Developmental and Evolutionary Aspects of Female Attraction to Babies
By Dario Maestripieri, PhD
Do People Think Baby Faces are Cute?
Austrian ethologist Konrad Lorenz (1971) argued that humans have a natural propensity to be attracted to the features of baby faces and that this innate perceptual bias evolved to enhance interest in infants and motivation to engage in caregiving behavior. To illustrate his point, he drew silhouettes of human and animal babies and adults and emphasized that the baby faces shared distinctive features including a round shape, protruding forehead, large eyes, and round protruding cheeks. The toy and the film industry have, over the years, produced dolls, stuffed animals, and cartoon characters that increasingly resemble human babies (e.g. Hinde & Barden, 1985). The marketing analyses and commercial success of these industries seem to have proved that Lorenz was right. But is it really true that most people find baby faces attractive?
In a recent study, a graduate student and I investigated preferences for baby faces across four age groups: children (6-10 years), adolescent (11-15), young adults (19-35) and middle-aged/elderly (46-75) (Maestripieri & Pelka, 2002). All study participants (n= 112) were heterosexual European Americans from middle-class backgrounds in Chicago and Los Angeles. Participants were shown 20 pairs of images and asked to identify which image of the pair they preferred. The images included: 5 silhouettes (face profiles) of adult animals (rabbit, cat, dog, elephant, and bear) matched with their infant counterparts; 5 silhouettes of adult human faces (3 male, 2 female) matched with human infant faces; 5 color photographs of adult animal faces (male lion, male orangutan, female orangutan, female gorilla, male chimpanzee) matched with their infant counterparts, and 5 color photographs of adult human faces (3 male, 2 female) matched with human infant faces. All of the photographs were rated for equivalence of attractiveness to their matched counterparts.
All individuals, regardless of sex and age, preferred the photos of baby faces to the photos of adult faces. However, no preference for babies emerged for the silhouettes, despite the fact that these silhouettes were nearly identical to those used by Lorenz to illustrate his perceptual bias hypothesis. If one argues that responses to the silhouettes provide the most valid test of Lorenz's hypothesis because, unlike the photos, they provide no clues of individual identity and are less likely than photos to trigger beliefs and emotions associated with one's views of infants or adults, then the conclusion must be that our findings do not support Lorenz's hypothesis. People, in general, seem to like photos of babies better than photos of adults but for reasons other than an innate perceptual bias toward infantile facial features.
Do Human Females Find Baby Faces Attractive More than Males?
A modified version of Lorenz's hypothesis is that a perceptual bias toward finding baby faces attractive does exist but is only present, or is more pronounced, in females than in males, because women have been the primary infant caregivers for much of our evolutionary history. Consistent with this hypothesis, some previous studies have shown that women are more attracted to pictures of baby faces than men, but this difference is apparent in some age groups but not others (e.g., Berman, 1980; Feldman, Nash, & Cutrona, 1977; Fullard & Reiling, 1976).
In our study, females across all 4 age groups showed a greater preference for silhouettes and photos of animal and human babies than males. The sex difference was greatest for the silhouettes of humans and minimal for the photos of animals. Female attraction to baby face silhouettes was highest among children and adolescents, and lower for the older age groups. In contrast, male interest in infants remained stable across the four age groups. Thus, there may be a perceptual bias toward finding infantile facial features attractive but this bias is more likely to be found or expressed in human females than in males. Why are young girls so attracted to baby faces?
The Function of Early Female Attraction to Babies
Early sex differences in attraction to baby faces, or to babies in general, could be the product of socialization (e.g. in many cultures, parents and society encourage girls to play with dolls or to take care of younger siblings; Edwards 1993) or biological variables such as prenatal exposure to hormones (Herman, Measday, & Wallen, 2003; Leveroni & Berenbaum, 1998), or a combination of both. Regardless of its causes, the function of early female attraction to infants is probably to facilitate the acquisition of parenting skills through observation and hands-on experience. In this view, female interest in infants should emerge early in development and remain elevated until the first reproductive event, to ensure that females will have enough parenting experience and motivation to successfully raise their first child. After the first child, continued interest in all infants (as opposed to one's own infant) will no longer be crucial for offspring survival. If this hypothesis is correct, one may expect that a change in female interest in infants should occur at puberty, when girls become sexually mature and potentially fertile.
Do Puberty and Early Environment Affect Female Preferences for Baby Faces?
A previous study reported that 12-year-old girls who had reached menarche were more attracted to pictures of infant faces than same-aged girls who had not reached menarche (Goldberg, Blumberg & Kriger, 1982). The authors of this study suggested that possible neuroendocrine changes associated with the onset of menstruation may increase selective attention and responsiveness to infantile features, and that such attentional changes would function to increase opportunities to observe and respond to infants in the years between menarche and actual childbearing. An alternative explanation, however, is that girls with early menarche had greater interest in infants than girls with late menarche even before the onset of menarche. If this interpretation is correct, then the finding to be explained would not be why post-menarcheal girls have higher interest in infants than pre-menarcheal girls, but why girls who reach puberty early are more interested in infants than girls who reach puberty late.
Timing of menarche is known to be affected by genetic and nutritional factors (e.g. Brooks-Gunn, 1988). A number of recent studies have also shown that early menarche is associated with father absence from home and/or early family conflict and stress (e.g., Ellis & Garber, 2000; Kim & Smith, 1998; Wierson, Long, & Forehand, 1993). These findings are consistent with the hypothesis that, under some circumstances, early menarche may be part of a reproductive strategy that emphasizes precocious reproduction in stressful environments or in situations in which male commitment to relationships or male parental investment is not expected (Belsky, Steinberg, & Draper, 1991; Chisholm, 1999; Draper & Harpending, 1982). Since early interest in infants may be functionally related to the success of early reproductive attempts, girls who reach menarche early should exhibit earlier and more intense interest in infants than girls who reach menarche late.
My graduate students and I tested this hypothesis in a sample of adolescent girls (n= 83; 61 European American, 19 African American, 1 Hispanic, and 2 of mixed-race descent) recruited in Chicago and Boston (Maestripieri et al. under review). The girls' ages ranged from 11 to 14 years. Girls exhibited a clear preference for images of infants vs adults irrespective of menarche. Consistent with our hypothesis, we found that girls with early menarche had a significantly higher preference for human baby faces, and in particular for their silhouettes, than girls with late menarche. Once the possible effects of age, race and previous experience with infants were controlled for, however, the association between timing of menarche and interest in infants became weak. Moreover, it turned out that this association was mostly driven by another variable, father absence, which was strongly and independently correlated with both timing of menarche and with preferences for infant stimuli. In fact, father absence was associated with an overall greater preference for baby faces across the 4 sets of pictures and independent of age and previous experience with infants.
Our findings suggest that father-absent girls reach menarche earlier and exhibit greater attraction to baby faces than father-present girls of the same age, which may suggest greater readiness for parenting or a greater tendency to find opportunities to acquire parenting experience. In other words, by being more attracted to infant stimuli, rapidly maturing girls may acquire crucial parenting skills earlier in life and be better equipped for early reproduction and child-rearing. The mechanisms by which father-absence may lead to the expression of this life strategy need to be further addressed by future research (but see Comings, Muhleman, Johnson, & MacMurray, 2002). Future studies should also further investigate the role of biological and environmental variables in the development of female interest in infants during childhood and adolescence and the relation between this variable and later parenting.
This work was supported by a grant from the Center for Early Childhood Research (McCormick/Tribune Foundation) and by NIH grants R01-MH62577 and K02-MH63097. I thank Nicole DeBias, Kristina Durante, Suzanne Pelka, Jim Roney, and Geertrui Spaepen for their helpful contributions to this research.
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About the Author
Dario Maestripieri earned his PhD in Psychobiology from the University of Rome "La Sapienza" in 1992. He is currently an Associate Professor of Human Development, Psychology and Evolutionary Biology at the University of Chicago and an Affiliate Scientist at the Yerkes National Primate Research Center of Emory University. His research interests focus on the biology of behavior from a comparative perspective. One line of research examines neuroendocrine, ecological and evolutionary aspects of social behavior in nonhuman primates. Another line of research examines evolutionary aspects of human mating and parenting. Professor Maestripieri has published over 100 scientific articles and book chapters and recently edited the book Primate Psychology. He was awarded the 2000 APA Distinguished Scientific Award for Early Career Contribution to Psychology in the area of Animal Learning and Behavior/Comparative Psychology and is currently the recipient of a Career Development Award from the National Institute of Mental Health.