Skull duggery ping.
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So the forces that pull the spine towards the chin and the chin towards the spine are connected and may also be connected to the enlargement of the top of the skull. Wow. Not really earth shattering.
I wouldn’t be surprised if they find out the skull shape shifting process has nothing to do with anything they think it does. I remember an experiment the russians did on foxes. They bred them to be more docile in cages to help the fur industry. All of a sudden they started getting dog like secondary characteristics...white spots in their coats, odd colors, floppy ears, barking...all because they bred for a subdued fight/flight response to stress.
The movements of human skull development that pinches spine to chin together could be something as simple as a response to dietary changes, or lack of sun exposure due to indoor living. Or something completely unexpected like a result of not going barefoot.