almost 40 years old. It predates most of the concerns that the test itself could be culturally biased. There have been huge changes since then, to the point that today’s tests don’t even measure the same thing. The L-M purported to give a mental/actual age ratio, (multiplied by 100) whereas the current tests attempt to determine your actual/average ratio. The newer scoring methods, along with a renorming to match the changes from the Flynn Effect, has brought the scores much more in line with a standard Gaussian distribution. What that boils down to is, modern tests don’t claim that 3% of people have IQs in the top 1/2% of the population.

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