Can humans ever talk to animals?Yes its been done. More than one primate has been taught sign language. Probably the most famous was koko the gorilla (check out Wikipedia and YouTube). Koko was able to communicate at a surprisingly advanced level and demonstrated the ability to understand quite complex problems set up for her. Her levels of intelligence and social interaction were roughly compared to that of a 5yr old human, but such comparisons, especially when applied at an inter species level, can only ever be rough, and also misleading.
We humans tend to anthropomorphise; we project human behaviors and thought patterns onto other species, sometimes with awful results, and though the woman who ran the experiment with Koko was well aware of this, a lot of anthropomorphic projections were present in her personal recollections of it; we can't seem to help doing this. On the other hand, Koko's interactions actually showed a lot of immediately recognizably human wants, feelings and curiosities, so perhaps primates are all wired in a similar way socially speaking. The jury is out.
There was some pretty awful side effects though; when the funding for the experiment ended koko was placed in a caged habitat with other gorillas who obviously couldn't sign. When her teacher visited her a couple of years on koko said that the other gorillas were just dumd animals who couldn't talk and could she come back? Also could she have some Coke?
One gorillas life ruined if you ask me..if we teach them we are obligated to keep them in a communcative environment.
Dolphins have successfully been taught to comprehend a pretty extensive human vocabulary, and to respond to questions using a yes/no/don't know array of buttons. They have also been taught to vocalise much of our speech sounds, though obviously some sounds will be beyond their ability to produce.
Dolphin experiments differ from that with primates in that a dolphin can always fit back into its social group; they apparently already posess the ability to communicate so the moral problems of opening pandoras box do not apply as with primates. It would also be fascinating to dicover whether the ideas of good/evil, moral/immoral behavior are really limited to human intelligence. Initial results indicate that this is not the case..but no definitive answer is yet available.