Researchers from the University of California have found that the average human body temperature is decreasing year by year, but they have yet to be able to explain the cause of this phenomenon.
In the mid-19th century, German physician Reinhold August Wunderlich established the average human body temperature . He emphasized that fever was a symptom of illness, not a disease, and produced temperature charts at a general hospital in Tubingen, where he served as director.
Based on the work of French doctors showing that the inflamed parts of the human body have a higher temperature than the rest and that the average human body temperature is 36.8 degrees Celsius (98 degrees Fahrenheit). ,5 degrees Fahrenheit), he set out to prove and refine it. Using a thermometer, he took the temperatures of more than 25,000 patients, yielding more than a million results. In 1868, he published his findings and determined that the average human body temperature is 37 degrees Celsius.
The average human body temperature is 37 degrees Celsius.
This assessment has been adjusted over time. We all know that body temperature changes during the day, being lower in the morning and highest around 6pm, in addition to that there is a difference in temperature between men and women.
However, since then, scientists have noticed something strange. Average body temperature seems to be dropping. A 2017 study that looked at more than 250,000 temperature measurements from 35,000 British patients found an average temperature of 36.6 degrees Celsius. In addition, another study published earlier this year found basal body temperature. The average body temperature in Americans has steadily decreased by 0.02 degrees Celsius for a decade since 1860.
A new study published in the journal Science Advances finds something even stranger. In the Tsimane Health and Life History Project, conducted in 2001, studied the Tsimane people, an indigenous group living in the Bolivian Amazon region who are known for their excellent health. , the researchers found their average temperature had dropped rapidly, by about 0.05 degrees Celsius per year.
Looking at the medical records of 5,500 Tsimane people between 2002 and 2018, the researchers analyzed and adjusted for factors that can affect a person’s body temperature, including ambient temperature, infection, and temperature. body weight. In less than two decades, the Tsimane’s body temperature has dropped to the same level as that of Americans for more than two centuries.
“No matter how we analyzed it, it showed a drop in body temperature,” said Thomas Kraft, a researcher at the University of California. Even if we limited our study to less than 10% of adults who were diagnosed as healthy by a physician, we found a similar drop in body temperature over time.” The average Tsimane body temperature is 36.5 degrees Celsius (97.7 degrees Fahrenheit). So what happened?
Michael Gurven, Professor of Anthropology at the University of California, explains: “ This could be due to the increase in modern healthcare and lower rates of mild infections than in the past . However, although general health has improved over the past two decades, infectious diseases are still common in rural Bolivia. Our results suggest that inflammatory diseases alone cannot account for the drop in body temperature.”
Thomas Kraft added: ‘Another possibility could be that our bodies don’t have to work so hard to regulate the internal temperature because we already have air conditioning in the summer and heaters in the winter. As for the Tsimane people, although they do not have access to modern technology to regulate body temperature, they have more access to clothing and blankets.”
Although it is difficult to determine what causes changes in body temperature, the team believes that measuring average temperature and its variation across a population can be used as an indicator of health. health in general, like longevity.