Observe people as animals and you will see animals
But it's more than that. Much of human misery comes from the problem that we don't think of ourselves as animals, and as such tend to abuse ourselves and our bodies in ways that we would never think of treating animals. Specifically, not exercising our bodies, feeding ourselves junk food, putting people that hate each other in the same room, and not neutering most people.
More insidious is the lack of social connection. People are designed to live in packs. There is speculation that our brains are the size that they are just so we can cope with our social position to each individual in a group -- the brain size of animals scales linearly with the size of the packs that they roam in. From this scale, humans are ideally suited to live in groups of one hundred and fifty people.
Funnily enough, this is the basic size of a platoon in the Army. It's the point at which a small company becomes a large company with hierarchy. It's the point where people stop being your neighbours and become strangers. Basically, it's the point you stop knowing everyone.
The other side to this pack animal business is that people have a basic, human need to hang out. It's not all in the head or a symptom of low self-esteem -- if you don't spend time talking to other people, you will go psychotic. One of the worst punishments prisoners have is solitary confinement. Just being in a room with no-one to talk to is not a healthy way to live. This is why teleconferencing and working from home turn out to be such bad ideas -- people try it, find out how socially isolating it is, and get lonely. Community is incredibly important. People will gladly kill and die for community. Charles Manson sucked in young girls and turned them into killers by giving them a family.
Everything is an example of a community. Online communities are replacements for the communities which aren't possible outside -- cars, economy and fear have all made people into single-serving friends. This is why the Internet and telephones are so popular -- they fill the need for connection. (And sex, of course).
Point is, we would never treat animals this way. And the lunacy of trying to live your life alone can be finally brought home if you buy a game called The Sims, which is a connection simulator in itself. In the Sims, you have a little human. And the human has needs. You play the game, and you tell the Sim to go to bed on time, keep his room clean, study and phone up friends. At some point, I realized it was 3 am, and I was telling the Sim to go to bed so he could go to work tomorrow, and I hadn't seen anyone in two weeks. Since I decided to think of myself as an animal, I've been treating myself much better.