Revising body temperature norms: How modern life cools us down

The body temperature of a healthy person was determined in the 19th century. New research indicates that since that time, the standard considered to be 37 degrees Celsius has changed. We explain what influenced this and what temperature is proper.

The norm widely accepted worldwide for the temperature of a healthy person is the result of 19th-century science. It was established by German doctor Carl Wunderlich, who initially set the reference point at 37 degrees, which was adjusted to 36.6 degrees.

Recent studies show that the old norms – although rightly set for their time – do not reflect contemporary realities. A healthy person does not have a temperature of 36.6 degrees Celsius, but usually slightly less.

Although studies conducted in 2017 in Great Britain confirm 36.6 degrees, other studies in the United States lower the norm. In 2019, for residents of Palo Alto, California, it was 36.4 degrees Celsius.

A drop was also observed in communities living in extremely different conditions, like the Tsimane, a Bolivian farmer-gatherer tribe. In their case, the temperature has been dropping rapidly in recent years by around 0.05 degrees per year and currently is 36.5 degrees Celsius.

A group of doctors and anthropologists, led by Professor Michael Gurven from the University of California in Santa Barbara, has analyzed this phenomenon. According to them, the change in human body temperature is the result of several factors that can collectively be defined as scientific and technical progress.

One of the detailed causes cited is the improvement in overall health status – thanks to better hygiene, access to clean water, vaccines, and modern medicines, we have, on average, fewer infections, and the body has to expend less energy to manage mechanisms responsible for combating them.

In developed countries, access to air conditioning and heating is also widespread. As a result, we use less energy for thermoregulation, which also results in a slight average drop in body temperature.

The researchers also considered communities on which the impact of science and technology seems to be the smallest. Although the Tsimane do not have access to modern medicine or technology for cooling and heating, they do have access to blankets and modern clothing.

The conclusions presented by the researchers indicate that there is no single factor responsible for the observed changes. They are due to a combination of factors that can be generally defined as an improvement in living conditions: the average inhabitant of our planet lives now in much better conditions than in the 19th century.