# Why are we 98.6°F? **URL:** \ **Category:** Factual Questions\ **Created:** [December 1, 2020, 5:46pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938 "2020-12-01T17:46:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 5:46pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/1 "2020-12-01T17:46:54Z")
And not 98.5 or 99.2? Yes I know there is individual and and situational variation. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [December 1, 2020, 5:51pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/2 "2020-12-01T17:51:11Z")
98.6 F is 37 C. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 1, 2020, 5:51pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/3 "2020-12-01T17:51:31Z")
Actually, we aren’t any more, according to this: [Fevers and Normal Body Temperature: 98.6°F Is No Longer The Rule (webmd.com)](https://www.webmd.com/lung/what-is-a-fever#1) "The 98.6 F standard dates to the mid-1800s. German doctor Carl Wunderlich measured the armpit temperatures of about 25,000 people and came up with an average of 98.6 F. Newer research suggests that the number has since gone down. In a recent review, scientists looked at temperature records from three periods between 1860 and 2017. The average oral temperature slowly fell by about 1 degree to 97.5 F. A person’s age, gender, or weight didn’t make a difference, nor did the time of day." ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [December 1, 2020, 5:52pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/4 "2020-12-01T17:52:10Z")
Are you asking how it was figured out, or what advantage there is to that particular temperature? ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 5:53pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/5 "2020-12-01T17:53:19Z")
Interesting. Call it “N°” then. My question still stands. ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 5:54pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/6 "2020-12-01T17:54:34Z")
How did it come to be; not how did it come to be measured ---
**Author:** ![Icarus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/icarus/32/72_2.png) [@Icarus](https://boards.straightdope.com/u/Icarus)\ **Post date:** [December 1, 2020, 6:02pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/7 "2020-12-01T18:02:54Z")
ISTM that the temperature measurement devices and scales came first. Then it was used by Dr. Wunderlich, as described above, to determine an average body temperature for humans. Just like one might measure the temperature of a sofa, or pair of boots, using the existing devices and scales. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 1, 2020, 6:04pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/8 "2020-12-01T18:04:34Z")
No, the people with actual temperatures came first, long before anyone measured it. I think the OP is asking about the body’s thermal regulation systems. ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 6:05pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/9 "2020-12-01T18:05:59Z")
Sorry I’m not talking about how it’s measured. I’m asking why it’s a universal biological constant. (Acknowledging again that there are exceptions and variations. I mean as a general rule it baseline.) My question is about adaptation, not quantification. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [December 1, 2020, 6:06pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/10 "2020-12-01T18:06:47Z")
## Homeostasis From Wikipedia: > In biology, homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [December 1, 2020, 6:20pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/11 "2020-12-01T18:20:39Z")
> [@lissener](#): > > it’s a universal biological constant It’s not. Other animals have other temperatures, and there’s lots of variation among humans as well, with some people mostly below the average and some mostly above. Are you asking why humans are warm-blooded? ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [December 1, 2020, 6:30pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/12 "2020-12-01T18:30:53Z")
> [@Czarcasm](#): > > "The 98.6 F standard dates to the mid-1800s. German doctor Carl Wunderlich measured the armpit temperatures of about 25,000 people and came up with an average of 98.6 F. What he came up with was 37 C, rounded to the nearest whole number. As kenobi\_65 pointed out, 37 C is equivalent to 98.6 F, but that extra decimal place makes the measurement look more precise than it actually is. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [December 1, 2020, 6:33pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/13 "2020-12-01T18:33:25Z")
It’s 98.6 because her lovin’ is the medicine that saved me. ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 6:33pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/14 "2020-12-01T18:33:35Z")
I mentioned those exact exceptions and variations in the post you pulled that quote from. And clearly I mean among humans, not other animals. And no it’s not just about why we are warm-blooded, full stop. To the extent that 98.6° is recognized as the average human temperature, taking as read all the exceptions and variations, why did we evolve that temperature _range_ let’s call it, and not 30° cooler or warmer. Was that the approximate temperature of the primordial sea when we left it? Or the general weather conditions when mammals appeared on earth? Or since other mammals have different average temperatures, the air temp when Homo sapiens first appeared? This is not a question about measuring techniques, or general warmbloodedness, but about how our own temp settled to within that range and is not wildly variable outside of that. Thanks! ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 1, 2020, 7:14pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/15 "2020-12-01T19:14:44Z")
Well, other mammals really don’t have very different average temperatures, since the range is generally given as 97 - 103 F. That’s an extremely narrow band given the range of sizes, weights, and habitats that mammals exhibit. The likely conclusion therefore is that mammals got that temperature because it worked and later species, including humans, kept the same model. That puts the question back 200 million years but the answer is going to be the same. There is a good balance point between energy intake and output function at around 100F. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [December 1, 2020, 7:15pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/16 "2020-12-01T19:15:48Z")
Basically body temperature is an equilibrium between energy required to maintain common frames/organs, environmental temperature profiles the organism evolves to inhabit and the relative surface area available to shed internal heat. ---
**Author:** ![DavidNRockies](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidnrockies/32/6279_2.png) [@DavidNRockies](https://boards.straightdope.com/u/DavidNRockies)\ **Post date:** [December 1, 2020, 7:27pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/17 "2020-12-01T19:27:40Z")
There’s rarely an opportunity _for_ a Keith reference, much less the reference itself. If for no other reason than that … a hat tip to you, Sir. For any who were out of the loop … I take this digression a single (albeit valuable) step further afield: [![](https://i.ytimg.com/vi/1TL-F5iLo28/hqdefault.jpg?sqp=-oaymwEmCOADEOgC8quKqQMa8AEB-AH2A4AC4AOKAgwIABABGGUgWShTMA8=&rs=AOn4CLCb73l4m7d_-g-7jUabN0bH12Jb5A "Keith - 98.6 (1967)") ](https://www.youtube.com/watch?v=1TL-F5iLo28) ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [December 1, 2020, 7:34pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/18 "2020-12-01T19:34:52Z")
> [@lissener](#): > > This is not a question about measuring techniques, or general warmbloodedness, but about how our own temp settled to within that range and is not wildly variable outside of that. Ah. That’s well outside of my limited biological expertise, so I’ll step out. For what it’s worth, even birds are within a few degrees of mammals (depending on what they’re doing at the time) according to [this](https://www.sciencedirect.com/science/article/abs/pii/030096299190122S), so maybe it has to do with the efficiency that **Exapno\_Mapcase** mentions. ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [December 1, 2020, 7:47pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/19 "2020-12-01T19:47:54Z")
Ah of course: with external variables such as ambient temperature and humidity and pressure etc., balanced with the heat created by our metabolism, and the limits of our native temperature regulators. Thanks everyone ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [December 1, 2020, 7:52pm UTC](https://boards.straightdope.com/t/why-are-we-98-6-f/926938/20 "2020-12-01T19:52:24Z")
Another possible reason for “why that range of temperatures for humans (and other mammals)” is [at the end of the Wikipedia entry on “warm-blooded,”](https://en.wikipedia.org/wiki/Warm-blooded#Defense_against_fungi) with several cites: > [@](#): > > It has been hypothesized that warm-bloodedness evolved in mammals and birds because it provided defense against fungal infections. Very few fungi can survive the body temperatures of warm-blooded animals. By comparison, insects, reptiles, and amphibians are plagued by fungal infections. [Next page](https://boards.straightdope.com/t/why-are-we-98-6-f/926938.md?page=2)