I'm sure we discussed this before - one suggestion was that the temperature of the average healthy human body hasn't changed, but that enough people back in the day were running a low-grade fever at any given time that the observed average was skewed?
We probably have, but I forgot and re-discovered it anew. But yeah, that's the proposition.
I heard a theory that the changes in body temperature just reflect fewer chronic infections.
I also read something concerning that suggested that body temperature is one of the main defenses against fungal infection.
"A warmer environment may enable some fungi to evolve a higher temperature tolerance. If a fungus can jump the temperature barrier, then humans and other mammals could become hosts to novel fungal infections. A yeast that normally grows in wetlands or on apple trees could possibly evolve to live in goats or bats or humans."
...
I learned something I hadn't known before, which was that there is considerable fossil evidence for huge fungal blooms in the boundary between the Cretaceous and Paleogene periods, after the catastrophic impact and volcanic eruptions that brought the era of dinosaurs to a close. Monosson describes research work that suggests that the major advantage of mammals in that boundary was that their hot body temperatures provided strong resistance against pathogenic fungi during that huge bloom period. (I had the distracting question of why that wouldn't have protected dinosaur species that were also endothermic, but I realized that it actually did in the sense that those species were on their way to being birds.)
A yeast that normally grows in wetlands or on apple trees could possibly evolve to live in goats or bats or humans."
It would be interesting to read the research because this sounds pretty unlikely. Parasites are generally quite host-specific, and where they cross species barriers it's normally between closely related species. Humans share quite a few diseases with mammals, a few with birds (avian influenza), one or two with lizards, and almost none with fish - the exceptions are parasites that have a life cycle involving both a fish and a fish-eating mammal such as a bear.
The idea of parasites jumping the barrier from plants to animals is quite something.
Happy birthday, belatedly. Or early, if you use European dating.
Some other possibilities suggested in the article were seemed compelling: (a) that people are doing less physically taxing labor, and (b) ambient temperatures are stabler.
Moby had the best explanation, I thought. Back in the old days they put thermometers in the butt.
As part of the study, the authors investigated the possibility that the decrease could simply reflect improvements in thermometer technology; thermometers used today are far more accurate than those used two centuries ago. "In the 19thcentury, thermometry was just beginning," Parsonnet said. To assess whether temperatures truly decreased, the researchers checked for body temperature trends within each dataset; for each historical group, they expected that measurements would be taken with similar thermometers. Within the veterans dataset, they observed a similar decrease for each decade, consistent with observations made using the combined data.
That is a very weird assumption to make for a dataset covering a period of seven decades! Are we actually supposed to believe that when the nonagenarian Jacob Jones, formerly a Corporal in the Grand Army of the Republic, tottered into the veterans' clinic for his checkup in 1930, the staff reverently extracted the special 1862 vintage thermometer, kept for his exclusive use, from its mahogany case?
11 it can be tested too as there are still plenty of those old thermometers lying around in museums and such
re: 12
I'd imagine they read differently now. Minor leaks, changing shapes of vessels over time, etc. But yeah, I bet it's entirely within the competence of researchers to allow for that and then work out the differences. When I used to work at a science museum they had loads of 19th and early 20th century thermometers.
Personally, I run pretty cold. Maybe to do with my thyroid condition, or maybe not, but it wouldn't be unusual for me to have a temperature of under 97F (under 36 C). If mine is over 37C, then I'm probably ill.
I do run warmer than my wife; I hang out around 98 most of the time, while she's usually under 97. Though it's not like we take a lot of "actually well" baseline readings, though she does get her forehead scanned at the doctor frequently, with often even cooler results.
When I was a kid my goldfish always died from some kind of fungus growing on them. Maybe I just didn't clean the tank often enough.
Let's all post our SAT scores and baseline body temperatures.
Did SAT scores tank with covid or something?
ACT scores did and likely won't recover for a decade.
Maybe he should have applied to different schools?
In the long run, we all end up with the same body temperature.
20: No, we will be warmer than our ancestors were at the same time post mortem.
I decided to eschew the more nuanced versions of the joke because cremation.
It's not appropriate to make any jokes if you're at a cremation.
it can be tested too as there are still plenty of those old thermometers lying around in museums and such
Oh, sure. And you could easily test them against known constants like the melting point of water, etc.
I was just casting doubt on the idea that all the doctors would still be using 70-year-old thermometers on their elderly veteran patients. I think it'd be more likely that Cpl Jones in 1862 had his temperature taken with a thermometer made in, say, 1853, and in 1920 with a thermometer made in about 1913, because that's what the doctor would happen to have in his kit.
And in that case, it seems to me, it's very difficult to say that Cpl Jones' body temperature fell over that period, rather than the thermometer just getting better.
Poor Cpl Jones, 80 years old and still an E-4 after 60 years in the service.
Worse, he's an E-3. https://en.wikipedia.org/wiki/Lance_Corporal_Jones
9: jumping back, I don't know why less variation in ambient temperature would mean body temperatures get lower. It would mean that I have to spend less energy thermoregulating, yes. It might mean that I become less good at thermoregulating - that would make sense, intuitively, if you have someone who spends their life indoors in a stable environment then they'll be less able to deal with being outdoors in extreme cold or heat.
But why would it mean that your body changes its thermoregulatory target?
Yeah. I still think it's the butt-thing, plus the lower level of inflammation/infection.
28: I think the idea was that thermoregulating more would require higher metabolism, which would mean higher ambient temperature as side effect. Maybe less plausible put that way.
I always make sure the nurse uses a thermometer that was manufactured within 10 years of my birthdate when _I_ go to the doctor.
There's a fungus that attacks the roots of Douglas fir in the PNW and human feet in some tropical places. Same fungus.
We asked if it was one of the fungi that could colonize your boots and then your feet and forestry prof gave a short exasperated reminder to dry your boots out daily.
That only works if you go inside every day.
Speaking of heat, I just got home from an amazing trip through Asia, but a lifetime of North Carolina summers totally did not prepare me for the "cool season" in Thailand. Which was suspiciously similar to an NC summer day, except more humid. A lot more humid. Either they are the toughest people on earth, or they're made of asbestos. Especially the ones standing over a grill on a sidewalk all day, which seems downright superhuman. I guess you must get used to it eventually because everybody I saw there was still alive, but holy moly.
Survivorship bias. Also, don't feed the bears.
36 was my thought on seeing photos from the 1930s of people standing around in the open in Singapore wearing three-piece suits. I'm sure they were made of light material, but even so, good lord.
Obligatory Kipling: Pagett, M.P.
https://www.kiplingsociety.co.uk/poem/poems_pagett.htm
I always make sure the nurse uses a thermometer that was manufactured within 10 years of my birthdate when _I_ go to the doctor.
Exactly. It's like getting the wine pairings right. If you're a '68, the thermometer shouldn't be any newer than a '77.