Lyn's recent comment about how beards make men look more attractive, has a little more to say about it.
A lifetime of mouth breathing leads to the jaw dropping backwards, and the teeth being much weaker in their seats.
The "ugly chin" she refers to is caused by mouth breathing and a lack of difficult to chew food. Both of these ensure the jaw muscles stay strong and the teeth stay in place and the whole assemblage doesn't fall backwards.
I used to think that the slackjaw, small, receding chin was attractive when I was younger. I now see that it is actually a recipe for about 30% of what makes people sick these days.
When you are building up your body strength, don't forget your jaw. Plus, women dig it, to the men.
The beard gives the illusion of a thick, properly aligned jaw.
And those of you, who like me, are starting to see it drop backwards, you can reverse the process by nose breathing and chewy food. IE, giant fat steaks. Fat being the operative word.