'Normal' body temperature? Not really.

Once a year, I go back to my alma mater and do a guest lecture about biological clocks in an Anatomy & Physiology class. Knowing how many pre-meds are among the 200 students in the room, I try to start with some examples of rhythms in human physiology (and disease), and the first one is body temperature, busting the myth that 98.6F (37C) is the "normal" temperature:

Now Orac links to an excellent post that explains it all - the entire history of the idea that 37C is normal and what the real difference, means and fluctuations there are. Read the whole thing.


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This is something I looked at because of my work critiquing the "aquatic ape" idea. They have a variety of dubious claims about human body temp: that it's very unlike primates and like whales, that it doesn't vary, and so on. The page about body temperature on my site is one of the most frequently viewed pages on the site (the page in question, if anyone is interested, and the subject is a always one of the top search strings that get people there. There seems to be a lot of interest in the subject. That page has also been used by at least one science answer site, so I guess I did something right. Basically it's what that post says (and thanks for linking to them; I always like more handy info): it varies during the day, it varies according to health, from person to person, and it isn't exactly 98.6 as we North Americans like to say, or 98.4 as the Brits say.

I've also got some bits on the body temps of other primates, whales, and a few other mammals.

Thanks for that link. And I should have also linked to this post where there is much more information.

My temp has consistently been 97.5 across every clinic, hospital, emergency room, etc. that I've ever been in unless I had an illness that affected it.

Year after year, unless I'm running a fever, I don't break 98. I've got so many data points at this point, there's really no doubt that 97.5 is my normal body temp.

I've got so many data points at this point, there's really no doubt that 97.5 is my normal body temp.

Have someone measure it at 4 in the morning when you're asleep. Then measure it after running a mile. It'll be significantly lower the first time and higher the second, and neither will be 97.5F. Yet you won't be abnormal when you're asleep or after running.