I defer to e.e.norcod's medical slant, though remain curious, about any connection between the COD part and cod pieces. At any rate, facial hair on men for various decades was fashionable and e.e.norcod's post also offers sound practicality to fashion.

As to the difference he mentions between male jowls and their chins, could it simply be a difference in hair/bristle pattern growth?

A simple layperson wants to know, if for no other reason than personal grooming.