Ordering another beer at the bar often feels like an impulsive, spontaneous decision.
But a surprising new study suggests that many of us are predisposed to alcohol use even before birth.
Scientists from Swansea University surveyed more than 250 people about their drinking habits while measuring the length of their fingers.
It’s thought that finger length is a measure of the amount of testosterone we were exposed to in the womb – and therefore how ‘masculine’ we are.
According to the findings, the more testosterone we are exposed to in the womb, the more alcohol we drink as adults – although it is unclear why.
“Alcohol consumption is a major social and economic problem,” said study author John Manning, professor of evolutionary biology at Swansea University.
‘It is therefore important to understand why alcohol consumption shows significant differences between individuals.
‘It is possible that differences in alcohol consumption already exist in the womb.’
Ordering another beer at the bar often feels like an impulsive, spontaneous decision. But a surprising new study suggests that many of us are prone to drinking a lot of alcohol long before birth
An index finger that is relatively short compared to the ring finger indicates that one has been exposed to a lot of testosterone in the womb, while a relatively long index finger indicates a lower exposure to testosterone in the womb
Professor Manning is best known for his work on 2D:4D digit ratios – the difference in length between the index and ring fingers.
He thinks that having a longer ring finger than the index finger means that you are more exposed to testosterone (the male sex hormone) in the womb.
If you have a longer index finger than your ring finger, this means that you have been exposed to more estrogen (the female sex hormone) in the womb.
Both boys and girls are exposed to testosterone in the womb, and all people have different levels of male and female sex hormones.
“The digit ratio (2D:4D) indicates the relative length of the second and fourth digits,” Professor Manning said.
‘This ratio is considered a biomarker for the balance between fetal testosterone and estrogen.’
For this new study, Professor Manning and colleagues measured the ring and index fingers of 258 adult students – 89 men and 169 women.
Participants were also asked about their drinking habits, which were recorded as grams of alcohol consumed per week.
This hand has an index finger (2D) that is shorter than the ring finger (4D) – something researchers know has a low digit ratio (file photo)
In general, people with higher alcohol consumption had a ‘low digit ratio’ (meaning their ring finger is longer than their index finger) and thus had higher testosterone exposure in the womb.
This association between alcohol consumption and low digit ratio was strongest in men with long ring fingers on the right hand.
Although the exact reason for the link is unclear, Professor Manning thinks that having more testosterone in us increases alcohol tolerance, perhaps because our blood absorbs less of it.
“Enzymes in the stomach of men can reduce the absorption of alcohol by 30 percent, while women absorb more into the bloodstream,” he said. The sun.
The findings, published in the American Journal of Human Biologysuggests that our alcohol consumption habits are “dependent on prenatal sex steroids,” the team says.
However, more research would be needed to investigate ‘causal relationships’ – whether they can prove that exposure to testosterone in the womb causes us to drink more alcohol in adulthood.
The team admits that the study only used college students, which may represent a very specific subset of the population when it comes to drinking habits.
However, the students – recruited from the Medical University of Lodz in Poland – were ‘not alcohol dependent’.
Both boys and girls are exposed to testosterone in the womb and all people have different levels of male and female sex hormones (file photo)
There have been numerous studies linking 2D:4D digit ratios to certain physical and social trends, including income, athletic potential, anxiety and diet.
A 2021 University of Vienna study found that women with a ring finger longer than their index finger (indicating prenatal testosterone exposure) have better hand strength.
Researchers in Scandinavia also found that hungry people with longer ring fingers than index fingers order more typically “masculine” foods, such as steak instead of salad.
Previously, researchers at Swansea University discovered that children born to mothers with an above-average income had longer ring fingers.
“High-income mothers may secrete high levels of testosterone relative to estrogen early in pregnancy, causing their male and female children to become masculine,” Professor Manning said at the time.
“Low-income women, on the other hand, may secrete low levels of testosterone, which will feminize their male and female children.”