So I remember when there were a bunch of arguments about whether or not dwarven women have beards - I also remember there were arguments within those arguments about the functionality of beards in general.
But regardless of any matters of taste, I want to know biological/evolutionary reasons to justify either beards or the lack thereof, regardless of gender. Basically, I'm hoping to learn something.
From what I understand - The primary purpose of beards is similiar to that of a lions mane. It serves both as ornament and as armor. Yes, armor - in evolutionary terms, beards are actually pretty decent armor. Most animals have bites and slashes without a lot of penetrating depth, so killing blows usually need to be landed against the neck else you run a high risk of the other creature getting a chance to fight back.
Apparently, in Lions at least, those thick manes offer a bit of neck protection, making it extremely difficult for other lions to get a good grip or deal as much damage to such a vulnerable location. The reason only male lions have maness as that lions dont really fight other animals, and only male lions fight other male lions - as such, theres no reason for females to have the manes.
On the decoration front, a healthy, long, and dark mane signifies a healthy lion. In a pride based group, this would naturally lead to accelerated dimorphism.
Of course, having "no reason to have manes" means there would still probably be enough selection pressure from the male side of the equation to give them a smaller one. So why don't they have it? Because the females are hunters - they rely on their swiftness and stealth, not their combat prowess against equal opponents, and thus manes are actually a real hindrance. So they have been selected against. In addition, manes are a huge cause of heat stress in hot climes, where even males have them diminished in size, and in all locations they provide a nice location for parasites to thrive - so there is an overall penalty to being maned (enough that the protection angle alone would likely not be enough to generate them).
As a final note, lions manes are adaptive - if grown to maturity in a much warmer location, their mane will be much smaller and lighter in colour. This is interesting because of its possible ramifications on DF - even ignoring the adaptive parts, it might be best to make tropical dwarves :::gasp::: relatively beardless. Of course, living underground much of the time, dwarves shouldnt be as affected by this as many other races, but something to keep in mind.
Now, lets derive a couple pros and cons from this information
Pros:
Increased Defense
Sign of health, thus more attractive to mates
Can keep you warm in cool climes (though not as much as all around fur)
Makes you appear bigger and more threatening
Cons:
Causes heat stress in warm climes
Provides home for parasites
Makes you appear bigger (and thus makes stealth more difficult)
Slows you down a bit
So thats a bit of info on manes - not neccesarily applicable to beards, but something to keep in mind. Next time, I'll try and go into the evolution of beards in people (as far as I can discover), and then generalize that to discover how it would apply to dwarves. I'm also going to spend some time on the physical cause of beards (testosterone in particular) and talk about hyenas.
If anyone else has corrections, let me know - I've got now idea the accuracy of much of the info I find.