In my talk yesterday I briefly mentioned this digit length nonsense, the idea that you can tell men from women by the relative length of their index finger (women are supposed to have longer index fingers than men). I only gave a brief overview of the fallacious idea because I wrote about it over ten years ago and also brought it up at a conference before, and of course everyone remembers everything I ever wrote or said, right? But then today, I spotted this in the wild:

Oh no! It’s real! There are anti-trans inquisitors who think they can reliably diagnose sex by looking at your fingers! I guess I need to repeat myself more.


  1. calgor says

    I was under the impression that the relative lengths of the ring finger vs index finger was due to testosterone exposure (at least partly) in the WOMB!

    And if that is the case, how does that have any connection with the grown adult’s sex?

  2. KG says

    Meanwhile, transphobia gains another win in the Yoo-Kay: the only gender identity clinic for children is being forcible closed, with thousands on its waiting list, and a vague promise of regional centres opening next spring. I’m sure the transphobes will celebrate all the additional suicides that will result.

  3. billseymour says

    I’m not surprised that spouting anti-trans baloney is continuing apace.

    One of the candidates (who shall remain shameless) in the Republican primary for US Senator from Missouri has a TV ad about “protecting women’s sports” (which, as near as I can tell, are not in any danger), in which she correctly identifies one trans woman athlete who won one race.  The phrase, “small sample size”, comes easily to mind.

    (She has a reasonable chance of winning the primary because she’s been endorsed by our current junior Senator who has expressed support for violent insurrectionists.)

  4. says

    Calgor didn’t read the article I linked to. There is a slight statistical bias, but you can’t use it to recognize individual differences.

  5. Matt G says

    Wow, who knew that relative digit length could accurately predict specific activity in the human cortex! Next up: gender determination by dousing!

  6. StevoR says

    No questioning

    Huh? Why not question.? Sounds dodgy as F to me.

    I guess they mean no question – & yeah, I’m the very last person who can talk here given my typos – but still.

  7. llyris says

    Oh dear. Well this is inconvenient. Does this mean my kids have two fathers? Where did the eggs come from and what did I gestate them in? This raises so many questions the scientific community would surely find fascinating.
    And where’s my male priviledge? I want that too.

  8. Ridana says

    So this is supposed to indicate gender now? Back when I heard it, it was supposed to indicate orientation.

  9. microraptor says

    I’ve got one particular finger I’m always happy to let transphobes get a really close look at.

  10. says

    My LEFT ring-finger is about a couple millimeters longer than the index finger, but my RIGHT ring-finger is the same length as the index finger. I guess I must be intersex or something…?

    If any dipstick demands to see my fingers before letting me into the men’s room, I’ll probably just show them the middle ones.

  11. silvrhalide says

    The Venn diagram of the transphobic idiots who are obsessed with digit length and the morons who couldn’t find the clitoris with both hands and a map are just a series of concentric circles.

  12. larpar says

    My index fingers are longer than my ring fingers. Do I need to turn in my man card or can I just cut off the tips of my index fingers?

  13. StevoR says

    Although guess pedantically you could do that second one only it would hurt & harm you and do sod all good.

  14. Tethys says

    My left ring finger is longer than my right, and both are slightly longer than their respective index fingers. That in itself is evidence that finger length is not strongly correlated to gender.

    Any reason why the study only looks at one hand?

  15. macallan says


    My LEFT ring-finger is about a couple millimeters longer than the index finger, but my RIGHT ring-finger is the same length as the index finger. I guess I must be intersex or something…?

    Mine are the other way around and I’m mostly left handed, so…

  16. unclefrogy says

    If some idiot asks to see your fingers to determine your sex I recommend that you give him a Moe Howard answer real close and personal.

  17. bcw bcw says

    @9 I agree, back when, the finger-length test was supposed to indicate if you were gay.

  18. says

    My indexes are shorter than my ring fingers, and my only concern is that it makes four finger typing difficult (index and middle on both hands). Then again, typing full hands is easier with longer reaching ring fingers. (Damn that permanently twisted pinky finger, broken when I was a teen….)

    The etymology of the racist pseudoscience “phrenology” is “mind” plus “study”. Should this digit nonsense be called “manology” (“manus”, meaning hand in Latin)? It would be apt for the transphobic and homophobic panic of the males “studying” this claptrap.

  19. says

    There’s a Japanese heavy metal guitarist called BabySaster. They dress in the gothic lolita style, and wear a face mask that conceals their lower face. Some people have speculated that BabySaster is actually male, and \I came across some folks who think because BabySaster has “man hands” they must be male.

    That got me thinking about my hands. They’re not big, and my fingers are thin. It made me wonder if people would identify my hands as male or female if I shaved the hair off the back of my hands. I’ve got slightly long fingernails on my right hand for fingerpicking on guitar, so a shot of it might be more likely to be perceived as female.

    A lot of Japanese musicians follow the visual kei concept, where besides wearing flamboyant costumes, hair, and makeup their gender presentation is often androgynous. A good example is the Japanese heavy metal guitarist Hizaki, who wears elaborate dresses onstage that look like something an 18th Century European noblewoman would wear, although he identifies as male.

  20. calgor says

    PZ @4
    The point I was attempting to make was that finger length was affected by the exposure of testosterone while the fetus was developing in the womb. Since the testosterone is “set” by the mother at this point, it is arguably independent of the fetus and its ultimate sex category. (Yes, I am aware of the myriad of other factors which would contribute, but I have vague recollections of a 1999/2000 report(?) that womb testosterone levels was quite a significant player)

    So unless puberty had some skew on the results (but again, the report suggests not) then the only thing that the finger ratio demonstrates is the testosterone level of the mother during pregnancy.

  21. John Morales says

    calgor, your point has already been refuted thus:

    There is a slight statistical bias, but you can’t use it to recognize individual differences.

    A bit like saying men are taller (statistically) than women.

    Take two normal probability density functions with (rather slight) different means, there’s a lot of overlap.

  22. Silentbob says

    We can laugh, but as we speak (er write) arguments of this level of fatuousness are being used to ban trans people from sport.

    Trans woman who has medically transitioned but was forced through “male” puberty? – statistically more likely to be taller, therefore unfair.

    These cis women? Totes fair.

  23. calgor says

    John @27
    For a second time, my point is misinterpreted.
    The report (unless I am really missing its intent) states that it is impossible to determine the sex of an individual given the finger ratio despite there being a provable difference between males and females in that ratio. That is due to the difference being too small to allow credible determination.

    Where as the point I thought I was make (obviously mistakenly if this thread is anything to go by) is it is the level of testosterone exposure of the fetus in the womb which is a greater contributing factor to the ratio irrespective of the actual sex of the fetus, so if a female fetus is exposed to higher levels of testosterone, the ratio would be greater by default.

    There was suggestions based on this that this effect could also be a contributing factor to homosexuality – higher testosterone exposure for female fetus, increased chance of lesbianism, correlated with increased finger ratio. Though, I do believe correlation was disproved.

  24. StonedRanger says

    Dang. My left ring finger is only an inch long, while my index finger is closer to three and a half inches. I thought I was male and now Im confused. I hope my wife doesnt find out, she is going to be mad.

  25. John Morales says

    calgor, ah, OK.

    You refer to the causation of the correlation, not to the significance of the correlation.