This is good but I’d want to see deeper dives into why this wouldn’t have been selected for. Could it plausibly really just be a fat-burning thing? Why wouldn’t that have been selected for by, say, agricultural humanity? (And why wouldn’t this metabolic parameter be modulated adaptively/physiologically?) Does this mess with subtle neural processes with effects that researchers don’t know how to measure, e.g. in a way that affects peak intelligence?
I think that calorie needs did matter to agricultural humanity. When there wasn’t enough food, people could starve in winter.
I spoke about two hypotheses in my post, fat-burning is just one of them.
The cavefish are interesting because they exist in an environment that actually has strong evolutionary pressure for shorter sleep. They can mate with surface fish, so without any evolutionary pressure, the differences between them wouldn’t be sustained. There are also multiple caves that all have evolved shorter sleep.
And why wouldn’t this metabolic parameter be modulated adaptively/physiologically?
Parameters don’t evolve directly. Evolution is about whether or not a given mutation is advantageous or isn’t.
Parameters don’t evolve directly. Evolution is about whether or not a given mutation is advantageous or isn’t.
Yeah… but I’m saying, why wasn’t this modulated physiologically? Lots of stuff is modulated physiologically. Why wouldn’t it be modulated by how much food there’s been recently?
Reducing the amount of orexin in the body might be very well the way it’s modulated physiologically. Plenty of animals hibernate in the winter when they sleep more and eat less.
Ok now I think you just didn’t get what I mean by that. I mean how a bacterium will make lactase when there’s lactose, but won’t make lactose when there isn’t lactose. That’s a physiological adaptation as opposed to a genetic adaptation. It’s of course mediated by genetically programmed mechanisms, but the variation is mediated by physiological changes, not by naturally selected changes in a gene pool. I’m asking why orexin wouldn’t be physiologically adaptive to the amount of food that’s generally around.
I mean how a bacterium will make lactase when there’s lactose, but won’t make lactose when there isn’t lactose.
It’s quite easy to have a receptor protein that binds to lactose and then leads to a protein being expressed that turns lactose into lactase.
“amount of available food in the environment” is not as simple to measure inside of a cell and as a result, the regulation is much more complex.
I’m asking why orexin wouldn’t be physiologically adaptive to the amount of food that’s generally around.
That assumes that orexin is independent of food that’s around, which clearly isn’t true. Fasting increases orexin levels, it’s just that chronic food restriction that doesn’t change it.
Hm. So orexin is increased initially during a fast, and also when eating high-caloric food? That’s weird. Do people who eat high-caloric food need less sleep?
This is good but I’d want to see deeper dives into why this wouldn’t have been selected for. Could it plausibly really just be a fat-burning thing? Why wouldn’t that have been selected for by, say, agricultural humanity? (And why wouldn’t this metabolic parameter be modulated adaptively/physiologically?) Does this mess with subtle neural processes with effects that researchers don’t know how to measure, e.g. in a way that affects peak intelligence?
Maybe another reason why it might not have been such a great fitness advantage is that activity was effectively constrained by daylight availability?
I think that calorie needs did matter to agricultural humanity. When there wasn’t enough food, people could starve in winter.
I spoke about two hypotheses in my post, fat-burning is just one of them.
The cavefish are interesting because they exist in an environment that actually has strong evolutionary pressure for shorter sleep. They can mate with surface fish, so without any evolutionary pressure, the differences between them wouldn’t be sustained. There are also multiple caves that all have evolved shorter sleep.
Parameters don’t evolve directly. Evolution is about whether or not a given mutation is advantageous or isn’t.
Yeah… but I’m saying, why wasn’t this modulated physiologically? Lots of stuff is modulated physiologically. Why wouldn’t it be modulated by how much food there’s been recently?
Reducing the amount of orexin in the body might be very well the way it’s modulated physiologically. Plenty of animals hibernate in the winter when they sleep more and eat less.
But then why don’t modern well-fed humans sleep much less without detriment? (Or do they?)
Because evolution didn’t had the time to select for the mutations that would result in that outcome.
Ok now I think you just didn’t get what I mean by that. I mean how a bacterium will make lactase when there’s lactose, but won’t make lactose when there isn’t lactose. That’s a physiological adaptation as opposed to a genetic adaptation. It’s of course mediated by genetically programmed mechanisms, but the variation is mediated by physiological changes, not by naturally selected changes in a gene pool. I’m asking why orexin wouldn’t be physiologically adaptive to the amount of food that’s generally around.
It’s quite easy to have a receptor protein that binds to lactose and then leads to a protein being expressed that turns lactose into lactase.
“amount of available food in the environment” is not as simple to measure inside of a cell and as a result, the regulation is much more complex.
That assumes that orexin is independent of food that’s around, which clearly isn’t true. Fasting increases orexin levels, it’s just that chronic food restriction that doesn’t change it.
Hm. So orexin is increased initially during a fast, and also when eating high-caloric food? That’s weird. Do people who eat high-caloric food need less sleep?
Where did you get the claim about eating high caloric food?
“Here, we review a fat-burning mechanism that is turned on by the brain hormone orexin during high-caloric food consumption.”
Maybe they’re not saying that the diet upregulates orexin?
We’re talking about a physiological adaptive mechanism.