Human beings

they, we
them, us
who, whom
our, their
these, those

I reccomend you check this web page:
http://en.wikipedia.org/wiki/Pronoun

It depends. I mean, either may be possible

Also, in the right contexts, you.

fivejedjonAlso, in the right contexts, you.

Not only 'they' but also 'we' and even 'you' work?

Taka fivejedjonAlso, in the right contexts, you.Not only 'they' but also 'we' and even 'you' work?

Human beings are a strange species. We/they don't normally like being naked.

I call upon you, fellow human beings, to end this strife. You have the power to ...

So they all wok fine and have the same meaning?

Human beings have caused serious damage to the environment. They don't know what they have done to nature.
Human beings have caused serious damage to the environment. We don't know what we have done to nature.
Human beings have caused serious damage to the environment. You don't know what you have done to nature.

fivejedjon.I call upon you, fellow human beings, to end this strife. You have the power to ...

Right. That seems to work. Thanks.

TakaSo they all wok fine and have the same meaning?Human beings have caused serious damage to the environment. They don't know what they have done to nature.Human beings have caused serious damage to the environment. We don't know what we have done to nature.Human beings have caused serious damage to the environment. You don't know what you have done to nature.To me, they

fivejedjon They are not exaactly the same In the second, the speaker is clearly associated himself with all other human beings. In the first, s/he is distancing himself/herself from those who have caused the damage.In this context, the speaker is distancing himself/herself from other human being to an absurd degree.

Distancing himself/herself. Good expla