Humans have great intuition for hidden potential. They gain a +2 racial bonus on Sense Motive checks. In addition, when they acquire an animal companion, bonded mount, cohort, or familiar, that creature gains a +2 bonus to one ability score of the character’s choice. This racial trait replaces the bonus feat trait.
Okay, so quoted above is the Eye for Talent alternate racial trait for humans. Pretty neat if you're a Cavalier or Hunter who wants a stronger or smarter beast buddy.
But let's say you're a Cavalier with the Huntmaster archetype or a Hunter with the Packmaster archetype, which grant you multiple animal companions at once (albeit, with your effective Druid level divided among them). Does the +2 bonus to any ability score apply to all of your companions, or only one of them?
I think it applies to every companion you have, but this sounds like the kind of thing where it could be ruled either way.
I'd say it applies to any and all companions you get. It specifically says "when you acquire" an animal companion, etc.
each, just like if you had a mount and an animal companion it would effect both.