Had some conversations and basically a question came up (in my mind at least) - why do humans have a body temp of 98.6F (as measured in the usual places)?

Why is this regardless of size, weight, muscular level, etc?

Is there something magic about this number based on human biochemistry or something? Or something completely random?

quote:

Originally posted by konata88:
Had some conversations and basically a question came up (in my mind at least) - why do humans have a body temp of 98.6F (as measured in the usual places)?

Why is this regardless of size, weight, muscular level, etc?

Is there something magic about this number based on human biochemistry or something? Or something completely random?

A long time ago in Europe, if I'm not mistaken on the date and location, a doc figured the average person had an average body temp of 37 Degrees Celsius. That equals 98.6 in Fahrenheit.

I saw a news blurb a few days ago that our average body temps have dropped something like 1 degree since about a century ago.

quote:

why do humans have a body temp of 98.6F

It's range of temps, a narrow range, not just that specific number. Outside that range, things start to go wrong. Like, when you have a fever, say, of 104 F, some bad shit is going inside. Or, have severe hypothermia. You won't last, if those out of range temps persist.

As to why? God made us that way.

My temp is ALWAYS 97.8 F. I have always wondered why my normal body temp is .08 degrees lower than the norm.

The answer is: all humans do not have an average temperature of 98.6. It is just a convenient number, much like the fiction that your max. heart rate is 220 minus your age. Humans are far more complex that this.

For example my average temperature is 97.3 and has been for at least 70 years.

What I read is that in the last hundred years general health has improved and people suffer less from inflammation based issues like gout and such that tend to cause light fever. As a result the average reasonably healthy person temperature has gone down about most of a degree. But 98.6 still works as a useful upper limit as temp varies durng the day and by the person, for most people, 99 deg is about where they start to feel crappy.

“Average” body temperature is an interesting question. The average was first determined by many measurements in Germany, and then rounded up to the nearest degree Celsius. The rounding was because temperatures varied and specifying an average to the nearest 0.1 degree made no sense. When that got converted to Fahrenheit, though, the rounding was overlooked/ignored, and 98.6 is actually higher than the true average. There was an article in The Wall Street Journal about the subject some months ago and how it’s now recognized that 98.6 is too high. Some people may have concluded that the average has somehow dropped due to environment or other factors, but IMO it’s actually due to the long ago error in converting a rounded 37°C to an exact 98.6°F.

That was the opinion of John Paulos who discussed all that in his 1988 book Innumeracy: Mathematical Illiteracy and its Consequences.

I am frequently amused by similar metric to Imperial conversions to this day. In books about guns, for example, there will be references to the effective range of this or that weapon that state something like “600 yards (548.6 meters)”: “Oh, I’m 549 meters from the enemy, so I’m safe.”

As for the original question of why most people’s temperatures are very similar, I can’t say other than to point out that whatever the average is, it’s just an average. Individual temperatures vary; mine is 97.8°, and that’s closer to the real average than 98.6.

That is actually somewhat of a scientific mystery. There was an interesting study that hypothesized that it has to do with fungi.

Reptiles and amphibians are vulnerable to thousands of different kinds of fungi. Mammals like us seem resistant to all but a couple hundred, and the reason is probably the relatively high body temperature we run, very inhospitable to fungus species.

So it's postulated that after the big asteroid wiped out the dinos, the competitive stage was set between the surviving cold-blooded ectotherms, and the hot-blooded mammals. The mammals won, and took over most of the planet (for better or worse).

The study further determined an optimal temperature for combatting fungi. That temp was almost exactly 98.6°F.

(There is a price, however. We're basically walking furnaces, and to maintain internal combustion have to continually take in fuel, most humans eating some 3x a day.)

Because her lovin' is the medicine that saved me ...

kkina - interesting.....

Just to clarify - i wasn't specifically saying 98.6 exactly. Just a value in the nominal sense - as opposed to 50F or 150F.

OKCGene has it correct. Further the threshold for a fever is above 38 degrees Centigrade which is 100.4 degrees Fahrenheit.

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Originally posted by trapper189:
OKCGene has it correct. Further the threshold for a fever is above 38 degrees Centigrade which is 100.4 degrees Fahrenheit.

That's fine but not really the question being posed..... kkina has the correct gist of the question....

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Originally posted by konata88:
kkina - interesting.....

Just to clarify - i wasn't specifically saying 98.6 exactly. Just a value in the nominal sense - as opposed to 50F or 150F.

I see. Well, the fungus theory still kind of answers that. If the optimal fungus-killing temperature is a narrow range centered around 98.6, then why deviate outside that range? Human biochemistry is complex enough to support a very tight metabolic heat range, and environmental selection pressure has millions of years to impose a high degree of fine-tuning.

By the way, does this mean I'm smarter than a 5th grader?

quote:

Originally posted by kkina:

quote:

Originally posted by konata88:
kkina - interesting.....

Just to clarify - i wasn't specifically saying 98.6 exactly. Just a value in the nominal sense - as opposed to 50F or 150F.

I see. Well, the fungus theory still kind of answers that. If the optimal fungus-killing temperature is a narrow range centered around 98.6, then why deviate outside that range? Human biochemistry is complex enough to support a very tight metabolic heat range, and environmental selection pressure has millions of years to impose a high degree of fine-tuning.

Agree. The clarification wasn't directed at your response per se.

Actually, your (very good) question is basically about the biological concept of homeostasis. Humans also have very narrow ranges for ion concentrations and pH (remember in The Andromeda Strain when the virus turned out to have a narrower pH range than humans?). There must be some adaptive value to maintaining such tight ranges, maybe something to do with mammalian biochemistry as you suggested.

I'm sure there's theories out there, and my brain is already tapped out trying to remember my decades old bio studies.

I am always 97.5ish. If I get to 98.6 I have a fever. Been that way since I was a kid.

quote:

Originally posted by sig77:
I am always 97.5ish. If I get to 98.6 I have a fever. Been that way since I was a kid.

I'm the same way 97.5 average, if I hit 99, then that's a fever for me.

quote:

Originally posted by RichardC:
Because her lovin' is the medicine that saved me ...

[FLASH_VIDEO]


Link to original video: https://youtu.be/dEjm0uP8DqQ [/FLASH_VIDEO]

98.6°F is known to be the average body temperature on Mars.

98.6 because your ancestors who differed from that value, either higher or lower, tended to die before they could procreate. In other words, chicks dig it.