Humor! :D

That's actually a very good one, I never thought about it but making jokes out of something is quite human. Some primates can laugh, but I'm not sure that they make jokes specifically for that reason. The main thing for me would have to be our rather strange regard for other species. No other creature keeps zoos. Not many creatures use guns either, but I think you get my idea.

The way we think and the way we interact with our environment. No other animal is as destructive as humans. I always thought it weird that humans keep other animals around for companionship.

Wow, now I feel really stupid looking at all the long, eloquent posts! XD

I believe that to be human it is all about creativity and emotion. After all this is how we have gotten to where we are today (not counting the economical disaster).

i think what makes us human is that,

we all hurt one time or another, we all cry, (no matter who you are, how much money or friends you have, we've all hurt atleast once)

we love, and we make mistakes,

what really makes us human is the fact the we can forgive MOST things.

I think its our Ego

If 'human' can be described as the average human being, I'd say that morality is what makes us human.
If you mean that the definition of 'human' is the biological definition, then we are human because we are able to adapt to our environment without necessary evolution.