7 ms·

This reminds me of the fact that humans used to be able to hibernate (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117993/ https://www.ncbi.nlm.nih.gov/pmc/art

This reminds me of the fact that humans used to be able to hibernate (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117993/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117993/) and (https://www.popularmechanics.com/science/a35033907/early-humans-hibernation/ https://www.popularmechanics.com/science/a35033907/early-hum...)

lukan 2y ago
From glancing over, it does not really seem a confirmed fact, but a hypothesis. "They chose to spend the worst part of the year trying to sleep through it inside of relatively safe caves, and to do that, they sacrificed nutrition and vitamin D from the sun." Also it does not really matter for your vitamin D levels, if you are outside in winter in the north or in a cave. The sun is too low for the body to produce Vitamin D anyway (only the Inuit for example do not need sun, to produce Vitamin D btw. ) And that they lacked nutrition in winter can also just mean, that there simply was not much food in the winters, which is kind of expected, before humans developed storage and preservation technologies?
- seszett 2y ago
  > only the Inuit for example do not need sun, to produce Vitamin D btw As far as I can tell, they need vitamin D just like any other life form and can only synthesise it from the sun, just like all other lifeforms on Earth. They might have adapted to reduced amounts of available vitamin D though[0], because they don't have much of it available to them in the first place and because there's really no other source than producing your own from the sun, or eating things that have produced it from the sun. So they have a vitamin D deficiency, but it's less severe than for most people. [0]https://www.erudit.org/en/journals/etudinuit/2016-v40-n2-etudinuit04225/1055442ar/ https://www.erudit.org/en/journals/etudinuit/2016-v40-n2-etu...
  - hyperthesis 2y ago
    Don't they (traditionally) also have a much higher meat intake than average, which supplies vitamin D?
    - amenhotep 2y ago
      They particularly prized whale and seal blubber - very good vitamin D sources. Also present in the livers of the fish they'd eat raw.
  - lukan 2y ago
    I might have believed a urban legend then. I will look into that.
  - dredmorbius 2y ago
    Humans cannot synthesise vitamin D, but we can acquire it through diet from other sources, including particularly fresh fish, which are abundant in Inuit diets. Note that numerous of the sources listed here are fortified (that is, have additional vitamin D added), however it does occur naturally in some sources as well: <https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-sources https://www.dietaryguidelines.gov/resources/2020-2025-dietar...>
    - legulere 2y ago
      > The major natural source of vitamin D is synthesis of cholecalciferol in the lower layers of the epidermis of the skin, through a photochemical reaction with Ultraviolet B (UV-B) radiation from sun exposure or UV-B lamps.[ https://en.wikipedia.org/wiki/Vitamin_D https://en.wikipedia.org/wiki/Vitamin_D
      - dredmorbius 2y ago
        Yeah, very poor wording on my part as I was addressing the false claim in GP that only sunlight-based synthesis would provide vit-D. Diet is an alternate source. More in my other follow-up response.
        seszett 2y ago
        I said that they couldn't have another way to synthesise vitamin D than sunlight, it can only be synthesised by sunlight. So for the Inuit, vitamin D mostly comes from diet. The claim I was responding to was "they [unlike other humans] don't need sun to produce vitamin D". They do, they just don't rely much on this source because it doesn't work in their environment.
        dredmorbius 2y ago
        Fair enough. We both could have communicated more clearly :-/
    - 2y ago
yread 2y ago
That first article from BMJ 1900 reads a bit like Gulliver tales. The second article is about hominids 400k years ago, quite long ago
- rrr_oh_man 2y ago
  400k years ago is not "quite long ago" on an evolutionary time scale.
  - yread 2y ago
    Sure, when you're looking at bacteria vs humans these guys are like our twins. But these non-homo hominins were not even our ancestors, they are close to Denisovans https://www.nature.com/articles/nature12788 https://www.nature.com/articles/nature12788 Our last common ancestor was ~990k years ago (table 1). That's quite long ago in human development
piuantiderp 2y ago
High serotonin, cold exposure, low sunlight. Almost makes you think one could hibernate. But then, to what purpose? Would likely shorten the lifespan, increase risk for cancer
- l2p 2y ago
  Space exploration seems like the obvious candidate to me.

lukan 2y ago

From glancing over, it does not really seem a confirmed fact, but a hypothesis. "They chose to spend the worst part of the year trying to sleep through it inside of relatively safe caves, and to do that, they sacrificed nutrition and vitamin D from the sun." Also it does not really matter for your vitamin D levels, if you are outside in winter in the north or in a cave. The sun is too low for the body to produce Vitamin D anyway (only the Inuit for example do not need sun, to produce Vitamin D btw. ) And that they lacked nutrition in winter can also just mean, that there simply was not much food in the winters, which is kind of expected, before humans developed storage and preservation technologies?

seszett 2y ago
> only the Inuit for example do not need sun, to produce Vitamin D btw As far as I can tell, they need vitamin D just like any other life form and can only synthesise it from the sun, just like all other lifeforms on Earth. They might have adapted to reduced amounts of available vitamin D though[0], because they don't have much of it available to them in the first place and because there's really no other source than producing your own from the sun, or eating things that have produced it from the sun. So they have a vitamin D deficiency, but it's less severe than for most people. [0]https://www.erudit.org/en/journals/etudinuit/2016-v40-n2-etudinuit04225/1055442ar/ https://www.erudit.org/en/journals/etudinuit/2016-v40-n2-etu...
- hyperthesis 2y ago
  Don't they (traditionally) also have a much higher meat intake than average, which supplies vitamin D?
  - amenhotep 2y ago
    They particularly prized whale and seal blubber - very good vitamin D sources. Also present in the livers of the fish they'd eat raw.
- lukan 2y ago
  I might have believed a urban legend then. I will look into that.
- dredmorbius 2y ago
  Humans cannot synthesise vitamin D, but we can acquire it through diet from other sources, including particularly fresh fish, which are abundant in Inuit diets. Note that numerous of the sources listed here are fortified (that is, have additional vitamin D added), however it does occur naturally in some sources as well: <https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-sources https://www.dietaryguidelines.gov/resources/2020-2025-dietar...>
  - legulere 2y ago
    > The major natural source of vitamin D is synthesis of cholecalciferol in the lower layers of the epidermis of the skin, through a photochemical reaction with Ultraviolet B (UV-B) radiation from sun exposure or UV-B lamps.[ https://en.wikipedia.org/wiki/Vitamin_D https://en.wikipedia.org/wiki/Vitamin_D
    - dredmorbius 2y ago
      Yeah, very poor wording on my part as I was addressing the false claim in GP that only sunlight-based synthesis would provide vit-D. Diet is an alternate source. More in my other follow-up response.
      - seszett 2y ago
        I said that they couldn't have another way to synthesise vitamin D than sunlight, it can only be synthesised by sunlight. So for the Inuit, vitamin D mostly comes from diet. The claim I was responding to was "they [unlike other humans] don't need sun to produce vitamin D". They do, they just don't rely much on this source because it doesn't work in their environment.
        dredmorbius 2y ago
        Fair enough. We both could have communicated more clearly :-/
  - 2y ago

yread 2y ago

That first article from BMJ 1900 reads a bit like Gulliver tales. The second article is about hominids 400k years ago, quite long ago

rrr_oh_man 2y ago
400k years ago is not "quite long ago" on an evolutionary time scale.
- yread 2y ago
  Sure, when you're looking at bacteria vs humans these guys are like our twins. But these non-homo hominins were not even our ancestors, they are close to Denisovans https://www.nature.com/articles/nature12788 https://www.nature.com/articles/nature12788 Our last common ancestor was ~990k years ago (table 1). That's quite long ago in human development

piuantiderp 2y ago

High serotonin, cold exposure, low sunlight. Almost makes you think one could hibernate. But then, to what purpose? Would likely shorten the lifespan, increase risk for cancer

l2p 2y ago
Space exploration seems like the obvious candidate to me.