Biological basis for sex differences in math ability

That there is some biological basis behind the observation that men are better at math than women is plain old common sense, because there have never been any sociological explanations that made sense. Via Steve Sailer, I read an article about some scientific research that more definitively points to a biological connection.

Scientists have known that different levels of the hormones testosterone and estrogen in the womb account for the different finger lengths ...

Exposure to testosterone in the womb is said to promote development of areas of the brain often associated with spatial and mathematical skills, he said. That hormone makes the ring finger longer. Estrogen exposure does the same for areas of the brain associated with verbal ability and tends to lengthen the index finger relative to the ring finger.

To test the link to children's scores on the College Board's Scholastic Assessment Test (for which the name has changed a number of times in the past 100 years), Brosnan and his colleagues made photocopies of children's palms and measured the length of their index and ring fingers using calipers accurate to 0.01 millimeters. They used the finger-length ratios as a proxy for the levels of testosterone and estrogen exposure.

The researchers then looked at boys' and girls' test performances separately and compared them to finger-length ratio measurements. They found a clear link between high prenatal testosterone exposure, indicated by the longer ring finger compared to the index finger, and higher scores on the math SAT.

Similarly, they found higher literacy SAT scores for the girls among those who had lower prenatal testosterone exposure, as indicated by a shorter ring finger compared with the index finger.

The important thing to get out of this is that there is an intra-sex correlation between sex hormones and math scores, and this is in the direction one would expect. More prenatal exposure to the male sex hormone testosterone correlates with higher math scores. This suggests that sex hormones also explain why men, on average, have higher mathematical ability than women. Larry Summers should wave this research paper in the faces of those at Harvard who got him fired.

However, I also believe that this finding, by itself, does not fully explain the connection between math ability and sex hormones. The stereotype is that the kids who are good at math are the nerdy non-athletic kids, the opposite of the high-testosterone football playing kids. So although there is a scientifically validated correlation between prenatal testosterone and math, there is an anecdotal opposite correlation for teenage boys. Less testosterone in the teenage years seems to predict higher math performance.

Comments

[Tim Lundeen]

My recollection from Kimura's book, Sex and Cognition, is that math ability versus in-utero testosterone level is hill-shaped, and higher and lower levels of testosterone both decrease math ability versus the "just right" level.

A good book, btw.

[GrannyJ]

Oh M'Gawd! Here I am, at 80 years of age, discovering just why I preferred math to other subjects & scored better at math than at verbal on assorted standardized tests, even though I had a career as a journalist. It's all because my ring finger is slightly longer than my index finger!! Oh, yes, I happen to be female.

[Jody]

Random somewhat related note:

I think I qualify as a freak - on my right hand, the ring finger is quite a bit longer than the index finger, but on my left hand, the index finger is slightly longer than the ring finger.

[SFG]

Larry Summers should wave this research paper in the faces of those at Harvard who got him fired.
E pur si muove! Giordano Bruno was right, he still got burnt.

Oh M'Gawd! Here I am, at 80 years of age, discovering just why I preferred math to other subjects & scored better at math than at verbal on assorted standardized tests, even though I had a career as a journalist. It's all because my ring finger is slightly longer than my index finger!! Oh, yes, I happen to be female.
I love these silly responses. Group A is on average more X than group B, thus ALL members of group A have more X than ALL members of group B. Showing two overlapping bell curves debunks this in a minute, but people like to pretend they don't know better.

And I'd be careful about assuming nerds don't have high testosterone levels without taking saliva samples from the science fiction club. (It's easy--just put a cheerleader in glasses and a Star Trek shirt and walk her by, then collect the drool.) Not all stereotypes are correct, though they do have a grain of truth. Most likely it's a combination of testo levels with whatever goes wrong in autism and five other factors we don't know about yet.

[John]

Why would you assume that playing sports does not require mathematical ability? SPecifically spacial relations, as correlated in the article. Being able to mentally track the locations, speed and distance of moving objects and people is paramount in most athletic events. Isn't whether a student chooses to focus his skills athletically or academically unrelated to the underlying ability?

[SFG]

I suspect many stereotypical engineers, etc. have good visuo-spatial skills but lousy gross motor and fine motor coordination. Most likely coordination uses additional brain systems that aren't well developed in stereotypical nerds.

You've got to remember, the line about only using 10% of our brains is BS, but we still don't know what everything does, and we especially don't know how all the pieces work together.

[David Alexander]

Of course, this discussion leads me to ask if high testosterone is connected to the idea of increased Math ability, what explains the poor math skills of black males who have a tendency to have higher testosterone levels?

BTW, for arguments sake, my index finder is longer than my ring finger.

[SFG]

Because there are 50 other things affecting math ability besides testosterone level, obviously. The study just tells us that across human populations, people with more testosterone tend to be better at math. But math ability is affected by lots of other things too.

[Spungen]

Because there are 50 other things affecting math ability besides testosterone level, obviously.

Obviously, because my ring finger is (only slightly) longer than my index finger. I always hated math. According to standardized test scores I was supposed to be a lot better at it than I actually was.

[SFG]

You might have had a good level of innate mathematical aptitude but no interest in the subject. It's hard to study something you're just not interested in.

[Jack]

My ring is longer; that makes sense, because in standardized tests, I always did best in Math. Like Spungen, though, I was more interested in other subjects. The stereotype of the "dumb jock" and "smart nerd" are way overblown. Some athletes are very intelligent, although, sure, if you compare them to physics professors, they will look dumb in comparison.

[LK]

Hi I just happened across this site while googling on the above topic, and I must say I find this odd. I am female but my ring finger is much longer than the index (ard 1.5cm difference), and I really hate maths/physics.

Didnt do half as well in it as I did for Arts and Art. But I love computers, tinkering with formulas, troubleshooting, sorting data, etc... would this be the 'maths' for me?

[SFG]

Could be. Remember that testosterone is one of lots of factors affecting math ability, so there's no reason you won't have lots of counterexamples going either way.

[DG]

I think these finger studies are just pseudo-science. Most studies say men with low-average testosterone levels and women with high testosterone levels are best at math. I think it's hard to picture someone who looks like George W. Bush as a rocket scientist for a reason. Men born with naturally higher testosterone probably just have more "primitive" brains and can't deal with abstraction as well.

[DG]

George Bush is also proof that the "upper classes" are not more sophisticated or intelligent than "lower classes". That is the view this blog seems to advocate. I'm going to guess that the author is a white-bread simpleton like Steve Sailer.