How our bodies adapt to extreme temperatures – until it gets too hot
No matter where you’re from, there are things you can do to cope better with extreme temperatures. But it takes work to stop our bodies’ adaptations from slipping backwards over winter, and there are limits to how far we can go
Recent hot weather in the UK has prompted discussions about how our bodies adapt to extreme temperatures. Many Europeans, including my UK colleagues, have noticed that their cheeks are pink, damp hairs stick to their brows, and they sigh more during this unprecedentedly hot summer. While the heat may seem tough to cope with for those used to milder climates, it turns out that British and German ancestry do not provide any genetic advantage for tolerating Australia's heat.
Our bodies naturally function optimally with a core temperature between 36.5°C and 37.5°C (97.7°F to 99.5°F). When the temperature rises above 40°C (104°F), our organs can start to shut down. To maintain a stable internal temperature, our bodies have evolved various mechanisms to monitor and regulate the external environment and internal conditions.
Thermoreceptors in our skin detect external heat and relay information to the brain. When the brain perceives external heat as a threat to our core temperature, it creates an uncomfortable feeling of being hot, prompting us to remove clothing, seek shade, or engage in cooling behaviors. The brain also triggers unconscious cooling mechanisms in response to heat.
By sending our heart rate up and faster to circulate blood from the core to the skin, our bodies work to release warm blood to the periphery, where it can be cooled by air.
Evaporative cooling through sweating is another cooling mechanism. As sweat evaporates, it draws heat away from our skin, thereby reducing our core temperature. However, when the outside temperature is the same or hotter than our body temperature – like recent temperatures of 38°C in the UK – we cannot rely on simple convection to lose heat. Therefore, sweating becomes even more crucial in these instances.
Our bodies also undergo seasonal acclimatisation when exposed to regular heat. Over time, people living in hot climates develop better self-cooling abilities. Blood flow to the surface increases, sweating starts sooner, and we produce more sweat overall. Additionally, heat shock proteins are produced by our bodies in response to heat exposure, helping to repair and refold damaged proteins and protect cells from thermal stress during subsequent heat exposures.
Even individuals from cooler climates can adapt to heat through exposure, although the speed of adaptation may vary. Studies have shown that Danish cyclists who trained in a hot climate like Qatar experienced improved performance after two weeks of daily outdoor training, despite not being accustomed to such temperatures. This suggests that anyone can adapt to extreme heat with sufficient exposure, regardless of genetic factors or early-life exposure.
However, some individuals may not feel as acclimated as they are physiologically. This could be due to psychological factors, as emotional responses to heat can influence our perceptions and comfort levels. Air conditioning may provide temporary relief, but it does not address the underlying physiological adaptations our bodies undergo to cope with extreme temperatures.
Written by urgent.news from New Scientist's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
