update:
This is a quote from a 1% redditor Mod CT-7567_R a year back on the topic of Paul's rapid aging.
It’s not the sun (at least now). He surfs at 6am and wears sunscreen, he made an episode on this and tallow alone is an SPF4. He also wears big hats when out in mid day. It could be the salt drying out his skin? Although I’d imagine the tallow based sunscreen would offer a layer of protection.
So he is not! outside cooking his skin all day.
update:
I am not able to build a case for "the salt drying out his skin" doing so much damage. But the whole post was well thought out. I'll include it.
Nutritional issues mentioned by members as possible factors:
excessive protein
excessive methionine
too much sugar
Random lifestyle:
Excess Sun (but not really, he's cautious)
Excessively lean (about 10% BF. He is quite lean)
Salt Damage
Unknown factors with no evidence:
Chemicals/Hormones