Personally, I'd be surprised if most mammals weren't generally happier than people. Cats, dogs, and sea mammals seem to have it all figured out. Apes and monkeys, less so - chimpanzees are brutal.

    Tiger got to hunt.
    Bird got to fly.
    Man got to sit and wonder why, why, why?
    Tiger got to sleep.
    Bird got to land.
    Man got to tell himself he understand.

- Kurt Vonnegut, Cat's Cradle

Or as Blaise Pascal put it in Pensées:

>When I have occasionally set myself to consider the different distractions of men, the pains and perils to which they expose themselves at court or in war, whence arise so many quarrels, passions, bold and often bad ventures, etc., I have discovered that all the unhappiness of men arises from one single fact, that they cannot stay quietly in their own chamber.