Pharyngula

Lua Yar talks about…

The neurobiology of intelligence

Where do people get the idea that intelligence has a biological basis? Oh yeah, from those geneticists, whose research has shown that intelligence levels can be inherited. One fairly new development for researching intelligence is through the conduction of brain imaging studies.

Recently, two neuroscientists by the names of Richard Haier of the University of California, Irvine and Rex Jung of the University of New Mexico, compiled a review of 37 such intelligence imaging studies. With this data, and current neurobiology studies that indicate intelligence is a measure of how well information travels through the brain, Haier and Jung formulated what they call the Parieto-Frontal Integration Theory (P-FIT). This theory identifies the stations of the brain, chiefly found in the frontal and parietal lobes, that network to produce intelligent information processing. So, whether you are smart or stupid depends, in part, on differences in connections between, and composition of, specific areas of the brain.

Haier and Jung have made many contributions to intelligence research. They discovered that it is unlikely that a single “intelligence center” exists, as the regions of the brain related to general intelligence are dispersed throughout the brain. In another study, general intelligence levels between the sexes were determined to have essentially no disparity, and yet their neural structures are different, with women having more white matter and men having more gray. This indicates that intelligence levels are independent of brain design.

Of course, can all of this just be taken with a grain of salt, because how does one really measure intelligence?

Comments

  1. #1 Anton Mates
    October 1, 2007

    In another study, general intelligence levels between the sexes were determined to have essentially no disparity, and yet their neural structures are different, with women having more white matter and men having more gray.

    I think, from the article, that their study actually didn’t find that. It found that intelligence test performance was more correlated with the amount of white matter in women, but with the amount of gray matter in men.

  2. #2 soteos
    October 1, 2007

    “how does one really measure intelligence?”

    With a ruler?

    Good stuff. Let’s figure out how those brains work so we can start rewiring them. I’d like to hear more about those neural structures that make men and women different.

  3. #3 Mike Haubrich, FCD
    October 1, 2007

    Of course, can all of this just be taken with a grain of salt, because how does one really measure intelligence?

    I’ll take two grains of salt, because it seems to me that before anyone can effectively measure intelligence, they would have to formulate a solid definition of intelligence. Definitions are Wilkins’ department.

  4. #4 Jonathan
    October 1, 2007

    with women having more white matter and men having more gray.

    That’s funny, the other studies I have read all say women have more grey matter and men have more white matter.

  5. #5 Azkyroth
    October 1, 2007

    Since as I understand it white matter is, to simplify somewhat, mainly connections between neurons, I wonder if more white matter in one sex indicates a tendency to use more distributed parallel processing techniques for processing information that would be handled in a more local, possibly serial-ish way in the other sex. …does the above make sense?

  6. #6 Thanny
    October 1, 2007

    Intelligence is a property of functioning brains. Brains are built by genes. You don’t need to conduct research to determine that intelligence has a biological basis.

    It’s 100% biological.

    You also don’t need research to show that people inherit different levels of intelligence. That’s decided as soon as you accept evolution and judge yourself smarter than a banana.

  7. #7 miko
    October 1, 2007

    “It’s 100% biological.”

    Yeah, as is anything a living thing does, in a broad sense. There is an interesting discussion to be had, though. Clearly genetics influences intelligence. Clearly other things do to. And just because we’ve named something “intelligence” doesn’t mean such a thing exists… intelligence has only operational definitions and is in many ways just a cultural/folk category and not a scientific concept.

    What the metanalysis does is attempt to identify a mechanistic underpinning of “intelligence,” which would of course be a major achievement and step toward a conceptually grounded way of defining intelligence. Though I think it’d be best to come up with new terms for different cognitive abilites.. intelligence is probably lots of little widgets and processes interacting in complex ways, and the word has too much baggage.

  8. #8 Guru
    October 1, 2007

    “They discovered that it is unlikely that a single “intelligence center” exists, as the regions of the brain related to general intelligence are dispersed throughout the brain.”

    I would think that the whole brain is responsible for intelligence; that is what it is for, isn’t it? (Provided your definition of intelligence is broad enough, including emotional intelligence etc.)

  9. #9 Phoenician in a time of Romans
    October 1, 2007

    Intelligence is a property of functioning brains. Brains are built by genes. You don’t need to conduct research to determine that intelligence has a biological basis.

    It’s 100% biological.

    Like muscle tissue? Presumably this would mean that weight training or aerobic exercise has no effect, right?

  10. #10 sailor
    October 1, 2007

    “Intelligence is a property of functioning brains. Brains are built by genes. You don’t need to conduct research to determine that intelligence has a biological basis. It’s 100% biological.”
    “Like muscle tissue? Presumably this would mean that weight training or aerobic exercise has no effect, right?”
    What #6 was saying is true – both muscles and brain have a biological basis, that does not mean either cannot be modified by environmental factors.
    I think it reasonable to suppose that there is no such real thing as true general intelligence. Mensa members are good at a particular kind of task (the kind of test they take) and may be completely hopeless at many other things including useful skills like empathy. General intelligence is a rather poor construct, and would be better broken down into a variety of more specific problem solving abilities.

  11. #11 Caledonian
    October 1, 2007

    Definitions are Wilkins’ department.

    No, asking questions and providing no means for even trying to answer them is Wilkins’ department.

    Operationalizing imprecise terms is scientists’ job.

  12. #12 Caledonian
    October 1, 2007

    Phoenician in a time of Romans:

    It’s 100% biological.

    Like muscle tissue? Presumably this would mean that weight training or aerobic exercise has no effect, right?

    ‘Biological’ does not equal ‘predetermined’, PiatoR.

    The amount of exercise you get determine how well developed your predetermined muscular potential is, where it’s developed, and how – but there are still inborn limits to how musculature can be developed, and some of those limits are determined genetically.

    Intelligence, whether used in the most unspecific or operationally precise senses, is similar. The environment can stunt development quite easily, or development can be encouraged, but eventually severe diminishing returns curtail further development no matter how congenial the environment becomes. Those limits are predetermined, some genetically.

  13. #13 windy
    October 1, 2007

    You also don’t need research to show that people inherit different levels of intelligence. That’s decided as soon as you accept evolution and judge yourself smarter than a banana.

    Strictly speaking, it doesn’t ‘follow from evolution’ that people must inherit differences in intelligence. Our taillessness evolved, but it isn’t necessary that people must inherit different levels of not having a tail (the tails that do turn up in humans are usually not inherited). Intelligence is unlikely to be fixed to that extent, but you need to look elsewhere than bananas to prove it.

  14. #14 B. Dewhirst
    October 1, 2007

    Lets see if you can spot…

    Begging the question…

    Strawman argument…

    argument from personal incredulity/ argument from ignorance

  15. #15 oxytocin
    October 1, 2007

    Intelligence is a vigorous area of research in psychology. The construct, g, is throught to be composed of several domains of intellectual capacity. The gold standard of intelligence testing, the Wechsler Adult Intelligence Scale, 3rd Edition {WAIS-III) uses the theory that intelligence is divided into crystalized (knowledge based) and fluid (problem-solving) intelligence, and then each of these are further subdivided into separate components, such as vocabularly, mathematical reasoning, pattern recognition, social problem solving, etc.

  16. #16 Anton Mates
    October 1, 2007

    Jonathan,

    That’s funny, the other studies I have read all say women have more grey matter and men have more white matter.

    So apparently each sex’s IQ results are more strongly correlated with the type of brain tissue it has less of. Interesting. Perhaps male and female brains generally lie on opposite sides of some optimum (for IQ performance) grey/white proportion?

  17. #17 Brownian
    October 1, 2007

    Of course, can all of this just be taken with a grain of salt, because how does one really measure intelligence?

    It’s measured via hollowed-out and halved coconuts banged together to make the sound of clop-clopping horses.

  18. #18 Sideways
    October 1, 2007

    The fact that intelligence is inheritable does not necessarily imply that it is genetic. Surnames are inheritable too after all.

    Difference in intelligence between species is for the most part determined by genetic factors (e.g. bananas have no brains). Intelligence differences between individuals–setting aside developmental disabilities–seems determined largely by environmental rather than genetic causes, rather like muscle mass or dental health.

  19. #19 Caledonian
    October 1, 2007

    Intelligence differences between individuals–setting aside developmental disabilities–seems determined largely by environmental rather than genetic causes, rather like muscle mass or dental health.

    There’s a reason men not only have more muscle mass than women on average, but find it easier to develop – and it’s not an environmental factor.

  20. #20 Sideways
    October 1, 2007

    Only you, Caledonian, could take your own metaphor out of context.

    I doff my hat to you sir!

  21. #21 Caledonian
    October 2, 2007

    You are missing the point, sir.

    Those things you refer to as determined largely by environmental causes appear so only because you’re ignoring the genetic influences. Genetics has a major impact on the things you’re discussing.

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