In the mid-1800s, German physician Carl Reinhold August Wunderlich set the standard for the human body temperature at 98.6 degrees Fahrenheit. But after over two dozen studies have disputed Wunderlich’s research, a new average body temperature has emerged. And it’s lower than we originally thought.
Before arriving at such a number, Wunderlich analyzed 25,000 patients, taking their respective body temperatures through the armpit. Published in countless medical texts, parents today still reference his 19th-century findings to gauge how sick their child is.
As of today, the new average body temperature is 97.5 degrees Fahrenheit, according to a study conducted at Stanford University.
Dr. Jennifer Parsonnet, professor of medicine, health research, and policy and senior author of the study, attributes this drop in temperature to a significant change in human physiology over time.”The environment that we’re living in has changed, including the temperature in our homes, our contact with microorganisms, and the food that we have access to,” Parsonnet told Medical News Today.
The Study
As part of her research, Parsonnet examined data recorded over a span of 157 years. In total, she looked at over 677,423 temperatures taken from 189,338 individuals.
Parsonnet’s pool of data hails from three varying sources:
- Pension records of Civil War veterans from 1862 to 1940.
- The National Health and Nutrition Examination Survey I conducted by the US Centers for Disease Control and Prevention (CDC) from 1971 through 1974.
- The Stanford Translational Research Integrated Database Environment from 2007 through 2017.
What Parsonnet discovered from analyzing the data thoroughly impressed her. The “temperature has continued to decline at the same rate,” Parsonnet told the Wall Street Journal.
The temperatures of Civil War veterans registered higher than those taken from individuals in the 1970s. The modern temperatures remained the lowest of the batch.
But 97.5 Degrees Fahrenheit Isn’t Official
In spite of the overwhelming amount of examined data, complications remain. There are several different ways to take an individual’s temperature, some with a greater margin of error than others. For instance, temperatures taken by the armpit, tend to be lower.
The data used for the Stanford study also did not account for differences in temperature-taking methods.
Body temperature also varies according to uncontrollable factors such as age, gender, time of day and physical activity.
For these reasons, the Stanford researchers don’t advise the standard US body temperature for adults being updated accordingly.
Regardless of the study’s complications, medical professionals around the world believe the average human body temperature should be revisited, considering the comprehensive body of data supporting Parsonnet’s new average body temperature and the outdated nature of Wunderlich’s 19th-century standard.
Frank Rühli, director of the Institute of Evolutionary Medicine at the University of Zurich and a peer-reviewer of the Stanford study weighed in on the topic. “Medical norms and guidelines and thresholds for interventions need to be adjusted,” Rühli told The Wall Street Journal. “That is the major issue.”