Do non-human animals have language? Which cognitive abilities would it be necessary for them to have in order to have language (e.g., beliefs, desires, and other intentional attitudes, both one's own and attributed to others; elicitation and construction of rule-based structures, constituent dependencies and other structural capabilities)?

Can non-linguistic animals acquire the same concepts as humans? How do non-linguistic animals develop conceptual representations, and how do they structure them? Is there a relationship between non-human animals and babies, both of them non-linguistic beings?

Does language rightly occupy a central place in comparative studies between humans and non-humans?

What other complex mental systems can we study to aid in our inquiry about these questions (e.g., morality, since it presupposes intentional attitudes and colaborative behavior, perhaps two important elements in the communicative aspect of the evolution of language, etc.)?

How can we test for these questions?