This Trait allows anyone to bite as secondary attack for 1d2 damage. The Universal Monster Rules say "most creatures possess one or more natural attacks". Toothy half-orcs have tusks like orcs and can bite with them as primary attack for 1d4 damage. Orcs racial description includes them having tusks but a bite attack isn't mentioned. Still as half-orcs wouldn't get that from their human side I assume orcs can bite despite it not being mentioned anywhere? What about other humanoids?
Do humanoids without any traits or alternate racial features or other source of additional natural attacks have any natural attacks? And if so does the following apply?
"[...]if a creature has only one natural attack, it is always made using the creature’s full base attack bonus and adds 1-1/2 times the creature’s Strength bonus on damage rolls. This increase does not apply if the creature has multiple attacks but only takes one. If a creature has only one type of attack, but has multiple attacks per round, that attack is treated as a primary attack, regardless of its type."
How would you treat a strong elven fighter in a grapple saying he want to bite the opponent's nose?