Animals can without doubt use symbolic systems, whether the sounds they naturally make, or the systems researchers teach them. But symbolic systems are not lang

Animals can without doubt use symbolic systems, whether the sounds they naturally make, or the systems researchers teach them. But symbolic systems are not languages. Symbolic systems can work because both communicating parties will share the system. But an important feature of language is that it can be used to communicate ideas which are not shared - you can communicate something that the listener has never heard before, and in fact, you can communicate something which no one has ever even thought before (well assuming that's actually possible.) One thing to show that these symbolic systems were languages would be to teach the meaning of a new symbol to these animals using only the existing symbols. I don't know if these researchers have tried, but I don't expect that it will be possible to. Language is the probably the defining feature of humanity.