Autism and 2d/4d Finger Ratio

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I've read that people with Autism may of been exposed to high levels of testosterone during fetal development. A physical indication of this is having a index finger that is significantly shorter than the ring finger, particularly on the right hand. I'm interested in finding out the percentage among us that have this indicator.

Sounds like junk science to me. Have any links to quality information on this? I'd never looked and the difference, but my index finger is shorter. What do you consider significantly shorter?

well, me, too but....indeed where do you get that one from?

Last edited by ediself on 30 Nov 2010, 10:26 am, edited 1 time in total.

My index finger is shorter then my ring finger but only by a third, same on other hand.
I do not know if this is significant.

My index finger is the same length as my ring finger on both hands.

Here is an interesting link that provides information:

http://fingerlengthdigitratio.wordpress.com/2008/10/01/finger-length-related-to-autism-low-digit-ratio-094/

Interestingly, this is also considered a characteristic of confident athletic people. Keep in mind that there may be other genetic or environmental influences in autistic people that may account for our sensory, social, and motor skills issues.

One thing I found particulary interesting was the link they found with aspergers and more autistic people. They found that the more profoundly autistic people had a lower 2d/4d ratio than people with aspergers. Folks with aspergers had a ratio somewhere between the people with autism and what is considered a normal ratio. Lower ratio equates to how much shorter the index finger is than the index finger. This is explained in detail on the website.

FWIW, my ratio is .935.

But correlation is not the same as causality.

are you sure our index fingers did not cause our autism?

This poll has problem. If it is slightly shorter then do I pick significantly shorter or equal? And how do I measure it? My index finger is slightly shorter if I measure each finger from the the wrinkle of the base joint where it meets my palm, but it is slightly longer if I measure how far it is from my wrist. The reason being is that the ring finger knuckle is lower than the index finger's knuckle. But maybe you mean fingers at the skeletal level, which would be better measured from the wrist. So I just put equal since that seems the best guess.

Well, I'm guessing my ratio is .944 if I did it correctly.

My index finger is shorter on both hands.
The ratio for my right hand is 0.956.

Got any more sources on this 2d/4d ratio theory? I would be interested to see if the bulk of the evidence supports it, and whether it has a following among the wider scientific community.

I'm not sure that this survey will tell you much, since male autistics outnumber females four to one, and significantly longer ring fingers are theorized to be usually predominant with higher testosterone levels, to which females usually aren't exposed. - LJS

Yep yep yep.

I am female but have the male ratio(short index finger).

It's really not, it applies to many things, not just autism.

Other disorders, male/female differences, sexual orientation, musical/mathematical ability vs. grammar and language skills.

Very interesting research IMO and most people with AS actually do have a short index finger, the ratio is usually even greater in those with classic autism.

The link provided above seems to establish at the very least a correlation. But it seems to be a stretch to elevate in-vitro testosterone to a root cause. Perhaps that combined with some other genetic issues?

I didn't look at that link but I got a little obsessed with the whole thing awhile ago lol.

Most men have the low ratio, as well as most people(including women) with ASD and some related disorders.

I don't think anything can really explain one single cause of autism at this point, though. It's just interesting to see the correaltion.

Low 2D:4D is also linked with left-handedness and dyslexia, as is autism and AS.