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From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Disc Compatibility?
Date: Sat, 8 Mar 2025 12:22:58 -0500
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On 3/7/2025 11:10 PM, Jeff Liebermann wrote:
> On Fri, 7 Mar 2025 22:00:21 -0500, Frank Krygowski
> <frkrygow@sbcglobal.net> wrote:
> 
>> On 3/7/2025 8:35 PM, Jeff Liebermann wrote:
>>>
>>> Primitive man was a pyromaniac.  Whenever the necessary combustibles
>>> and appropriate weather were available, primitive man would start and
>>> tend a fire.  Most sources claim that the fire was mostly to keep man
>>> warm during various ice ages.  However, I believe the man was
>>> hypnotized by the flickering flame.
>>>
>>> At some point in the distance past, man set fire to his dinner and
>>> thus invented cooking.
>>
>> I read an interesting article claiming that fire may have been critical
>> to evolution of humans. The claim was that cooking makes food much
>> easier to digest, and thus extract nutritional calories.
>>
>> Since our large brains consume an outsized portion of our calories, that
>> cooking over fire was necessary to the evolution of large brains.
>> Without cooking, the theory goes, large brained proto-humans would have
>> starved.
>>
>> https://pmc.ncbi.nlm.nih.gov/articles/PMC124895/
>>
>> "In the average adult human, the brain represents about 2% of the body
>> weight. Remarkably, despite its relatively small size, the brain
>> accounts for about 20% of the oxygen and, hence, calories consumed by
>> the body."
> 
> I don't think it's 20% oxygen (by weight) but rather is 20% sugar or
> glucose (by weight):
> 
> "Sugar for the brain: the role of glucose in physiological and
> pathological brain function"
> <https://pmc.ncbi.nlm.nih.gov/articles/PMC3900881/>
> Same as above except in easier to read PDF format:
> <https://pmc.ncbi.nlm.nih.gov/articles/PMC3900881/pdf/nihms-510105.pdf>
> "In humans, the brain accounts for ~2% of the body weight, but it
> consumes ~20% of glucose-derived energy making it the main consumer of
> glucose (~5.6 mg glucose per 100 g human brain tissue per minute)."
> 
> "It has been suggested that action potentials have been rendered
> highly efficient through evolution, and thus most of the energy
> consumed in the brain is used on synaptic activity"
> 
> Also, please note that oxygen, by itself, does NOT contain calories.

My assumption was that the oxygen used by an organ is proportional to 
the number of calories consumed by that organ. Of course oxygen is 
nearly weightless, and of itself does not contain calories. That's 8th 
grade stuff.


-- 
- Frank Krygowski