In order to answer this question, you will certainly turn to the principle of homeostasis.

Homeostasis is a set of phenomena that occur in living organisms to maintain a stable internal condition despite external disturbances. This theoretical balance is affecting different aspects, and thermoregulation (temperature) is one of the most relevant.

Human thermoregulation used different mechanisms to keep the homeostasis: the most prominent are vasodilatation and vasoconstriction. The first one occurs to decrease body temperature and the second one aims the opposite, using mechanisms as sweating or shakes.

Thermal imaging allows us to see those fascinating processes. But what is even more exciting (and complex) is that not all living beings are governed by the same thermal mechanisms. We find 3 main types:

• Homeotherms: Organisms that are capable of generating heat themselves to maintain that balance regardless of the environmental temperature (i.e. birds and mammals, among them human beings)
• Poikilothermic: They do not have the ability to generate heat by themselves, so their internal temperature depends on the environmental conditions. It is said that they are cold-blooded and need external factors like the sun or wind to keep their thermal balance (i.e. reptiles, amphibians, etc.)
• Heterothermic: They exhibit characteristics of both poikilothermy and homeothermy on a daily or annual basis. For example, bears are homeothermic during one part of the year, and during winter they decrease their metabolism and hibernate, becoming poikilothermic.

Thanks to infrared thermography we can observe and quantify the heat transfer processes through the changes in skin temperature. This fascinating topic leads us to applications on sports and health sectors as injury prevention or internal load management. But to be honest, we are still in the very early stages of understanding human thermoregulation and its links to injuries, pathologies, metabolism, emotions, etc. So, even if it seems that the thermal mechanisms are clear, we will need a lot of research to better understand how other living beings manage their homeostasis and if humans beings might be able to adapt their metabolism as bears do to hibernate.

References:

• Romanovsky, A. A. (2018). The thermoregulation system and how it works. Handbook of clinical neurology, 156, 3-43.
• Carpes, F. P., Mello-Carpes, P. B., Priego Quesada, J. I., Pérez-Soriano, P., Salvador Palmer, R., & Ortiz de Anda, R. M. C. (2018). Insights on the use of thermography in human physiology practical classes. Advances in physiology education, 42(3), 521-525.