Just not getting old enough mate.
No idea on age of that fella, don't really concern myself with that but he doesn't show the wrinkles, longer head etc. I just look at their teeth too for wear, again age can look older than they really are if their teeth work hard in tough country.
My particular experience, they get to a certain age and as they grow their tusk size grows but... depending on the wear they get on their tusks from digging in the traprock for roots etc is a deciding factor.
Deer are the same, antler growth peaks in their prime 5 years plus but it gets to a point where their antlers start getting smaller and take on strange shapes.
Different areas have different nutrition so have to be looked at on their own of course.
How many pics have I seen in magazines and especially online, people calling themselves deer experts show a pic of an old stag showing all the physical and regenerative signs of regress with a sad old head... and say "a cull stag to save the bloodlines" where in truth if the animal was left to keep breeding, it's offspring would be awesome still up to his age.
Or stags are killed at double-4 or 5 and propped up as some trophy to excellence
No, but kill it, as it's small antlers of odd shape (usually from damaging in velvet, always never considered by the experts because they can't see those signs either) aren't trophy class, and the old meat isn't the best. Makes no sense.
Pigs are the same, in good soft conditions tusks get longer and longer then start to regress, just like we do too.