Ever heard of Noam Chomsky? Bright guy, a linguist and a political science geek. Very intelligent. He has some theories on language that imply that only human beings are true language users (nevermind that there is no concrete definition of what it means to "use language"), and these theories are held in high regard. He is of the view that primates, dolphins, etc., are completely incapable of complex communication with one another. Language, he posits, is an innate human ability. I believe he even goes so far as to call it "genetic"...
Now, given the genetic argument, one can argue that Chomsky is dead wrong. Let's look at the recent discoveries in mapping genomes, first. One of the things that they have noticed is that the genes that control certain traits are located in the same areas of the genome between two species. ie.: there is a gene that controls the size of an individual's hands and feet -- this gene is in the exact same place in both mice and men. (No literary allusion intended.) There are genes that control basic bodily structures -- the formation of arms and legs, of heads, etc. -- and those genes fall into the same places across large numbers of vertebrate species. That said, I find it highly unlikely that human beings have this one basic gene for language that somehow we, and only we, have.
This is not to say that any animal is capable of human language. Quite the contrary. Just because a gene resides in a similar spot does not mean that the gene in question will be expressed the same way. There's a tremendous difference between the foot of a mouse and the foot of a homo sapiens sapiens, despite having genes in the same location. This is just to say that the physical structure changes.
In the left temporal lobe, there are two structures -- Wernicke's Area and Broca's Area -- and they are the seat of language, a complex little ripple in the cerebral cortex that give rise to language. CAT scans of ancient skulls of hominids, including Neandrathals, show that these areas not only existed in our early ancestors, but that they were well-developed. Furthermore, modern primates, dolphins, and whales, all show advanced structures in the left temporal lobe...
I'll leave the final decision up to you, of course...