If you look up the entry for androgenetic alopecia in Wikipedia, you’ll find it filed under the category of “genetic disorders.” Other easily-accessed sources like eMedicine and Medscape use similar nomeclature - not surprising, as male pattern baldness has widely been perceived throughout history as something in need of a cure, and there have probably been more purported ‘cures’ for alopecia than for any other condition of human appearance [7, 15].  Indeed, even researchers studying the effects of baldness on perception almost uniformly treat their subject as a disease.  German facial perception researcher Ronald Henss typifies this view:

Male pattern baldness may be considered as a benign disease with a very high prevalence … although the major effects of male pattern baldness concern the psychological and the social realm, there can be no doubt that its causes are biological. Throughout the ages an endless number of endeavors to discover an effective cure were doomed. However, recent progress in medical research has revealed the underlying biochemical mechanisms. For the first time in history, there are effective prescriptions, and even more efficient means will be developed.

In short, androgenetic alopecia is biological in origin, and considered undesirable by those ‘afflicted’, therefore it should be considered a disease. This view, while almost uniformly accepted, is deeply flawed. A more effective case can be made to show that male pattern baldness is in fact a risky but successful evolutionary adaptation.

Biologist Robin Baker [2] believes that, “No gene can persist in a population at the 6 per cent level unless on average it imparts some reproductive advantage to the individual concerned.” Baker is referring here to genes contributing to homosexual behavior, but the point is equally relevant to early-onset alopecia, which has been pegged at much higher rates - in one study performed in Singapore, 32% among young adults aged 17 to 26 years [24]. There are other hints in the case of homosexual behavior that point the way to an understanding of the reproductive advantage that alopecia might bestow, which I will examine in more detail later.

In trying to pin down an evolutionary basis for the persistence of alopecia in the human gene pool, it is unnecessary to sift through the voluminous information available concerning the ‘underlying biochemical mechanisms’ that lead to male pattern baldness, such as the exact impact of dihydrotestosterone in shrinking susceptible hair follicles. Most research on baldness has focused on these pathways due to the enormous payoff that comes from ‘cures’ of even barely detectable effectiveness. There are, however, two matters of interest concerning the underlying biology: that the process is activated by sex hormones and that the condition is heritable.

What is more interesting, in determining an evolutionary explanation, is the question of social impact. It doesn’t matter much how the peacock got its feathers; the real question is why peahens like them so much.

Evidence concerning the impact of baldness on social perception can be traced back to studies utilizing schematics and artist renditions of men in the early 1950s through to more modern studies using computer-assisted composite systems, retouched photos and fitted hairpieces. Their findings are generally vague and often at odds with each other, even when taking into account the different methodologies. Henss [12] summarizes:

For many variables … the empirical evidence is mixed, or there appear to be no substantial effects of baldness at all. An interesting example is perceived intelligence. Four studies reported a positive effect…[but] the studies that employed facial photographs suggest that male pattern baldness may have little impact on perceptions of intelligence and related attributes.

He attributes the conflicting findings to the fact that perception of faces is not dominated by any single attribute, but rather a complex mesh of the entire configuration, the ‘Gestalt’ effect of facial analysis [3,11]. He provides one example from his studies where a model bucked the trend of diminished sexual attractiveness among bald targets and was judged by a small margin to be sexier without hair. Henss believes baldness affects different faces different ways, but notes “unfortunately, the important role of the individual target has been largely neglected in previous research.”

However there is one effect of baldness that appears consistently in all the tests that measured it. Moerman [18] found that the drawing of the bald man was judged to be 52 compared to 42 for the drawing with hair. Wogalter and Hosie [25] found the balding composite to appear older as well, 33.4 years to 27.5. Cash [6] found that photos of nonbald men were judged 2-3 years younger than their actual age while bald men looked 2-3 years older. Henss’ research [10, 11] finds “significant zero-order correlations between the amount of hair loss and estimated age (.58).” He also found that for 9 targets the overestimation of age ranged from .5 to nearly 5 years. Butler [5] used a bald model; after computer morphing to a hairy pate the man appeared significantly younger. Sigelman et al. [23] found that “donning a hairpiece lowered the perceived age of each model by at least three years.” Muscarella and Cunningham [19] used wigs to alter appearance and found a decrease in the amount of hair increased the perceived age. 

Thus a common and consistent finding in the empirical evidence is that balding men appear older (an average of .5-10 years depending on the study) than non-balding men. Henss takes this as an obvious fact and gives it little further attention: “Not surprisingly, the loss of cranial hair has a strong impact on perceived age. A bald head appears to be considerably older than a full head of hair.”

Actually, there is a recent study that contradicts this assertion [21]. It found that among elderly (70+) men, there was no difference in perceived age between bald and hirsute men. Whether this sheds light on the evolutionary roots of alopecia is debatable. Life expectancy has increased dramatically in modern times, as has the average age of the population. It would be interesting to find out at what minimum age such a lack of difference can be found. It might point to the existence of a window of impact for alopecia. During the most sexually active years, baldness makes men appear older than they are; past a certain point that perception fades away.

Combining this possible ‘window of impact’ with the fact that baldness is stimulated by the sex hormone testosterone and its offshoots; that early-onset alopecia generally begins near sexual maturity; that genes cannot persist in populations (at the levels that genes for alopecia persist in humans) without imparting a reproductive advantage … we begin to divine a picture of what might really be going on in early-onset baldness: upon sexual maturity, a certain small but sizable percentage of the male population appears to age faster than its counterparts, a process that has unpredictable cosmetic effects upon the subject beyond the perception of age but that must impart some reproductive advantage or else it would have disappeared from the gene pool.

So, what, exactly, is going on here?  Is it possible that appearing older could possibly impart a reproductive advantage? Yes.

Evolutionary psychologists argue that men have evolved to desire youthful sexual partners, at lease for casual sexual encounters. Desires for long term mates may place less emphasis on youth, but in general the pattern is widely noted. The reverse is true among chimpanzees, where older females are considered more desirable sex partners than younger ones. This is likely a result of diminished pair-bonding and male parenting contributions among chimpanzees compared to humans; an older chimp who has proven her fertility and has parenting experience is more likely to produce a viable offspring from the mostly casual sexual encounters that occur [20]. Different species and different sexes respond to different fitness indicators.

And as David Buss has shown, male humans’ preoccupation with youth is not evidenced among women, particularly when they are seeking a long-term mate [4]. This is a crucial point in unravelling the mystery of alopecia. If age plays a factor in how women choose mates - if older age is a fitness indicator to human women - then it becomes apparent how appearing to be older might impart a reproductive advantage.

Buss’ research suggests just such a relationship. On average, worldwide, women desire a long-term mate that is 3.42 years older than they are. Additionally, Buss found that women generally place more emphasis than men on earning capacity, status, dependability, and stability. All of these traits are arguably more likely to be found among older men, so it is possible that women would scan for older men when seeking these traits. Muscarella and Cunningham considered this aspect of baldness in light of a multiple-fitness model of perception, suggesting that “male pattern baldness evolved as a signal of senescence and social maturity … The senescence feature of male pattern baldness may be an advertisement of social maturity … [that] includes enhanced social status.” And Keating and Bai [14] believe that “receding hairlines may have universal value as a status cue because of an association with age.”

It is additionally possible that age might be a fitness indicator in and of itself, as is evidenced among certain birds [8]. Women might value older men simply because they have proven they are capable of living a long time, thus their offspring would inherit the traits that lead to a long life (by hunter-gatherer standards anyway), giving them a greater chance to sire offspring, leading to greater numbers of grandchildren.

Of course there is a bait-and-switch going on here. The men in question only seem older. They do not have the added years of experience, of survival, of opportunity to collect wealth and status. They are faking it. In response, it would seem that the prudent thing for women to do would be to ignore hirsuteness when determining a man’s age. If it was just as easy for a peacock to fake his plumage as it was to actually grow it, then peahens would long ago have stopped being so entranced with the real thing. Instead the research shows that hairline does affect women’s perception of age.

Returning now to Baker and Bellis’ theories [12] on homosexual behavior:

The advantage of bisexuality lies in its exponents potentially having a higher rate of reproduction than the average for the society in which they live. As we have noted, earlier and better learning of sexual technique gives bisexuals a competitive advantage over other men in gaining sexual access to women. The more bisexuals there are in the population, however, the greater the chance that their competitors are also bisexual - and the more common bisexuals become, the less the advantage enjoyed by any one individual as a result of this bisexuality.

There are several potential parallels to note here. One is the greater reproductive rate that bisexuals maintain. Baker and Bellis determined that this is the reproductive advantage that permits the genes for homosexual behavior to persist in the population. Earlier sexual experience and greater numbers of sexual partners mean that bisexuals tend to have children earlier in life than heterosexuals, thus are more likely to have children before dying. The balancing factors are well known: higher risk of sexually transmitted disease, homophobia, the evolutionary ‘risk’ of siring an exclusive homosexual who will produce no offspring. Together, these advantages and disadvantages tend to balance each other:

We have seen that, in a population in which bisexuals are rare, those who are bisexual enjoy considerable advantages over heterosexuals.  The result is that the genes for bisexuality increase in proportion to the population. Conversely, as bisexual behaviour becomes more common, the advantage enjoyed by bisexual individuals decreases and the costs increase. If the behaviour becomes too common, the reproductive rate of bisexuals falls below that of heterosexuals, and the proportion of bisexuals in the population begins to decrease once more. The inevitable result of this interplay of costs and benefits as the proportion of bisexuals rises and falls is that eventually the proportion of bisexuals stabilises. Moreover, it stabilises at precisely the level at which the average success of bisexual behaviour in each generation is just the same as the average success of heterosexual behaviour.  Therefore, the answer to our question - who does better reproductively, bisexuals or heterosexuals? - is ‘neither’. The only difference between the two is that the reproductive success of bisexuals is more precarious.

Androgenetic alopecia might be explained in the same fashion. Fooling women into thinking he is older than he is, a young balding man would theoretically be considered by a greater number of women. For example, a 22 year old hirsute man would have best luck with an 18-19 year old woman (looking for a man 3.42 years older than she is.) He would have less of a chance with a woman who is 20-23 years of age. The women most available for him to procreate with, therefore, are females from puberty to around age 19, a range of about 6-7 years.

A balding 22 year old male, however, who appears to women to be around 26, would have a greater chance of success with women in the 20-23 year-old range. Therefore, his field of opportunity is significantly larger than the hirsute man - 10-11 years, that is, women from puberty through to 23 year olds (who are, on average, looking for older men). This could conceivably lead to a higher reproductive rate for balding men.

It could be argued that a 15 year-old female might have no interest in either a 22 year old male or a 26 year old male, and if she did it would probably be for the former. Still, I think there is at least the possibility that looking a little older than his peers might subtly increase the pool of a young balding man’s potential mates, by seeming to better embody the traits that women in their most fertile years (between the early and mid 20s in a typical foraging society [13] ) are looking for in a mate.

Continuing the comparison to bisexuality, alopecia also presents a higher-risk strategy than hirsuteness. The gestalt theory of facial response means that baldness’ effect on appearance and sexual attractiveness is highly unpredictable. This seems to be reflected in the study results and I think it’s also a common personal observation: some men look good bald, some look okay, some look downright goofy. The gene cannot know in advance what effect it will have, and chances are high that it could have a negative impact on sexual and/or overall attractiveness.

As with homosexual behavior, bald men are subject to both increased psychological stress (depression, self-loathing, anxiety, etc.) and ridicule from others.  Baker and Bellis suggest that homophobia might be a genetic defense against the ‘tactic’ of bisexuality, and the same argument could be made about ridiculing of premature balding.

Not having cranial hair also disables another fitness indicator - the hair itself. Steven Pinker [20] notes:

Luxuriant hair is always pleasing, possibly because it shows not only current health but a record of health in the years before. Malnutrition and disease weaken the hair as it grows from the scalp, leaving a fragile spot on the shaft. Long hair implies a long history of good health.

In modern culture, long hair may be more commonly extolled as sign of virility and health in women, but look at any bodice-ripper cover and you’ll find Fabio or a look-alike: the image of virile man with long, healthy hair. Bald men are unable to mount such a display.

Early-onset androgenetic alopecia also seems to have other more direct risks. It has been associated with several medical conditions: coronary heart disease, enlargement of the prostate, prostate cancer, disorders of insulin resistance (e.g. diabetes and obesity), and high blood pressure (hypertension) [9, 16, 17].

Finally, as with bisexuality, baldness as a sexual deception only remains effective so long as bald men remain a minority. If half of all men were youthfully bald, women would presumably ignore hairline as a measure of age, and the risks associated with alopecia would lower the reproductive rate of its exponents.

Baker and Bellis’ work remains controversial. I include it to help demonstrate what a possible reproductive advantage for alopecia might look like. Whatever it turns out to be, there must be some advantage. Even Henss observes “The conspicuous sex difference and the correlation with age strongly suggest that male pattern baldness evolved because it served important functions during human evolution.” Yet he ignores the implications of his research and continues to refer to alopecia as a disease.

Disease is defined by the Oxford American dictionary as a “disorder of structure or function in a human” and disorder is defined as “a disruption of normal physical or mental functions”. If androgenetic alopecia is a successful adaptation practiced by a significant minority population, it should referred to as neither a disease nor a disorder (though it might be considered a disease by those who experience its effects most strongly). A precise understanding, and the research that would provide it, is called for. But simply labeling male pattern baldness a ‘benign disease’ or a ‘genetic disorder’ is misleading and inaccurate. Nothing that has such a demonstrable impact on social and sexual perception during crucial post-pubescent years can reasonably be tossed aside so simply or be found to persist in the population at such a concentration. Since homosexual behavior is relatively rare and considered undesirable by many people (including many of those ‘afflicted’), should we also label it a ‘benign disease’ or a ‘genetic disorder’? We should not. We should glean the full explanation of its persistence. The answer will most likely provide insight to scientists seeking a ‘cure’ for baldness and a sense of understanding to those experiencing its effects. It is time to reconsider why it is that some men ‘prematurely’ lose their hair.

1 This assumes that women are primarily using physical cues to judge the age of potential mates.  Of course in the modern era it’s easy enough to look at a driver’s license or other verifiable data on birthdays, and we keep dutiful record of our actual ages (though it is not always truthfully reported). While it would require empirical evidence to support, I think it is reasonable to assert that first impressions of age - even in the era of blog profiles and internet dating - are garnered primarily from visual impressions, which are harder to fake than a birthdate.

2 This does raise a flag, though. For men to be ridiculing their balding counterparts, they must have knowledge that the men are balding prematurely. And if the men can tell, why wouldn’t women recognize the fakery? Possibly, the success of the baldness adaptation may depend on the extent of baldness. A little might go a long way. Baker draws a comparison between bisexual behavior and sickle cell anemia (in which one copy of the gene protects you and two copies makes you sick), and I will suggest a similar analogy for alopecia - another part of its high-risk strategy - get a few of the genes for baldness and you look subtly (and enticingly) older; get too much of a good thing and you just look like your hair is falling out. Similar arguments have been made for Schizophrenia. [**] Obviously this is highly speculative absent empirical data.

References:

1Baker R:  Sperm Wars. London, Macmillan Publishers Ltd., 1996, pp 282-292.

2Baker R, Bellis, M:  Sperm Competition: Copulation, Masturbation and Infidelity. Chapman and Hall, 1995.

3Bruce V, Young A: In the Eye of the Beholder. The Science of Face Perception. Oxford, Oxford University Press, 1998.

4Buss DM: Evolutionary Psychology: a new paradigm for psychological science. Psychological Inquiry, 1995;6:1-30.

5Butler J, Pryor B, Greider M: Impression formation as a function of male baldness. Percept Mot Skills 1998;86:347-350.

6Cash, TF: Losing hair, losing points?: The effects of male pattern baldness on social impression formation. J Applied Soc Psychol 1990;20:154-167.

7Cordwell JM: Ancient beginnings and modern diversity of the use of cosmetics; in Graham JA, Kligman AM (eds): The Psychology of Cosmetic Treatments. New York, Praeger, 1985, pp 37-44.

8Forstmeier, W., Kempenaers, B., Meyer, A., Leisler, B., 2002. A novel song parameter correlates with extra-pair paternity and reflects male longevity. Proc. R. Soc. Biol. Sci., Series B 269 (1499), 1479 – 1485.

9Giles G, Severi G, Sinclair R, English D, McCredie M, Johnson W, Boyle P, Hopper J: Androgenetic Alopecia and Prostate Cancer: Findings from an Australian Case-Control Study. Cancer Epidemiology Biomarkers & Prevention 2002;11: 549-553.

10Henss R: ‘Spieglein, Spieglein an der Wand …’ Geshlect, Alter und physische Attraktivität. München, Psychologie Verlags Union, 1992.

11Henss R: Gesicht und Persönlichkeitseindruck. Göttingen, Hogrefe, 1998.

12Henss R:  Social Perceptions of Male Pattern Baldness. A Review. Dermatol Psychocosm 2001;2:63-71.

13Hrdy, S B: Body Fat and Birth Control. Natural History,  Oct, 1999.

14Keating CF, Bai DL: Children’s attributions of social dominance from facial cues. Child Dev 1986;57:1269-1276.

15Kligman AM, Freeman B: History of baldness from magic to medicine. Clin Dermatol 1988;2:41-48

16Matilainen V, Makinen P, Keinänen-Kiukaanniemi S: Early onset of androgenetic alopecia associated with early severe coronary heart disease: a population-based, case-control study. J Cardiovasc Risk. 2001 Jun;8(3):147-51.

17Matilainen V, Koskela P, Keinänen-Kiukaanniemi S:  Early androgenetic alopecia as a marker of insulin resistance. The Lancet, Volume 356, Issue 9236, Pages 1165-1166

18Moerman DE: The meaning of baldness and implications for treatment. Clin Dermatol 1988;6:89-92.

19Muscarella F, Cunningham MR:  The evolutionary significance and social perception of male pattern baldness and facial hair. Ethol Sociobiol 1996;17:99-117.

20Pinker S:  How the Mind Works. New York, Norton & Company, 1997.

21Rexbye H, Petersen I, Iachina M, Mortensen J, McGue M, Vaupel J, Christensen K: Hair Loss Among Elderly Men: Etiology and Impact on Perceived Age. J Gerontol A Biol Sci Med Sci. 2005 Aug;60(8):1077-82.

22Shaner A, Miller G, Mintz J: Schizophrenia as one extreme of a sexually selected fitness indicator. Schizophrenia Research 70 (2004) 101 – 109.

23Sigelman L, Dawson E, Nitz M, Whicker ML: Hair loss and electability: The bald truth. J Nonverbal Behav 1990;14:269-283

24Tang P H, Chia H P, Cheong L L, Koh D: A community study of male Androgenetic alopecia in Bishan, Singapore. Singap. med. j. 2000, vol. 41, no5, pp. 202-205.

25Wogalter MS, Hosie JA: Effects of cranial and facial hair on perceptions of age and person. J Soc Psychol 1991;131:589-591.

Written from research for, and in partial support of, the fictional play Root Cause. Please note I am not an actual scientist, and make no claim to the validity of the following argument, nor do I have any plans to conduct actual research to prove or disprove its particulars. I do welcome constructive comments however! This draft was completed in 2007.