> 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.
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.