Comment by austin-cheney | Hacker News Reader

Comment by austin-cheney | Hacker News Reader

> However, the mechanisms linking cerebral blood flow increase to metabolic changes in the brain affecting cognition remain unclear.

Stanford research published after that article provides that answer: Face shape. It's not just better cognitive performance but the alternative contributes to face shape commonly perceived as "not beautiful".

The Stanford research, and no I don't have a link, concludes there are two activities responsible for these traits: slurping soft foods and mouth breathing. The alternative to chewing hard foods is slurping soft foods and the frequent activity of slurping alters the shape of a person's face as they grow because humans were really only designed to consistently slurp soft foods in infancy, but the shape of the face will elongate to compensate for slurping along with inferior jaw bone strength.

The alternative to nose breathing is mouth breathing, which drastically lowers oxygen intake which mimics and contributes to sleep apnea like conditions even while awake. There is a measured cognitive decline associated with the degree of oxygen suppressed in air intake. Mouth breathing also negatively contributes to developmental face shape, but less so than slurping soft foods.

I don't get why mouth-breathing drastically lowers oxygen intake.

As I understand it, when exhaling, the nose create backpressure that facilitates gas transfer in the lungs.

However, my nose is decorative, and I must breath though my mouth. No repercussions as I can mountain climb.

Makes no sense - I'd expect the opposite, given how easier it is to breathe in and out larger volume of air through the mouth than through the nose.

Why? Internally to the face the nasal cavity is massive and largely not restricted, especially compared to the throat (pharynx) which is restricted and can accept only small volumes of air at a time. Because of that the body must work substantially harder to permit large air volumes through mouth breathing.

Just search google images for "pharynx". The visual difference in size is striking.

1. Your nose connects to the same tube as your mouth. Both paths pass through the throat and pharynx.

2. Compare the aperture size of the nostrils to the mouth and throat

3. Just look at the internal structure of the nasal cavity. It's a sensory organ and designed to maximize surface area contacting the air. In other words, it's full of obstructions that intentionally reduce airflow

Your thesis here is nonsense. You can't change a downstream restriction by changing conditions upstream.

If anything, adding restriction is probably what helps. By restricting airflow upstream of the lungs, you create a partial vacuum within the lungs which probably substantially alters the conditions for gas exchange. A partial vacuum probably greatly enhances CO2 rejection from the blood, but I'm not a biochemist.

I take it you invented some baseless conjecture. As a casual suggestion try searching the web for "mouth versus nose breathing" and see what the results say.

One of my biggest complaints about software developers is that so many claim to be engineers, but instead of measuring things (which is what engineers do) so many invent their own conclusions that tend to be wrong almost every time. It's disappointing.

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