My Brain is Fried
Overheating a mammalian body leads to dire consequences. When the brain’s temperature exceeds its normal range, it causes lesions, protein denaturation, and organ failure. Animals in arid desert environments evolved anatomical features to cope with oppressive heat. We’re familiar with the jackrabbit’s enlarged ears, containing a network of blood vessels that constrict and dilate to shed excess warmth during exercise. Researchers in the 1970s compared the convective properties of jackrabbit ears to copper tubes, by sticking both objects in a wind tunnel. To mimic the shape of the sensory organs in a new material, they poured an aluminum cast modeled from a Belgian hare’s amputated ear.
Antelopes and other artiodactyls use a clever technique to stabilize cranial temperature, known as selective brain cooling. When exerted, the animal’s nostrils flare up and pass air over a mucus-covered surface. The cooled breath is housed in a cavernous sinus, adjacent to a lattice of arteries and veins. Warmer blood from the heart interfaces with the cavity, maintaining a lower temperature in the head. Caribou in the Arctic Circle use countercurrent heat exchange to elevate their core temperature in frigid conditions. The animal’s hooves are significantly cooler than the rest of their body. The extremities have to remain pliable, so the fats in these areas have a low melting point. No mittens necessary.