The need for copulation and food are considered animal desires, because animals have them as well. Even being in full isolation man feels hunger and the urge to reproduce. Desires for wealth, power, fame and knowledge are considered human desires, since we need to be surrounded by other people to satisfy them.
Man is born, his animal and human desires develop, and then he eventually discovers that their realization does not satisfy him, since his secret but true aspiration which he cannot yet realize and formulate, falls outside the limits of this world. Man receives this desire from above. It is neither given by nature as animal desire, nor does it develop under the influence of a society with human desires.
Courtesy of http://www.youtube.com/watch?v=OhGWLh0fLuw