What makes homo sapiens "human"?

Firstly, I don't think there is any natural justification for a human/animal split. I think it is a simple case of anthrocentrism.However, I would query one point: Really? I haven't seen any. There's some exceedingly poor evidence that you can teach chimpanzees something that vaguely approximates rudimentary language. But as far as I know no evidence that they use any in their natural world.I'd say language remains a uniquely human attribute qualitively different from the communications of any other animal.

Cool. Interesting, but not language. I've also seen that. I've also seen critques of the whole field. In my opinion (q.v. Stephen Pinkers' [i]The Language Instinct[i]) claims of sign language in chimps have been grossly exagurated and rely heavily on generous levels of interpretation by the experimenters. Although one case of Orang Utan language learning still stands above other examples.In any case no animal language learning has approached even the linguistic capabilities of an intelligent two year old and certainly has never approached that of a typical adult. I'm not sure I understand the relevance of your point? Of course ancestral, and 'branch', homonids will have possessed some kind of intermediary between human language and ape communication. I'm unsure as to what you mean by 'meaningfully unique'? Meaningful in what sense?

Ok. I would most definetly disagree with that as a useful definition of language. By language I mean a communication form with grammar and the ability to express abstract concepts as a bare minimum.There is utterly no doubt that animals can express emotional states to other animals (anyone with a cat or a dog can tell you that) or that they are capable of significant feats of communication (witness chimps hunting monkeys). Animals are also capable of verbally expressing specifics (prarie dogs have different calls for different kinds of predators) or transmitting those verbalisations culturally (different groups of prarie dogs have different calls).However, I don't consider these feats to be language. With the exception of the last item on that list, humans are capable of all of the above without ever using language and the last is no more than having a short vocabulary - no more language than telling a dog to sit, stay or fetch is language.

Don't be absurd. I said the evidence from the chimps wasn't evidence that they speak language, not that it was evidence they don't. Whale song, elephant vocalisations and dolphin noises can all be analysed, looking for syntactic patterns and data density. They don't have the patterns, complexity or data density that are (apparently) needed for language. All human languages do.

Rubbish. How would you communicate in a non-ambiguous way 'the cat sat on the purple hat last tuesday when it was raining' using just facial expressions and gestures? Assuming I don't know sign language that is. Sign language is not equivalent or comparible to simple facial expressions or gestures. Vocabulary may not be the best word. Repotoire perhaps? The point remains, the have a few calls which carry different meanings. These meanings cannot be combined in a combinatorial fashion; i.e. not language.

Yes, animals are capable of impressive feats. And some impressive examples of communication - however, the level of communication involved even in chimp hunts is tiny compared to the level of communication that is going on just in the debate. Still not language.

Whoa there, dude! Self awareness is a whole different kettle of fish. I would be astonished if the majority of mammals (at least) are not self-aware to varying degrees.

I was using self aware as a synonym for consciousness.

Silly argument, q.v.Would you agree that bats evolved from fish? How is then that bats can fly but fish cannot?