High Metabolism Allowed Evolution Of Greater Intelligence In Humans

As Haidut mentions here, good to see increasing recognition for the role of metabolism in intelligence.

"Humans are distinguished from the other living apes in having larger brains and an unusual life history that combines high reproductive output with slow childhood growth and exceptional longevity1. This suite of derived traits suggests major changes in energy expenditure and allocation in the human lineage, but direct measures of human and ape metabolism are needed to compare evolved energy strategies among hominoids. Here we used doubly labelled water measurements of total energy expenditure (TEE; kcal day−1) in humans, chimpanzees, bonobos, gorillas and orangutans to test the hypothesis that the human lineage has experienced an acceleration in metabolic rate, providing energy for larger brains and faster reproduction without sacrificing maintenance and longevity. In multivariate regressions including body size and physical activity, human TEE exceeded that of chimpanzees and bonobos, gorillas and orangutans by approximately 400, 635 and 820 kcal day−1, respectively, readily accommodating the cost of humans’ greater brain size and reproductive output. Much of the increase in TEE is attributable to humans’ greater basal metabolic rate (kcal day−1), indicating increased organ metabolic activity. Humans also had the greatest body fat percentage. An increased metabolic rate, along with changes in energy allocation, was crucial in the evolution of human brain size and life history."

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature17654.html

https://www.sciencedaily.com/releases/2016/05/160504141118.htm

 

Interesting. With increasing investment into larger brains, there demands ample "backup measures" to ensure long-term survivability, such as increased body fat percentage, social safety nets, communal parenting/emphasis on group cooperation, and the cultivation of crops of caloric density.

 

I used to have a large skull as child. Baseball caps could barely fit my head. My friends remarked on it. One guy, something of a bully, used to call me "big head". I was at the top of my class, too.

I think, as bad as it sounds, that my skull and, yeah, intellectual capacity have diminished somewhat throughout the years. For years I have wondered what was wrong with me, until I tried cyproheptadine and it made my anxiety disappear for a while, but also caused pain in my teeth. I ended up googling "braces" and "anxiety" and found articles like this one:

Is traditional orthodontic treatment just modern day cranial binding?
(Dental Extractions and Braces | autonomic-response.co.uk)

I have put the pieces together and there is no doubt that a lot of my issues, at least to a significant extent, are related to the orthodontic braces I wore from 1999 to 2006. The internet abounds with stories from people who have had very bad side-effects, both aesthetic and let's say "mental-health related", from mainstream orthodontic treatment.

Of course, these stories are "anecdotal", so here's a proper study:


The effect of orthodontic treatment on the concurrent development of the craniofacial complex

The thing is this: I wonder if the assembly line orthodontics has, you know, forced my teeth into a, let's call it a more "mainstream" shape... which would correspond to a smaller skull? And then my skull followed suit. I don't know, this is highly speculative on my part. I mean I'm sure the braces have messed my skull up somewhat but I don't know about the fine details.

I feel great when peating. More vigorous, more happy, more energetic. But my weird physical symptoms, the weird feeling on my face and skull, the muscular spams throughout the body... it all gets kind of worse in this high energy state. Like I wonder if having a somewhat messed up skull puts me in a less than optimal situation when it comes to trying to achieve an optimal energy state via peating. But I hope that's just neurotic thinking.

 

There is a "mainstream shape" but it's not necessarily towards a certain skull size. There are some characteristics that make having had orthodontics obvious: like vertically straight top incisors. Orthodontics can also create or worsen an overbite by locking the mandible one-tooth back. This could lead to tmj and the irritating of the trigeminal nerve which can explain facial pain. The teeth orientate the cranium bones, thus forcing the skull into an improper shape. That has many implications. When the teeth are free to move - post-braces- they might slowly progress towards more functionally proper positions. My guess is good metabolism and low serotonin will support the correction.

 

Well, the "mainstream shape" thing... There certainly are correspondences between the shape of one's face and skull and one's personality and intelligence. Phrenology is not a quack science. But this is delicate territory.

I have found several anti-orthodontics articles by practitioners of "craniosacral therapy". In one of them, if I recall correctly, the author says that each tooth corresponds to a particular region of the skull's surface. That doesn't seem too far-fetched to me.

As for my teeth spontaneously moving back to the right position, unfortunately that doesn't seem to be happening at all.

 

When I was a kid, my head was visibly bigger than my body lol but my parents thought it was cute. In school and among my family, it was my nickname, big head [insert my name]. I used to miss a lot of school days throughout the year and I didn't study for exams or prepared for anything but I averaged around the 5th of my class (usually 30 students) up until 8th grade when I got serious and decided to study and I got always 1st (not only of my class but also of the entire school) until 12th grade :) In the beginning I thought it was offensive to be called big head but then I embraced it because my father had told me "those who have big heads are usually leaders and know how to take good decisions." Certainly going on low carb (keto) diet was not a good decision though :P

 

Craniosacral therapists know about this stuff and will manipulate the cranial bones; the teeth will adjust to the corresponding position. Some might use a removable dental appliance in unison to work from both directions.
The teeth won't move spontaneously, but from function (like chewing, and the swallowing pattern).

 

Why do birds that have higher metabolism than us don't have big brains? Sometimes I find it confusing to say that a "high metabolism" (or metabolic rate) will lead to higher intelligence or higher longevity. There are so much parameters and variables in the human body and what we are doing here seems often a bit too simplistic and absolute.

 

https://www.sciencedaily.com/releases/2016/06/160613153411.htm

"The first study to systematically measure the number of neurons in the brains of birds has found that they have significantly more neurons packed into their small brains than are stuffed into mammalian and even primate brains of the same mass."

 

I come from a family of big heads. All eight siblings larger than average heads. Always wondered if that meant anything besides having to by large hats:)

 

Very interesting, thanks! So why aren't they more intelligent?

 

That's good to know, thanks. I think I'll try craniosacral therapy.

 

I think needing braces is more the result of a face that isn't large enough / too long. I doubt this has anything to do with small/big skulls. I find that people with larger faces have often straight teeth, whereas longer faces have their teeth crowded. Could be a lack of vitamin K or Boron, both seemed to have made my head larger. I have a hard time believing that restricting your teeth position at near/adult age would shrink the skull and the brain, there's no example in nature of such thing as far as I know. The neurological problems often cited could be from bacteria that gets in wisdom teeth spots when they are removed.