Steve has an interesting post on assortative mating in which he purports, in passing, that blondes have greater sex appeal, citing Peter Frost's hypothesis that blonde hair was sexually selected in Northern Europeans (I'll post on the assortative theme later). A danger in discussing which traits might be sexually selected is that the ponderer will likely go with what they personally find sexy and ask why such things might be sexually selected, rather than work from an independent angle. For example, I am very picky about the upper eyelids -- if they have that half-moon shape, that really does it for me. I've heard Michael say once that he likes this feature too -- but then, we're probably weirdos, or at least that's the conclusion until someone can show that a large fraction of guys prefer this feature, and that there's good reason to think it was sexually selected. Unlike half-moon eyes, blonde hair color receives lots of attention as a potentially sexually selected trait, but is a key prediction met -- are blondes sexier?

Below the fold, I briefly review some theory but mostly present data from all winners in three beauty contests, which indicate no overrepresentation of blondes. I conclude that hair color is of weak importance at best in accounting for sexiness, that the role of sexual selection in accounting for hair color variation is also weak at best, and that the perception that men are more likely to find blondes sexy is due to a passing fad for blondes during the decade from the mid-1970s to the mid-1980s.

First, Steve notes:

One of the most common storylines in movies is this: the blonde debutante gets engaged to the blonde fraternity president, but then she falls hard for the tall, dark, and handsome boy from the wrong side of the tracks.

The idea again is that blonde hair is sexy in females, not males. But just as common as the above scenario is the guy whose feelings for his fair-haired maiden waver once he becomes enchanted by a woman with coal eyes and raven tresses. For instance, in The Hunchback of Notre Dame (see here starting at line 57), the once pure priest Frollo describes how, after watching the gypsy Esmeralda dance and sing, he became so bewitched that he could not stem the tide of lust rising within him and fell madly in love with her. Shakespeare's "Sonnet 147" expresses a similar predicament: the speaker's got it bad for a bad girl! Not the first, nor the last. Interesting though literature and film may be, let's get to the theory and data.

Starting with the predictions from theory, the hypothesis that icy climes select for greater sex appeal is probably wrong. Gangestad & Buss (1993) showed that people in more pathogen-wracked areas emphasize "good looks" more strongly, and these are generally not icy areas. Think about the rest of the animal kingdom: where are the sexy, showy specimens with the most ornate song patterns? Same answer: mostly pathogen-infested areas, the tropics, etc. Consider the quintessential animal with exaggerated sexually selected traits -- the peacock -- whose rarer variant is native to Southeast Asia, and whose more common variant is native to the world's germ-cauldron (South Asia). Hamilton & Zuk's (1982) explanation was that these traits signaled better health to mates, no small feat in such areas. So, the prediction is that sexual selection will be very weak in Northern Europe (defined as the non-Mediterranean countries), where blondeness reaches substantial frequencies.

But even if sexual selection were a strong pressure there, what independently motivated evidence is there that blondeness is sexy, so that males who are sexually selecting would choose it over brunette hair? Again, the only good guess people have made is that sexually selected traits signal lack of being parasitized. For hair, though, this has mostly to do with the texture, lustruousness, and so on, not color -- although I'm willing to be corrected if someone knows of studies showing that blonde hair is more likely than dark hair to thwart the entry of pathogens into the scalp area. In any event, the main problem remains: in general, pathogen pressure is relatively very low in areas where blondeness is prevalent.

Turning now to the data, I recently posted about the list of who Maxim magazine ranked the hottest women for 2006, and there was no evidence of overrepresentation of blondes. The same is true for the other "lad mags" that you see in drug stores. Now I look at two other datasets that are probably more informative than who Maxim thought was hot in 2006: the winners of the Miss Universe and Miss USA beauty pageants. (The Miss America competition is not primarily a beauty pageant, as looks account for just 35% of the score). Such lists are preferable for testing the "sexy blonde" hypothesis since the individuals represent a very elite level of eminence. I looked up galleries of the winners, and if a girl's hair color wasn't clear from that, I did a Google image search for her. I judged overrepresentation based on the frequency of light hair according to Peter Frost's map at the Wikipedia entry for hair color.

For Miss Universe (gallery), there are 56 data points: 12 (21.4%) have light hair, 43 (76.8%) have dark hair, and 1 (1.8%) is pretty in-between. Now, 21.4% is surely a greater fraction of blondes than there are worldwide, but remember that Miss Universe doesn't represent the entire world -- it's mostly Europe and its offshoots, plus the white and mestizo populations of Latin America, and a tiny handful of East Asian countries (not China). For the non-Mediterranean areas of Europe, 21.4% is on the low-end of normal, but on the high end of normal for the Mediterranean (and so, for the mostly Mediterranean-looking Latin Americans who compete). I interpret this as supporting the null hypothesis of no effect of hair color on sexiness.

As for Miss USA (gallery), there are 60 data points: 17 (28.3%) have light hair, 38 (63.3%) have dark hair, and 5 (8.4%) have borderline hair. Although the fraction is larger here, remember the US is much blonder than the Mediterranean and Latin American countries who are also big contenders in the Miss Universe competition. Because the vast majority of the US population has been Northern European since the pageant began in 1952, we should determine overrepresentation based on the Northern European areas of Peter Frost's map. Doing so, we see that 28.3% is easily at expectation, and if anything is a bit on the low-end of normal for a predominantly Northern European population. Again, this result supports the null hypothesis.

In sum, we note that when put to a stringent test, blondes appear no sexier or uglier when compared to brunettes. Datasets such as Miss Universe and Miss USA are particularly instructive since the bar is set rather high. Then whence the perception that men find blondes sexier? There is an interesting temporal wrinkle in the data -- blonde winners are not evenly distributed in either dataset. For Miss Universe, from 1952 - 1974, 17.4% of the 23 winners are blonde; from 1975 - 1984, 60% of the 10 winners are blonde; and from 1985 - Present, either 8.7% or 13.0% of the 23 winners are blonde (depending on whether you are generous and code the 1 borderline girl as blonde). There thus appears to be a general lack of interest in blondes (and if anything, a dispreference for them), punctuated by a decade where blondes were very fashionable. Does the same pattern show up in the Miss USA dataset? Pretty much. From 1952 - 1973, 25% of the 24 winners were blonde; from 1974 - 1986, 50% of the 14 winners were blonde; and from 1986 - Present, 18.2% of the 22 winners were blonde. We note again the spike in blonde fashionableness from the mid-1970s to the mid-1980s.

I suggest that those who came of age during this Blonde Decade -- those who were born between roughly 1955 and 1970 -- may have unwittingly projected their perception of the sexiness of blondes onto time periods for which the view is not true. Combine this with the theoretical problems noted earlier, and it seems likely that sexual selection's role in increasing the frequency of blondeness is weak at best. That still doesn't answer the question of why blondeness evolved -- though I'll leave that for another post (or someone else can take it up). The explanation that I (and others) find most convincing for now is based on Jerome Kagan's work, starting in the mid-1980s, which has showed that light irises correlate with behavioral inhibition, suggesting that in Northern Europeans there was selection for different values of certain personality traits, which happened to also affect their eye & hair color.

Appendix: Hair color data for Miss Universe and Miss USA winners

Miss Universe (L = light, D = dark, M = borderline)

L 1952-Armi Helena Kuusela Kovo-Finland
D 1953-Christiane Magnani (Martel)-France
D 1954-Miriam Jacqueline Stevenson-USA
L 1955-Hillevi Rombin-Sweden
D 1956-Carol Laverne Morris-USA
D 1957-Gladys Zender Urbina-Peru
D 1958-Luz Marina Zuluaga-Colombia
D 1959-Akiko Kojima-Japan
D 1960-Linda Jeanne Bement-USA
L 1961-Marlene Schmidt-Germany
D 1962-Norma Beatriz Nolan-Argentina
D 1963-Ieda Maria Britto Vargas-Brazil
D 1964-Kiriaki “Corinna” Tsopei-Greece
D 1965-Apasra Hongsakula-Thailand
L 1966-Margareta Arb Arvidsson-Sweden
D 1967-Sylvia Louise Hitchcock-USA
D 1968-Martha Maria Cordeiro Vasconcellos-Brazil
D 1969-Gloria Maria Diaz Aspillera-Philippines
D 1970-Marisol Malaret Contreras-Puerto Rico
D 1971-Georgina Rizk-Lebanon
D 1972-Kerry Anne Wells-Australia
D 1973-Maria Margareta Moran Roxas-Philippines
D 1974-Amparo Muñoz Quesada-Spain
L 1975-Anne Marie Pohtamo-Finland
D 1976-Rina Messinger-Israel
D 1977-Janelle “Penny” Commissiong-Trinidad/Tobago
L 1978-Margaret Gardiner-South Africa
D 1979-Maritza Sayalero Fernández-Venezuela
L 1980-Shawn Nichols Weatherly-USA
L 1981-Irene Lailin Sáez Conde-Venezuela
D 1982-Karen Dianne Baldwin-Canada
L 1983-Lorraine Elizabeth Downes-New Zealand
L 1984-Yvonne Ryding-Sweden
D 1985-Deborah Carthy-Deu-Puerto Rico
D 1986-Bárbara Palacios Teyde-Venezuela
D 1987-Cecilia Carolina Bolocco Fonck-Chile
D 1988-Porntip Nakhirunkanok-Thailand
L 1989-Angela Visser-Holland
D 1990-Mona Grudt-Norway
D 1991-María Guadalupe “Lupita” Jones Garay-Mexico
D 1992-Michelle McLean-Namibia
D 1993-Dayanara Torres Delgado-Puerto Rico
D 1994-Sushmita Sen-India
D 1995-Chelsi Pearl Smith-USA
M 1996-Yoseph Alicia Machado Fajardo-Venezuela
D 1997-Brook Antoinette Mahealani Lee-USA
D 1998-Wendy Rachelle Fitzwilliam-Trinidad/Tobago
D 1999-Mpule Keneilwe Kwelagobe-Botswana
D 2000-Lara Dutta-India
D 2001-Denise Marie Quiñones August-Puerto Rico
D 2002-Oksana Fyodorova (Oxana Fedorova)-Russia (dethroned)
D ---Justine Lissette Pasek Patiño-Panama
D 2003: Amelia Vega Polanco-Dominican Republic
L 2004: Jennifer Hawkins-Australia
D 2005: Natalie Glebova-Canada
D 2006: Zuleyka Jerris Rivera Mendoza-Puerto Rico

Miss USA

D Jackie Loughery 1952
D Myrna Hansen 1953
D Miriam Stevenson 1954
L Carlene King Johnson 1955
D Carol Morris 1956
D Leona Cage 1957
L Charlotte Sheffield 1957
M Eurlyne Howell 1958
D Terry Lynn Huntingdon 1959
D Linda Bement 1960
D Sharon Brown 1961
D Macel Wilson 1962
L Marite Ozers 1963
L Bobbie Johnson 1964
L Sue Downey 1965
D Maria Remenyi 1966
D Sylvia Hitchcock 1967
D Cheryl Ann Patton 1967
D Dorothy Anstett 1968
L Wendy Dascomb 1969
D Debbie Shelton 1970
D Michele McDonald 1971
M Tanya Wilson 1972
D Amanda Jones 1973
L Karen Morrison 1974
D Summer Bartholomew 1975
D Barbara Peterson 1976
L Kimberly Tomes 1977
L Judi Andersen 1978
M Mary Therese Friel 1979
L Shawn Weatherly 1980
L Jineane Ford 1980
L Kim Seelbrede 1981
D Terri Utley 1982
D Julie Hayek 1983
D Mai Shanley 1984
D Laura Martinez-Herring 1985
L Christy Fichtner 1986
D Michelle Royer 1987
D Courtney Gibbs 1988
D Gretchen Polhemus 1989
D Carole Gist 1990
M Kelli McCarty 1991
L Shannon Marketic 1992
D Kenya Moore 1993
D Lu Parker 1994
D Chelsi Smith 1995
D Shanna Lynn Moakler 1995
D Ali Landry 1996
D Brook Lee 1997
D Brandi Sherwood 1997
M Shawnae Jebbia 1998
D Kimberly Ann Pressler 1999
D Lynnette Cole 2000
L Kandace Krueger 2001
D Shauntay Hinton 2002
D Susie Castillo 2003
L Shandi Finnessey 2004
D Chelsea Cooley 2005
L Tara Elizabeth Conner 2006

Labels: babes and hunks, Pigmentation