In evolutionary biology, the ‘Life History Theory,’ first proposed in the 1950s, postulates that when the environment is favorable, the resources used by any organism are devoted for growth and reproduction. Conversely, in a hostile environment, resources are transferred to so-called maintenance programs, such as energy conservation and defense against external attacks. Scientists developed this idea to a specific field of medicine: the erroneous activation of the immune system that causes autoimmune diseases. By studying mice suffering from a model of multiple sclerosis, the research team succeeded in deciphering how exposure to cold pushed the organism to divert its resources from the immune system towards maintaining body heat.