Men Pick Up Cues To Ovulation In Woman’s Faces
Apparently women’s ovulation isn’t as concealed as scientists once though. According to Swedish researchers Cora Bobst and Janek Lobmaier, University of Bern, Muesmattstrasse, Switzerland, men pick up on subtle changes in a woman’s face around the time of ovulation.
Prior research has found that men prefer the scent of women around ovulation over women not currently in their most fertile condition. This was assessed by men who judged the overall sex appeal of the scent left by women on worn t-shirts. Similarly, women are judged to have sexier voices around ovulation. The body shape of women has also been found to change during ovulation by becoming more symmetrical and that the ratio between the hips and the waist becomes more pronounced and sexier. Women’s faces have also been shown to be lighter in colouration surrounding fertility in their cycle.
Higher levels of estrogen also seems to be linked to overall attractiveness in female faces, suggesting that it may trigger the changes.
The Current Study
In the current study, the researchers aimed to discover the exact physical changes in the face which makes them more appealing and sexy to men. Thus far, no direct measurement, besides overall attractiveness and preference for the faces had been documented.
The first part of the experiment involved the production of images. Twenty-five original images from different women were obtained. They were photographed during the late follicular phase (ovulation) and again during their luteal phase (non-ovulating). Importantly, none of the women reported using hormonal contraceptives, as previous studies have shown that the changes surrounding ovulation are not apparent in this group.
The 25 faces were then merged to produce two average faces representing the follicular phase (ovulation) and the luteal phase (non-ovulation). This was done with the help of computer software.
“Averaging a group of faces into one image reveals consistent characteristics of this group while characteristics that are not shared are averaged out,” say the researchers.
The fertile and non-fertile faces were used as end points across a spectrum of fertility – high and low. From there, faces were transformed in two steps, by 50% and 100%, toward the fertile and non-fertile faces.
Using landmarks as measured on the non-fertile and fertile faces, it was possible to modify 20 images from the original set of women to produce an image representing a fertile and non-fertile image for the same woman. This was done so that comparisons could be made of one woman against herself in high and low fertility.
The researchers note that despite the changes in the face, the overall differences were minute (see image).
The subjects, 36 men, then rated the images on their attractiveness, flirtatious, which was more caring, and which they figured they were more likely to get a date.
Men consistently chose the more fertile face with respect to all categories. Men also responded faster when choosing the ovulating face and reported higher level of confidence in their selection.
The researchers note that the findings do not reveal the exact cause of the shape differences. However, they guess that estrogen likely plays a significant role in creating a softer jaw and suppressed eyebrow growth. However, the direct effects of estrogen on the female faces was unlikely in this case, say the researchers, as estradiol remained constant while both photographs were taken. However, progesterone levels were significantly lower during the more fertile phase suggesting that it is the key hormone in affecting the changes in the face. Another possible route is with a surge of luteinizing hormone, although, this was not measured in the study.
During ovulation, women, it seems, ramp up their efforts in soliciting male attention by subtle changes in their faces, and, as outlined earlier, changes in their odor, symmetry, hip-to-waist ratio, and voice. Not mentioned in this current article, but women also change their behaviour to be more flirty during ovulation which is showcased through nonverbal channels.
We must always remember that not only are men competing to attract the most desirable women, but women are also competing against other women to attract the most desirable men. One of the ways they do this, as shown by this study, is through an accumulation of subtle changes. Overall, the changes signal fertility, health, and also sexual receptivity.
Interestingly, the results show that men prefer the faces of women in their fertile phase over those in the non-fertile phase, and that they can readily discern the difference.
From an evolutionary stand-point, the findings are interesting in that male preferences in female faces is likely driven by their subtle but detectible changes as women near peek fertility. As they are modulated by small fluctuations of hormones, overall, the physical changes end up being quite subtle. However, many subtle changes operating simultaneously can add up to a more pronounced signal – especially if one is particularly tuned into a specific woman – as is the case during monogamous relationships.
Taken one step removed, it is interesting to note that women, who have features of the “ovulating face,” with a rounder jaw line, rather than a square or masculine jawline, at all times (their basic morphology) will appeal more sexually attractive even while not ovulating. The same goes for other feminine features including feminine voice, odor, symmetry and socially warm nonverbal behaviour.
It is perhaps the effects of the hormones on the face that has driven evolution to favour women who have “cheated” their faces to be rounded and softer so as to appeal to men year round. Often, this is exactly how the effects of sexual selection operate. Overall, it is those women who naturally have features that mimic ovulation, even while not ovulating, that have an easier time attracting and maintaining the attention of men, particularly men of higher value. This then favours the persistence of the particular face’s qualities in future generations.
Image Credit: Varvara
Bobst, Cora and Janek S. Lobmaier. Men’s preference for the ovulating female is triggered by subtle face shape differences Hormones and Behavior 62 (2012) 413–417.
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