# Liberal Arts Blog — 98.6 F: the Body’s Optimal Temperature, Average Temperature, or Neither?

Liberal Arts Blog — Monday is the Joy of Math, Statistics, and Numbers Day

Today’s Topic — 98.6 degrees (Fahrenheit): the body’s optimal temperature, average temperature, or neither?

After seven posts on geometry, time for a break. Let’s talk temperature. When I was growing up, my understanding was that you wanted to have a temperature of precisely 98.6 degrees. Any deviation was undesirable. 99 degrees was a source of concern and anything over 100 degrees was a cause for alarm and a call to the doctor. Apparently, I was quite mistaken. I later learned that 98.6 degrees is just an average, not the optimal temperature. But then in January I learned that it is “no longer the body’s norm.” Really? What’s the scoop? Experts — please chime in. Correct, elaborate, elucidate.

WHERE DID THIS 98.6 DEGREES IDEA COME FROM ANYWAY?

1. “Nearly 150 years ago, a German physician analyzed a million temperatures from 25,000 patients and concluded that normal human body temperature is 98.6 degrees Fahrenheit.”

2. “That standard has been published in numerous medical texts and helped generations of parents judge the gravity of a child’s illness.”

3. But new studies suggest that the number is not correct. Was the 1869 study by Carl Friedrich Reinhold August Wunderlich flawed? or has the human body changed?

THE 98.6 NUMBER WAS CORRECT IN 1869 BUT HAS DECLINED TO 97.5 TODAY — WHY?

1. For starters, we are “taller, heavier, and live longer.”

2. And then we have many fewer infectious diseases than we used to.

3. Dr. Julie Parsonnet, an infectious disease specialist at Stanford has “analyzed 677,423 temperatures collected from 189,338 individuals over a span of 157 years.” The conclusion: the number 97.5 degrees is the current norm and that “a population-level change in inflammation is the most plausible explanation for a decrease in temperature.”

REASONS THE QUALITY OF THE DATA OF THE NEW STUDY HAS BEEN QUESTIONED

1. No consistency in the way temperatures were taken over time: axillary, oral, ear, or rectal. “Ear and rectal temperatures tend to be half a degree higher than oral temperature. Axillary temperature, taken in the armpit, tends to be one degree lower.”

2. No consistency in time of day temperatures were taken. And there is huge diurnal variation in human temperature. See above graphic. The low in the graph is 97.2 the high is 99.5 degrees. (from Wikipedia — second link below)

3. Instruments used differed.

NB: At what level does a patient have a fever? Anecdotally, I have heard numbers of 100.4 and 100.8 F from physicians. Wikipedia’s range for “normal” is “97.7 to 99.5.” This seems quite out of date. Adjusted for time of day: anything above 99 degrees in the early morning versus 99.9 in later afternoon is considered a fever.” A table in the second link breaks down the ranges by oral, rectal, and tympanic. All I think need updating. Experts?

Any thoughts on temperature? Please share the coolest thing you learned this week related to math, statistics, or numbers in general. Or, even better, the coolest or most important thing you learned in your life related to math.

This is your chance to make someone else’s day. And to consolidate in your memory something you might otherwise forget. Or to think more deeply than otherwise about something dear to your heart. Continuity is key to depth of thought.

Passionate about education, thinking citizenship, and art.

## More from John Muresianu

Passionate about education, thinking citizenship, and art.