If this theory held true, wouldn’t we already be seeing heat resistant fungi that attacked humans on tropical islands and equatorial areas that have high temperatures for much of the year?
Good thought process here, but most places with very warm weather are equatorial, which means the variation in temperatures is much lower than you would see in london, which means that more organisms die that are unprepared for the temperature swing in london and south korea, prompting a much bigger selection effect, and often earlier emergence. The South Africa strain is a good example of what you're talking about however!
isn't the required selection pressure one that promotes heat-shock-resistant proteins? not sure why the variance matters more than heat. body temperature is year-round 98.6... awfully close to Singapore, say
Sure! There are lots of microbes that do survive at body temperature in and around places where the temperature stays at body temperature. However, our immune system usually already has antibody responses to these organisms, because environmental microbes in these areas have been able to survive at that temperature for a long time (as long as there has been a native population of bacteria) and we've had exposure to these for a long time. The microbes in places where there is variance, are less likely to be on our immune system's list of prime suspects, which is why body temperature plays a larger part in these instances. In this way, more instances of variance mean more mutations of previously unknown (to our immune systems) bacteria, which is why they're so dangerous! Hope that helps clear things up!
But then shouldn't we be seeing massive casualties from people traveling from Northern regions to tropical islands? Someone from Iceland would reasonably lack immunity to heat-resistant bacteria as they're 100% guaranteed to be missing from Iceland where the temperature *record* is 86.9 degrees and the median is far below that.
Now... tropical-only diseases are indeed a thing - malaria, dengue fever, yellow fever, but these have been known for centuries. It is also common to get a "stomach bug" when eating untreated water in tropical regions but that's rarely deadly. But we aren't aware of any deadly fungus in, say, Costa Rica that exclusively preys on travelers from the far north who don't have recent ancestors from the tropics.
You *could* point out to every humans ancestors coming from sub-Saharan Africa and thus carrying some resistance to such bacteria genetically, but then how do we explain the lack of massive European casualties in, say, Australia which has a tropical climate and its own unique ecosystem due to being far away from other continents? Same for South/Central America and various islands in the Pacific ocean - surely they have their own unique bacteria/viruses/fungi which should be killing Icelanders en masse if they visit?
I love this substack so far, it is like a succinct Slate Star.
If this theory held true, wouldn’t we already be seeing heat resistant fungi that attacked humans on tropical islands and equatorial areas that have high temperatures for much of the year?
this was my thought, too. like south Korea and London can spawn super fungi, but not the many many places that are much warmer?
Good thought process here, but most places with very warm weather are equatorial, which means the variation in temperatures is much lower than you would see in london, which means that more organisms die that are unprepared for the temperature swing in london and south korea, prompting a much bigger selection effect, and often earlier emergence. The South Africa strain is a good example of what you're talking about however!
isn't the required selection pressure one that promotes heat-shock-resistant proteins? not sure why the variance matters more than heat. body temperature is year-round 98.6... awfully close to Singapore, say
Sure! There are lots of microbes that do survive at body temperature in and around places where the temperature stays at body temperature. However, our immune system usually already has antibody responses to these organisms, because environmental microbes in these areas have been able to survive at that temperature for a long time (as long as there has been a native population of bacteria) and we've had exposure to these for a long time. The microbes in places where there is variance, are less likely to be on our immune system's list of prime suspects, which is why body temperature plays a larger part in these instances. In this way, more instances of variance mean more mutations of previously unknown (to our immune systems) bacteria, which is why they're so dangerous! Hope that helps clear things up!
But then shouldn't we be seeing massive casualties from people traveling from Northern regions to tropical islands? Someone from Iceland would reasonably lack immunity to heat-resistant bacteria as they're 100% guaranteed to be missing from Iceland where the temperature *record* is 86.9 degrees and the median is far below that.
Now... tropical-only diseases are indeed a thing - malaria, dengue fever, yellow fever, but these have been known for centuries. It is also common to get a "stomach bug" when eating untreated water in tropical regions but that's rarely deadly. But we aren't aware of any deadly fungus in, say, Costa Rica that exclusively preys on travelers from the far north who don't have recent ancestors from the tropics.
You *could* point out to every humans ancestors coming from sub-Saharan Africa and thus carrying some resistance to such bacteria genetically, but then how do we explain the lack of massive European casualties in, say, Australia which has a tropical climate and its own unique ecosystem due to being far away from other continents? Same for South/Central America and various islands in the Pacific ocean - surely they have their own unique bacteria/viruses/fungi which should be killing Icelanders en masse if they visit?
You're applying logic to fear porn.
People absolutely love scientify fear porn.
You're still right.
Also, the climate warming models have been woefully wrong for decades. https://issuesinsights.com/2021/06/28/putting-climate-models-on-trial/
Thanks that comment cleared it up for me!
you should get some credit from the The Last of Us ep1 scriptwriters for this