Source: West Point/Flickr/Free Image/Public Domain

Although many of us like to think that we have a “type” of partner we are most attracted to, and that our preferences stay consistent over time, research has shown that our likes and dislikes are as changeable as a British weather forecast.

In tough environments, where food is difficult to come by and infectious disease is a real threat, people prefer heavier partners. It makes sense: underweight individuals are less likely to survive when times are hard, whereas those who are carrying a little extra padding are able to cope with food shortages or acute bouts of illness.

Even more interesting is research showing that these preferences probably aren’t locked in: people who have recently emigrated from an inhospitable to a cushy environment express preferences halfway between those of lifelong inhabitants of either location.

Some studies have shown that our mate preferences can even be influenced by imagining we live in a harsh or safe environment.

What researchers haven’t done (until now) is test whether changes in environment result in changes in preferences in the same people. For obvious reasons this is a tricky question to answer: we can’t simply take people from a comfortable environment and deposit them in some apocalyptic hellhole. Can we?

Source: The U.S. Army/Flickr/Free Image/Public Domain

Carlotta Batres and David Perrett from the University of St. Andrews in Scotland did the next best (worst?) thing. They followed cadets in a University Officer Training Corps as they passed through a 10-day grueling boot camp. On the day before the camp began, 23 male and eight female cadets were shown faces on a computer screen. Their task was to move a slider one way or the other to adjust the appearance of these faces, making them appear more or less fat (in the lingo of the scientists, “adipose”), until the faces were at their most attractive.

A few days later and midway through the training camp, the cadets again performed the face manipulation task. After another few days, the cadets saw the faces for the third and final time. They had spent a week and a half dragging themselves through underwater tunnels, rising at dawn to parade up and down muddy fields, and cleaning toilets with toothbrushes (I have no idea if this is what they did: I’m getting all this from 1970s war movies). After all that, had their face preferences changed?

Results

Batres and Perrett found that male cadets shifted from a baseline preference for underweight women to slightly heavier (though not overweight) women during the boot camp. This is good evidence that the tough regime of the camp caused the men’s preferences to change. The change occurred rapidly, within three days, and was at a plateau by the final session, which suggests that remaining in a consistently harsh environment doesn’t exacerbate the effect.

Female cadets didn’t change in their preferences for adiposity in men’s faces, although the number of female cadets was rather small — we might have greater in the results if the scientists had tested more than eight female cadets.

Nevertheless, Batres and Perrett speculate that, because body weight is strongly linked to female fertility (underweight women are less likely to menstruate, conceive, or carry a fetus to full term), men may have evolved to pay special to women’s weight after changes in the harshness of . It may be less important for women to attend to weight changes in men.

For an audio version of this story, see the 14 February 2017 episode of The Psychology of Attractiveness Podcast.

Support Rob at patreon.com/psychology and receive bonus podcasts and blogs.