If the hypothesis that going below 22C would activate brown fat burning & starving the tumor subsequently in due process, hold - this should have some evidence in people living in very cold climates (e.g. Siberians, Eskimos etc). I don't think the prevalence is statistically different in them. Would love to hear if someone knows more about it.
This seems presumptuous to me. Living in cold climates does not necessarily correlate with being cold more than people living in warm climates.
I grew up in Norway. The coldest winter I experienced saw 3 weeks of -30 celsius. I've lived in London the last 22 years. I didn't freeze more in Norway. We had better insulated houses, and far better winter clothes, because we needed to. And so if anything I more frequently get "caught out" and have to add extra layers of clothing etc. in the UK because you can get away with not being prepared for a cold winter here, while in Norway you will have a proper winter coat etc.
Had 2 Swedish people visiting Cape Town over winter, they said it was the coldest winter of their lives...the houses have no insulation, windows &doors drafty. Average house temperature indoors approx 10-15celcius.
Being from Scandinavia myself I’ve also visited Southern Europe several times during winter, thinking I’ll get a boost of sunshine, and it’ll be like spring. But the 10 C inside gets me every damn time, because as soon as you stop moving and sit down, you start freezing over.
My own apartment is so heavily insulated that even in the winter, it’s almost to make the indoor temperature drop below 20!
Where in southern Europe did you go? Where I'm from (Greece) it gets down to -20 C in the winter, so our houses are very well insulated and heated. They have to be, otherwise we'd burn up in the summer as well.
So a Russian professor came to teach in the south of Brazil (roughly same latitude as Cape Town). Apparently he had never experienced so much cold. Temperatures are rarely negative, but houses aren't heated.
Many from the southern US who visit cities in the Northern US are absolutely shocked to encounter places such as subway stations or shops without chilly air conditioning in the summer months. It had probably been quite some time since they'd been indoors for any significant amount of time without heavily cooled air.
NYC is interesting in this way, in a given year living here it’s very likely you’ll spend considerable time outside or in unconditioned spaces in windy 15F/-10C as well as humid 95F/35C weather.
There are obviously places in the US with far more extreme temperature fluctuations, but most of them are fully car dependent and many people living there can wind up experiencing the weather firsthand for seconds at a time (in parking lots), unless they deliberately choose to do otherwise.
Indeed. I lived in Boston for nearly twenty years. Car ownership there is usually more hassle than not and it's also quite expensive. Most housing near subway stations is also incredibly expensive so most people rely on spotty bus service supplemented with longer walks, bicycles, and taxis/ride shares for transport. In total, I must have spent months of time in 90F-100F humid summer sun or 10F howling wind late at night traveling or waiting for busses/trollies outdoors. The worst though was around March when it's just warm enough for the salty snow and ice either falling from the sky or lining the ground to be slush so you're perpetually damp, but it's just around the freezing point and windy. To boot, everything is grey and filthy and everybody else is miserable and you question how many more of those seasons you've got left in you. But the crisp autumn days and warm summer nights around there are absolutely magical. It almost seems worth the punishment.
Same experience in the Bay Area. Older houses have terrible insulation, so indoor temps are lower than further north where good insulation and ample heating exists.
> This seems presumptuous to me. Living in cold climates does not necessarily correlate with being cold more than people living in warm climates.
I understand the sentiment. While we have done climate control to our comforts, I am talking of environmental factors at large. Just because Norway has great heating & insulation doesn't imply Scandinavian climates are as good as Spanish ones. We get exposed to lower temperature climates in higher latitudes, and that thermal effect if any should add up over the few decades of human lifespan or even in the genetic assessment in terms of prevalence (in my OP). We are talking in statistical sense - not an individual trial.
Proper & consistent indoor thermal regulation have been around in past few decades, whereas useful medical record keeping has been around for a good two centuries in most of Europe & America (maybe slightly longer). So, my inquisitiveness is to check if this hypothesis matches with statistical observations in the northern population. And several medical studies do factor in environmental temperature (going by my brief exposure during grad school). These factors are not disregarded because we have great ACs for temperature management or sunscreens to block the UV. If human interventions could so effectively mitigate, skin cancer prevalence would be uniform around the globe (which absolutely isn't) due to effective sunscreens sold nowadays.
I think the more important factor here is internal body temperature, and if people living in colder climates exhibit the sorts of adaptations related in the article. It's quite possible to be outdoors in very cold conditions and have little to no core body temperature changes.
AFAICT, homeostatic temperature in humans does not vary by a great deal. It is 37±1°C always. I haven't come across a study where any large deviation was stated.
Human bodies lose heat very quickly. We evolved from a primate line which lived in South Central African plains. Our hand/feet digits are great radiators. Although still debated, our skin tone originally could have been light, much like the skin under the primate coats (with brown and African skin tones being later developments in evolution, when we started to get less furry & produced higher melatonin). So the evidence generally points in the direction that we are just another warm-blooded species without much thermal attributes. Given that, environment should show some kind of statistical difference if this cancer pathway's reliance on temperature is so pronounced. Its hard to measure, because there are several confounders in the biochemistry. It is also hard to find a body of people who have lived in both cold & hotter climates simultaneously to make direct comparisons
And I am saying I think this is presumptuous, as it doesn't match my experience.
I would argue based on experience that I would expect people in London to have been exposed to more cold than the average Norwegian.
By all means, it's worth checking, but my point is that if you don't find a difference, the logical conclusion is not that cold does not work, but that people in colder places don't get that cold.
EDIT: I would also argue that proper heating has been around for centuries, not decades. Regulating temperature down is a lot harder than regulating it up. In fact, the house I grew up on was a log house heated in part by a wood fire during winters - we used electrical ovens during fall or spring, but the wood oven could easily dump far more heat into the house in a very short amount of time, because it heated up a large stone chimney that was exposed in all the main rooms. But even a tiny cast iron oven can heat up a small house in no time if it's decently insulated - Norway's best established current cast iron oven manufacturer is over 160 years old. My grandparents cabin is heated that way, and you'd get it from freezing to room temperature in less than half an hour.
Yes -- my wife and I are both from the northern midwest. We live in San Francisco now. We are actually colder here in the winters, then we ever were in the midwest, because houses in San Francisco are not insulated, and don't have good heating systems. Whereas houses in the midwest are essentially little heating plants.
Life in the midwest is organized around staying warm and it works very well.
We do appreciate the blue skies and the sun of California, however. In the midwest in the winter, you can often go weeks without seeing the sun.
We also like the houses in California. They're historic and beautiful and in many cases greatly elegant. Also, easy (arguably continuous) outdoor access is a beautiful thing. But there is great irony in paper maché houses being, relatively, so much more expensive.
The inhabited Minnesota and North Dakota areas haven't seen multiple weeks of -30C/-22F in a very long time. Global Warming has affected these places as well. Not to say it doesn't reach <-22F at times (only down to -10F for a day or 2 in 2020 for Fargo, ND), but it's never weeks of that cold.
I belive in my lifetime from central ND there has not been that consistent cold of that for ~10 years but, a few weeks in a row of -10 were much more common. Although Grand Forks may be an exception as they are usually 5-10F cooler than central ND.
Out of curiosity, would you mind linking to a few brand/models of what you would consider a proper winter coat? I have mostly lived in milder climates and would be interested in knowing what kind of gear can keep you warm by -30C
Not -30C, but something similar to this[1] jacket on top of a shirt and warm undershirt have kept me reasonably warm in -20C canadian winters. The best way to stay warm is to have a windproof outer layer, then layer up (light layers!) underneath to trap the warm air close to you.
That looks like a pretty light jacket. I might wear that kind of thing skiing, but I'd want something heavier for in-town. A heavier jacket is nice because it's a pain to put on and take off a lot of layers just for a short trip outside.
I have a jacket similar to this one [1], and I find it to be a nice medium. However, if I had to do any work outside, I would get an actual parka.
That's the kicker, it's lighter weight, but the "omni-heat" insulation* keeps me just as warm as a heavier down jacket, if not warmer. I even managed to work up a bit of a sweat while outdoors at 3am this past Feburary in my jacket.
Though I don't doubt that I'd need a heavier/longer jacket if I were further north, but here in southern Ontario it's more than good enough.
The observation about wind proof outer layer is spot on. On the other hand the jacket from the link is too short for my taste. It requires special trousers to match.
One needs something that reaches knees to stay warm in lighter trousers.
I visited Northern Alberta ages ago, so I can imagine. But at least every house I went to was properly insulated (can you tell UK building standards annoy me)
I think there are likely many many confounding factors that would make extracting that data difficult. Separate from environmental/cultural factors we know that traditionally cold-weather cultures (Inuit for example) have genetic adaptions, including within the brown-fat cell pathways (for example: https://www.nature.com/articles/525429d). This would also make for confounders.
I think it's reasonable to go look for existing evidence, but it'd also be difficult to extrapolate.
Eskimo people have a mutation related to metabolism that prevents going to keto state when eating mostly meat. That alone can make proposed mechanism not working for them.
Plus the persistent cold exposure may not be there due to warm clothes.
For me more interesting is the story of cancer among aboriginal population of Australia. They do not use much clothes and at night there it can be rather cold.
I believe there is some evidence that those who grew up in colder climates prefer warmer interior temperatures. Imagine you live in Norway. In the winter, you need to heat your home so you pick a temperature you prefer. Now imagine you live in Seattle. You might not need to regularly heat your home to the degree required in Norway. When the temp dips below your normal temperature, you might acclimate to it instead of turning on the heat.
Possibly. I don't yet follow what relationship this fact has to finding evidence of lower cancer rates. Is it maybe you were answering to some other reply?
Well, people in this thread are saying the people in cold countries should have a lower cancer rate. My point is that people in cold countries may keep their homes warmer, and they might not spend much time below 22C, whereas people in more temperate climates may spend more time below 22C even if the climate is warmer.
In fact, cancer incidence and all cause mortality increase the further you are from the equator.
Brown fat activation is not efficient from an energy perspective. If you live somewhere cold, with generally sparse food supply, burning precious calories to warm yourself up isn’t a winning strategy. I highly doubt brown fat activation is more prevalent in the colder climate populations.
The inverse might actually be true, colder climate people tend to over-heat their houses and over-dress for cold making their core temperature on average warmer. Where as hotter climate people tend to under-dress and over cool their house with air conditioning making their core temperature on average cooler.
I read different take on that. There is a recent hypothesis that humans has a budget of energy that is spent each day independent of calorie intake, like 2500 kkal for a male, unless the body switches to the starvation mode with persistent multi-months calorie deficit.
If one does not do a physical activity and does not spent energy to warm the body, the body instead spends that energy budget on various expensive activities like synthesis of hormones (like testosterone for males) or to activate immune system more than necessary leading to asthma. But immune system for normal function does not require much energy and as long as one eats enough, the persistent cold exposure should not affect it.
