facial development schizopost

[loty]

i've been thinking about the whole issue of craniofacial development from a completely different angle and wondering whether the facial structure is limited in any way due to the brain’s energy requirements.

the brain is a very expensive organ in terms of energy. it accounts for 20% of the body’s energy expenditure and only makes up 2% of the body’s mass. evolution has therefore favored structures that make the brain as efficient as possible in terms of blood flow, oxygenation, and temperature regulation.

the skull is obviously necessary for protecting the brain, and the whole system of blood vessels is contained entirely within the skull. the fascinating thing is that the bones of the midface and the base of the skull are responsible for the geometry of this system.

the arteries, including the internal carotid and vertebral arteries, run through very specific places in the skull and then spread out over the cavity of the skull. the base of the skull affects the path these arteries will follow.

what’s particularly interesting is that cranial base growth has an important influence on the projection of the face. If the cranial base flexes forward during development, the mid-face tends to project more. If the cranial base angle is flatter, the face tends to be recessed.

so, here’s the hypothesis

Craniofacial development might not be subject only to considerations of beauty or form. It might also be subject to considerations of the most efficient form of circulation.

If the skull is developing in a way that maximizes the blood flow and minimizes the thermoregulatory load on the brain, this could indirectly affect the position of the maxilla and the mandible.

This could explain the prevalence of certain craniofacial configurations in the human race, despite the enormous diversity of the human genome. This could be due to the fact that the brain places certain restrictions on the development of the skull.

The face might simply exist as a sort of structural afterthought to the development of the brain, as opposed to something that necessarily exists for the purpose of chewing food or breathing.

if that’s the case, the face might be governed by certain kinds of developmental factors that influence the growth of the brain.

things like nutrition, metabolic rate, and overall growth environment might play a role in the formation of the cranial base, which in turn might affect the rest of the facial skeleton.

 

[dragomog]

dnr

 

[notamonLTNsub5]

this simply isn't biologically possibly.

 

[loty]

this simply isn't biologically possibly.

the cranial base morphological aspects affecting facial projection are already well established in craniofacial biology. the premise is not biologically impossible. the hypothesis is simply that there are constraints related to brain growth and cranial base development that may indirectly affect facial structure.

 

[notamonLTNsub5]

the cranial base morphological aspects affecting facial projection are already well established in craniofacial biology. the premise is not biologically impossible. the hypothesis is simply that there are constraints related to brain growth and cranial base development that may indirectly affect facial structure.

all of your features are genetically capped including brain size lol, the morphological aspects are taken way out of proportion, you should of resolved to the consensus that things like this are already determined basically undermining the whole theory.

 

[PharmaPhaggot]

Exept the relevant metric for brsin function is synapse amount and planning, not brain size

 

[Scandicel]

Exept the relevant metric for brsin function is synapse amount and planning, not brain size

did you geniuenly read ts

 

[PharmaPhaggot]

did you geniuenly read ts

Skimmed

 

[loty]

Exept the relevant metric for brsin function is synapse amount and planning, not brain size

while the size of the brain does not in itself determine the brain's function, it is still correlated with the number of neurons and the overall potential for connections in a species. synapse arrangement is more critical for cognitive abilities, although skull growth is limited by the size of the brain. correct me if im wrong, im not too educated on this type of stuff

 

[PharmaPhaggot]

while the size of the brain does not in itself determine the brain's function, it is still correlated with the number of neurons and the overall potential for connections in a species. synapse arrangement is more critical for cognitive abilities, although skull growth is limited by the size of the brain. correct me if im wrong, im not too educated on this type of stuff

Number of neurons is also not a very relevant metric, it just sets the upper limit foe synapsd formation but very few reach it anyway

 

[loty]

Number of neurons is also not a very relevant metric, it just sets the upper limit foe synapsd formation but very few reach it anyway

that’s basically what I meant. neuron count doesn’t influence cognition directly, but it still influences the potential capacity for neural connections. the main point was that the growth of the brain still imposes structural limits on the growth of the skull.

 

[PharmaPhaggot]

that’s basically what I meant. neuron count doesn’t influence cognition directly, but it still influences the potential capacity for neural connections. the main point was that the growth of the brain still imposes structural limits on the growth of the skull.

Right but this impact is on an irelevant metric, will not affect function what so ever so there isnt gonna be any evolutionsiry pressure to select this so it wouldnt explain any difference, there is selection preasure for face tho so it csnt be the afterthought, neurogenesis is also pretty much as genetic as it gets, theres nothing you could do to evem come close to significantly chsnging it

 

[loty]

Right but this impact is on an irelevant metric, will not affect function what so ever so there isnt gonna be any evolutionsiry pressure to select this so it wouldnt explain any difference, there is selection preasure for face tho so it csnt be the afterthought, neurogenesis is also pretty much as genetic as it gets, theres nothing you could do to evem come close to significantly chsnging it

yeah, that's fair, neurogenesis and overall brain growth are mainly under genetic control, and therefore there's not likely much scope for the environment to influence that. however, the point i was getting at with the brain volume was that it puts physical constraints that the skull must accommodate during growth, although again, you're right that facial morphology is likely subject to its own selection pressures.

 

[PharmaPhaggot]

yeah, that's fair, neurogenesis and overall brain growth are mainly under genetic control, and therefore there's not likely much scope for the environment to influence that. however, the point i was getting at with the brain volume was that it puts physical constraints that the skull must accommodate during growth, although again, you're right that facial morphology is likely subject to its own selection pressures.

And then even if the theory is practicslly irelevant then maybe? If the size of the brain is irelevant i see no reason for need for restrictions, it could make the brain a bit smaller and get vessels there, and even if it wad needed these vessels are incredibly tiny, so even a system is small, we also dont know which restricts which or if they restrict at all no matter if the restriction is logicsl or not, youd need genetic analisyses for it to be reasonable

 

[loty]

And then even if the theory is practicslly irelevant then maybe? If the size of the brain is irelevant i see no reason for need for restrictions, it could make the brain a bit smaller and get vessels there, and even if it wad needed these vessels are incredibly tiny, so even a system is small, we also dont know which restricts which or if they restrict at all no matter if the restriction is logicsl or not, youd need genetic analisyses for it to be reasonable

my point was simply that the growth of the brain must be accommodated physically in the skull, but without genetic or developmental evidence for that, it’s rather speculative.

 

[PharmaPhaggot]

my point was simply that the growth of the brain must be accommodated physically in the skull, but without genetic or developmental evidence for that, it’s rather speculative.

Who says that? I could just flip it around and say all growth by the cranium must be accomodated by the brain

 

[loty]

Who says that? I could just flip it around and say all growth by the cranium must be accomodated by the brain

i mean, of course, that the skull literally increases in size as it develops to allow for brain growth, but that’s just simple biological knowledge, and as I said, the connection to facial form was just a speculative idea anyway.