The selection and attraction of a suitable mate is of fundamental importance to all species. It is perhaps not surprising then that dating TV shows, featuring men and women competing for the attentions of a potential partner, are so popular. Indeed, viewers have tuned in to series such as Blind Date, Take Me Out, and The Bachelor for decades.
But this year, Channel 4 in the UK took the format a “bold” step further, launching a new dating program, Naked Attraction, which features men and women selecting from a range of potential suitors, each of whom appear on the program entirely naked. First, the lower body is revealed, next the torso, then the face, and finally the voice. At each stage, the contestant discusses the traits they are attending to and their attractiveness, before eliminating one of the available suitors.
A range of physical features are discussed, including body shape, genital size, body hair, hair style, teeth quality, and the presence of tattoos. Though this form of dating is not (I presume) one with which most of us are familiar, the importance placed on appearance, and the information we obtain from appearance (whether consciously or unconsciously), is something to which we can all relate. Indeed, these characteristics can provide important information that allows us to select only healthy partners.
Here’s some of the science behind how we pick a potential mate.
Body shape
Body shape is one of the most widely-discussed aspects of physical attractiveness. Our perceptions of the ideal body shape are often manipulated by the media, advertising, or the fashion industry. But certain physical traits can reveal deeper physiological truths.
Prior to puberty, for example, girls and boys display a similar waist-to-hip ratio. But at puberty, estrogen and testosterone stimulate in women the accumulation of fat in sex-specific areas. Therefore, women typically display a waist-to-hip ratio of about 0.67:0.80—although these ratios increase further after childbirth and menopause.
Waist-to-hip ratio is also associated with a range of health conditions in women, such as cardiovascular disease and breast cancer, and can also be an indicator of the likelihood of conception. Hence women with higher waist-to-hip ratios display poorer health and are less likely to conceive. Consequently, waist-to-hip ratio provides important information about a woman’s age and reproductive status.
It is important to note, of course, that levels of body fat also influence ratings of physical attractiveness and perceived health, though waist-to-hip ratio and body mass index may signal different information. In particular, body mass index may reveal the ability to endure energy-intensive pregnancy and breast feeding while waist-to-hip ratio indicates youth and fertility.
With regard to male body shape, research often focuses on the importance of height. Indeed, although the preference for a “tall, dark, handsome stranger” is a cliché, there is a biological basis for this preference, with only healthy men being able to invest the physical resources required to develop tall stature. Hence, height is associated with positive physical and mental health.
It is also related to important social outcomes, such as social status, educational success, and income, which may reflect perceptions that tall men are more assertive and dominant than shorter men. Consequently, research suggests that tall men are more desirable to women and are themselves able to attract more attractive partners.
Teeth
When assessing the physical attractiveness of potential partners, people often comment on the color or shape of teeth. The color and shape of our teeth is not, of course, arbitrary; they can reveal important information about our health and genetic quality. For example, tooth loss is associated with poor general health, nutritional deficits, and conditions such as cardiovascular disease and stroke.
Teeth spacing may also indicate the presence of specific genetic disorders, such as Rapp-Hodgkin Syndrome and Robinow’s Syndrome, while tooth color is influenced by a range of factors including diet and age, leading to teeth appearing darker and yellower as we get older.
As a consequence, people place considerable importance on the appearance of their teeth; in the US alone, about $1 billion per year is spent on purely cosmetic dental procedures. A 2012 study investigated the manner in which teeth color and spacing influence ratings of physical attractiveness. It concluded that deviations from normal spacing and/or darker, yellower teeth are perceived as unattractive, particularly when judging women.
Body modification
People also often seek to alter and enhance their appearance through the use of cosmetics, hair dye, and jewelry. More permanent modification through the use of tattoos is also common, though these are associated with a range of health risks. These include allergic reactions to tattoo colors, bacterial infections, and the transmission of blood-borne diseases, such as HIV.
The ability to obtain and maintain a tattoo without an adverse reaction may be dependent on physical fitness and immunocompetence, so the presence of a tattoo (that has not resulted in the aforementioned difficulties) can act as a signal of physical quality. Men may be most likely to display tattoos as a cue to physical health; tattoos are most common among men aged 25 to 34, and men are more likely than women to acquire multiple tattoos that cannot be concealed by clothing. Hence, women rate men with tattoos as healthier than those without.
Of course, while we attend to a range of physical traits when evaluating potential partners, it is important to note that the importance we place on any single trait varies across time and context. When assessing partners for short-term casual versus long-term committed relationships, or when choosing between individuals, prioritized traits might differ. Additional research is required, however, to establish the relative importance of each feature—and the manner in which people may dishonestly signal their true quality and intentions. And apart from that, let’s not overlook the importance of a good sense of humor. Looks aren’t everything.
This post originally appeared at The Conversation. Follow @ConversationUS on Twitter.