In a new study titled ‘Mating strategy flexibility in the laboratory: Preferences for long- and short-term mating change in response to evolutionarily relevant variables’, the research team captured the relationship preferences of 151 heterosexual male and female volunteers (75 men and 76 women) by asking them to look at pictures of 50 potential partners, and to indicate whether they would prefer a long or short-term relationship with each.

The researchers then showed the participants a series of images of luxury items related to wealth, including fast cars, jewellery, mansions, and money.

Finally, the participants revisited the images of their potential partners, and sorted them by their preferred relationship type again. After viewing the wealth images, both male and female participants selected more partners for a short-term relationship compared to the original result - an increase of about 16%.

Dr Andrew G. Thomas who led the research explains: “Not all people prefer long-term committed relationships. Evolutionary psychologists believe that whether someone prefers a short-term relationship over a long-term one depends partly on their circumstances, such as how difficult it might be to raise children as a single parent.

“Importantly, when those circumstances change, we expect people to change their preferences accordingly. What we have done with our research is demonstrate this change in behaviour, for the first time, within an experimental setting. After participants were given cues that the environment had lots of resources, they became more likely to select individuals for a short-term relationship.

“We think this happened because humans have evolved the capacity to read the environment and adjust the types of relationships they prefer accordingly. For example, in environments which have lots of resources, it would have been easier for ancestral mothers to raise children without the father’s help. This made short-term mating a viable option for both sexes during times of resource abundance. We believe modern humans also make these decisions”.

The researchers also found that participants changed their relationship preferences after being shown a slideshow of dangerous animals, and videos of people interacting with infants.

Dr Thomas says: “We also found that other types of cues had an effect. When the participants were given cues that the environment contained young children, they were more likely to select individuals for a long-term relationship. Dangerous environments seemed to cause both men and women to choose more long-term partners, though some women chose more short-term partners instead”.

The research, conducted in collaboration with Dr Steve Stewart-Williams from the University of Nottingham, can be found in the latest issue of Evolution and Human Behaviour here.