It's no secret that women tend to feel the cold more than men, and scientists pin this on metabolic and hormonal differences. But researchers in Israel have proposed an alternative and, frankly, rather outlandish explanation. Their contention is that men and women are evolutionarily inclined to prefer different temperatures to create space between them, thereby curbing aggression and increasing survivability.
The cold gives me space
Dr. Eran Levin of Tel Aviv University’s School of Zoology and colleagues noticed that in many species, males and females are split over their ideal temperature preferences. For their study, the team of researchers analyzed 40 years' worth of records on the behavior of wild bats and birds in Israel.
They found that male birds and bats tend to prefer higher altitudes, such as near the summit of mountains, while the females preferred to linger in valleys where the temperature is higher. Writing in the journal Global Ecology and Biogeography, where they presented their findings, the scientists added that male mice also prefer colder places than females.
Just like males and females in many species feel pain differently, the researchers in Israel propose that the same nervous system differences may underlie different temperature preferences -- and it may all be rooted in evolutionary biology.
“This is because, with birds and bats, it causes genders to be separated outside breeding season, which reduces competition between males over females. It reduces aggression caused by competition for females between males, and reduces aggression toward females and their children,” Levin told Times of Israel.
Besides creating space between males and females, sex-based temperature perception differences may stimulate females to care more for offspring. When females feel cold more, they are more inclined to warm their young, who in many cases require outside action to help with temperature regulation.
"Our findings suggest that females are found in higher ambient temperatures. We term this differential sex-related thermal preference (DSTP) and propose that it is a broad phenomenon common in many endotherms, acting as a significant force shaping dispersal, sociality and behaviour of animals, and should be explored from this wide perspective," the researchers concluded.
But does this explanation apply to men and women, too? The researchers in Israel seem to think so, claiming that the same evolutionary pressures apply to humans, thereby creating breathing room between the sexes.
“It is meant to make the couple take some distance from each other so that each individual can enjoy some peace and quiet,” said co-author Dr. Tali Magory Cohen.
A study published in the Journal of Applied Physiology found that the resting metabolic rate, the amount of energy the body burns at rest, is 23% higher among men than in women. A slower metabolism means less heat is being produced. Men also tend to have more muscle, which is great for generating heat. Other studies found that estrogen lowers women's body temperature by causing heat to dissipate and slowing blood flow to the hands and feet.
But are these physiological differences underlined by some evolutionary forces? Perhaps. For instance, humans first surfaced in the warm African savannah, where staying cool was important. Men must have been much more active as they went on hunting and gathering parties, while women tended to children and 'home base'. Being more active and with larger muscles, men have had to adapt ways of not overheating, which is where sweating comes in. Indeed, men tend to sweat more than women.