@Ritchie It's not a coincidence that balding men have ridges on the galea.
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If they have ridges on the front that means that the metopic suture hasn't fused properly and fused too early.
If they have ridges at the center, then the coronal suture hasn't fused correctly.
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I checked saw images of babies with craniosynostosis and I saw how their headhapes are similar to the ones of balding men.
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Notice the Norwood 7 horseshoe pattern some of them display. I doubt that this is a coincidence.
In the articles about craniosynostosis it's mentioned that this condition leads to cranial pressure because the scull can't provide enough space for the expanding brain. I think that this cranial pressure is what triggers overdevelopment and hypertrophy of the scalp muscles mentioned in this study.
Androgenic alopecia, also known as pattern hair loss, is a chronic progressive condition that affects 80% of men and 50% of women throughout a lifetime. But despite its prevalence and extensive study, a coherent pathology model describing androgenic alopecia's precursors, biological...
pubmed.ncbi.nlm.nih.gov
It's still unclear to me why men who have their metopic suture fused prematurely lose more hair at the crown while men who have their coronal or sagittal suture have predominantly frontal hair loss.
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Notice Zinedine Zidane's head shape and ridges and his hair loss pattern.
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Then look at this guy's head shape.
And when a balding man shaves his head it clearly doesn't look the same as when a non balding man does.
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Non balding men can't have galeas like these.