Averaged face of blue-eyed male subjects (left). Averaged face of brown-eyed male subjects (right). Czech population. (Kleisner et al., 2010)
Karel Kleisner’s team is continuing its work on eye color, face shape, and perceived personality traits:
We tested whether
eye color influences perception of trustworthiness. Facial photographs of 40
female and 40 male students were rated for perceived trustworthiness. Eye color
had a significant effect, the brown-eyed faces being perceived as more trustworthy
than the blue-eyed ones. Geometric morphometrics, however, revealed significant
correlations between eye color and face shape. Thus, face shape likewise had a
significant effect on perceived trustworthiness but only for male faces, the
effect for female faces not being significant. To determine whether perception
of trustworthiness was being influenced primarily by eye color or by face
shape, we recolored the eyes on the same male facial photos and repeated the
test procedure. Eye color now had no effect on perceived trustworthiness. We
concluded that although the brown-eyed faces were perceived as more trustworthy
than the blue-eyed ones, it was not brown eye color per se that caused the stronger perception of
trustworthiness but rather the facial features associated with brown eyes.
(Kleisner et al., 2013)
Eye color is thus associated in males with
a specific face shape, even when the men are of the same ethnic background,
i.e., Czechs in this study. Face shape is more robust if eye color is brown and
less so if eye color is blue. Furthermore, a robust male face seems to evoke an
image of dominance and trustworthiness, whereas a less robust one is perceived
as being less dominant and less trustworthy.
When the first study came out, in 2010, I
thought this association between eye color and face shape was due to ethnic
admixture, i.e., some of the brown-eyed participants had Jewish or Roma
ancestry. If this were so, however, face shape would vary to a greater degree among
the brown-eyed participants than among the blue-eyed ones, yet the current
study found no such difference. The “ethnic admixture” explanation also fails
to explain why blue eyes are associated with a less robust face in men but not
in women.
Are
European facial features actually female
facial features?
There thus seems to be a linkage between
eye color and face shape. This finding is consistent with findings for other European
physical traits, especially bright or colorful facial features. These European
traits—white skin, multi-colored hair, multi-colored eyes, and a less robust face
shape—are actually female traits.
They seem to be due to a selection pressure that first acted on early European
women and then spilled over on to early European men. This phenotypic change
affected both sexes because the traits in question are at most mildly
sex-linked. The direction of sex linkage is consistent with the above model of selection. Hair color became polymorphic in Europeans through the emergence of brighter hues, but this evolutionary change is most pronounced in European women. According to a twin study, hair is lighter in women than in men, with red hair being especially more common. Women also show more variation in hair color (Shekar et al., 2008). Again, this evolutionary trend seems to have been driven by European women with European men tagging along.
There is also unpublished evidence that “European” hair and eye colors (i.e., non-black hair and non-brown eyes) are associated with a higher degree of estrogenization before birth, as indicated by digit ratio. This prenatal estrogenization might also favor a more feminine face shape. Face shape would thus correlate with eye color because of a shared determining factor: the degree to which the fetus is estrogenized or androgenized in the womb. Such a correlation would have been stronger in the male participants than in the female participants because estrogenization is overdetermined in females, i.e., almost all girls are exposed to enough estrogen in the womb to feminize their face shape, whereas this level of estrogenization would be reached only in blue-eyed boys.
In one respect, however, the blue-eyed face looks less feminized, the chin being relatively narrower and longer. It might be that this is what happens when the trajectory of facial development is initially programmed for a feminine appearance before birth but is not supported by circulating estrogen later in life.
References
Frost, P. (2008). Sexual selection and
human geographic variation, Special Issue: Proceedings of the 2nd Annual
Meeting of the NorthEastern Evolutionary Psychology Society. Journal of Social, Evolutionary, and
Cultural Psychology, 2(4),169-191.
http://137.140.1.71/jsec/articles/volume2/issue4/NEEPSfrost.pdf
Frost, P. (2006). European hair and eye
color - A case of frequency-dependent sexual selection? Evolution and Human Behavior, 27,
85-103 http://www.sciencedirect.com/science/journal/10905138
Kleisner, K., L. Priplatova, P. Frost,
& J. Flegr. (2013). Trustworthy-looking face meets brown eyes, PLoS One, 8(1): e53285. doi:10.1371/journal.pone.0053285
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0053285
Kleisner, K., T. Kočnar, A. Rubešova,
and J. Flegr. (2010). Eye color predicts but does not directly influence
perceived dominance in men,
Personality and Individual Differences, 49, 59–64.
Shekar, S.N., D.L. Duffy, T. Frudakis,
G.W. Montgomery, M.R. James, R.A. Sturm, & N.G. Martin. (2008).
Spectrophotometric methods for quantifying pigmentation in human hair—Influence
of MC1R genotype and environment. Photochemistry
and Photobiology, 84, 719–726.
32 comments:
Part 1
I have said this before in your comments, but feel this is worth saying again:
Male-female face shape differences decompose to three forces:
- Testosterone, at least prenatally, is associated with a broader shape
- Development - men develop for longer, in both childhood and adult stages compared to women. Children have broader faces relative to adults. Greater development is associated in the anterior-posterior plane with anterior retreat of the cheeks, anterior progression of the chin and anterior progression of the nose.
- Size - as men develop for longer, and possibly for other reasons, they have a larger final size of face relative to brain (which is larger than in women, but not so much as the face is increased in size). Large size, particularly relative to masculinization, is associated with an increase in prognathism.
For visualisation see:
- Examining the effect of 2D:4D ratios on face shape - (Second to fourth digit ratio and face shape, Fink et al 2005), which separates prenatal hormones from sex differences by using 2D:4D. "In view of the data we present here, facial characteristics that have been previously reported to be perceived astypically ‘masculine’ or ‘feminine’ may be a composite of at least two factors operating differently on facial shape...extended growth (and) the prenatal hormonal environment affects (which) another dimension which is supposedly ‘robusticity’.
- Controlling for allometric scaling within sex (Thin-Plate Spline Analysis of Allometry and Sexual Dimorphism in the Human Craniofacial Complex, Rosas and Bastir 2002), which controls for size but not development time or sex hormones.
"Sex-specific shape changes " (separated from size) between males and females are: "In males, the nasoglabellar profile becomes curved and projecting, and thesubnasal profile rotates clockwise. The nasal roof is elevated, and the nasal floor shifts downwards. The outer table of the occipital clivus rotates counterclockwise. The chin is lowered" (i.e. the chin gets longer ", and the gonial region gets strongly curved."
"A mean-male TPS transformation revealed a larger piriform aperture, achieved by an increase of the angulation of the nasal bones and a downward rotation of the anterior nasal floor.
"In contrast, the mean-female TPS (thin-spline plates) transformation was characterized by a relatively small nasal aperture. The occipital clivus inclined anteriorly, and muscle insertion areas became smoothed. Besides these variations, both maxillary and mandibular alveolar regions became prognathic"
"Allometric shape changes" (separated from sex) between males and females are:
"With increasing centroid size, the subnasal clivus becomes enlarged and rotates counterclockwise; the increment of the mandibular ramus height leads to a more pronounced angulation at gonion; the antero-posterior dimensions of the splanchnocranium are reduced; the face is expanded supero-inferiorly; the face appears relatively larger than the neurocranium" ... "As a result, the alveolar region becomes prognathic.
Part 2:
- Looking at the trajectory of shape changes from adult to child Different Cranial Ontogeny in Europeans and Southern Africans, Sardi and Rozzi 2012 , which shows how longer development changes facial shape, when facial size is kept constant
" Facial development involves increases in facial and nasal height (and crucially not width!) , being more accentuated in Europeans than in Southern Africans. (it is unclear whether these are Khoi-San type or classic Negroids, but the morphological shape changes are consistent with classic Negroids) (Southern Africans) seem to retain younger traits during adulthood. In heterochronic terms, face in Europeans followed acceleration; it undergoes greater changes in shape, with respect to age and size, with a similar final size (Table 2, Fig. 2). This set of characters does not differ at birth but progressively diverge.
Size-related shape changes on PC1 (this PC is associated with the main axis of child-adult differentiation) are also lower in Africans than Europeans (Fig. 5C), being slopes significantly divergent (Table 2). Transformation grids indicate that main postnatal changes occur at the sagital plane; the nasal cavity became taller and narrower, (with) the nose and the palate more distally located in relation with the orbit (Fig. 5D–E). These changes are more pronounced in Europeans.
Putting all this together, I see evidence for Europeans being more developed, and thus in a sense, more masculinised (in the very loose sense adult women could be said to be masculinised compared to female children), but not through having large faces or high testosterone, but not more feminised.
The narrow shape of the European face being due to longer development also helps explain their projecting noses, where compared to Africans and tropical people the nasal cavity became taller and narrower, (with) the nose and the palate more distally located in relation to the orbit).
If the narrow shape of the European face were due to prenatal low testosterone levels, then their projecting noses would remain unexplained... It is more parsimonious to see them both as part of the same mechanism.
Satoshi Kanazawa argues the opposite in "Why Beautiful People Have More Daughters": that brown eyes are "mysterious" whereas blue eyes are "trustworthy."
The reason is that the pupil is more visible in blue eyes. Thus, the size of the pupil (its dilation or contraction) can be accurately observed and a conclusion can be made about the emotions being experienced.
In brown eyes, the dilation of the pupil would be more difficult to observe, hence the impression that people with brown eyes are mysterious or hard to read.
This might just be me, but I perceive the blue eyed face to be more dominant, prettier for sure, but also more dominant.
To me the brown eyed face seems big, dumb and dopey.
The distrust of weak features linked to blue eyes is significant for men only, An explanation has to explain how the sex link to blue eyes originated, Peter's does.
The blue eyed men had longer, narrower jaws, that is a characteristic of 'highly attractive' men, see here . As the study says 'attractiveness and dominance/masculinity may reflect different aspects of male mate quality'. IMO Leonardo DiCaprio is a good example of a blue eyed man who is attractive to women without having dominant masculine looks. One wonders what he would have looked like without the blue eyed gene.
Robert Trivers is of the opinion that women have a deeper understanding of deception. They are certainly better with language. An unmasculine male face could be read as signalling a male with greater capacity for deception, thereby leading to blue eyed men being seen as untrustworthy.
Razib's post on the study seems to be arguing a point Cochran made about recessives, which you have dealt with (On the impossibility of blue eyes). He is still pushing the idea that blue eyes were a side effect of skin colour, with the sinister implication that those with darker skin than Scarlett Johansson need to have their vitamin D levels 'corrected'.
'HIGH-dose oral supplementation in an at-risk population may have an adverse effect on cardiovascular risk for those individuals who have the strongest biological response to vitamin D'
Anon,
This issue was addressed by Denise Liberton in her study of West African and European face shape:
"Human facial features show extensive variation within and among populations. By investigating the relationship between dimorphism in facial features and genetic ancestry in different populations, we can explore the roles of sexual and natural selection on the human face. We measured sexual dimorphism in facial traits while controlling for the effects of overall size differences and then tested for interactions between sex and genetic ancestry. The study sample consists of 254 subjects (n=170 females, n=84 males), ages 18-35, showing West African and European genetic ancestry sampled in the United States and Brazil [...] females in all three samples had many additional significant correlations that were not seen in males, while males had very few correlations that were not found in females. The results of these analyses suggest that selection on females is driving the differentiation in facial features among populations."
http://www.ashg.org/2009meeting/abstracts/fulltext/f21301.htm
This finding is consistent with the work of anthropologists like Louis Bolk and others, i.e., Europeans have more neotenous faces than do Africans, and this trend is stronger in women.
The nose might indeed be an exception to this trend, although we don't know enough about the appearance of early Europeans before 25,000 BP. It may be that these early Europeans were bigger-nosed than later Europeans.
Davani, Chris, and Sean,
It's not eye color that triggers the impression of trustworthiness or dominance. It's the face shape that goes with the eye color. Yes, this impression might be culturally mediated. There will be further studies to replicate this finding in other populations.
I am not convinced. Is there any set of data of similar experiment performed on animals and primates ?
I believe very clear eyes occur in nordic predators such as wolves, husky dogs and siberian tigers. And i see two situations:
1)very clear versus dark eyes in predation/hunting behavior.
2)very clear versus dark eyes in mating behavior and male competition.
It should not be a very big deal to measure the reaction of a potential prey, say a dear, in front of a reallistic reproduction of wolves with different eye colors. There are very good naturalised stuffed wolves in many museum that could be retrofitted with different eyeballs.
Same for mating or male/male competition, the initial response (before the test subject realizes it's a fake) of a female in oestrus in front of fake males with different eye color would be interesting.
National Geographic has published a report of male lion competions whith a dummy male having either a black mane or a yellow mane and the article mentioned the clear-manes lions are always attacked first. The clear mane is probably an indication of low testosterone or low agressivity.
I very much doubt the nose was an exception. Second-to-fourth digit ratio and facial shape in boys: the lower the digit ratio, the more robust the face "Regression analyses depict the same shape patterns as in adults, namely that the lower the 2D : 4D, the smaller and shorter the forehead, the thicker the eyebrows, the wider and shorter the nose, and the larger the lower face."
Selection would remove variation.Sexual dimorphism in multiple aspects of 3D facial symmetry and asymmetry defined by spatially dense geometric morphometrics. says " In a sample of gender-matched young adults (18-25 years) with self-reported European ancestry, we found greater variation in male faces than in women for all measurements."
Ben10 it's about a particularly feminine face shape in men being linked to blue eyes, as a result of sexual selection of women for novel eye colours. Perceptions of a dominant-looking face wouldn't be altered by the eye colour.
dominant-looking face
This finding is consistent with the work of anthropologists like Louis Bolk and others, i.e., Europeans have more neotenous faces than do Africans, and this trend is stronger in women.
The nose might indeed be an exception to this trend, although we don't know enough about the appearance of early Europeans before 25,000 BP. It may be that these early Europeans were bigger-nosed than later Europeans.
Europeans may be more neotenous in the relative proportion of the viscerocranium to the neurocranium, but I have far more confidence in a morphometric study done last year, which actually compares the total shape similarity to infants of African and European faces and finds Europeans as more peramorphic over the ramblings of a someone from the 19th century.
It is clear that, when controlling for size, more developed faces have more anterior positioned cheeks, a relatively narrower and more projecting nose, a relatively narrower and taller face and a relatively shorter and more retruding jaw (and a more projecting chin is there as well).
These are also largely the diagnostic characteristics of the Caucasoid face in a cross racial analysis context.
They are not the diagnostic characteristics of a (particularly size controlled as in the Rosas and Bastir paper) female relative to male face (where is the flatter nose, where are the more projecting cheeks? where is the prognathism?).
The diagnostic characteristic of 'more developed' would be superior function. So why did European men evolve beards that hide their 'developed' faces from their womenfolk eh?
When they offered the job on Twilight to Robert Pattinson, it was on the condition that he had little gaps put in between his teeth. White people tend to have malocclusion because they have faces too small for their teeth. Blacks tend to have natural gaps.
This man is a Senegalese type. (Polygyny is more common in Senegal than anywhere else on earth.)
The Kleisner study says "brown-eyed faces tended to have a rounder and broader chin, a broader mouth with upward-pointing corners, relatively bigger eyes, and eyebrows closer to each other." By my way of thinking they incline to the Senegal type of black African shown in the link. Note that I am not claiming the image represents an archetypal dominant face, there is more than one type of male mate quality, but I do think it shows selection for an appearance that wins women over. Women report men deceive about their sincerity and depth of feeling. Looking trustworthy would be a big asset for a man, nowhere more than in a polygynous mating system.
Sean: "dominant-looking face"
excellent link, but from the front, i thought it was actually a woman (high cheekbone, vaguely asian).
The nose is also very interesting.
http://mathildasanthropologyblog.wordpress.com/2008/09/05/ancient-carved-ivory-portrait-of-a-cro-magnon-man/
"The diagnostic characteristic of 'more developed' would be superior function. So why did European men evolve beards that hide their 'developed' faces from their womenfolk eh?"
Evolve beards? Most of the big beards i see on the TV aren't Europeans so it's not like beards are a European-only characteristic.
.
"Looking trustworthy would be a big asset for a man, nowhere more than in a polygynous mating system."
A polygynous low male investment environment is where it's least necessary for the men to look or be trustworthy.
.
My first thought was - if it's correct that varying hair and eye colours in northern Europe was due to disproportionate sexual selection on females because of competition for men who could provide food in that environment then if over time that disparate selection led to a feminization of facial features over the whole population then might there not be a pressure to compensate somehow?
I was thinking cultural things like retaining facial hair or tattoos as a way of re-masculinizing but some of the things Anon #1 says seem to possibily fit the bill also:
"The narrow shape of the European face being due to longer development also helps explain their projecting noses"
and
"Development - men develop for longer"
A bit of sexual dimorphism to compensate?
A polygynous low male investment environment is where it's least necessary for the men to look or be trustworthy.
Perhaps it's deception. Appearing to be trustworthy without actually being so.
Yeah i guess. I just would have thought the advantage of looking trustworthy would be proportional to how much the females needed high male investment but then again, now you mention it, in environments where the females *needed* high male investment then their (and the deceptive men's) offspring wouldn't survive very well. So being a fake trustworthy man in that environment might be relatively pointless?
Here is a quick summary of what I am aware of regarding the genes/loci that influence normal variation in human facial morphology. If anyone is aware of any other genes/loci that influence the morphology of the human face then could you help me by adding to this post.
Firstly, a study conducted by Zhou et al. (2005) showed that alleles of GHR are responsible for variation in mandible ramus height, specifically that of the I526L allele. The CC genotype results in the longest mandible ramus, whilst the AA genotype results in the shortest mandible ramus. In the same year, Coussens and van Daal (2005), showed that an intronic SNP in the FGFR1 gene (rs4647905 G/C) is responsible for variation in cephalic index. Specifically, at SNP rs4647905, the GG genotype correlates with increased cephalic index, whilst the CC genotype correlates with decreased cephalic index and longer faces. The GC genotype being the intermediate. As far as I am aware these two studies are the first to show any evidence regarding actual genes and precise loci that influence normal facial morphology, despite some later studies saying that they are the first.
A study by Matthes (2008) (A Preliminary Genetic Investigation of Normal Variation in Facial Features) provided evidence that the genes BRAF, TRPS1, COL11A1, FGFR2, and LMNA are also responsible for variation in human facial features. The SNP rs3789806 G/C (BRAF) influences nose width and perhaps nasal bridge projection. The SNP rs2049873 A/T (TRPS1) influences the distance between the eyes. The SNP rs2229783 T/C (COL11A1) appears to influence maxillary height and various nose dimensions. The SNP rs2981435 C/A (FGFR2) influences maxillary height. The SNP rs505058 G/A (LMNA) influences various facial width parameters, including the spacing between the eyes.
Tomoyasu et al. (2009) also showed that alleles of GHR are responsible for variation in mandible ramus height. This time the polymorphisms identified were that of P561T and C422F. Furthermore the C422F polymorphism was found to be in linkage disequilibrium with P561T. Subjects with genotype CC of polymorphism P561T and genotype GG of polymorphism C422F had significantly greater mandible ramus height than those of genotypes CA and GT.
Im et al. (2010) showed that the loci 18q12.2, 5q15, 9q34.2, and 5q34 influence biocular width (ex-ex) whilst 17q22 (noggin?) influences intraocular width (en-en). The loci 5q34, 13q33.3 and 1p36.22 apparently are responsible for variation in eye size/eye prominance. 4q32.1 influences Nose length (n-sn), and finally 15q22.31 influences the potrusion of the nose (sn-prn).
Apparently a study by Ermakov et al. (2010) has showed that genetic variants of ENPP1 are also responsible for variation in facial features, such as upper facial height, head width, and lower facial height (according to abstract).
Boehringer et al. (2011) identified that SNP rs1258763 (GREM1) affects nose width whilst SNP rs987525 (near CCDC26) affects the bizygomatic distance.
Sherwood et al. (2011) found a number of loci on chromosomes 3, 6, 11, 12 and 14 that influence various craniofacial dimensions.
Paternoster et al. (2012) has recently established that variants of PAX3 appear to influence nasal bridge projection, specifically the SNP rs7559271 G/A. This finding was also reaffirmed by the recent the GWAS performed by Liu et al. (2012), although it was a different SNP, being that of rs974448 G/A. Liu et al. (2012) also identified several other genes implicated in controlling facial morphology. These were PRDM16 at SNP rs4648379 T/C which appears to affect nose width and TP63 at SNP rs17447439 G/A, C5orf50 at SNP rs6555969 T/C, and COL17A1 at SNP rs805722 T/C which all influence the distance between the eyes.
I would very interested to know if anyone else has any knowledge/thoughts/ideas on how variants of genes involved in the Notch signaling, WNT signaling, Hedgehog signaling, TGF Beta signaling, or the RAS/MAPK pathway could control normal variation in facial morphology.
http://www.ncbi.nlm.nih.gov/pubmed/18041401 - "a previously adduced hypothesis of an association of lighter eye and hair color with higher, i.e., more feminized, 2D:4D received no support in both samples" ("A contemporary sample of 109 Lithuanian men and women was compared with data from a historical sample of 100 Lithuanian men and women, collected and published in the 1880s and rediscovered only now").
Anon, re'pointless' In west Africa women are self supporting through garden agriculture, they do all the work and they all get mated, so sexual selection works on males. Sexy son
Sexual selection operates on one sex. In polygyny it's men. The part of the world with the most polygyny is Senegal. It's also the part of the world where the best examples of the most extreme and specialized type of black African is found: Senegal(Baker,1974).
von Eicksted on this type: "he bridge of the nose is bulky, quite low and broad, in profile usually straight, with a rounded tip. The nostrils are characterized by their special size, broadness and inflatedness, with often pronounced diagonal-oval forms. The inflated nostrils are mostly quite distinguished from the bridge, but they often pass over to it (funnel nose). Prognathy is always to be found, accompanied by an extraordinary thickness of the soft parts of the mouth area. The mouth itself is quite big, ... The chin is soft, sometimes even receding."
Kleisner et al says "A trustworthy male face was characterized by dilations of the TPS deformation grid in the mouth area"
'Anon', as you mentioned nose width, you may be interested to know about Honeymoon rhinitis, and this.
1 - Applied to skin color, the sexual selection hypothesis Proposes That male preference for light-skinned females Explains The Presence of light skin in areas of low sun radiation. ACCORDING to this proposal, in areas of high sun radiation, natural selection for dark skin overrides the evils of universal preference for light females. But in areas in Which natural selection ceases to act, Becomes more important sexual selection, and human causes Populations to become light-skinned, and females to be lighter than evils. The sexual selection hypothesis Proposes That human sexual dimorphism of skin color Should be positively Correlated with distance from the equator. So According To That prediction human sexual dimorphism Should Increase with Increasing latitude, with a positive correlation Between Increasing distance from the equator and Increased sexual dimorphism.
2 - Natural selection Favour dark skin everywhere, though to a lesser extent at higher latitudes. Therefore differences in skin color racial were caused by sexual selection. Available evidence suggests that in each society to lighter-than-average skin color is preferred in a sexual partner. Such a preference would generate sexual selection for light skin that counteracts natural selection for dark skin. The observed latitudinal gradient in skin color may result from the balance between natural and sexual selection.
4 - If intensity of sexual selection is determined by the overall ratio of men to women and the Incidence of polygyny (which affects the ratio of men to women who are sexually among those available). In tropical environments, men competed against other men for a limited number of available women. Male mating success would depend on having traits that excite and retain female attention. But in tropical zones convergent evolution did not occur due to natural selection for dark skin counteracted the female sexual preference for lighter skin color´s men and evolution of highly visible male colorful physical traits.
5- It can be apply to optimization of male morphology due to female choosers. Anyway there are tentative nature of the evidence regarding masculinity and disease in humans, the complex and uncertain picture emerging from the animal literature on sexual ornaments and immunity, the absence of consistent, cross-cultural support for the predictions of the immunocompetence hypothesis regarding preferences for masculinized stimuli, and evidence that facial masculinity contributes very little, if anything, to overall attractiveness in real men.
"Anon, re'pointless' In west Africa women are self supporting through garden agriculture, they do all the work and they all get mated, so sexual selection works on males."
Yes i agree with that however for the same reason males being trustworthy is less important.
However on reflection maybe relatively speaking it is still more useful in that environment than one where males *need* to be trustworthy. In that second kind of environment although falsely appearing trustworthy might be sexually useful it's not reproductively useful as the offspring *need* the real thing.
So relatively speaking maybe you're right.
So why did European men evolve beards that hide their 'developed' faces from their womenfolk eh?
Sean: Beards are not more attractive to women in a modern context. Not persuaded that they are evolved to mimic a relatively enlarged jaw / disguise a smaller one. Han Chinese don't have them, Aborigines and New Guineans do, South Asians have heavier beards than Europeans, etc. Larger beards also covary with greater levels of testosterone, which makes no sense for a compensatory adaptation.
And just because greater facial development as well as greater size and greater testosteronization of face shape are all male traits, what makes you think greater facial development is strongly attractive to women? After size and testosterone and health are added, facial development level is probably of marginal importance to male or female attractiveness (a large, allometrically scaled up, strongly tesosteronized but "neotenous" face probably would be of similar attractiveness to women than a more peramorphic face).
Anon,
Yes, I'm aware of that study (http://www.ncbi.nlm.nih.gov/pubmed/18041401). The main shortcoming was that the method of measuring digit length was not the same for the two datasets. J.T. Manning is interested in pursuing his work on digit ratio and hair/eye color, but this topic doesn't seem to be a high priority for him.
Tyrion Lannister,
Point #4 is incorrect. Women are ambivalent toward male skin color. Light skin is perceived as "cute" but cuteness is not necessarily a desirable male characteristic. This takes us back to H. Wagatsuma's paper on the social perception of skin color in Japan. Japanese women consider lighter-skinned Japanese men to be esthetically beautiful while considering darker-skinned Japanese men to be more manly, dominant, and trustworthy.
It's only the Saami-admixed Baltic area population where there is low 2D:4D with blonde hair. At the western end of the European steppe tundra zone the blonde hair /high 2D:4D relationship holds good.
Beards augment perceptions of men's age, social status, and aggressiveness, but not attractiveness.
'[A] large, allometrically scaled up, strongly tesosteronized but "neotenous" face' - is not what Europeans have, it's what west Africans have. 'Geometric morphometrics of male facial shape in relation to physical strength and perceived attractiveness, dominance, and masculinity' says "highly attractive and taller men had longer, narrower jaws and wider/fuller lips" Are you going to deny West African men have 'wider/fuller lips'. Or that estrogen orients women toward darker skinned men.
'[A] large, allometrically scaled up, strongly tesosteronized but "neotenous" face' - is not what Europeans have, it's what west Africans have.
Overall centroid sizes of the face are similar in Africans and Europeans in the study I cited (and indeed similar as far as I recall in most of the morphometric studies I recall).
I am agnostic regarding whether Africans have a facial shape more influenced by testosterone.
But it is good that you recognize their neotenous character once adjusted for size.
The main shortcoming was that the method of measuring digit length was not the same for the two datasets. J.T. Manning is interested in pursuing his work on digit ratio and hair/eye color, but this topic doesn't seem to be a high priority for him.
OK, but why is this a major shortcoming for considering variation internal to the 2 samples, which is the relevant to this study?
Both samples have a sex difference between men and women, in the expected "Male = low, female = high direction"
In neither sample does this sex difference correlate in such a way that the male->female change vector correlate to a dark eyes->light eyes change vector.
Differences in measurement methods between the first and second sample damage the study's findings with respect to change over time (diachronic change) but do not weaken its findings (on synchronic associations) as to the lack of association between 2d:4d (and thereby in utero sex hormone levels) and lighter and darker eye pigmentation (at least, within the norms of European development ontogeny for these traits).
West Africans are not systematically more craniofacially neotenous than Europeans. Here. Just as the blue eyed men with 'a less robust face, characterized by a smaller nose, chin, and mouth,' in the study were not systematically more craniofacially neotenous than the brown eyed ones :'In one respect, however, the blue-eyed face looks less feminized, the chin being relatively narrower and longer.'
"After size and testosterone and health are added, facial development level is probably of marginal importance to male or female attractiveness"
I think some aspects of facial development are significant e.g. jaws and chins. It may just be a cliche but there's an idea that aristocratic men i.e. men where the sexual selection has been disproportionately on the females, have no chins.
I think if you showed men and women pictures of just the lower face below the mouth you'd see a significant gender-based difference in percieved attractiveness based purely on that.
The guy on the left has what appears to be a wider mandible but a smaller and less square chin. A wider mandible is associated with males whereas a relatively weak chin is not, thus, I am a little confused over why the guy on the right supposedly looks more feminine--I do not see it.
I do think that the guy on the right looks more classically handsome, though.
One other thing, were the raters of trustworthiness themselves 50% brown-eyed and 50% blue-eyed, and was gender of the raters evenly represented? People tend to trust, and, well, like people who look like themselves. Perhaps the raters themselves had faces that look more like the face of brown-eyed people, or they had relatives who look like the face of the brown-eyed guy, so they were predisposed to liking him...
All this talk of noses and chins...
The first thing I noticed was the eye-eyebrow distance and volume of the eyes (greater in the brown-eyed guy.)
Sadly, the blue-eyed guy looks like a Nazi, the brown-eyed guy like a terrorist, IMO. But I did immediately perceive the brown eyed guy as friendlier looking; ole blue eyes looks more 'jock'. I think it's the eye-region size that makes the brown-eyed face look more 'open'.
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