Things science bloggers should know

1: Men have 3 pts more IQ than women, explaining the gender pattern in professional employment that we see. Seriously. I guess we don’t need any more STEM related blogging.

2: Jason is stirring up trouble again. Regarding science and religion.

3: What is the consensus on scientific consensus?


  1. #1 The Science Pundit
    December 30, 2009

    I love when Jason does that!

  2. #2 Bryan
    December 30, 2009

    I don’t think it’s accepted that the difference is 3 points. Some studies show it; others don’t. The problem is using a made-on-purpose-to-have-no-sex-differences IQ test to measure whether there is a sex difference on intelligence.

    I’m agnostic about the true score difference being 3 points.

    You don’t seem to understand how a small mean difference at a group level can lead to big under-representation/over-representation at the extreme ends of a distribution?

    That kind of amuses me.

  3. #3 Bryan
    December 30, 2009

    If you want further things to gape about, I think the literature shows conclusively that large effects exist (d > 1.0) on specific cognitive abilities– versus general intelligence.

    I also think the link to hormones as a partial cause is undeniable.

    You probably know more about this than I– have you ever heard of congenital adrenal hyperplasia?

    I could be spelling it wrong. Familiar to you?

  4. #4 Greg Laden
    December 30, 2009

    Byan, you are such a twerp, and a dishonest one at that. I’m pretty sure that I’ve made clear to you why I think your comments on male vs. female IQ are misguided, and it has nothing whatsoever to do with the numerical or statistical effects you refer to. I don’t know why you can’t get that.

    Your amusement is misplaced and absurd. Please readjust. (The medication.) Or at least read the words in the comments and text you are responding to.


  5. #5 skeptifem
    December 30, 2009

    Dudes who say shit like that have no idea what it is like to grow up in this world female.

    I spent a good chunk of my life claiming that I was “bad at fixing things” and “not mechanically inclined”. I believed it because I didn’t have the oppertunity to try, and I didn’t think that I would do well with something that felt culturally wrong to try. This has been documented over and over again in studies of people of color and women, where their cultural expectations have a very real effect on their test scores.

    Later on, through regular run-of-the-mill problem solving (cars breaking down, improving protocols at work, troubleshooting broken things at home/work, etc) I found out I was pretty damn good at it. Guess what I probably would have done poorly at on an IQ test before that? If you think you are a shitty problem solver who cannot do problems that involve math/mechanical issues then guess what? You will suck at those things. There just ISN’T a section on an IQ test that can work the other way around. Things like empathy or taking care of others are not considered a component of intellect, so guys who would be outside their gender comfort zone aren’t penalized on their IQ tests via culture. Girls are, all the time. There are a fair amount of girls who think being smart at anything is improper. These are big problems that can’t be factored out of IQ studies, they are ever present- it would be very difficult to get some sort of a control group that has not been exposed to these ideas. So, I don’t really care if they wanna claim a 3 point difference; I don’t think 3 points matters all that much anyway. People who act as though this MUST be evidence of some natural inferiority are fucking morons, considering the constant discouragement girls face 3 points is god damned amazing.

  6. #6 Bryan
    December 31, 2009

    Sorry, skeptifem, I think you are overstating the conclusions I’d reach from a 3 point difference, if it indeed really exists.

    I am at a point in my career where I see a paradox: I don’t like the idea of testing a single person and telling him to be a mechanic, or cop or CPA because of his/her score. The hit/correct rejection rate would be better than chance, but the false alarm/miss rate would be unacceptably high.

    As one piece of the puzzle in a single person’s career development, IQ can be useful.

    The dilemma comes when looking at groups versus individuals. Compare 1000 CPAs to 1000 cops to 1000 mechanics. Mean IQ’s will vary considerably.

    The effect of an IQ difference on groups of people is profound, even if some people in the group succeed where the IQ predicts failure and vice versa.

    I can show you mathematically how much money an IQ test can save– ROI– by using an IQ test. In the long run, that’s outstanding for the company, but we do with the good employee we never hired, or the crappy one we did?

    I dunno the answer, but I think the effects on aggregate-level data are so powerful, that this a top priority for scientific funding (bring on the “non-racists” too then. It should be a simple matter to produce the theory and data that explain this environmentally, and get that published in a respectable journal).

    I wonder if Greg’s world view can explain why CAH females perform as well as males on math/spatial tests, and prefer “male” toys like GI joe and trucks over “female” toys like barby and the dish set (or why in general a huge literature on toy preference shows that parental influence has zero effect)?

  7. #7 Stephanie Z
    December 31, 2009

    why in general a huge literature on toy preference shows that parental influence has zero effect

    Well, that’s pretty much exactly incorrect. There are studies showing that other things have an effect as well, but when parental preferences are measured, they have a substantial effect.

  8. #8 Holmes
    December 31, 2009

    I think this Bryan chap lives in Bizarro Land where everything is opposite.

  9. #9 Bryan
    December 31, 2009

    I will cite three meta-analyses with huge N sizes showing Cohen’s d (the effect) to be exactly (iirc) zero.

    But, no one will click on the links.


    No matter what you think of me, you should check out this literature. It’s fascinating.

    Look at your index finger compared with your ring finger?

    Which is longer?

    This is the called the 2d4d ratio. It’s caused by hormones.

    If this makes no sense, here’s a picture:

    Most men have ring fingers longer than index fingers. Most women are usually equal in the ratio, or the opposite. Exceptions certainly exist.

    The ratio predicts lots of things (albeit weakly to moderately) from sexual orientation to performance on math and spatial tasks to aggression levels.

    Here’s an example on a huge-sample study of sex differences in math performance:

    In spite of the reduced level of experimental control, this large scale study brought some clarity into the relation between mental rotation task (MRT) performance and a number of variables where contradictory associations had previously been reported in the literature. Clear sex differences in MRT were observed for a sample of 134,317 men and 120,783 women, with men outperforming women. There were also MRT differences as a function of sexual orientation: heterosexual men performed better than homosexual men and homosexual women performed better than heterosexual women. Although bisexual men performed better than homosexual men but less well than heterosexual men, no significant differences were observed between bisexual and homosexual women. MRT performance in both men and women peaked in the 20–30 year range, and declined significantly and markedly thereafter. Both men and women showed a significant negative correlation between left and right digit finger ratio and MRT scores, such that individuals with smaller digit ratios (relatively longer ring finger than index finger) performed better than individuals with larger digit ratios.

    The hormonal effects, though, are very complicated. From what I remember, higher than normal testosterone levels in men decrease math performance; whereas in women, it increases math performance.

    Estrogen levels show similar effects but on verbal abilities (where women squarely kick ass). Women are far more likely then men to process language in both hemispheres. Right handed males with very high probability process language only in the left hemisphere (this seems like Greg’s area?)

    Verbal and math scores within person for females change with the menstrual cycle as hormone levels rise and fall.

    This is my memory of a literature I haven’t read in a few years. If it’s incorrect, someone will show me that, but please cite data and not 1 sentence dismissals based on my stupidity or sexism or whatever.

    So, curious, what’s your 2d4d ratio? How would you introspect on your math versus verbal skill set?

  10. #10 Bryan
    December 31, 2009

    In my last post, I meant that I think language is greg’s area of expertise. It wasn’t a ding.

    It seemed unclear when re-reading it, so I post this clarification here.

    Good night.

  11. #11 Stephanie Z
    December 31, 2009

    Greg, does Bryan have a post in moderation for those three links?

  12. #12 Greg Laden
    December 31, 2009

    Nope. The only thing in moderation right now is a gucci ad and a death threat. Samo samo.

  13. #13 Stephanie Z
    December 31, 2009

    Too bad. I was really curious how they’d gotten there.

  14. #14 Observer
    December 31, 2009

    Intelligence in men and women is a gray and white matter

    Men and women use different brain areas to achieve similar IQ results, UCI study finds

    Irvine, Calif. , January 20, 2005

    While there are essentially no disparities in general intelligence between the sexes, a UC Irvine study has found significant differences in brain areas where males and females manifest their intelligence.

    The study shows women having more white matter and men more gray matter related to intellectual skill, revealing that no single neuroanatomical structure determines general intelligence and that different types of brain designs are capable of producing equivalent intellectual performance.

    “The study shows women having more white matter and men more gray matter related to intellectual skill, revealing that no single neuroanatomical structure determines general intelligence and that different types of brain designs are capable of producing equivalent intellectual performance.

    “These findings suggest that human evolution has created two different types of brains designed for equally intelligent behavior,” said Richard Haier, professor of psychology in the Department of Pediatrics and longtime human intelligence researcher, who led the study with colleagues at UCI and the University of New Mexico. “In addition, by pinpointing these gender-based intelligence areas, the study has the potential to aid research on dementia and other cognitive-impairment diseases in the brain.”

    Study results appear on the online version of NeuroImage.

    In general, men have approximately 6.5 times the amount of gray matter related to general intelligence than women, and women have nearly 10 times the amount of white matter related to intelligence than men. Gray matter represents information processing centers in the brain, and white matter represents the networking of – or connections between – these processing centers.

    This, according to Rex Jung, a UNM neuropsychologist and co-author of the study, may help to explain why men tend to excel in tasks requiring more local processing (like mathematics), while women tend to excel at integrating and assimilating information from distributed gray-matter regions in the brain, such as required for language facility.”

  15. #15 skeptifem
    December 31, 2009

    Thank god bryan and observer are here to mansplain the defectiveness of my brain when I do well at “masculine” subjects. I would have thought I was a human being with unique attributes (you know, the kind that men seem to have even when they bake well or take good care of children), but now I know I am just an abnormal woman and that’s where my talents come from.

  16. #16 Greg Laden
    December 31, 2009

    Embrace your abnormality! It is Statiztically Provenz!

    But really, Bryan’s heart is in the right place.

    He just wants to make sure the corporations he works for do not accidentally hire someone like you. For the best, really.

  17. #17 ERV
    December 31, 2009

    My IQ is quite a bit higher than my brothers (my bro wanted a smart little sister– he coached me for the first test I took).

    I also preferred ‘boy’ toys like building blocks and computer games to dolls (because I loved my bro and wanted to play with what he played with).

    Math was always my favorite subject (bro and dad taught me the math bro was learning. bro is 5 years older than me).

    And, wait for it– my ring finger is a teeny bit longer than my pointer finger.

    So I guess theres no denying it.

    Im a d00d.

    Better cancel my pap on Monday.

  18. #18 yolande
    December 31, 2009

    I have been following this blog and other related ones for a few days now (rather bemusedly) and it is my humble opinion that IQ tests are a complete waste of time because all they really show is how well a person can do the test. Some people are good at doing tests and others not. It has nothing to do with intelligence.

    If someone does 500 IQ tests, practises and learns from them, eventually they will keep doing better. It doesn’t make them more intelligent. Just means they are proficient at doing tests.

  19. #19 Jim Thomerson
    December 31, 2009

    The index finger vs ring finger length is a Mendelian characteristic which is sex influenced. The homozygote expression is the same in males and females, but the heterozygote expression is sex influenced. Pattern baldness is another example of sex influenced characteristic. Heterozygous males are bald, heterozygous females are not. Homozygous balds are bald in both sexes.

  20. #20 Greg Laden
    December 31, 2009

    index finger vs ring finger length is a Mendelian characteristic which is sex influenced.

    I’m pretty sure this is not true. I think it used to be thought of as true, but on further study turns out to be the effect of intrauterine hormones. At least, of the couple’few dozen papers I’ve read on this since this recent spate of research on it started (in the 1990s) nothing I know of refers to the simple Mendelian pattern, and the only Mendelian models I know of are forty years old or so, and when you look at them the intrauterine conditioning makes more sense than the genetic explanation.

    Kinda like IQ, huh?

    Anyway, if there is a recent reference demonstrating (not just referencing) a d/r inheritance pattern I’d love to see it!

  21. #21 daedalus2u
    December 31, 2009

    I have read a little of the digit length literature. Mostly in the context of it being a marker for in utero androgen exposure and Simon Baron Cohen’s “extreme male brain” idea of autism (which I don’t really like). The rate limiting enzyme for testosterone synthesis is normally inhibited by NO (that is the normal regulation pathway), so low NO does cause high androgen levels. The rate limiting enzyme is a P450 which makes superoxide which consumes NO, so high androgen levels are also low NO levels. The estrogen receptor is coupled to nitric oxide synthase, so premenopausal women have higher NO levels (that is part of why they have lower incidence of CHD). I think that is also why they tend to be smaller than men (historically), and why they are now larger.

    High androgen levels cause hair growth which expands the niche where the bacteria I am working with grow, so they make more NO/NOx which feedback-inhibits androgen synthesis.

    I think the association of digit length with androgen exposure is because androgen exposure correlates with NO, and it is NO that does the digit length regulation. Bone growth is regulated by NO (in a bunch of ways).

    Digit length ratio is also a marker for impaired fetal growth, and it is affected in twins by the gender of the opposite twin. I saw a paper where females with congenital adrenal hyperplasia (21 hydroxylase enzyme deficiency which generates lots of androgens and results in masculinized genitalia) had the same ratio as normal females.

    I think it is extremely unlikely that the digit ratio is determined by a single or a few genes. If it is heritable in a Mendelian fashion it would have to be and something as subtle as finger length seems too complicated for that.

  22. #22 Bryan
    January 1, 2010

    Exceptions to a rule based on a group difference in now way invalidate the rule. They are wholly worthless, unless the group difference is so large, the distributions don’t overlap.

    Let’s not open the can of worms on Bem’s (completely environmental) explanation for sexual orientation as an adult: girls playing mostly with boys should be lesbians as adults; boys playing mostly with girls, should be gay as adults. Interesting stuff; but complete derail.

  23. #23 ERV
    January 1, 2010

    Did… did Bryan just call me a dyke?


  24. #24 Greg Laden
    January 1, 2010

    Allow him his fantasies.

    Or not.

  25. #25 Bryan
    January 1, 2010

    You guys aren’t familiar with Bem’s “exotic becomes erotic” theory of sexual orientation.

    Check it out; you probably would like it (it’s clever enough for me to consider, even given my
    “it’s mostly nature– not nurture–”
    world view). It is a completely 100% environmental explanation for sexual orientation.

    Via classical conditioning, what scares us as kids sexually attracts us as adults.

    An anthropologist would eat it up, as he gets into all kinds of cultural examples that support his idea.

  26. #26 Greg Laden
    January 1, 2010

    Bem is a well known kook who thinks we can communicate telepathically via something a lot like the Star Wars “force.”

  27. #27 Bryan
    January 1, 2010

    Bem is the guy who has the psych bull article on Ganzfeld studies (re paranomal crap).

    It was however, published in psych bulletin.

    Typical Greg, close the mind to possible new knowledge or a counter argument by attacking the man.

    Bem’s paper was published in psych review, the most elite journal in psychology (1 pub there = tenure most anywhere).

  28. #28 nwo rebel soilder
    January 1, 2010

    just look at us everything is backwards everything is upside down. doctors destroy health, lawyers destroy justice, universities destroy knowledge, goverments destroy freedom, the major media destroy information and religion destroy spirtuality this is not by accident but by design.

  29. #29 nwo rebel soldier
    January 1, 2010

    @gregladen:isnt the true measure of wisdom the abilty to entertain any idea no matter how obsurd, so why do you insult this bem guy is communicating telepathically such an obsurd idea. remember that scentist that said the earth was round not flat no one would take him seriously and they laughted at him.i sure hope your not a scientist greg because that would be to much.

    i believe in everything until its disproved. so i believe in fairies, the myths, dragons. it all exists, even if its in your mind. whos to say that dreams and nightmares arent as real as the here and now?

  30. #30 daedalus2u
    January 1, 2010

    nwo, you have a strange notion of what you consider to be wisdom. I consider it being able to separate good ideas from bad ideas depending on how close they correspond with reality.

    The number of wrong ideas is the one thing that is actually infinite. You want to believe in that infinite set after you have whittled it down by the finite set of what can be “proven” to be wrong. Good luck with that.

  31. #31 Jim Thomerson
    January 2, 2010

    I must confess that my basic genetics course was in 1959. Here is one current site which is still stuck in the 20th century so far as ring vs index finger genetics goes.

    Since the early 1980’s, females have dominated the ranks of bachelors graduates, and more recently the ranks of Master’s graduates. Haven’t seen any figures on PhD’s. This imbalance is greatest among black and Hispanic graduates. This has gone on for some 30 years; so, by now, or soon, the majority of degreed people in the USA will be female. So what? he asks.