He has a very sophisticated system for this: the heart and circulatory system regulate, among other things, the microcirculation, i.e. the small vessels, they are opened and closed. We give off 30 percent of our total heat through the neck and head area. The hands are our window: we can use them to regulate blood circulation up to 600 times over. We can close them, for example in winter, when they are freezing. Or we can open them up, they turn bright red, they have good blood flow, and we lose significant amounts of heat to the environment. Environments of over 35 degrees during the day can only be endured if you turn on your brain. The brain has to say: "It's too warm now, I'll go somewhere else, I'll take off my clothes, I'll open the window."