Women who have an index finger shorter than their ring finger may be stronger, a new study suggests.
Researchers looked at people’s 2D:4D digit ratios – the difference in length between the index and ring finger – and how this is related to muscle strength.
A lower 2D:4D digit ratio (having a shorter index finger than ring finger) is already thought to indicate higher exposure to testosterone in the womb.
In experiments, women with a lower 2D:4D ratio tended to have higher grip strength than women with a higher 2D:4D ratio, the researchers found.
An index finger that is relatively short compared to the ring finger indicates that one has been exposed to a lot of testosterone in utero, whereas a relatively long index finger suggests a lower exposure to testosterone in the womb
2D:4D DIGIT RATIO
The 2D:4D digit ratio is a biomarker that reflects the level of testosterone a male was exposed to in the womb during pregnancy.
2D:4D digit ratio is the ratio between the length of a person’s index finger (2D) and ring finger (4D). It’s calculated by dividing as ring finger length by index finger length.
A lower 2D:4D digit ratio is said to indicate higher exposure to testosterone in the womb – and is therefore suggestive of masculinity.
Meanwhile, a higher 2D:4D digit ratio is said to indicate lower exposure to testosterone in the womb – and is therefore suggestive of femininity.
The new study was conducted by researchers at the Department of Evolutionary Anthropology, University of Vienna, Austria and published in Proceedings of the Royal Society B.
2D:4D ratio has already been linked to male strength, but until now its link with women’s strength has been ambiguous, they claim.
‘A lower 2D:4D ratio – and higher prenatal testosterone exposure – is linked to higher grip strength in adulthood,’ study author Katrin Schäfer told MailOnline.
‘This has been established for men for quite some time, and now we could show the same mechanism for women.’
The team measured the digit ratios and handgrip strength of 125 healthy women between 19 and 31 years of age from a remote region in Austria.
Handgrip strength was measured using a dynamometer – a device with a handle that’s often used for routine medical screening of patients’ grip strength.
Reduced hand grip strength is already associated with increased severity of a range of chronic conditions, including cardiometabolic disease and chronic obstructive pulmonary disease.
2D:4D digit ratios, meanwhile, were measured using a mobile A4 scanner (CanoScan LiDE 200).
The research team took scans of women’s hands (pictured) to find out their 2D:4D digit ratio
Overall, the academics found a ‘clear association’ between lower 2D:4D digit ratio and handgrip strength in women.
In other words, a longer ring than index finger (and therefore exposure to more prenatal testosterone in the womb) was positively associated with handgrip strength and therefore muscular fitness.
The researchers say they controlled potential confounding factors, such as age, environment, ethnicity and exercise, that could have influenced the association.
Overall, they argue in favour of 2D:4D as a biomarker for prenatal testosterone exposure, despite some perceived limitations by other academics in the past.
Hand grip measurement for the study was measured using a Jamar plus digital hand dynamometer (pictured)
One of the arguments against it is that men have bigger body parts, including fingers, which impacts the 2D:4D ratio.
‘We do believe that is a reliable biomarker and the best non-invasive biomarker that we can use to study humans in general and particularly from a retrospective point of view,’ study author Sonja Windhager told MailOnline.
‘Experimental possibilities in this field are highly limited for ethical reasons.’
There have already been numerous studies looking into how various factors are linked with the 2D:4D ratio.
Earlier this year, researchers in Scandinavia found hungry people with low 2D:4D digit ratios ‘make more masculine food choices’.
Also this year, Swansea University researchers found children born to a mother with an above-average income had a lower 2D:4D digit ratio.
HOW CAN YOU MEASURE YOUR 2D:4D RATIO?
To measure your finger straighten it and look at the palm of your hand.
At the base of your index and ring fingers there are likely to be creases. Your index finger is likely to have one crease, the ring finger is a band of creases.
Select the crease closest to the palm and choose a point on the crease midway across the base of the finger.
Mark it with a pen. Measure it from the mark to the tip of the finger.
To measure your finger straighten it and look at the palm of your hand. At the base of your index and ring fingers there are likely to be creases. Your index finger is likely to have one crease, the ring finger is a band of creases