Like all mammals, we cool using the miracle of evaporation: when heat turns water into steam, the energy lost chills the skin underneath. Most animals take advantage of this natural refrigeration by panting—taking short, shallow breaths to evaporate saliva in their throats and on their tongues. As the water evaporates and cools the skin, blood in the veins just beneath is also cooled. This chilled blood then cools the rest of the body. Panting, however, suffers from two constraints.
