Not 36.6° and not 37°. The average normal body temperature of a human is getting lower.

For many years, the average body temperature for adults was considered to be around 37°C, based on 19th-century research. Recent studies indicate that this average has decreased to approximately 36.39°C in the U.S., reflecting a drop of about 0.59°C since the 1800s. This conclusion is supported by data from 190,000 Americans measured between 1862 and 2017. Factors contributing to this decline include improved health conditions, vaccinations, and advancements in medicine, which reduce the need for the body to elevate its temperature in response to infections. Additionally, modern living conditions, such as heating and air conditioning, may also play a role. It's important to note that a body temperature below 37°C is not necessarily a cause for concern, as the normal range is wider, influenced by factors like age, sex, and daily rhythms.