Here is my hypothesis. Our body temperature is expensive and evolutionary not 'stable'. In the past, it would make sense that in environments with lower bacteri

Here is my hypothesis. Our body temperature is expensive and evolutionary not 'stable'. In the past, it would make sense that in environments with lower bacterial threats, the group would select for lower body temperature in order to preserve energy. In order to do that, individuals with too low a body temperature would be removed from the group due to infections. This would create a balanced system between body temperature (energy expenditure) and bacterial immunity. With the development of antibiotics, this changed. The previous bottom of the group is not culled anymore, removing the barrier of the imbalance. Therefore, the group is 'safely' selecting for lower body temperatures.