Tuesday, July 2, 2013

The Boob-Resource Hypothesis: Why Is Bigger Better?


It has been quite a while since I've made an entry in to the "Groundbreaking science - men like boobs" category.  In the past, I've made the following statement on this topic: "Men like big breasts, therefore women evolve larger breasts. It's an evolutionarily solid argument, assuming of course that male preference exerts any pressure on the evolution of female secondary sexual characteristics." Indeed, evidence is mounting that humans have a great propensity to rely on their perceptions of attractiveness to make mate choices. Body size, leg length, hair color and length, skin tone, and various facial features have all been studied as important attractiveness traits. But now the big question: what about boobs? If you talk to men, any men really, then you'll find that they like to look at breasts, any breasts really. But you will also probably discover that all breasts are not equal in the eyes of men. The range of breast sizes that men prefer can range dramatically. Why is this?

If we go back to my "evolutionarily solid argument" then perhaps, my "men like big breasts" statement may include an untested assumption that larger-is-better. Hmmm...well, let's think about this. Men find boobs attractive because evolution finds them attractive, boobs providing (unconscious) information on health,  nulliparity, age, sexual maturity, and/or fertility. Okay, I'll buy that. But we aren't exactly hunter-gatherers anymore. Evolutionary pressures are likely different in post-industrial societies, right? The conclusion of most of the studies on this question circles back to our original category of "groundbreaking science - men like boobs."

A newish study, published in PLoS ONE, looks at this question again. The authors take the time to point out some problems with the other studies in this area. Not that they are wrong but namely the inconsistencies in the presentation of the boobs. For example, when men are presented with computer-generated boobs (usually from one angle only) then they are found to like medium to large sizes. The authors also point out that previous studies haven't fully accounted for within- and cross-cultural differences. For example, commitment-phobic, sexist males like bigger boobs. But also, that men living in resource (food, money, etc.) limited regions also prefer larger breasts. Is this an all-men-like-big-boobs issue or is this a evolutionary, bigger-boobs-mean-access-to-more-resources issue? To get at this, the authors broke their big study down into two parts.

Study 1: Does your socioeconomic status affect your preference for breast size?

The authors went to the state of Sabah, Malaysia, on the island of Borneo. This state is one of the least developed, lowest average income area in the country. However, it is also a highly uneven area, with large disparities in socioeconomic status. The researchers recruited participants from Kota Kinabalu (high economic status), the township of Ranau (medium), and three villages in the West Coast Administrative Division of Sabah (low). These participants were asked to self-assess their BMI and socioeconomic status compared to other Malaysians (less secure, same, more secure). To evaluate attractiveness perceptions based on breast size, the researchers created rotatable 3D animations of female figures that had characteristics closely matched to the ethic group studied. They set the breast size of the figure at five cup-size levels. The participants were then asked to view a figure and rate it on a survey.



The researchers found medium breast size to be most attractive in Kota Kinabalu and Ranau but that Ranau like bigger ones than Kota Kinabalu. In the rural villages, large breasts were found to be more attractive than they were in the other two areas. When the results were examined a correlation was found that indicated that lower financial security was associated with a preference for larger breast size. These results add evidence towards what I'll call "the boob-resource hypothesis."

Study 2: Do hungry men like larger breasts?

Study 1 has an important limitation: inter-regional differences. If you combine the results of rich sexist men with poor patriarchal men then you possibly end up with a natural confound that limits your conclusions. One way to fix this is to limit your participants to the same environment and then focus on a particular dimension. In this case, the researchers chose a proxy for resource security: hunger. This choice is based on previous work that has indicated that hungry men rate heavier female body size as attractive. It is hypothesized that that this "insecure or threatening" state causes men to idealize more mature physical characteristics that signal the ability to handle a threatening environment. Okay, I can go with that I guess. The idea is that the hungrier the man the bigger his attraction to large breasts. So the researchers recruited British white men (as ethnicity matters in this kind of study) from the University of Westminster as they entered and exited a dining hall during dinner. These participants were asked for their demographic information and then asked to report their hunger on a 7-point scale. The researchers then asked only those men that reported the two hungriest and two most satiated responses to continue. Then the participants were asked to rate a set of 3D animations of female figures (like in Malaysia just changed to British characteristics). The researchers found that hungry men rated larger breasts as more attractive. These results support the other body size work as well as these researchers' Study 1 results. It appears that we can add even more support to the boob-resource hypothesis.

Okay, so what does all of this mean? Let's consider that the human female is the only primate that has permanent, full-form breasts when not pregnant. Breasts consist mostly of adipose tissue (a.k.a. fat), and fat is energy. If breast size is a reliable indicator for calorie reserves then resource-limited males should like larger breasts. The authors found support for this for both long-term (socioeconomic) and temporary (hunger) situations. However, look at other parts of a woman's body and you'll notice that the breasts are not the only areas that store fat, and that breast size is correlated with body mass. So more study needs to be done on the relative importance of breast size and body size, respectively, as indicators.

Read the full study (for free!) here:

ResearchBlogging.orgSwami, Viren, & TovĂ©e, Martin J. (2013). Resource Security Impacts Men’s Female Breast Size Preferences PLoS ONE, 8 (3) DOI: 10.1371/journal.pone.0057623




(image via Wikimedia Commons)
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