Original photo by yaoinlove/ iStock
In 1851, German physician Carl Wunderlich conducted a thorough experiment to determine the average human body temperature. In the city of Leipzig, Wunderlich stuck a foot-long thermometer inside 25,000 different human armpits, and discovered temperatures ranging from 97.2 to 99.5 degrees Fahrenheit. The average of those temperatures was the well-known 98.6 degrees — aka the number you hoped to convincingly exceed when you were too “sick” to go to school as a kid. For more than a century, physicians as well as parents have stuck with that number, but in the past few decades, experts have started questioning if 98.6 degrees is really the benchmark for a healthy internal human temperature.
Oops, incorrect!
It's a fibAlthough primates (such as Homo sapiens) are warm-blooded creatures, birds have some of the highest internal body temperatures in the animal kingdom. Some hummingbirds, for example, have body temperatures as high as 112 degrees Fahrenheit.
For one thing, many factors can impact a person’s temperature. The time of day, where the temperature was taken (skin, mouth, etc.), if the person ate recently, their age, their height, and their weight can all impact the mercury. Furthermore, Wunderlich’s equipment and calibrations might not pass scientific scrutiny today. Plus, some experts think humans are getting a little colder, possibly because of our overall healthier lives. Access to anti-inflammatory medication, better care for infections, and even better dental care may help keep our body temperatures lower than those of our 19th-century ancestors.
In 1992, the first study to question Wunderlich’s findings found a baseline body temperature closer to 98.2 degrees. A 2023 study refined that further and arrived at around 97.9 degrees (though oral measurements were as low as 97.5). However, the truth is that body temperature is not a one-size-fits-all situation. For the best results, try to determine your own baseline body temperature and work with that. We’re sure Wunderlich won’t mind.
Numbers Don't Lie
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Warm-blooded animals are called ______.
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Warm-blooded animals are called homeotherms.
Technically, humans can hibernate.
Many mammals — from the humble ground squirrel to the majestic grizzly — practice some form of hibernation, slowing down certain bodily functions to survive winters. Naturally, that raises a question: “Humans are mammals. Can we hibernate?” While the answer is slightly more complicated than it is for a pint-sized rodent, the answer is yes … with caveats. The main component of hibernation is lowering body temperature. When this occurs, the body kicks into a low metabolic rate that resembles a state of torpor, a kind of extreme sluggishness in which animals require little to no food. Because most of our calories are burned up trying to keep our bodies warm, de-prioritizing that requirement would essentially send humans into hibernation — but this is where it gets tricky for Homo sapiens. First, humans don’t store food in our bodies like bears do, so we’d still need to be fed intravenously, and second, sedatives would be needed to keep us from shivering (and burning energy). In other words, it would be a medically induced hibernation, but hibernation nonetheless. A NASA project from 2014 looked into the possibility of achieving this kind of hibernation for long-duration space travel, and while the findings weren’t put into practice, there were no red flags suggesting a biological impossibility. Today, NASA continues its deep sleep work by gathering data on the hibernating prowess of Arctic ground squirrels.
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
