A 2020 study from Stanford University has found that human body temperature - previously standardised at 37°C - has been steadily declining over the last 200 years or so.
Using historical records, the research team found that the current average body temperature is probably now around half a degree lower.
“[…] we determined that mean body temperature in men and women, after adjusting for age, height, weight and, in some models date and time of day, has decreased monotonically by 0.03°C per birth decade.”
The drop is currently unexplained, but suggestions include : decline in physical activity, the effects of antibiotics, improved hygiene & etc.
Also see :Thermoregulation