“The average human body temperature is exactly 98.6°F (37°C).”

For over a century, the idea that the average human body temperature is precisely 98.6°F (37°C) has been a widely accepted standard. This benchmark originated from the extensive work of German physician Carl Wunderlich in the mid-1800s, who compiled millions of temperature readings from approximately 25,000 patients and published his findings in 1868. His average became the ingrained number taught in schools and used in medical practice.

However, modern scientific scrutiny reveals that Wunderlich's original research had limitations, including the use of less accurate mercury thermometers and predominantly axillary (armpit) measurements, which can be lower than core body temperatures. More recent studies, some analyzing data spanning over a century, indicate that the average human body temperature is actually slightly lower today, closer to 97.9°F (36.6°C). This shift is attributed to factors such as improved public health, reduced chronic infections due to antibiotics, and widespread climate control.

The continued belief in the exact 98.6°F figure largely stems from its simplicity and how deeply it was integrated into medical education and public understanding as a fixed, universal norm. In reality, an individual's normal temperature can fluctuate throughout the day and varies based on personal characteristics like age, sex, and activity level, making a single, precise number an oversimplification.