But the rate of heat loss from a body lying on a porch is not perfectly linear — the body loses heat faster in some circumstances than others, and factors like the position of the body, the amount of residual body fat insulating the core, the specific wind conditions on the porch, and the general principles of thermal dynamics all influence how quickly the core temperature falls.

Young people, and particularly young women with a higher proportion of subcutaneous fat than the average young man, may be somewhat better insulated against rapid core temperature loss than others.

This is speculative, but it is consistent with observations in other hypothermia cases.

The Principle That Changed Medicine

Whatever the precise physiological explanation for Jean Hilliard’s survival, her case became one of the most prominent examples of a principle that physicians had been slowly working toward for decades: the principle that severe hypothermia does not automatically mean death, and that aggressive efforts to rewarm even a patient who appears to have died from cold exposure can sometimes produce a survivor.

The maxim “No one is dead until they are warm and dead” had been expressed in various forms in the medical literature before 1980.