If I ask you to picture a stereotypical Hollywood hardman, who springs to mind? Vin Diesel, perhaps?
Jason Statham? How about Bruce Willis? Or maybe The Rock?
As well as their bulging muscles, these four share another conspicuous
physical characteristic: a distinct lack of hair.
Is this a coincidence? The consequence of a baseless cultural trope?
Or is there some sort of biological link between beefiness and baldness?
Let’s cut to the chase and dive headfirst into this hairy topic:
do higher testosterone levels cause baldness in men?
I’m Stu, and welcome to Debunked,
where we sort the truths from the myths and the facts from the misconceptions.
This video is sponsored by Ground News.
Before you say “what’s this hairy man doing talking to me about baldness?!”,
…this is our writer for this particular episode. So before we look in depth at Mark’s findings,
let’s start with a simple observation.
Men’s testosterone levels — along with their physical strength — peak during adolescence
and early adulthood. Testosterone production then slowly declines,
at a rate of about 1% per year, throughout middle age.
If high testosterone levels caused baldness directly, we might therefore expect baldness
to peak during adolescence, with scalp coverage growing increasingly dense over time.
It doesn’t take a particularly keen observer
to notice that this isn’t the case. So what’s going on here?
Let’s roll back the millennia for a moment. In the Ancient Mediterranean
World – including in Egypt, the Roman Empire, and the Byzantine Empire –
young males were sometimes forcibly castrated. The motivations were varied,
but included the creation of eunuchs (who served as guards in women's quarters).
Hippocrates, the famous Ancient Greek physician – after whom modern medicine’s famous Hippocratic
oath is named — made two observations of the unfortunate victims of this brutal practice:
‘EUNUCHS ARE NOT SUBJECT TO GOUT,
NOR DO THEY BECOME BALD’
We’ll leave the gout part to the rheumatologists,
but this suggests Varys would like more like this than this.
The link between testicles and balding was re-established in the 20th century.
In 1942, Yale-based anatomist James Hamilton published a
paper in Developmental Dynamics on baldness — or the lack thereof —
in men who were unable to produce significant quantities of testosterone.
Some of the study participants lacked fully formed testicles from childhood,
while others had been castrated.
Hamilton observed that none of the participants who had been affected from
early childhood exhibited male-pattern baldness,
whereas many of those who were castrated later in life did.
This finding clearly illustrates that testosterone exposure plays
a role in balding – but to what extent?
To further test the relationship between testosterone and baldness,
Hamilton administered testosterone treatment to 12 of the men who were affected from childhood
and re-examined them a year later.
At the follow-up appointments,
he found that even though all 12 men had received the same dose of testosterone,
only four of the men had developed typical male-pattern baldness.
He also found that, for these four men, hair loss ran in the family.
Clearly, the link between baldness and testosterone isn’t totally clear-cut.
Let’s have a closer look at the science.
Firstly, it’s not the action of testosterone itself that causes hair loss.
Via an enzyme called 5α-reductase, testosterone is converted into dihydrotestosterone, or DHT.
In the scalp, the binding of DHT to androgen receptors in hair follicles causes the follicles
to shrink, and the hairs they produce get thinner and thinner until the follicle becomes dormant.
Don’t be too peeved with DHT though because it’s this stuff that allows you to grow facial hair!
The effect of DHT on hair loss is perhaps most
clearly confirmed by observing what happens in its absence.
In men with a rare genetic deficiency in the 5α-reductase enzyme, the conversion
from testosterone to DHT is impaired and less testosterone is converted. As we might expect,
men with this condition do not exhibit typical male pattern baldness.
According to recent research into predictors of baldness, things get stranger still:
a 2022 study has suggested that the ratio between a man’s index finger and his ring
finger – known as the 2D to 4D ratio – might be a predictor of male pattern baldness.
For the participants in their study, they found that a lower 2D to 4D ratio
(i.e. a longer ring finger relative to the index finger) was associated with a six-fold
increase in the likelihood of balding in men aged over 37 and a half years.
WAIT… WHAT? Let me have a look…..OH GOD!!
Further study is needed, but the theory goes that hormone exposure
in the womb might influence both the 2D to 4D ratio and – via changes in
the AR gene – future sensitivity to androgens like testosterone and DHT.
While the findings of this study are potentially significant,
they don’t equate to an absolute scientific truth. Unfortunately, the certainty with which
they’re reported in tabloid headlines might lead people to think otherwise.
With the countless articles covering hair loss it’s easy to get over excited by quick cures
and supposed new revelations, when really the headlines don’t tell the real story.
If only there was a way to decipher what’s being emphasized, what is being exaggerated,
what’s biased, and what’s even being left out entirely, if there was would you use it?
Well there is!
The Ground News website and app helps you debunk the headlines and understand who’s framing their
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For the best way to stay informed checkout Ground News by clicking on my link in the
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Right, let's return to the complicated topic of DHT and establish whether or
not it is dihydrotestosterone levels that determine whether or not a man goes bald?
Well, as so often is the case with science – it’s complicated.
While higher than average DHT levels may be implicated in hair loss in some, scientific
studies have also reported that male pattern baldness occurs in men with normal hormone levels.
So there must be at least one more piece to the puzzle?
Indeed, research in recent decades does point to an additional factor, suggesting that the
sensitivity of the hair follicle receptors to DHT determines susceptibility to balding.
Remember James Hamilton’s observation that the testosterone-treated participants who
lost their hair were those who had bald family members?
This is a bit of a smoking gun – the sensitivity
of hair follicle androgen receptors to DHT is largely determined by genetics.
Scientists have identified a variant in the androgen receptor (AR) that is
more common in men who have early-onset or severe hair loss, and research is ongoing.
So, while the ability to produce a sufficient quantity of testosterone – and hence DHT – from
puberty is certainly a prerequisite for male-pattern baldness in later life,
it’s not the sole determining factor.
Vin, Bruce, Dwayne, and Jason may or may not have particularly high
testosterone levels – the state of their scalps doesn’t tell us.
The key to their chiseled physiques is likely less
mysterious — plenty of protein and endless hours at the gym.
One thing we know for certain, though,
is that it’s never been more fashionable to be smooth up top.