Leprosy and Scandinavian babes
Speaking of the ubiquity of recent selection, I’m in the middle of looking at the recent selection of various traits that have to do with sexiness in different parts of the world. The primary selection pressure concerning physical attactiveness is, of course, pathogen prevalence — what stronger force could there be for making us care about how hot a person is? Since the sexiest birds evolved in the tropics — areas of high pathogen prevalence — there is no reason to think that humans would turn out any differently, to a first approximation. Hamilton & Zuk (1982) proposed that ornateness was a signal of health in more germ-ridden species, and that mates would choose the more ornate individuals to give their offspring a leg up in chasing the moving target of evading pathogens. (They looked at variation in pathogen prevalence in North American birds, not those from the tropics, but it’s clear which species are more decorated.)
Continuing in that vein, Gangestad & Buss (1993) showed that the degree to which individuals (both male and female) emphasized “good looks” in a potential mate correlated highly with local pathogen prevalence. The correlation is not caused by latitude or climate per se but truly by the pathogen prevalence — the raw correlation is +0.38 (p less than .05), but when controlling for the possible confounds of latitude, geographical region (e.g., Africa, Europe, etc.), and average income, the correlation becomes +0.72 (p less than .001). If the effect were merely due to differences in latitude, continent, etc., then the correlation should decrease in magnitude, whereas it nearly doubles. The obvious corrollary, which Gangestad & Buss don’t mention, is that populations adapted to historically more pathogen-stricken areas will on average be more physically attractive, since both sexes emphasize (and thus, probably choose based on) good looks in a partner. To my knowledge, no one has showed that yet, but I plan to shortly by analyzing data on how different countries have faired in the Miss Universe contest.
However, Scandinavia would appear to be a glaring exception — though pathogen pressures have been less severe than in the Mediterranean, they fair well in beauty contests and are thought of by non-Scandinavian whites (and maybe other groups) as more beautiful than other Northern European groups. (See the Appendix for the Miss Universe-derived scores of Northern European countries.) And yet, there is an exception to this exception — Scandinavia was the one holdout in Europe for leprosy, which continued pretty much up to the start of the 20th C. From William McNeill’s Plagues and Peoples (p.185):
Hansen’s disease appears to have established itself in Europe and the Mediterranean coastlands in the sixth century A.D. Thereafter, together with other infections classified as leprous, it remained of major importance until the fourteenth century. Leprosaria were established outside thousands of medieval towns. By the thirteenth century one estimate puts their number in all of Christendom at 19,000.
And though leprosy faded in most of Europe in the 14th C (p.186),
Hansen’s disease did continue to exist, on a significant scale, in Scandinavia and more sparsely in other parts of Europe as well.
The Encyclopaedia Britannica article on leprosy agrees that leprosy continued in Scandinavia after it had begun to subside elsewhere in Europe during the 14th C. McNeill guesses that it could have continued due to the practice of huddling close together every night to keep each other warm, since leprosy requires prolonged contact with an infected person to be transmitted to the next host. It is no accident, then, that the physician who discovered the microbial cause of leprosy, Armauer Hansen, was a Norwegian who worked in the historically largest city of Norway — Bergen — since it is difficult to conduct painstaking research where there are few subjects to investigate. So, though low overall in pathogen prevalence, Scandinavia had a much higher prevalence of leprosy from Medieval times almost right up to the present.
Of course, leprosy is a disfiguring skin disease, one that would have made a sufferer a virtual Darwinian dead-end, as no one would want to mate with them. Scandinavian males today, as shown by Buss’ (1989) [pdf] cross-cultural survey, do not care much about whether or not a potential partner is good-looking (and of course, neither do the females), in line with the historically low pathogen prevalence of their environment. However, no matter how willing Scandinavians may be to overlook sub-perfect breast development, graying hair, and so on, damn few would be so openminded as to willingly mate with a leper. Our modern sensibilities are offended by the sight of mere genital warts — imagine viewing a nude person with festering sores encrusting a fair fraction of their body. Talk about a selection pressure! Especially when this pressure lasted for at least 700 to 1000 years, or from 28 to 50 generations depending on exactly how long and whether a generation equals 20 or 25 years; and particularly in a population that experienced little inward gene-flow.
The only study to attempt to quantify the narrow-sense heritability (or h^2) of good looks, using a twin design, is McGovern et al (1996), which showed a DZ concordance rate of 0.33 and a MZ concordance rate of 0.65. The broad-sense heritability = 2(MZ – DZ) or 0.64, and since the MZ rate is almost exactly twice the DZ rate, we can assume that most of this genetic component is additive, so let h^2 = 0.64. The Breeder’s Equation
says that the response to selection R, equals the selection differential S (or how high the parents’ mean is above the population mean) multiplied by h^2. If leprosy was a strong enough pressure so that the parents’ mean would have been at just the 52.2 percentile, then S = 0.0558 SD; this multiplied by h^2 of 0.64 = 0.035712 SD increase in attractiveness per generation. Multiply that by 28 generations of selection, and the overall increase is 1 SD, comparable to a gain of 15 IQ points or 3 to 4 inches of height. If the selection lasted for the rough upper-bound of 50 generations, then the parents in each generation would only had to have placed in the 51.2 percentile — barely above-average in either case.
Some caveats: this assumes minimal inward gene-flow from populations not also subject to leprosy pressures, which would have blunted the response to selection. However, inward gene-flow from other Northern European countries wouldn’t have mattered much up to about 1400, since other regions were also plagued by leprosy. From 1400 to 1900, I can’t find estimates of gene-flow into Scandinavia (though I’m sure they’re in the literature), but it must have been very low, as this region is one of the most homogenous. The pressure probably relaxed around 1900, after the infectious nature had been discovered and medical intervention began wiping out the disease. Still, that’s only 4 or 5 generations ago, hardly enough time to undo 28 to 50 generations of directional selection, and surely good looks were not selected against during the 20th C. Last, it would be desirable to uncover independent confirmation that Scandinavians were more affected by leprosy pressures than other Northern Europeans. There are genes in the HLA that are implicated in susceptibility to leprosy, but I couldn’t find allele frequency distribution data on ALFRED. By hypothesis, Scandinavians would show greater frequency of such alleles compared to other Northern Europeans (at least the populations included in the chart below).
Finally, we don’t have a convenient metric of attractiveness, let alone data on the difference in means across various populations, but this simple calculation shows that it’s entirely feasible for Scandinavians to have risen 1 SD above their previous Northern European mean. Of course, populations outside Northern Europe may have already undergone substantial selection for attractiveness (also due to pathogen pressure) before leprosy hit the scene in Northern Europe, and continued to experience such selection up to 1900 and maybe beyond. So, the claim is not that selection has made Scandinavians the most attractive population on Earth, but at the very least the most attractive of Northern Europe.
Appendix: While admitting that attractiveness will always remain somewhat subjective and more prone to errors of measurement than gauging height, there are universals in what features are considered attractive. Citations would be irrelevant (though you can look up Buss, Thornhill, Singh, and others if you’re skeptical). Hair-splitting aside, it’s not as if maculated skin, beady eyes, or a waist that’s pronouncedly wider than the hips are considered attractive by the world’s cultures. The Miss Universe pageant is one of the few arenas where individuals representing the world’s populations are subject to the same criteria, and where the scores reflect the preferences of the same target audience. True, there could be a non-trivial chance component since only one individual serves as a delegate for their entire population, not to mention the whims of the judges. Before the Civil Rights and national liberation movements of the 1960s, there may also have been a bias toward those of European descent (Miss Universe began in 1955). Nevertheless, the latter does not factor in here, as all countries are Northern European. And to remove as much of the chance component as possible, only countries who had entered 20 Miss Universe pageants were considered — 1 win out of 4 contests might represent a fluke, but Sweden’s 3 wins and 28 semi-finalist placings out of 54 contests cannot be a fluke.
The hotness score H was determined as follows:
Where W = number of wins, S = number of semi-finalist placings (S is multiplied by 0.1 to make sure semi-finalist status did not trump winner status), C = number of contests entered, and P = size of country’s population in millions as of the past three years. W, S, and C were culled from a website of Miss Universe statistics, and the population estimates were gotten from the country’s Wikipedia entry. The numbers inside the parentheses represent the country’s raw placing score per contest entered per unit of population, and since it varies by orders of magnitude, the (natural) log was taken, and this multiplied by -1 to remove the negative sign (for ease of inspection). This simplifies to the second line of the graphic. Lower H scores represent greater hotness — akin to 1st place being the greatest and 10th place the worst in a 10-contestant race. Below is a chart of Northern European countries ranked in ascending order of H scores (right column) — that is, in descending order of hotness. Again, don’t take the ranking too seriously, but it’s clear nonetheless that the Scandinavian countries really are, in some sense, hotter than the other Northern European countries.
Country W _ S _ .1S _ W+.1S _ C _ P _ H
Iceland 0 _ 4 _ .4 _ .4 _ 40 _ 0.3 _ 3.401
Finland 2 _ 18 _ 1.8 _ 3.8 _ 51 _ 5.3 _ 4.265
Sweden 3 _ 28 _ 2.8 _ 5.8 _ 54 _ 9.1 _ 4.439
Norway 1 _ 17 _ 1.7 _ 2.7 _ 49 _ 4.7 _ 4.446
Wales 0 _ 5 _ .5 _ .5 _ 30 _ 3 _ 5.193
Scotland 0 _ 5 _ .5 _ .5 _ 29 _ 5.1 _ 5.690
Denmark 0 _ 7 _ .7 _ .7 _ 41 _ 5.4 _ 5.757
Switzerland 0 _ 10 _ 1.0 _ 1.0 _ 46 _ 7.3 _ 5.817
Netherlands 1 _ 11 _ 1.1 _ 2.1 _ 48 _ 16.3 _ 5.920
Ireland 0 _ 7 _ .7 _ .7 _ 46 _ 6 _ 5.977
Austria 0 _ 7 _ .7 _ .7 _ 38 _ 8.3 _ 6.111
Belgium 0 _ 7 _ .7 _ .7 _ 52 _ 10.4 _ 6.650
England 0 _ 19 _ 1.9 _ 1.9 _ 36 _ 50.4 _ 6.862
Germany 1 _ 21 _ 2.1 _ 3.1 _ 55 _ 82.4 _ 7.288
France 1 _ 12 _ 1.2 _ 2.2 _ 55 _ 63.6 _ 7.371
Poland 0 _ 4 _ .4 _ .4 _ 23 _ 38.1 _ 7.692
Luxembourg 0 _ 0 _ 0 _ 0 _ 27 _ 0.5 _ UND
The primary selection pressure concerning physical attactiveness is, of course, pathogen prevalence — what stronger force could there be for making us care about how hot a person is?
I’m missing something here – shouldn’t we be interested in heritable traits?
shouldn’t we be interested in heritable traits?
Sure — and physical attractiveness has a narrow-sense heritability of ~0.64. The question is: which pressures will cause individuals to pay attention to some heritable traits rather than other traits? In this case, why would someone care so much that their mate be physically attractive? No matter what the particular story is, it all has to do with health, a robust immune system, and so on. The strongest pressure on the immune system is pathogens, since they 1) evolve, unlike environmental insults, and 2) reproduce more rapidly than we do.
If we figure out which HLA alleles in Scandinavian populations make them less susceptible to leprosy, we don’t have to imagine that they become more frequent due to a survival advantage — it could be that such alleles made their bearers more attractive than those with sores all over their body. So, this is heritable variation, but it also has to do with pathogen prevalence, since the alleles would drift in a population where there was no leprosy.
Sure — and physical attractiveness has a narrow-sense heritability of ~0.64.
I am not disputing selection for attractiveness!
Clearly, “attractiveness” is either correlated with reproductive success due to exogenous factors, or is “runaway” sexual selection.
What I don’t understand is the hypothesis that “attractiveness” is more correlated with pathogen resistance than with other factors of reproductive success.
What I don’t understand is the hypothesis that “attractiveness” is more correlated with pathogen resistance than with other factors of reproductive success.
If there is a high pathogen prevalence, then individuals will start to care more about attractiveness (as Gangestad & Buss 1993 showed), for either of the following reasons (or something else): 1) the “good genes” hypothesis says that individuals inspect mates to see who has the best genes to contribute to potential children, who will need top-notch protection from pathogens in a festering environment; and/or 2) the “parasite avoidance” hypothesis says that individuals inspect mates to see who is or is not likely to be currently infected. They may not want your good genes — they may just figure it’s safer to sleep with you compared to that guy with sores.
As an emphasis on physical attractiveness increases, then so will the mean attractiveness level of the population, as the more ugly individuals are refused mating opportunities. Also, where pathogens are more prevalent, it will be easier to determine which individuals are more healthy than others — a high pathogen load “puts people to the test,” disfiguring some while leaving others untouched, especially as concerns bodily symmetry. This easier inspection would facilitate the increase of the emphasis on good looks, since it won’t be difficult to assess the relevant information. Where there’s no leprosy, it would be hard to tell who was susceptible or not, unless you had a genome sequencer. :)
If the prevalence of leprocy explains Scandinavian attractiveness, any ideas about what explains the attractiveness of Somali women? Tuberculosis?
1) the “good genes” hypothesis says that individuals inspect mates to see who has the best genes to contribute to potential children, who will need top-notch protection from pathogens in a festering environment;
Fine, but this holds true for any characteristic. Why should we perceive pathogen-resistance genes as beautiful more than any other genes for reproductive success?
2) the “parasite avoidance” hypothesis says that individuals inspect mates to see who is or is not likely to be currently infected. They may not want your good genes — they may just figure it’s safer to sleep with you compared to that guy with sores.
Okay, but why should this lead to more beauty in uninfected people?
How about this: pure sexual selection? It would work as follows:
Parasite avoidance (#2) would select for notions of beauty which lead people to avoid infected mates. This has the side effect of creating notions of beauty which are the opposite of the symptoms which are being selected against. For example, if parasites tend to make you asymmetrical, symmetry will be thought beautiful. If they tend to disfigure your skin, clear skin will be thought beautiful, etc.
the attractiveness of scandivanian women is easy to understand: no mustaches.
the attractiveness of scandivanian women is easy to understand: no mustaches.
Seriously, I think blondness accounts for a lot. And probably height for the rest – I know height is not much of a factor in real life, but it seems to be important in the media and contests.
Wouldn’t ugly people always have each other to mate with? Sure they may prefer an attractive mate, but you get what you can. Is there any evidence that ugly people produce(d) fewer offspring than attractive people – in Scandanavia or anywhere else?
I would think there would need to be some cultural/societal attributes that selected against unattractiveness, probably thru a trait that correlated with unattractiveness.
Finally, on a somewhat related track. I’ve been mulling over European track and field times and have noticed certain patterns, which I wonder whether they are cultural or genetic:
First, Eastern European women, particularly Russians, dominate track and field and perform significantly better than EE men. Are Slavic women naturally better athletes than non-Slavic women?
Second, it’s always been pretty obvious that Eastern Europeans have dominated the strength related field events. Is this genetic.
Third, more surprisingly, there is a southwest/northeast gradient when it comes to distance versus speed events. Take a look at two similarly sized nations, Spain and Poland. Spain dominates events 1500 meters or more, while Poles appear to be the fastest white Europeans. France and Britain with the help of sub-Saharan Africans normally win the sprint events (400 m or less) and relays, but Poland does the best of the nations that field predominantly white athletes.
“the attractiveness of scandivanian women is easy to understand: no mustaches.”
Readers of gnxp have come to know your aversion to this trait, but there are other factors, aren’t there? After all, hot wax can be hairy girl’s best friend, but nothing will correct bad bones.
It’s mostly in the bones. See “Politically Incorrect: The Neglected Nutritional Research of Dr. Weston Price, DDS.”
This dentist and colleagues took pictures of people throughout the world, all races, from Gaels to Swiss, to Africans to Chinese to Peruvians, with particular attention to the dental aspects. Everywhere the people who were still living on the “traditional” diet–which varied enormously according to geography and culture–had the best development and the most attractive appearance. Whatever your personal those on the traditional diet were attractive in some general, universally acknowledged way, even if you might not wish to become physically intimate with them. Because cultural changes were occurring so rapidly during the 30s, diet could change within a short time. Siblings raised on bread and jam looked very different from the older ones raised on seaweed and oatmeal.
The key seemed to be good development of the palate, with enough room for all the teeth, even wisdom teeth. What did people do about these nuisances, wisdom teeth or crooked teeth, in the old days? In the old days, they weren’t nuisances because most peoples’ palates could accommodate them. By old days is meant “traditional diet” days. Those days were over for the affluent Euros, and even Asians (the Turks were great sugar guzzlers) by the 16th century. That sugar “rotteth the teeph” was well known to Elizabethans. Sugar, not sugar cane which is pretty good for teeth.
Also, good formation of the rest of the body, space between the eyes, shimmering hair, etc.
Some tradtional diets included a lot of grains, sometimes dairy, meat, fish, etc. However, there was no mass manufactured concoctions of grease and starch passing for nourishment.
Scandinavians generally have a good diet with lots of fish and high quality dairy for calcium. So maybe they tend to have good bone structure, I don’t know as I have never been there. Italians (I only went to the northern half of the country) had good bone structure and excellent hair. They generally eat pretty well.
I too feel uneasy about the selection for beauty because of leprosy. I cant see the mechanism that will cause only beautiful people to reproduce. Since the disease attacks beautiful people with the same intensity as ugly people, why should beautiful people reproduce more successfully? Possibly I am too obtuse to understand, but I cannot see the cause-effect mechanism.
On the other hand, where resources are scarce, parents do operate a triage system, and it is reasonable to assume that the uglier child gets less food and care. I have read many biographies of American black people, such as Malcolm X and Up from Slavery, and they reported the intense fondness of their parents for their whiter child (in these cases, Malcolm and Washington). Everybody attributes this to culture, but I am not sure. Even children prefer blond dolls.
In summary, I doubt the leprosy theory and propose slection by misery (disease+lack of food) and intrafamily triage.
PS When the great manmade hunger in Ukraina families butchered and cooked their children, blondies were a little bit safer. I say that on the basis of anecdote alone.
David — I think you’re saying what I’m saying in different words. So I agree.
Steve C — remember, we’re not just talking “sagging breasts, yellow teeth” ugly; we’re talking “body covered in leprosy sores” ugly. Do a Google image search for “leprosy” and see how ugly lepers are. It’s plain to see that looking that way is a fitness cost — and accumulating such costs over 28 to 50 generations, less healthy people will decrease in frequency, making the remainder more attractive.
Jaim — there is no mechanism that “causes only beautiful people to reproduce.” In my calculation, I assumed that the parents in each generation represented either the 51.2 percentile or the 52.2 percentile — we’re not talking “only super-hotties get to reproduce,” but “the average parent is barely above-average.” The key, again, is the fact that this selection operates over 28 to 50 generations, to use conservative estimates.
To use a different example, assume that Scandinavians on average were 3 inches taller than other Northern Europeans (which is roughly 1 SD for human height) — say, 6′ in Scandinavia and 5’9 elsewhere. That would be a very noticeable difference, comparable to what the Japanese (at 5’7 average) must sense when they visit the US (at 5’10 average). If we assumed that this height difference were due to directional selection for greater height in Scandinavia, and that it operated over 50 generations, that would requirely a per generation gain of just 0.06 inches (or 0.02 SD). Assuming h^2 for height = 0.7, this would only require the parents in each generation to be at the 51.1 percentile — again, barely above-average!
About height, blondness, etc. Most Miss Universe contestants are tall, so there must be something additional making Scandinavians hotter. Ditto for blondness — most of the countries included in the chart have a high proportion of blondes. Moreover, there is another area of the globe that acts as a powerhouse for beauty pageants — the Caribbean — where there is nary a blonde to be found. Ditto for up-and-coming India. If you look at Maxim-esque magazines, or the Tru online dating internet ads, they feature mostly brunettes.
Whatever makes Scandinavians hotter than other Northern Euros is not likely height (since the others are also pretty tall) or blondness (for the same reason). It’s likely things like skin tone and texture, facial features, symmetry, and so on.
Awgh! Americans attempting to do geography! If you ask anyone in Northern Europe, the list has 5 Northern European countries: the two listed Northern European countries outside Scandinavia (Finland and Iceland) are the top 2 of NE beauty and the three countries in Scandinavia are the bottom 3 of listed NE beauty. So, according to the list Scandinavia has the ugliest people in Northern Europe, not the other way around!
And mc, northern Europeans have disgustingly unhealthy traditional diets. If you want to try a truly traditional Finnish dish, try lard, butter and salt flavoured with sausage and potatoes. Mere education aimed at changing the diet has made the rate of death by cardiovascular disease drop massively in recent decades (but it’s still very high by world standards). Scandinavians have a better but still unhealthy diet (their rate of dying to diet-related disease is still much, much higher than, say, typical Mediterranean rates). And in Sweden and Finland much of the fish eaten today is toxic enough to be banned in all other countries…
we’re talking “body covered in leprosy sores” ugly. Do a Google image search for “leprosy” and see how ugly lepers are. It’s plain to see that looking that way is a fitness cost — and accumulating such costs over 28 to 50 generations, less healthy people will decrease in frequency, making the remainder more attractive.
But here you’re talking about people who actually got the disease. They’re not necessarily the ones with the “ugly” genes!
As jaim pointed out, if leprosy effects ugly people no more than attractive people, then how would leprosy seve as a selective pressure for attractiveness?
What sort of selective pressure accounts for Scandanavians (and Dutch) being taller than other northern Europeans? Unlike measuring height or other objective measurements like track times, is it even objectively true that Scandanavians are more attractive? It does seem to be a widespread notion, though it could be more due to other factors like health and wealth than to genetics.
About height, blondness, etc. Most Miss Universe contestants are tall, so there must be something additional making Scandinavians hotter.
Yes, but if the source population is blonder and taller it will have a larger effective population.
Jaakkeli — my only distinction is Northern vs Southern. A recent PLoS study showed that this is a highly consistent cut among European population substructure: http://genetics.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pgen.0020143
Basically, the Southerners are concentrated along the Mediterranean, and Northerners are everyone else — German, Irish, Finnish, etc.
The “hotness” equation seems to penalize nations with large populations. There will be some “noise” in the beauty selection process so winning is somewhat random.
Consider an extreme example. Assume the winner is randomly chosen from the contestants and that each nation has one contestant then a nation with a billion people would have a very low “hotness” score compared to a nation with a million people. Perhaps the population size could be scaled to account for the random component.
The judging process may also favor smaller population nations. If each nation gets one judge then the many European nations have far more votes than the lone judges from India and China. I suspect that the Han Chinese would find tall blondes with big noses exotic but not especially beautiful.
“And mc, northern Europeans have disgustingly unhealthy traditional diets. If you want to try a truly traditional Finnish dish, try lard, butter and salt flavoured with sausage and potatoes.”
Oh, really? I pictured them eating sardines and cod liver oil smeared on whole grain ryevita. My misperception. Very good coffee makers though, the Swedes.
But here you’re talking about people who actually got the disease. They’re not necessarily the ones with the “ugly” genes!
OK, I’ll try phrasing it a different way. They are the ones with ugly genes, in the sense that their immune system, skin composition, or whatever, are of inferior quality compared to those without leprosy.
- There is heritable variation in susceptibility to leprosy.*
- Such variation will be on full display where leprosy is endemic.
- Individuals will choose mates who do not manifest leprosy, i.e., those who have healthier immune systems, better skin composition, etc.
- Because having an excellent immune system, etc., is what mostly accounts for physical attractiveness, then individuals are choosing better-looking mates.
- This continues for tens of generations, and presto: the Swedish bikini team.
So the contention that leprosy affects both ugly and beautiful is what is wrong. That is, a person is attractive in virtue of manifesting superior health, especially where the battle against pathogens is vicious.
*Search Vogel & Motulsky’s Human Genetics for “leprosy” at Amazon: http://www.amazon.com/Human-Genetics-Approaches-Friedrich-Vogel/dp/3540602909/sr=8-2/qid=1161625244/ref=sr_1_2/102-1556762-4924912?ie=UTF8&s=books
The MZ concordance rate is .59, DZ rate is .1, so broad-sense heritability = .98. This is probably an overestimate, as there was difficulty in locating DZ twins compared to MZ twins in the area studied (South Asia). Still, high heritability. That means that not everyone who contracts the M. leprae bacterium will develop leprosy, and even those who do develop leprosy won’t necessarily develop the same type (there are mild and severe forms). This is the heritable variation on which the selection acts. This is the heritable variation which is an honest signal of genetic quality / health / etc.
Fly — right, there is noise, but it’s like the World Cup — the same areas tend to dominate, despite the individual outcomes being influenced by chance. Population size has to be factored in so that “overrepresentation” is apparent. For example, Puertro Rico has produced 5 winners and 16 semi-finalists out of the 52 contests they’ve entered. Yet, their country only numbers 3.9 million — the fact that such a tiny country (smaller than the DC metro area where I live) has produced almost as many winners as the entire US (7 wins) is astonishing. Far above their expected value based on population alone. The reasonable explanation is that they really are hotter than other people, on average.
If population size were given less emphasis, big countries would score higher based on sheer size alone. I do admit that when the population dips below 1 million (Iceland, several Caribbean countries, etc.), they seem to be rewarded based on tiny size, but above 1 million, they seem to fall in line with popular views of which groups tend to have hotter people (Sweden, Puerto Rico, etc., but not England).
agnostic, my point is still the same. It’s horrible to declare Scandinavia the victor, when your list says
1. Not in Scandinavia
2. Not in Scandinavia
3. In Scandinavia
4. In Scandinavia
5. Not in Scandinavia
6. Not in Scandinavia
7. In Scandinavia
8. Not in Scandinavia
…
I complained non-seriously, because this comparison has some pretty obvious issues like the penalty on being large. Oh, and BTW, there’s a natural way around that, if you’re only interested in spotting some countries that do better: just order the countries by size and see which ones are higher than they should be. By population, the list is predicted to be (I’m only going to bother checking Scotland, the rest relies on my great memory, and I’ll ignore Luxembourg)
1. Iceland
2. Wales
3. Ireland
4. Norway
5. Scotland
6. Finland
7. Denmark
8. Switzerland
9. Austria
10. Sweden
11. Belgium
12. Netherlands
13. Poland
14. England
15. France
16. Germany
Most countries are not far away at all from where they are on your list (which suggests that what you’ve listed is indeed more about size than anything else). There are only two countries notably above their expected ranking: Finland and Sweden. Iceland, Norway and Denmark are actually exactly where they’re predicted to be by their size! So, as you can clearly see, *Scandinavians* are just ordinary, except for Swedes. And how do Swedes differ from the other Scandinavians? They have loads of genes of Finnish origin, of course!
OK, I’ll try phrasing it a different way. They are the ones with ugly genes, in the sense that their immune system, skin composition, or whatever, are of inferior quality compared to those without leprosy.
This is where my theory differs from yours. I don’t assume that the beauty genes are the same as the healthy genes. It seems to me quite a leap of faith that the anti-leprosy genes just happen to make you more beautiful too. How do you know it’s not like the anti-malaria genes that also make you anemic?
?Far above their expected value based on population alone.?
I agree with this part. Sweden and Puerto Rica both indicate that population size alone doesn?t explain the number of winners. My algorithmic criticism related to the manner in which you included population in the equation. Your equation seems biased to favor your preferred hypothesis.
One way to fix the equation would be to separate out a noise function with a coefficient to control the amount of ?noise? in the selection process. As the noise coefficient is increased, a good equation should yield the expected result that all populations have equal ?hotness?.
?The reasonable explanation is that they really are hotter than other people, on average.?
That isn?t clear to me. Alternate explanations are:
The winners reflect the personal tastes of the judges. Bias in selecting judges then causes bias in the winners. Having more Chinese and Indian judges might change who wins. (Playmates and fashion models are different because the types of people selecting the winners are different.)
Or for each beauty trait distribution there may be individual national preference points. E.g., Chinese judges may reject large noses and big breasts while British judges reject flat noses and small breasts. The winners would then represent average values. Swedish contestants may lie in the sweet spot for judging group. (If the distribution of judges changed then the sweet spot would also change.) In this case the ?average? wins the contest but in many cases each nation would find it?s own contestant hotter.
Or there might be an exotic element. The Swedish winners may be sufficiently exotic to attract but not so exotic as to repel. In this case Swedish men might be more attracted to the Puerto Rican contestant and the Puerto Rican men might find the Swedish contestant more attractive.
Agnostic, I am sympathetic to what you are trying to do. Having a good measure of universal genetic beauty would be nice. However unlike athletic or math competitions, the evaluation of beauty seems very subjective. I believe there are attractiveness universals and that they may be related to genetic mutation load or pathogen load. However, using the Miss Universe contest results as evidence for evolved beauty seems a stretch.
To minimize the population bias, I fit (W+S) against log(C*P) and used the residuals as hotness scores, which gives the following result:
1. Sweden 18.58
2. Finland 9.27
3. Norway 7.72
4. Germany 3.33
5. England 2.90
6. Iceland 2.04
7. Switzerland -1.34
8. Netherlands -1.73
9. Luxembourg -2.29
10. Wales -2.64
11. Denmark -3.17
12. Ireland -3.79
13. Scotland -4.03
14. Austria -4.17
15. France -4.94
16. Belgium -5.69
17. Poland -10.05
Related interest…
http://www.eurekalert.org/pub_releases/2006-10/plos-alo101706.php
“In a new study, Alison Pischedda and Adam Chippindale explore the potential costs of intralocus sexual conflict in the genetically tractable fruit fly, Drosophila melanogaster. By measuring the inheritance of fitness across generations, and across the genome, they show that sexual selection provides no advantage to the next generation. To the contrary, having a fit parent of the opposite sex leads to dramatically lower rates of reproductive success. Sexually antagonistic genes, it appears, may have far-reaching effects on patterns of fitness inheritance.”
I don’t assume that the beauty genes are the same as the healthy genes.
Ahhhhh, I understand your complaint now. The argument is not that the alleles are the same for both, but that individuals who house alleles that promote good health will show both 1) lack of leprosy, or at least the less severe form, and 2) physical attractiveness. Right, these need not be the same alleles, though of course alleles that protect against leprosy will be a necessary, but not sufficient, condition for good looks in a leprosy-stricken area. So choosing mates who don’t show leprosy symptoms will have the side-effect of choosing good-looking mates.
Fly — It’s not that I’m trying to bias the calculation so it supports my hypothesis, but that I didn’t know how else to incorporate population size, not being the most dexterous at quantitative modeling. So I welcome any improvement on the scoring process from applied mathematician types. I doubt the overall picture will change much (as Topol2′s comment shows), but still, any fixes are welcome.
Physical attractiveness is somewhat subjective, but M.U. outcomes are unlikely to result from biases — if judges are biased to favor Puerto Ricans, why do Swedes also do well, despite not resembling them? Israel and Lebanon both won, yet so did Thailand and the Philppines, despite not resembling each other. If you look on that page of M.U. statistics, there’s no clear bias toward any one part of the world or any one phenotype or narrow range thereof. Ideally, you’d want to look at who shows up on Maxim or something that the masses read, but Maxim may look slightly different if the target audience is Swedish vs Nigerian. So the M.U. stats can be used to obtain a crude measure, but working with a crude measure at least allows you to get started. Otherwise it’s completely subjective (and believe me, I’d never rank Sweden above France).
Jaakkeli — OK, but many English-speakers include “those countries” under the name Scandinavia. If that’s historically inaccurate, fine: call Norway, Sweden, Denmark, Finland, and Iceland “Schmandinavia.” It’s irrelevant — I was just using “Scandinavia” as a shorthand for “the countries in which leprosy continued to be a selection pressure after 1400, when it faded away elsewhere.”
agnostic,
That is, a person is attractive in virtue of manifesting superior health,
That still begs the question as why/how health (somewhat an “objective” quality) is perceived as beauty (a “qualia”).
So choosing mates who don’t show leprosy symptoms will have the side-effect of choosing good-looking mates.
I still don’t get it. Why should this be the result after the leprosy threat is removed? If anything, it seems like the presence of leprosy in the population might swamp out any other factors, resulting in beauty = no leprosy, with less consideration to subtler factors.
Just to add another biasing factor to Fly’s list:
How politically savvy the local judges are – i.e. do they choose according to their own tastes and internal politics, or by “international” tastes and politics? I know that this is a very big factor in Eurovision contests.
For those who want a more obvious selection pressure from leprosy: pre-modern people of course got hysterical from the slightest suspicion of leprosy and a lot of ugly people were obviously sent to leper colonies simply because they looked suspicious. It would be interesting to dig up old bones, note the frequency of *actual* leper and then compare it how many people were sent to leper colonies. I’m not sure if anyone has done that, but there’s always anecdotal stuff: Finland has lots of former leper colonies and detailed church records of people being sent to them, but I remember a historian mentioning that not a single leper has actually been identified in old bones!
OK, but many English-speakers include “those countries” under the name Scandinavia.
Yes, like many Finns would include, for example, Columbians under the name Americans…
It’s irrelevant — I was just using “Scandinavia” as a shorthand for “the countries in which leprosy continued to be a selection pressure after 1400, when it faded away elsewhere.”
…and then point out that in America it’s common for half of the police to work for drug lords.
This is not just nitpicking, there’s a real difference between Scandinavians and Finns: leprosy spread from the south and thus it was a Scandinavian disease first, only then Finnish, and in Scandinavians Swedes should be the least hit. Your leper idea predicts the wrong pattern: Finland and Sweden should be the least pretty northern countries, not the other way around! Of course it all works fine with MY idea, that it was more about anti-leper hysteria hitting non-lepers. It’s even better. You don’t need many lepers to ignite a hysteria epidemic just as bad as a “reasonable” one and if there aren’t actual lepers to target, people still won’t feel safe until they’ve found enough suspicious-looking people to blame. (To make the theory even more amusing, I could point out that it was common in such situations to blame foreigners and Jews. The north never had enough aliens to blame, so people had to cull some locals. Multiculturalism made southern peoples ugly!)
BTW I could easily stop the games by pointing out that you seem to be simply mistaken: there’s no evidence of the north having seen more selection pressure from leprosy at all. That the disease was *found at later dates* says nothing about *how long it lasted*, because obviously leprosy also arrived later in the north! It most certainly didn’t last 1000 years here, because it hadn’t even arrived that long ago. Leper didn’t “continue” after 1400, it was just starting out then! This was the pattern with ALL diseases – they spread from the south and the disease was well forgotten in southern Europe by the time it reached the north. It was just natural for a disease like leprosy to peak in Finland centuries after it had peaked in France.
Besides, Scandinavia wasn’t “the last hold out of leprosy in Europe”. There are still leper colonies in Romania…
Wouldn’t female physical attractiveness have more to do with fertility since males will try to maximize the number of offspring while male physical attractiveness would be more related to pathogen resistance since females would be interested in the health of the offspring?
David — think of it this way. If in the US there was some pressure to choose mates who had very dark skin, this would have the side-effect of increasing the frequency of frizzy, curly hair because the two traits covary. Likewise, those who show no signs of leprosy will tend to be very healthy, and thus will also tend to be more attractive than average.
ntral.nih.gov/pagerender.f cgi?artid=1033440&pageindex=1
Finn — you’re right in general, but males also care about the health of the mother, and males care more about physical attractiveness than females do. Also, in the case of leprosy, even if the male doesn’t care about what genes the mother would contribute, it’s incredibly likely that he will still refuse to mate with a leper just because he doesn’t want to risk contracting leprosy himself.
Jaakkeli — blaming foreigners when a new disease appears is not necessarily irrational, especially if they come from a more pathogen-infested area, as the Jews did (along with other Mediterranean groups). The Europeans brought all sorts of diseases to the Americas, and the natives would have been perfectly right to blame the Europeans for the new epidemics, and to want to fence themselves away from the Europeans.
Also, it’s not easy to mistake someone who has leprosy, so the idea that lots of healthy people were carted off is unlikely. My prediction is that Sweden, Norway, and Finland should look better than England, Germany, the Netherlands, etc., not which should look better among Sweden, Norway, or Finland. The prediction is correct. Why, is another matter.
Of course leprosy has been a stronger selection pressure in what I’m calling Scandinavia — it disappeared from the other Northern European countries 600 years ago, meaning that whatever selection underway was the relaxed. And it did not arrive in 1400. Here are some relevant citations:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=15386293&query_hl=3&itool=pubmed_docsum
Leprosy was a well-recognized and dreaded disease in Denmark in the Middle Ages (AD 1000-1536). A large fraction of the population was affected by leprosy in the 13th century. This paper analyzes the correlation between signs of leprosy and risk of dying in the small Danish village of Tirup (AD 1150-1350). Seven different dichotomous osteological lesions indicative of leprosy are analyzed, and it is possible to score at least one of these conditions on 135 skeletons of adult or adolescent people (aged 14 or more). Scores were transformed to a statistic, lambda, indicating the likelihood that the person to whom the skeleton belonged suffered from leprosy. The analyses indicate that the prevalence of leprosy among adult people in Tirup was 26% (95% confidence interval, 17-35%).
And as for Norway:
http://www.pubmedce
But in the oldest Norwegian laws, Gulathing’s and Borgarthing’s Law, it is stated that a promise of marriage was not binding if one of the partners was found to be leprous, and lepers were exempt from military service. These facts lead us to believe, with reasonable certainty, that leprosy was fairly common in Norway by about A.D. 1000.
The idea is that the Vikings brought leprosy back with them after raiding Ireland. I can’t find exact estimates for Sweden or Finland, but it’s clear that it was prevalent by pretty much the same time as in Denmark or Norway. Infectious diseases work that way. Also, recall that I placed a lower-bound of just 700 years on how long I assume selection had been operating, so even if it arrived in 1200 and lasted until 1900, my calculations would still be right.
agnostic,
So am I right in thinking that a synopsis would be that Swedes and Finns conatin some of the most beautiful people today, due to recent selection for such, caused by leprosy – which arrived from lands to the South.
If so, would it be fair to say that MittelEurope around the Middle Ages was going through a similar selection for beauty, and the Mediterranean before that again?
So are we seeing a wave of beauty spreading from the tropics, mediated by disease and parasites??
If in the US there was some pressure to choose mates who had very dark skin, this would have the side-effect of increasing the frequency of frizzy, curly hair because the two traits covary.
Yes, but why should leprosy-resistance and beauty covary?
agnostic, you might want to look into the specifics of leprosy – this is from the wikipedia article:
..approximately 95% of people who are exposed to it do not develop Leprosy due to natural immunity.
as i understand it there is nothing here to suggest that the susceptible variant correlates with beauty (or anything else).
on the other hand, the source says this:
About 95% of people who are exposed to Mycobacterium leprae do not develop leprosy because their immune system fights off the infection. In people who do develop the disease, the infection can range from mild (tuberculoid leprosy) to severe (lepromatous leprosy). The tuberculoid form of leprosy is not contagious.
..which pretty much gives you the idealized phatogen needed for the theory to work.
So which is it? apologies if this is an obvious google question
agnostic, my point still is that you’re getting things badly wrong if you assume that leprosy being found in Norway in 1000 means that it was the same in Finland, just because you’ve decided that both are in “Scandinavia”. What you’re calling Scandinavia is an area something like 5 times the size of the UK, with sea and mountains separating the parts! Things like that didn’t happen simultaneously all over the place the second some Norwegian came back from a raid. In 1000, Finns weren’t yet even connected to Scandinavians in any notable way!
I never claimed that leprosy arrived in 1400 – leprosy is known to have been in Finland already in the late 1300s. The point here is, precisely, that it was brought into Finland by Swedes, who in turn most likely picked it up from the other Scandinavians – those who visited the south. That’s a lot of time retardation. Leprosy in 1400 was relatively new, centuries from peaking and had probably only arrived in the corner of the country closest to Sweden. I did some Googling and the best I could come up is a reference to century-old work estimating the highest prevalence of leprosy in Finland to be 1-3 per 10000 people, peaking in the late 1600s. In any case, it’s clear that leprosy had the high point somewhere in the 1600s and had a major decline after that, because the authorities actually decided to take some measures (which were taken earlier in Sweden, or what’s now Sweden, and leprosy declined there earlier).
And yeah, it may not be easy to mistake something else for leprosy, *IF* you know the symptoms of leprosy well. That’s just the point: that would’ve been a HUGE “if”! Every medieval peasant knew that leprosy was an unimaginably horrible disease, but very few knew the symptoms and pretty much none would be confident enough about their level of knowledge that they’d have no problem with someone with a weird-looking skin condition if the symptoms don’t fit what they know of leprosy. In the vast majority of cases, the most educated person available to “diagnose” would be some priest and in fact the Bible is full of misleading nonsense about the symptoms of leprosy. There were certainly no people trained in any way to recognize leper in 1400 and for long after that; decisions to exile “lepers” were done by peasants. (This is for Finland, but things would’ve been only barely better for Sweden. I know it was very different in the more civilized places, but that was what things were like here.)
in fact the Bible is full of misleading nonsense about the symptoms of leprosy
That’s because the word that’s translated as “leprosy” – sara`at (????) is not, in fact, that disease. The translators simply used the worst disease they knew.
(1) I would add to the list of nice blond people NorthWest Russians. They must be one of the most visually astounding people on Earth. Also Lituanians and other Baltics.
(2) If I understand, you are saying that in Scandinavia lepers and other bad looking people was sent to leper colonies, where they did not reproduce. And that the percentage of exiled people could reach 25% of each generation. So for 400 – 800 years there was a strong selection against ugliness.
But…
* lepers and ugly people, even if isolated, do reproduce and their children is healthy.
* leprosy and other skin diseases were NOT exclusive to Scandinavia. The Bible deals very much with skin diseases (????) which may not be leprosy but held the Hebrews of the Bible in sheer terror. These skin disfigurations (we dont know what it was, but must have been very common among Hebrews, up to the point that antisemitic Greek and Roman historians say that they were in fact expulsed from Egypt because of skin diseases) were so feared that elaborate procedures were established to avoid the infection including the idea that houses could be infected and must be quarantined and purified. Were the Hebrew more beautiful for the disease. We dont know, but all the abovementioned antisemites say that Jews were exceptionally healthy.
jaim klein, I’m not really buying this leprosy thing (nor the “data” on beauty), I just had fun proposing an idea that fits the supposed data better. I think it’s rather silly, actually. We’re not talking about 25 % of the population, we’re talking about 0.01 % (which was still high enough to make the place famous for leprosy). It is simply a mistake to assume that a reputation for leprosy means that it was common enough to play a real role in selection over a brief time. (But as for lepers reproducing: this is Finland, so I’d guess in medieval times most discovered lepers lived only until the next winter…)
(BTW back when leprosy had been peaking in Finland, that supposed high rate of the supposed “Jewish disease” was often used as “evidence” to argue for what was then the most common view on the origin of Finns – that we’re a lost tribe of Israelites.)
jaakkeli, I presume my mind was impacted by agnostic who wrote…The analyses indicate that the prevalence of leprosy among adult people in Tirup was 26% (95% confidence interval, 17-35%).No Finn needs to feel lost nowadays, as we are accepting long lost (like Portuguese Marranos, Ethiopian Falashas and Kaifeng huys) and brand new members. My sole familiarity with those tall ash-blond ice-eyed Russian beauties comes from new immigrants in Israel.
That’s a tiny village. Obviously infections tend to cluster together and you don’t need many sick people to get a high local rate. In Finland, leprosy was mainly seen in tiny, poor island villages, so even here the local rate in a village might’ve well reached 26 %, but a temporary rate of 26 % in a village of 50 people has little influence on the country’s genetic heritage. Agnostic is very badly mistaken if he thinks that’s typical. In other Scandinavian towns, they’ve dug up hundreds of old skeletons without finding any lepers; that just doesn’t tend to get written up into whole articles. Apparently no lepers at all have been found in similar digs in Finland.
My sole familiarity with those tall ash-blond ice-eyed Russian beauties comes from new immigrants in Israel.
Hah, then you’re surely seeing some formerly Finnic beauty!
We just shut down our own “reunification migration” program from Russia. Turned out that a lot of the returnees… well… weren’t.
Jaim — the fact that 95% of people have natural immunity to leprosy is proof that there was selection against alleles that made one susceptible to leprosy. (And as I said, there are genes in the HLA that are linked with leprosy susceptibility, but I couldn’t find data on their frequencies in different populations.) In fact, among Africans and Europeans, the most common form now is the tuberculoid form (the milder one), while among Asians the lepromatous form (the disfiguring one) is more common. That’s like influenza — Europeans have been exposed to it for so long that we hardly show symptoms in 2006, due to selection; but if influenza broke out among an uncontacted Hunter-Gatherer tribe in 2006, most of them would die.
Jaakkeli — leprosy is a horribly disfiguring disease (affects your skin, hair, eyebrows, bones, voice, and breath), so it is a huge pressure. No one would want to wander near you, let alone have sex with you. It arrived in Finland sometime before 1400 and lasted up till 1900 at least. This is at least 500 years, which is 20 – 25 generations — not “a brief time” if the pressure is high and the heritability also high, which is true for good looks and susceptibility to leprosy. Maybe Finns would not score as highly as Swedes or Norwegians, but all would score higher than the Dutch, since leprosy essentially vanished in the rest of Northern Europe by 1400. Therefore, for the past 600 years (24 – 30 generations) there has been zero selection related to leprosy in the rest of Northern Europe.
As for low-level prevalence vs an epidemic, this could easily balance out. In my calculations, I only used the average gain in good looks per generations — clearly, when the pressure is far stronger, adaptation will occur more rapidly. And if the peak happened more recently, then it will take longer for the relaxation of the pressure to occur. Finland’s peak was the 17th C (though it continued right up into the 20th C), and Norway had a peak as recently as the 19th C, in addition to the earlier ravages of the Middle Ages.
Now, maybe I’ve overestimated how much better-looking “those countries” have become due to leprosy pressures — maybe the difference is 0.75 SD instead of 1 SD; I just used 1 SD for convenience. The point is, whatever the difference in the average level of “physical attractiveness” turns out to be (and it will be non-trivial), this is largely accounted for by the prevalence of leprosy (though other factors are surely involved). The obvious conclusion when one group evolves to be better-looking than another is that one is under a harsher pathogen pressure, since little else makes people care so much about physical attractiveness — especially when the pathogen disfigures the outside in a way that cannot be hidden.
Under two separate metrics, “those countries” are better-looking than other Northern European countries. And popular stereotypes from all parts of the world maintain that Scandinavians are special in their good looks, while the English and Dutch are nothing special (though not necessarily ugly). Most stereotypes are correct, of course, at least in the direction, and often in magnitude as well (sometimes underestimating the magnitude).
leprosy is a horribly disfiguring disease (affects your skin, hair, eyebrows, bones, voice, and breath), so it is a huge pressure
In those days, people died from lots of things – a much huger selection pressure. I’m not convinced that in that context leprosy stood out in terms of selection.
And, of course, I’m not convinced that leprosy alleles covary with beauty alleles – in fact I see no reason whatsoever to suspect that they do.
It arrived in Finland sometime before 1400 and lasted up till 1900 at least. This is at least 500 years, which is 20 – 25 generations — not “a brief time”
You’re still misunderstanding me. The disease might’ve hit some small village hard, but no place had 26 % rates for 500 years. Presumably, selection will have to start from scratch if the next epidemic happens in a village that isn’t in the immediate neighbourhood of the previous one.
BTW Finland is over 0.1 % gypsy, starting from around 1500. Since we’re talking about a disease with a peak prevalence of around 0.1 %, this should mean that whatever influence selection due to leprosy has had on the gene pool is dwarfed by gene flow from South Asia. Since the tropics were presumed the center of hotness in your post, is this not a more likely explanation? (Not that gypsies would be *actually* known for good looks.) I can think of a bazillion other factors which have obviously had at least as much influence on the gene pool as selection due to leprosy and a lot of those will have much better correlations with the supposed data on beauty than your leprosy idea, while still being just as silly as “gypsies made Finns pretty”. (And of course I can come up with non-silly ones, too, but then I would also like to see non-silly data on beauty!)
And popular stereotypes from all parts of the world maintain that Scandinavians are special in their good looks,
The popular stereotype in Finland seems to be that Finns are the ugliest people on earth. It’s an obvious illusion: very few Finns regularily see large samples of non-northern-Europeans (and again, northern Europe = about what’s north of 55N), so a lot of people in Finland have never seen an ugly non-northern-European or even an ugly non-Finn, but the TV is constantly beaming us pictures of beautiful people from all over the world. So…
while the English and Dutch are nothing special (though not necessarily ugly). Most stereotypes are correct, of course, at least in the direction, and often in magnitude as well (sometimes underestimating the magnitude).
…a more likely explanation is that England and the Netherlands are very popular tourist destinations and far fewer people have ever seen a representative sample of Scandinavians.
(Of course, I’ve never seen what’s south of 55N, either, but I should be disqualified as an ethnic beauty judge anyway, because I’m way too much into blondes.)
David — then you don’t believe that attractiveness is an honest signal of health. This is a standard view, however, in most of evo psych / behavioral ecology / sociobiology. As for whether leprosy would’ve stood out –mozilla%3Aen-US%3Aofficial
http://images.google.com/images?q=leprosy&btnG=Search&svnum=10&hl=en&lr=&safe=off&c2coff=1&client=firefox-a&rls=org.
There are some great pictures in a book I checked out. Trust me, unless the average person in town looked like the Elephant Man, lepers would’ve stood out.
Jaakkeli — remember, I didn’t claim 25% of every town was affected. I just said that, on average, assume that the mean of the parents in each generation was at just the 51st or 52nd percentile. That’s equal to 1 IQ point or less. Another thing to note: I’m strictly talking about selection for good looks, not selection against leprosy per se. Let’s say only 0.1% are affected — because leprosy has such a long incubation period until symptoms show up, this can have the effect of making people more cautious in choosing a mate. “Better safe than sorry.” All leprosy has to do is induce a heightened fear / paranoia, so that people will give a slightly higher priority to “good looks” when choosing a mate.
Aha! I found one of the pictures from the book:
http://home.online.no/~fndbred/lepra.htm
This is from the Norwegian outbreak of the early-mid 1800s. He would stick out anywhere, and no one would want to kiss him or have sex with him.
There are no bad cooks, only people that arent hungry. I have never met an ugly girl. Swedish, English, Nigerian, Japanese, you tell me. Jaimito has spoken.
David — then you don’t believe that attractiveness is an honest signal of health.
I certainly do think that attractiveness is a signal of health – because sick people don’t look attractive. That doesn’t mean that people who are well look even more beautiful if they carry genes against diseases that they don’t have!
The equation beauty = health can come about in one of several ways, e.g.:
1. Other people have a disease but they don’t – i.e. they have immunity to a disease that everyone else has.
2. They don’t carry deleterious recessives – i.e. alleles for what would be a clearly deleterious phenotype in homozygous individuals, but in heterozygous individuals is very subtle
3. The phenotype is obviously deleterious
What I don’t think is that genes which confer immunity to a disease necessarily also confer beauty in the absence of that disease. In fact, we know of some cases (e.g. malaria) where the opposite is true!
BTW, You don’t have to convince me that leprosy is ugly.
because I’m way too much into blondes
yeah, me too…speaking of which, need to get into one now…. :)
All these arguments still don’t answer my question :
That still begs the question as why/how health (somewhat an “objective” quality) is perceived as beauty (a “qualia”).
Not arguing that leprosy is ugly and blondes are pretty, WHY and HOW is the repulsive/attractive feeling correlated to uglyness/beauty?
Isn’t the feeling under the dependence of some other genes than either health or beauty?
If so, where does this lucky correlation between attractiveness and “good” properties comes from?