What's So Special
About Being Human?
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Anthropologist Ian Tattersall talks about the things that make us human--spoken language, wearing clothes and makeup, and the way our brains work.
Ian Tattersall, paleontologist, evolutionary biologist, and primate behaviorist, is Curator of Anthropology at the American Museum of Natural History. His book, Becoming Human: Evolution and Human Uniqueness, explores the fundamental differences between humans and other primates. Amazon.com's Therese Littleton asked Dr. Tattersall about humanity's uniqueness and what evolution may have in store for us.
Question: When did you start to wonder about how humans are different from other animals?
Ian Tattersall: I started off as a paleontologist, interested more in the anatomy and relationships of our fossil relatives than in their behavior. Then I got sidetracked into the study of lemurs, our primate relatives that live in Madagascar. First I was interested in the extinct lemurs, but I got so fascinated by these wonderful animals as living beings that I spent several years studying them in the field. So when I came back to the study of human evolution in the mid 1980s, it was natural that I should be as interested in our predecessors' behavior as in the actual anatomies preserved in the fossils.
Question: You mention several features that define humans, such as "the fundamental human urge to adorn and elaborate." Are the most defining characteristics of humans behavioral or physical?
Tattersall: All species have both anatomical and behavioral differences that set them off even from their close relatives. And we certainly differ anatomically from apes in many more ways than they differ from each other. Indeed, I follow the story of how we acquired these differences at some length in the book. But it's undeniable that we differ most profoundly from the apes in the way in which we perceive and deal with the world around us. It's routine to look a little different from your closest relatives. But it's entirely extraordinary to behave so differently.
Question: Why don't the great apes adorn themselves?
Tattersall: Good question, and I wish I knew the answer, for that would mean I knew a lot more than I do--or any human does--about what goes on inside apes' heads. Apes are unlike any other of our primate relatives in that if you put a dot of paint on their face while they are unconscious, they will try to pick it off if they later catch a glimpse of themselves in a mirror. However, self-adornment probably requires a degree of detachment, of objectivity about oneself, of which apes aren't capable.
Question: Why haven't other species developed spoken language?
Tattersall: One of the things I try to emphasize in the book is that evolution is not a goal-oriented or even results-oriented process. There are huge numbers of ways of doing business in this very complex world we live in, and the way in which we have happened to adapt is only one of them. What's more, I don't see the human evolutionary record as one of progression toward language. Many species have very complex vocal (and gestural and scent-based) systems of communication; but even in the great apes, among whom quite a large variety of different vocalizations have been identified, vocalizations seem limited to expressing emotional states. We have managed to separate vocal sounds from emotion, and instead to attach them to symbols that we form in our minds. As far as we know, this is unique and an ability that was only relatively recently acquired. In fact, if we were to set the evolutionary clock back only a few hundred thousand years and run the whole process all over again, it's not clear to me that we could necessarily expect to see a linguistic Homo sapiens emerge again.
Question: In Becoming Human, you disagree with the "selfish gene" theories of Richard Dawkins, George C. Williams, and others as the primary explanation for physiological and behavioral development. Do you see any large-scale value to the study of sociobiology?
Tattersall: There may well be value to various sociobiological notions when you're studying highly but mindlessly organized societies such as those of ants, in which individual decision making is not a factor. But in a species such as our own, individuals are so, well, individual, and decision making is so complex that it's impossible to equate particular behaviors with particular genes, all of which are fighting with each other for representation in the next generation. Both organisms and their genotypes are much more complex than that would admit, and the bottom line is that natural selection can only vote up or down on individuals as wholes rather than on particular characteristics or behavioral decisions. If we can perceive regularities in specific behaviors, these are more likely due to ongoing economic realities (broadly defined) than to genetic imperatives.
Question: You assert that humanity has reached a sort of stopping point in our evolution. What changes in human populations, aside from catastrophic natural events and diseases, would allow humans to continue evolving, perhaps into another species?
Tattersall: I say that we have reached a plateau in our evolution because I don't see the necessary conditions existing for true innovation. In order for inherited novelties to become "fixed" in populations and subsequently the properties of new species, such populations have to be small and effectively isolated genetically from their relatives. I just don't see these conditions for change existing in the modern world, where our species is found everywhere, in increasing densities, and where individuals are incomparably more mobile than ever before. Only small laboratory populations could conceivably be isolated genetically from the rest of humankind, and I fervently hope that will never be allowed to happen. Even in the unlikely event that space colonies should ever be established, such colonies would need a lifeline to Earth, which would inevitably involve the possibility of genetic contact. And, of course, evolution is a totally unpredictable thing. Even if you could provide necessary conditions for change, they might well not prove sufficient.
Question: Should humanity strive to continue evolving?
Tattersall: I don't think so. That would be tantamount to admitting that there is something fundamentally wrong with ourselves that we can't fix on our own. Better and much more practical to use our energies learning to live with ourselves the way we are than trying to conjure up a deus ex machina!
Question: If human evolution continued, what might the next Homo species look--or think--like?
Tattersall: Intriguing question, even if I don't think we'll ever be in the position to test any answers we might come up with. Virtually all scenarios for future evolution up to this point consist of extrapolations from the past. Our brains have become larger over our evolutionary history, so they will become bigger still. We are a little less robustly built than our predecessors and have lots more technology to do the physical work for us, so our bodies will become frailer. And so on. But what I try to emphasize in the book is that our species is something entirely unprecedented, something that could not have been predicted from its past. And I also point out that natural selection is not a creative force; it can work only on variations that arise spontaneously--and are equally unpredictable. So I have to admit that if anything new is in the cards, I have no idea what it will be--except that it will almost certainly be a very big surprise!
Question: Will humans ever be able to conquer, as a species, the internal contradictions arising from the complex interactions between our brains' higher cortical areas and the ancient structures beneath?
Tattersall: The fact that we are complex, mysteriously motivated, and often unfathomable beings certainly results from the long and rather untidy evolutionary history of our brains--it must do! But despite the accretionary nature of our controlling organs and the fact that we do possess "higher" structures alongside some that were also possessed by very ancient ancestors indeed, we have to bear in mind that our brains do function as complex wholes. And we are so far from understanding what goes on in those complex wholes to generate our amazing human consciousness that I doubt that in the foreseeable future we'll find any foolproof physical way to deal with what we might now and then, or even always, see as the less desirable aspects of our cognitive function. What's more, I doubt that, if we thought about it long enough, we'd actually want to. But I certainly hope that we humans will find some way to stop making the same mistakes over and over again in our dealings with each other. We need to learn at least how to come to terms with our complex and conflicted--but undeniably interesting--selves!
Question: What message would you like readers to take away from your book?
Tattersall: I'd like them to understand that although we humans are truly distinguished from all other living organisms by our extraordinary cognitive capacities, those attributes haven't entirely separated us from the rest of nature. Our capacities, for example, are additional, not alternative, to those of apes--which is why we see so much of ourselves in them. Further, although our technologies have allowed us to see ourselves as existing outside--even above--local ecosystems, it is imperative we realize that our future well-being is linked to that of the global ecosystem as a whole. And most of all, perhaps, I would like readers to be aware that, as extraordinary as we may be, we got to be the way we are by an evolutionary process that was not extraordinary at all.
Becoming Human : Evolution and Human Uniqueness by Ian Tattersall
The Selfish Gene by Richard Dawkins
Read more on human evolution, psychology, health, behaviour, and biology in The Human Nature Review
The Human Nature Review © Ian Pitchford and Robert M. Young - Last updated: 28 May, 2005 02:29 PM