Revealed: 'Evolutionary difference' that makes men and women fight over the thermostat

The variation in how the two sexes feel the cold is not just seen in humans, but also spans other biological species. Photo / Getty Images

Women really do need the heating turned up, a study has revealed, after scientists proved other female species are drawn to higher temperatures because of an in-built "evolutionary difference".

Previous studies have suggested women feel the effects of the office air-conditioning more readily because of a variation in their average metabolic rate.

Evidence has also suggested women have different sensory mechanisms, meaning that they experience temperature differently than men.

But it has now been shown that the variation in how the two sexes feel the cold also spans other species.

These differences were not only evolutionary, the experts said, but could also be linked to sociological phenomena in animals and humans.

Researchers at Tel Aviv University's School of Zoology studied 13 bird species and 18 bat species to determine if the animals displayed geographical separation between the sexes.

They found male members of the species preferred lower temperatures than females, which led to physical distances between them at certain points during the breeding season.

The researchers said the findings indicated a variation in the "heat-sensing mechanisms" of males and females.

Dr Eran Levin, co-author, said: "Our study has shown that the phenomenon is not unique to humans; among many species of birds and mammals, females prefer a warmer environment than males, and at certain times these preferences cause segregation between the two species.

"In light of the findings, and the fact that this is a widespread phenomenon, we have hypothesised that what we are dealing with is a difference between the females' and males' heat-sensing mechanisms, which developed over the course of evolution."

'A chance to enjoy some separation from one another'

The average daily air temperature and body size were also significant factors in explaining the separation of birds, the authors said, but only temperature was significant for bats.

The variation between the sexes was similar to the differences in how we experience pain, the authors said, and was affected by our neural mechanisms as well as hormones.

Evolutionary reasons could help to explain these differences, Dr Tali Magory Cohen, study co-author, said, including the separation reducing competition over food between the sexes and keeping aggressive males away from the young.

Female mammals might also prefer warmer climates to protect their offspring when they were too young to regulate their own body temperature, she said.

The study, published in the journal Global Ecology and Biography, included more than 11,000 individual birds and bats using data collected over nearly 40 years.

These particular species were chosen because, being highly mobile, any geographical separation between the sexes would be clear, the authors said.

The authors suggested their findings might be a "broader evolutionary phenomenon" and could be a "significant force" in shaping behaviour and Levin and Cohen concluded: "The bottom line is, going back to the human realm, we can say that this difference in thermal sensation is meant to make the couple take some distance from each other so that each individual can enjoy some peace and quiet.

"The phenomenon can also be linked to sociological phenomena observed in many animals and even in humans, in a mixed environment of females and males: females tend to have much more physical contact between themselves, whereas males maintain more distance and shy away from contact with each other."