Study finds link between relative lengths of index
and ring fingers in men and behaviour towards women.
Men with short index fingers and long ring fingers
are on average nicer towards women, and this
unexpected phenomenon stems from the hormones these
men have been exposed to in their mother’s womb,
according to a new study by researchers at McGill
University. The findings might help explain why
these men tend to have more children.
The study, showing a link between a biological event
in fetal life and adult behaviour, was published in
the journal Personality and Individual Differences.
Men’s index fingers are generally shorter than their
ring fingers. The difference is less pronounced in
women.
Previous research has found that digit ratio –
defined as the second digit length divided by the
fourth digit length – is an indication of the amount
of male hormones, chiefly testosterone, someone has
been exposed to as a fetus: the smaller the ratio,
the more male hormones. The McGill study suggests
that this has an impact on how adult men behave,
especially with women.
“It is fascinating to see that moderate variations
of hormones before birth can actually influence
adult behaviour in a selective way,” says Simon
Young, a McGill Emeritus Professor in Psychiatry and
coauthor of the study.
Several studies have been conducted previously to
try to assess the impact of digit ratio on adult
behaviour. This one is the first to highlight how
finger lengths affect behaviour differently
depending on the sex of the person you are
interacting with.
“When with women, men with smaller ratios were more
likely to listen attentively, smile and laugh,
compromise or compliment the other person,” says
Debbie Moskowitz, lead author and Professor of
Psychology at McGill. They acted that way in sexual
relationships, but also with female friends or
colleagues. These men were also less quarrelsome
with women than with men, whereas the men with
larger ratios were equally quarrelsome with both.
For women though, digit ratio variation did not seem
to predict how they behaved, the researchers report.
For 20 days, 155 participants in the study filled
out forms for every social interaction that lasted 5
minutes or more, and checked off a list of
behaviours they engaged in.
Based on prior work, the scientists classified the
behaviours as agreeable or quarrelsome. Men with
small digit ratios reported approximately a third
more agreeable behaviours and approximately a third
fewer quarrelsome behaviours than men with large
digit ratios.
A previous study had found that men with smaller
digit ratios have more children. “Our research
suggests they have more harmonious relationships
with women; these behaviors support the formation
and maintenance of relationships with women,”
Moskowitz says. “This might explain why they have
more children on average.”
The researchers were surprised to find no
statistically relevant link between dominant
behaviours and digit ratios. They suggest future
research could study specific situations where male
dominance varies – such as competitive situations
with other men – to see whether a correlation can be
established.
See also
Verbal Aggression may have biological causes
identified by your finghers' length (2013-01-15)
Finger Length Linked to Prostate Cancer Risk
(28/01/2011)
For more information
“Fetal
exposure to androgens, as indicated by digit ratios
(2D:4D), increases men’s agreeableness with women”
D.S. Moskowitz, Rachel Sutton, David C. Zuroff,
Simon N. Young, Personality and Individual
Differences, March 2015 (available online 27
November 2014)
McGill University
MDN |