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Research on animals behavior leads sometime to evaluate Homo sapiens' too. Although humans are not my field of knowledge, during animal observation some questions arise by themselves. This essay is mostly a report of interpretations by specialists on the intriguing reasons behind adornments, particularly in female individuals and it reviews the association between female ornaments in humans and animals, with some conclusions from a viewpoint of an animals ecologist.
Female adornment in humans and animals
Francesco Nardelli 2015
Discussion paper
Research on animals behavior leads sometime to evaluate Homo sapiens too. Although humans are
not my field of knowledge, during animal observation some questions arise by themselves. This es-
say is mostly a report of interpretations by specialists on the intriguing reasons behind adornments,
particularly in female individuals and it reviews the association between female ornaments in hu-
mans and animals, with some conclusions from a viewpoint of an animals ecologist.
1. The evolution and signaling content of female orna-
mentation has remained an enduring challenge to ecol-
2. Females usually invest significant amounts of their re-
sources in offspring. The ingenuity allocated to elabo-
rate adornment reduce energy available for other pur-
I interviewed 43 women to ask this question: When we observe Homo sapiens, we found that males
of so called 'primitive people' adorn themselves with colored make-ups, feathers, etc., alike in the
large majority of animal species. When we examine 'advanced people', virtually only females use
The answers, synthesized, were: 'to look nicer' 33 (77%), 'to feel better or self confident' 9 (21%), 1
explanation (0.5%) was (reported in full): "In my opinion, the reason why women use makeup and
believe that it makes them 'more appealing' to both men and their personal tastes, is not a conscious
reason at all. Of course it appeals to us visually, but like you said, "why?" Well, I believe it's be-
cause of our hard-wiring when we were just starting out as a species and had to recognize the
healthiest individuals that possessed the best genes. If you notice, women go out of their way to
make their cheeks appear more flushed using blush, their eyes more defined using eyeliner, and
their lips brighter with lipstick. Well, this might
be done because subconsciously we're trying to
highlight that we are in fact 'healthy specimens' by
showing off good genes which is reflected in our
outward beauty. Women, by making their eyes
Spangled Cotinga (Cotinga cayana) - Trinidad Carnival
more defined, for example, would tell the man that they have good, working eyes and that they,
therefore, would be good mates. Same thing goes for creating red, flushing cheeks - this shows that
they are healthy and able to bare children. So, basically, the reason why women put on makeup is
much the same reason that birds try to attract mates with their beautiful feathers, to make them-
selves more appealing to the opposite sex and to nonverbally display their ability to reproduce suc-
Citations It has been hypothesized that female ornaments signal the genetic quality of indi-
viduals, or direct benefits such as parental care or other non-genetic maternal re-
sources. Thus, a male choosing to fertilize
the eggs from an elaborately ornamented
female might sire fewer or poorer quality
offspring than his rivals choosing to mate
with the drabber female, which has allo-
cated relatively larger proportion of her re-
sources into the eggs.
Spangled Cotinga breast feathers, Nail polish (R)
Two main hypotheses have been proposed to explain the evolution of female ornaments. The 'direct
selection hypothesis' predicts that female ornaments are under direct sexual selection by males or
selection via reproductive competition among females (Amundsen 2000). The alternative hypothe-
sis, the 'genetic correlation hypothesis', in turn suggests that female ornamentation is a genetically
correlated response to selection for male ornamentation. This idea originally gained some support
already from Darwin (1871).
Feathers ornaments - Blue-naped Chlorophonia (Chlorophonia cyanea)
Table 1. Overview of number of studies with negative, non-existing and positive association be-
tween ornament (carotenoids based, and other ornaments than carotenoids-based pooled) and
offspring quality
Taxonomic group Negative None Positive
Carotenoids are pigments synthesized only by plants, algae, some bacteria and some fungi, and thus
animals must obtain them through their diets (Goodwin 1984, Moran & Jarvik 2010).
The offspring in different animals face different selective pressures determined by the environment.
At the individual level trade-offs are expected, but in a good, nutrient-rich environment such trade-
offs may not necessarily become apparent (in contrast to low-quality environments).
For example, the great tit chicks of brightly ornamented mothers had lower fledging success
compared with chicks of drabber mothers only during environmental unfavorable conditions
(Mand, Tilgar & Møller 2005).
In general, males are expected to base their mate choice principally on phenotypic indicators that
are associated with female fecundity either directly, e.g. body size, (Sargent, Gross & van den
Berghe 1986; Kraak & Bakker 1998; Bonduriansky 2001; Byrne & Rice 2006) or indirectly e.g. or-
naments (Amundsen & Forsgren 2001; Massironi, Rasotto & Mazzoldi 2005). Even in species
where female ornaments are negatively associated with offspring fitness, elaborately ornamented
females may potentially have higher fitness than non-ornamented females. This may be very un-
likely, but would occur
if higher sexual attrac-
tiveness of daughters
of the bright mother
more than compen-
sates her reduced
number of surviving
However, in species
where ornament off-
spring trade-offs have
been demonstrated so
far, males preferring
ornamented relative to
drab females have
been shown in the
large majority of
Doutzen Kroes without and with makeup
animal species.
The most likely and especially interesting explanation is natural-
ly that there is simply no association between the ornament and
offspring quality.
These results have a number of implications. As predicted,
makeup had significant positive effects on ratings of female fa-
cial attractiveness at brief and longer inspection times. Ratings
of competence increased significantly with makeup look tested
on first glance and longer inspection. Effects were weaker and
more variable for ratings of likability and trustworthiness, alt-
hough generally positive.
Social psychologists have suggested that social warmth and so-
cial competence represent two universal dimensions of social
perception by which we
evaluate individuals and
groups (Etcoff 2011),
with warmth capturing "Glamorous makeup" female
traits related to social cooperation, and power/competence
capturing cues relevant to advantage in social competition,
such as status and dominance. Here it is shown a robust and
positive effect of increased beauty on social pow-
er/competence and a generally positive but more nuanced
and variable effect on social warmth.
Past studies have shown that attractive people are expected
to do better on the job, in school, and in life and are treat-
ed that way by being agreed with, deferred to, helped, and
Mandrill (Mandrillus sphinx), male
granted larger personal space. In a recent experimental study using a task for which physical attrac-
tiveness did not improve productivity, researchers demonstrated conclusively that employers expect
physically attractive workers to perform better at their jobs and be more competent. But, as sociolo-
gists Webster and Driskell noted when first proposing the idea of beauty as status, there are im-
portant differences between attractiveness and other status characteristics such as race or sex: beau-
ty is a malleable characteristic (Webster et al. 1983).
They predicted that, given the powerful effect of status, 'attractiveness' will assume increasing sig-
nificance as other characteristics such as race and sex fall into disuse.
Latest research (Leeuwen Van et al.
(2014) found that just like humans,
chimpanzees, too, like to spruce up
their style. A recent study published
in the journal Animal Cognition
found that chimpanzees also like to
keep up with the latest fashion trends
going around.
After many fellow chimps saw female
Julie place a piece of grass in her hair
- for no apparent reason - many of the
animals jumped in on the fashion
"This reflects chimpanzees' proclivity
to actively investigate and learn from
group members' behaviors in order to Female Chimpanzee "Julie" with grass straw
obtain biologically relevant information," said lead study author Edwin van Leeuwen, of the Max
Planck Institute for Psycholinguistics in The Netherlands.
Over 700 hours of video footage documented the trend. Prior to that, van Leeuwen had first noticed
that Julie would repeatedly put a stiff, straw-like blade of grass in one or both of her ears back in
2010. Even while grooming, Julie left the objects in place. Over time, other chimps starting mim-
icking a similar look to Julies'.
In order to find out why this was happening, van Leeuwen conducted a year-long study that exam-
ined 94 chimpanzees living in four different social groups in a sanctuary. The findings revealed that
one of the four groups regularly performed Julie's grass trick, which convinced eight of the 12
chimps in the group to also go for the same look. Even after Julie died, the trend is still going
strong, according to researchers.
"The fact that these behaviors can be arbitrary and outlast the originator speaks to the cultural po-
tential of chimpanzees," van Leeuwen concluded.
Conclusions I would suggest that attractiveness has
implications greater than before, and
the trend will continue in this way as
long as attractiveness remains an often
unconscious proxy for status and abil-
The beauty halo effect has been called
the 'what is beautiful is good' effect. (I
would add 'what is rare is beautiful' in
case of animals seen through human
eyes). In my opinion, makeup increas-
es inferences of warmth and coopera-
tion (likability and trustworthiness)
when faces are presented very briefly,
but it does not achieve that result on
South American Indios, males
longer inspection. In general, there is less agreement about whether beauty invariably signals social
cooperation, with some studies suggesting that there is a ”dark side” to beauty characterized by van-
ity, immodesty, or greater likelihood to cheat on a partner (Mobius et al. 2006).
My findings suggest that it may be
fruitful to disentangle the effects of
beauty from beauty enhancement.
It may be that natural beauty or natural
appearing beauty leads to positive in-
ferences of social cooperation, where
more obvious beauty enhancement
may lead to neutral or even negative
Finally, results provide additional evi-
dence that judgments of facial trust-
worthiness and facial attractiveness are
(at least partially) separable; the high-
est contrast makeup (glamorous)
South American Indios, females.
increases attractiveness significantly while at the same time decreasing judgments of trustworthi-
One potential source of the cosmetics effect on face perception
is increasing luminance contrast between the features (eyes
and lips) and the surrounding skin. Cosmetics increase lumi-
nance contrast by significantly darkening the eyes and lips.
Skin is neither significantly lightened nor darkened but by sun
tanning. However, luminance contrast effects for our natural
look compared to a face without makeup is only marginally
It is likely that cosmetics induce image changes other than
changes in luminance contrast contribute to our effects. These
include possible changes in the smoothness of skin tone, in the
redness of skin color or lip color, and in shading that accentu-
ates the cheekbones. Previous research has shown that makeup
can improve skin appearance, evenness and texture to appear
healthier, fertile, and youthful (Fink et al. 2006), and that skin
and lip color can contribute significantly to perception of sex
typicality and attractiveness (Stephen et al. 2009), with lip
redness enhancing femininity and attractiveness of female
Caucasian faces (Stephen et al. 2011). New Guinea indigenous, male
In sum, faces with cosmetics engage both fast, reflexive processes, and more deliberative conscious
processes. The fast, automatic effects are uniformly strong and positive for all outcomes.
In situations where a perceiver is under a high cognitive load or under time pressure, he or she is
more likely to rely on such automatic judgments for decision-making: facial images appear on bal-
lots, job applications, websites and dating sites.
These results underscore the malleability of judgments derived from facial images of a single indi-
vidual, judgments that can be highly consequential. When inferring trustworthiness, likeability, or
competence from an image we are influenced significantly not only by the attractiveness of the in-
herited phenotype but by the effects of the 'extended phenotype,' in this case, makeup.
Questions still remain unanswered: why in present human society females adorn themselves to a
largest extent than males? Have they become dominant or competition is getting tougher? Or...
Etcoff Nancy L., Stock Shannon, Haley Lauren E., Vickery Sarah A., House David M., 2011.
Cosmetics as a Feature of the Extended Human Phenotype: Modulation of the Perception of Biolog-
ically Important Facial Signals. Plos One, 1-8
Etcoff N. L., 1999. Survival of the prettiest: The science of beauty. New York: Doubleday.
Fink B., Grammer K., Matts P. J., 2006. Visible skin color distribution plays a role in the perception
of age, attractiveness, and health in female faces. Evol Hum Behav 27: 433442
Leeuwen Van E. J. C. et al., 2014. A group-specific arbitrary tradition in chimpanzees (Pan troglo-
dytes), Animal Cognition. DOI 10.1007/s10071-014-0766-8
Mobius M, Rosenblat T., 2006. Why beauty matters. American Economic Review 96(1): 222235.
Stephen I. D., Law Smith M. J., Stirrat M. R., Perrett D. I., 2009. Facial Skin Coloration Affects Perceived
Health of Human Faces. Int. J. Primatol. 30(6): 845857.
Stephen I. D., McKeegan A. M., 2010. Lip colour affects perceived sex typicality and attractiveness of
human faces. Perception 39: 11041110.
Webster M., Driskell J. E., 1983. Beauty as Status. American Journal of Sociology 89(1): 140165.
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Social learning in chimpanzees has been studied extensively and it is now widely accepted that chimpanzees have the capacity to learn from conspecifics through a multitude of mechanisms. Very few studies, however, have documented the existence of spontaneously emerged traditions in chimpanzee communities. While the rigour of experimental studies is helpful to investigate social learning mechanisms, documentation of naturally occurring traditions is necessary to understand the relevance of social learning in the real lives of animals. In this study, we report on chimpanzees spontaneously copying a seemingly non-adaptive behaviour ("grass-in-ear behaviour"). The behaviour entailed chimpanzees selecting a stiff, straw-like blade of grass, inserting the grass into one of their own ears, adjusting the position, and then leaving it in their ear during subsequent activities. Using a daily focal follow procedure, over the course of 1 year, we observed 8 (out of 12) group members engaging in this peculiar behaviour. Importantly, in the three neighbouring groups of chimpanzees (n = 82), this behaviour was only observed once, indicating that ecological factors were not determiners of the prevalence of this behaviour. These observations show that chimpanzees have a tendency to copy each other's behaviour, even when the adaptive value of the behaviour is presumably absent.
Full-text available
Physical attractiveness (beauty) affects both cognitions about individuals and their interaction patterns. Our proposed theoretical explanation for these phenomena links attractiveness effects to other cases of status generalization such as those produced by race or sex. Many effects of attractiveness can be explained by viewing it as a status characteristic and applying a theory of status charactersitics and expectation states proposed and elaborated by Joseph Berger and others. A test of the proposed explanation shows that (1) attractiveness produces predicted differences in both general and specific expectations; (2) attractiveness effects can be modified in combination with additional status characteristics; and (3) neither of the two above results is affected by sex of stimulus individuals or respondents, a differentiation of this explanation from one that relies on sexual or romatinc appeal.
Full-text available
Research on the perception of faces has focused on the size, shape, and configuration of inherited features or the biological phenotype, and largely ignored the effects of adornment, or the extended phenotype. Research on the evolution of signaling has shown that animals frequently alter visual features, including color cues, to attract, intimidate or protect themselves from conspecifics. Humans engage in conscious manipulation of visual signals using cultural tools in real time rather than genetic changes over evolutionary time. Here, we investigate one tool, the use of color cosmetics. In two studies, we asked viewers to rate the same female faces with or without color cosmetics, and we varied the style of makeup from minimal (natural), to moderate (professional), to dramatic (glamorous). Each look provided increasing luminance contrast between the facial features and surrounding skin. Faces were shown for 250 ms or for unlimited inspection time, and subjects rated them for attractiveness, competence, likeability and trustworthiness. At 250 ms, cosmetics had significant positive effects on all outcomes. Length of inspection time did not change the effect for competence or attractiveness. However, with longer inspection time, the effect of cosmetics on likability and trust varied by specific makeup looks, indicating that cosmetics could impact automatic and deliberative judgments differently. The results suggest that cosmetics can create supernormal facial stimuli, and that one way they may do so is by exaggerating cues to sexual dimorphism. Our results provide evidence that judgments of facial trustworthiness and attractiveness are at least partially separable, that beauty has a significant positive effect on judgment of competence, a universal dimension of social cognition, but has a more nuanced effect on the other universal dimension of social warmth, and that the extended phenotype significantly influences perception of biologically important signals at first glance and at longer inspection.
Full-text available
The luminance contrast between facial features and facial skin is greater in women than in men, and women's use of make-up enhances this contrast. In black-and-white photographs, increased luminance contrast enhances femininity and attractiveness in women's faces, but reduces masculinity and attractiveness in men's faces. In Caucasians, much of the contrast between the lips and facial skin is in redness. Red lips have been considered attractive in women in geographically and temporally diverse cultures, possibly because they mimic vasodilation associated with sexual arousal. Here, we investigate the effects of lip luminance and colour contrast on the attractiveness and sex typicality (masculinity/femininity) of human faces. In a Caucasian sample, we allowed participants to manipulate the colour of the lips in colour-calibrated face photographs along CIELab L* (light--dark), a* (red--green), and b* (yellow--blue) axes to enhance apparent attractiveness and sex typicality. Participants increased redness contrast to enhance femininity and attractiveness of female faces, but reduced redness contrast to enhance masculinity of men's faces. Lip blueness was reduced more in female than male faces. Increased lightness contrast enhanced the attractiveness of both sexes, and had little effect on perceptions of sex typicality. The association between lip colour contrast and attractiveness in women's faces may be attributable to its association with oxygenated blood perfusion indicating oestrogen levels, sexual arousal, and cardiac and respiratory health.
Full-text available
Numerous researchers have examined the effects of skin condition, including texture and color, on the perception of health, age, and attractiveness in human faces. They have focused on facial color distribution, homogeneity of pigmentation, or skin quality. We here investigate the role of overall skin color in determining perceptions of health from faces by allowing participants to manipulate the skin portions of color-calibrated Caucasian face photographs along CIELab color axes. To enhance healthy appearance, participants increased skin redness (a*), providing additional support for previous findings that skin blood color enhances the healthy appearance of faces. Participants also increased skin yellowness (b*) and lightness (L*), suggesting a role for high carotenoid and low melanin coloration in the healthy appearance of faces. The color preferences described here resemble the red and yellow color cues to health displayed by many species of nonhuman animals.
Full-text available
We decompose the beauty premium in an experimental labor market where "employers" determine wages of "workers" who perform a maze-solving task. This task requires a true skill which we show to be unaffected by physical attractiveness. We find a sizable beauty premium and can identify three transmission channels: (a) physically attractive workers are more confident and higher confidence increases wages; (b) for a given level of confidence, physically attractive workers are (wrongly) considered more able by employers; (c) controlling for worker confidence, physically attractive workers have oral skills (such as communication and social skills) that raise their wages when they interact with employers. Our methodology can be adopted to study the sources of discriminatory pay differentials in other settings.
Evolutionary psychologists have proposed that preferences for facial characteristics, such as symmetry, averageness, and sexual dimorphism, may reflect adaptations for mate choice because they signal aspects of mate quality. Here, we show that facial skin color distribution significantly influences the perception of age and attractiveness of female faces, independent of facial form and skin surface topography. A set of three-dimensional shape-standardized stimulus faces-varying only in terms of skin color distribution due to variation in biological age and cumulative photodamage-was rated by a panel of naive judges for a variety of perceptual endpoints relating to age, health, and beauty. Shape- and topography-standardized stimulus faces with the homogeneous skin color distribution of young people were perceived as younger and received significantly higher ratings for attractiveness and health than analogous stimuli with the relatively inhomogeneous skin color distribution of more elderly people. Thus, skin color distribution, independent of facial form and skin surface topography, seems to have a major influence on the perception of female facial age and judgments of attractiveness and health as they may signal aspects of underlying physiological condition of an individual relevant for mate choice. We suggest that studies on human physical attractiveness and its perception need to consider the influence of visible skin condition driven by color distribution and differentiate between such effects and beauty-related traits due to facial shape and skin topography.
Survival of the prettiest: The science of beauty Visible skin color distribution plays a role in the perception of age, attractiveness, and health in female faces A group-specific arbitrary tradition in chimpanzees (Pan troglo-dytes), Animal Cognition
  • N L Etcoff
  • Doubleday
  • B Fink
  • K Grammer
Etcoff N. L., 1999. Survival of the prettiest: The science of beauty. New York: Doubleday. Fink B., Grammer K., Matts P. J., 2006. Visible skin color distribution plays a role in the perception of age, attractiveness, and health in female faces. Evol Hum Behav 27: 433–442 Leeuwen Van E. J. C. et al., 2014. A group-specific arbitrary tradition in chimpanzees (Pan troglo-dytes), Animal Cognition. DOI 10.1007/s10071-014-0766-8
Survival of the prettiest: The science of beauty
  • N L Etcoff
Etcoff N. L., 1999. Survival of the prettiest: The science of beauty. New York: Doubleday.