Is it really important to prove that humans are different from animals?

A book I'm currently reading about anger, by Carol Tavris,* goes to some pains to distinguish anger as a human emotion from the anger or rage that animals feel when threatened. Tavris says (p. 33)

But in the case of anger, the differences [between animals and humans] are essential. The human symbolic capacity for learning give us a far greater range of choices than lower animals have. Human anger is not a biological reflex like the sneeze, nor simply a reactive display designed to ward off enemies.....

The author then follows with some specific ways in which humans are different from animals.

Tavris is trying to make this distinction between humans and animals in order to qualify some assertions that Charles Darwin made about the congruity between animal and human behavior. This is an introductory chapter in which the author sets up some of the antecedents of current psychological and pop-psychological views of anger that have developed in the last 200 years. (Short answer, as always: the original formulators of modern views about anger, for example Charles Darwin and Sigmund Freud, never intended their views to be taken as far as they have. In other news, that food you thought was bad for you is actually good for you, "if it's used in moderation.")

As far as I'm concerned, I'm convinced that humans express and probably experience anger differently from the way other animals do. I'm not conversant with all the evidence, but the evidence and argument that are offered are convincing.

But in a wider sense, is it even important? The chapter I took this example from discusses the evolution of thought on the psychology of anger, and I suppose the perception of differences between humans and animals are an important element in that evolution. But the book as a whole is meant as a thought-piece on anger--how to deal with it and whether society's assumptions about how to deal with it are healthy--and simply knowing that humans are different from animals does not really answer these questions. (I'm reminded of the "Simpsons" episode where Mr. Burns is suspected by the IRS of having stolen a trillion dollar bill, and the IRS agent says "we tried to use satellite technology. But all that tells us is that it [the bill] isn't on his roof.")

I don't write this as a crusade against Tavris's book. I've read only the first couple of chapters and it seems quite interesting and capable of offering a challenging and insightful experience. (In short, it will do wonders in yet again delaying my progress toward completing my dissertation.) But I do write this to give one example of something I've noticed in a lot of fields: the seeming necessity of proving that humans are, indeed, different from animals.

Two other examples of where else I've seen this:

• The debate over an assertion that Noam Chomsky allegedly made (which I allegedly read about in a book that was allegedly written by an author who I've allegedly and conveniently forgot the name of) that language is unique to humans. This assertion has sparked an effort by some linguists to either prove or disprove the contention that animals do not have language as humans understand it.
• C. S. Lewis (and others, I presume) has asserted somewhere (again, I don't have a citation....it's nice not to have to be tethered by "evidence" or "facts") that the distinction between animals and humans is that the latter, as far as he can tell, have souls while animals do not. (Come to think of it, maybe it's in Lewis's tract on the problem of pain, and in the chapter on animal pain.)
  

Why do people feel the need to differentiate humans for animals? I don't know. I suppose it has something to do with our spiritual nature or our vanity or whatever.

But for me, the important question is, how useful is it to make the distinction?

I suppose there are theological implications for asserting that humans are endowed with souls while all the rest of creation are not. Still, does Christian theology really depend on whether humans are specially created. Perhaps for some, this is a case, but I doubt that if a Christian who, having died and gone to heaven, finds out that Koko the ape had a soul and got to go to heaven too, would suddenly decline the invitation and go off to the other place. (For what it's worth, C. S. Lewis makes room, at least in theory, for the possibility that there might be other creatures, besides humans, who have souls....I'm thinking primarily of his science fiction trilogy and, if memory serves, of something he wrote in one of his Christian apologetics.)

I suppose also that if it can be shown that animals have language abilities in any meaningful sense (whatever "meaningful sense" means), maybe we can learn to speak to them; and even if animals do not, then maybe the quest to find out if they do tells us something about our own language or helps us define more precisely what we mean by language (because and as an aside, there seems to me to be a bit of circularity in the assertion that animals lack human-like language abilities (and for what it's worth, even if animals can speak, I don't think they'd make too-long, convoluted sentences like the one I am writing right now)). But does knowing that animal communication is different (or not) from that of humans really help us answer the pressing questions of linguists?

I suppose that if one is looking at the history of such things and expects to represent them accurately, one needs to take account of the debate over the differences between humans and animals. But at the end of the day, I think we should be more explicit about why the question matters at all.

*Carol Tavris. Anger: The Misunderstood Emotion. New York: Simon and Schuster, 1982.