6 ms·

It’s tempting to see things like this and think “well of course it does, because that’s how we evolved”. But I think that might just be post-rationalization? At

It’s tempting to see things like this and think “well of course it does, because that’s how we evolved”. But I think that might just be post-rationalization? At the very least, I think the argument _doesn’t_ hold for periodic famine, extreme temperatures, most disease, etc even though we also evolved with those things. Is there any guiding principle that separates the things-we-evolved-with-that-are-good vs the -that-are-bad? Or is it really just a case-by-case examination?

Jweb_Guru 1y ago
Entirely case by case. It's further confounded by the fact that a bunch of things that are bad for us don't exert strong selective pressure in the first place.
- annsjdhs 1y ago
  > don't exert strong selective pressure in the first place This assumes we understand how these things work in the first place. It’s very likely our understanding of evolution is incomplete. I make this mistake a lot: 1. See thing that’s been done a long time a certain way 2. Modern recommendation is don’t do thing 3. Revised modern recommendation says “actually wait, do thing” 4. Revised modern recommendation is now ok because our incomplete model has been updated, whereas it should have always been ok because it’s been that way for a long time Put another way: we should give more weight to a repeated pattern observed over thousands of years and heavily question any science that goes against it. Both sides are just estimations, but nowadays it’s almost assumed “old ways bad”. Way too many cases that end up being “way humans have operated for millennia is actually ok”.
  - Jweb_Guru 1y ago
    I agree with you in general, but we understand enough of the mechanisms for how selective pressure occurs that we know it is often not the deciding factor in population-level changes. For example, the smallest and most rapidly replicating bacteria have such intense selective pressure that they even select against noncoding introns (extra energy during replication!) but this effect is already gone for larger and less rapidly-dividing bacteria. A lot of stuff simply does not affect fitness (either direct reproductive fitness or species survival) enough for that to be the deciding factor in its propagation, and without recognizing that an awful lot of evolutionary biology / population genetics isn't going to make much sense. In other words, the default hypothesis when we find that something humans often did in the past is bad for our health should certainly not be that there is some evolutionary advantage to the behavior. We are a fairly homogeneous population that has suffered several severe bottlenecking events, has fairly long and slow reproductive cycles, and has relatively few children. We also have aggressive active immune systems. Under these circumstances selective pressure is not super high, even before accounting for any of the modern life factors people often bring up. That doesn't mean it doesn't exist at all obviously, just that it's very case by case.
usef- 1y ago
The things you mention are sudden extremes: famine (extreme hunger), extreme temperature, being hit by a disease. The highest skin cancer group seems to be those that get sporadic extremes of sun (eg. the indoor office worker that burns on the weekend). That kind of rapid change in sunshine quantity was tough to ever do naturally. Even if you could hide from the sun in (rare) caves in the middle of summer it would be for hours not weeks. It wasn't something done normally in life. I do think we also have observation on our side here, as it has been seen for a long time that people with outdoor occupations have lower skin cancer rates than indoor (eg "Occupational sunlight exposure and melanoma in the U.S. Navy", 1990). Why those stories never broke through to the mainstream is an interesting question. (I know they're out of fashion now, but the paleo community was talking about doing ~10 minutes of direct sun a day almost two decades ago, with strict guidance to avoid burning, roughly based on the above reasons)
- jerlam 1y ago
  > Why those stories never broke through to the mainstream is an interesting question. The mainstream media in the US has never been great at communicating any story with nuance or depth. In the 80s and 90s, foods that we've eaten forever were being demonized, like eggs. In 2020, people were being told they shouldn't go outside lest they come within 100 feet of another person. To their credit, the general population has never had a shorter attention span and so easily hoodwinked into believing misleading claims. Australia's sun recommendations for people of differing skin types is not bad: https://www.sbs.com.au/news/article/tailored-protection-australias-sun-safety-guidelines-adapt-to-diverse-skin-types/tq4d4ihxj https://www.sbs.com.au/news/article/tailored-protection-aust...
globular-toast 1y ago
Yeah, I've always found it a very weird and weak argument. There are plenty of things we've evolved with that would be considered pretty bad for us now. For example, we evolved as a polygamous species (like virtually all mammals), meaning harams, lots of sexless males and fighting etc. Also important to remember evolution operates at a population level, not individual. We are descended from females that were able to survive at least pregnancy and carry the second to term, but it doesn't matter if they die in the second pregnancy. We're descended from males that were able to mate with said females, but they could have died very shortly after mating. So if you follow "what we evolved with" then that's all you're likely to get.
- amanaplanacanal 1y ago
  Where do you get the idea that we evolved as a polygamous species? The few remaining hunter-gatherer societies don't work like that. I think that kind of polygamy came with agriculture.
  - globular-toast 1y ago
    The existence of porn should be enough to show that we aren't monogamous. That and the fact that virtually no other mammal is including all the great apes. Monogamy is a thing in birds and they are literally dinosaurs.
    - amanaplanacanal 1y ago
      I think possibly we are using different definitions of polygamy. If you mean one male monopolizes the females, I disagree. If you mean that individuals (both male and female) don't mate with just one person, then I agree.
qalmakka 1y ago
Exactly - as if evolution cared enough about keeping us healthy after childbearing age. It's hard to state "yeah we've evolved to live like that, of course it's good for us" because clearly keeping us alive after the age of 40 really wasn't _that_ necessary for human survival. There's a lot of perfectly natural stuff that hurts us, including sunlight. Most cancers will only occur in the latter half of our lives, where usually a human historically had already had several children that are now old enough to survive on their own.
- papyrus9244 1y ago
  > because clearly keeping us alive after the age of 40 really wasn't _that_ necessary for human survival. That's a very common misconception. Being alive after 40 is quite necessary if you are a member of a gregarious species that (bar exceptions) always lives in community. And it's not only about the survival of your own genes, it's about the survival of the genes of the whole community.
- DoctorOetker 1y ago
  Selection pressure does not simply select on "did or did not reproduce" it selects on reproduction rate (compare 2 individuals, both having parented a first child, but one dies afterwards while the other continues to occasionally reproduce before dying. The latter displays higher fitness. Its like any poisson process, a recent event does not inherently lower the probability density for the next event. Achieving the minimum necessary for reproduction is not representative of the distribution of reproductive success scores.
brightball 1y ago
Since I was a little kid I was always skeptical of slathering something all over my body just to go outside. Just thought…how did people survive before this stuff if we really need it so bad.
- adrianN 1y ago
  If you ask „how did people survive“ the answer is more often than not: „with great difficulty“. Take for example simple hygiene measures like using soap or brushing your teeth or disinfecting wounds.
  - datadrivenangel 1y ago
    Teeth brushing is not as important if you're not eating modern food. Processed sugars really are terrible (but delicious)
    - adrianN 1y ago
      If by modern you mean anything since agriculture was invented, then perhaps.
  - laserlight 1y ago
    Or, the answer is simply “they didn't survive”, which is the case for countless babies who died because an activity as simple as hand-washing wasn't known to be a matter of life and death.
- TinkersW 1y ago
  Often living in a different climate zone, US is well south of Europe.
  - lstodd 1y ago
    56th latitude person can be literally baked by northern mediterannean (~42 lat) March sun in a couple of days. But a couple months later.. no problems climbing mountains all day. We are very adaptable.

Jweb_Guru 1y ago

Entirely case by case. It's further confounded by the fact that a bunch of things that are bad for us don't exert strong selective pressure in the first place.

annsjdhs 1y ago
> don't exert strong selective pressure in the first place This assumes we understand how these things work in the first place. It’s very likely our understanding of evolution is incomplete. I make this mistake a lot: 1. See thing that’s been done a long time a certain way 2. Modern recommendation is don’t do thing 3. Revised modern recommendation says “actually wait, do thing” 4. Revised modern recommendation is now ok because our incomplete model has been updated, whereas it should have always been ok because it’s been that way for a long time Put another way: we should give more weight to a repeated pattern observed over thousands of years and heavily question any science that goes against it. Both sides are just estimations, but nowadays it’s almost assumed “old ways bad”. Way too many cases that end up being “way humans have operated for millennia is actually ok”.
- Jweb_Guru 1y ago
  I agree with you in general, but we understand enough of the mechanisms for how selective pressure occurs that we know it is often not the deciding factor in population-level changes. For example, the smallest and most rapidly replicating bacteria have such intense selective pressure that they even select against noncoding introns (extra energy during replication!) but this effect is already gone for larger and less rapidly-dividing bacteria. A lot of stuff simply does not affect fitness (either direct reproductive fitness or species survival) enough for that to be the deciding factor in its propagation, and without recognizing that an awful lot of evolutionary biology / population genetics isn't going to make much sense. In other words, the default hypothesis when we find that something humans often did in the past is bad for our health should certainly not be that there is some evolutionary advantage to the behavior. We are a fairly homogeneous population that has suffered several severe bottlenecking events, has fairly long and slow reproductive cycles, and has relatively few children. We also have aggressive active immune systems. Under these circumstances selective pressure is not super high, even before accounting for any of the modern life factors people often bring up. That doesn't mean it doesn't exist at all obviously, just that it's very case by case.

usef- 1y ago

The things you mention are sudden extremes: famine (extreme hunger), extreme temperature, being hit by a disease. The highest skin cancer group seems to be those that get sporadic extremes of sun (eg. the indoor office worker that burns on the weekend). That kind of rapid change in sunshine quantity was tough to ever do naturally. Even if you could hide from the sun in (rare) caves in the middle of summer it would be for hours not weeks. It wasn't something done normally in life. I do think we also have observation on our side here, as it has been seen for a long time that people with outdoor occupations have lower skin cancer rates than indoor (eg "Occupational sunlight exposure and melanoma in the U.S. Navy", 1990). Why those stories never broke through to the mainstream is an interesting question. (I know they're out of fashion now, but the paleo community was talking about doing ~10 minutes of direct sun a day almost two decades ago, with strict guidance to avoid burning, roughly based on the above reasons)

jerlam 1y ago
> Why those stories never broke through to the mainstream is an interesting question. The mainstream media in the US has never been great at communicating any story with nuance or depth. In the 80s and 90s, foods that we've eaten forever were being demonized, like eggs. In 2020, people were being told they shouldn't go outside lest they come within 100 feet of another person. To their credit, the general population has never had a shorter attention span and so easily hoodwinked into believing misleading claims. Australia's sun recommendations for people of differing skin types is not bad: https://www.sbs.com.au/news/article/tailored-protection-australias-sun-safety-guidelines-adapt-to-diverse-skin-types/tq4d4ihxj https://www.sbs.com.au/news/article/tailored-protection-aust...

globular-toast 1y ago

Yeah, I've always found it a very weird and weak argument. There are plenty of things we've evolved with that would be considered pretty bad for us now. For example, we evolved as a polygamous species (like virtually all mammals), meaning harams, lots of sexless males and fighting etc. Also important to remember evolution operates at a population level, not individual. We are descended from females that were able to survive at least pregnancy and carry the second to term, but it doesn't matter if they die in the second pregnancy. We're descended from males that were able to mate with said females, but they could have died very shortly after mating. So if you follow "what we evolved with" then that's all you're likely to get.

amanaplanacanal 1y ago
Where do you get the idea that we evolved as a polygamous species? The few remaining hunter-gatherer societies don't work like that. I think that kind of polygamy came with agriculture.
- globular-toast 1y ago
  The existence of porn should be enough to show that we aren't monogamous. That and the fact that virtually no other mammal is including all the great apes. Monogamy is a thing in birds and they are literally dinosaurs.
  - amanaplanacanal 1y ago
    I think possibly we are using different definitions of polygamy. If you mean one male monopolizes the females, I disagree. If you mean that individuals (both male and female) don't mate with just one person, then I agree.

qalmakka 1y ago

Exactly - as if evolution cared enough about keeping us healthy after childbearing age. It's hard to state "yeah we've evolved to live like that, of course it's good for us" because clearly keeping us alive after the age of 40 really wasn't _that_ necessary for human survival. There's a lot of perfectly natural stuff that hurts us, including sunlight. Most cancers will only occur in the latter half of our lives, where usually a human historically had already had several children that are now old enough to survive on their own.

papyrus9244 1y ago
> because clearly keeping us alive after the age of 40 really wasn't _that_ necessary for human survival. That's a very common misconception. Being alive after 40 is quite necessary if you are a member of a gregarious species that (bar exceptions) always lives in community. And it's not only about the survival of your own genes, it's about the survival of the genes of the whole community.
DoctorOetker 1y ago
Selection pressure does not simply select on "did or did not reproduce" it selects on reproduction rate (compare 2 individuals, both having parented a first child, but one dies afterwards while the other continues to occasionally reproduce before dying. The latter displays higher fitness. Its like any poisson process, a recent event does not inherently lower the probability density for the next event. Achieving the minimum necessary for reproduction is not representative of the distribution of reproductive success scores.

brightball 1y ago

Since I was a little kid I was always skeptical of slathering something all over my body just to go outside. Just thought…how did people survive before this stuff if we really need it so bad.

adrianN 1y ago
If you ask „how did people survive“ the answer is more often than not: „with great difficulty“. Take for example simple hygiene measures like using soap or brushing your teeth or disinfecting wounds.
- datadrivenangel 1y ago
  Teeth brushing is not as important if you're not eating modern food. Processed sugars really are terrible (but delicious)
  - adrianN 1y ago
    If by modern you mean anything since agriculture was invented, then perhaps.
- laserlight 1y ago
  Or, the answer is simply “they didn't survive”, which is the case for countless babies who died because an activity as simple as hand-washing wasn't known to be a matter of life and death.
TinkersW 1y ago
Often living in a different climate zone, US is well south of Europe.
- lstodd 1y ago
  56th latitude person can be literally baked by northern mediterannean (~42 lat) March sun in a couple of days. But a couple months later.. no problems climbing mountains all day. We are very adaptable.