1 Origins of Humanity

How did the human species arrive at its present form? And how does our species history bear on the nature of this form? The human species, as it now exists, possesses language, rational thought, culture, and a specific affective makeup: but there was a time when our ancestors had none of these things—or had them only to a very limited degree. How did we get from there to here? How did we become what we so distinctively are, given our early origins? To put it more philosophically: how is Homo sapiens possible?

This question belongs to the field of paleoanthropology, and a rich body of knowledge is associated with it, mainly based on fossils.¹ More broadly, it is a question of evolutionary theory. It has not much attracted the attention of philosophers. This is a book about philosophical paleoanthropology. It attempts to link questions from an empirical science to more strictly philosophical concerns. So it is interdisciplinary. The disciplines linked are anatomy, evolutionary biology, archaeology, linguistics, psychology, cultural studies, and philosophy. I would describe it as a work of “evolutionary philosophy” (evo-philosophy, for short): in it I philosophize about the science of evolution. If we wish to have a label for this composite field, analogous to the recently minted “cognitive science,” we might do worse than choose “emergence science.” We are trying to understand how a certain suite of characteristics emerged in a particular primate species, using all available resources. No other species has evolved these characteristics, at least to the spectacular extent that we have, and it is a puzzle how we could have evolved them. What might explain the remarkable emergence of humanity?

The book therefore deals with an explanatory question: how can we explain the transition from our early apelike ancestors to human beings as we are today? This is a big gap to bridge—an explanatory gap. Much of the discussion will concern what sort of explanation is acceptable—that is, with conditions of adequacy. I will lay down various explanatory metaprinciples. We are trying to reconstruct a piece of history—or prehistory—and we need to know what constraints our reconstruction must respect. Naturally, this will involve hypotheses about what did in fact happen in the distant past. But it will also involve inquiries into how things could have happened—with what philosophers call “rational reconstruction.” How is it possible to get from one state of nature to another? What sorts of intermediate stages make sense (that is, do not violate well-motivated constraints on evolutionary explanation)? Needless to say, the investigation is highly speculative, given the nature of the case. The form of the explanation consists in identifying and articulating the primary adaptations that powered the transition from early man to contemporary man (for short I will call this “the Transition”).² This is simply the question of how contemporary humans evolved from ancestral stock that had very different characteristics (though also clear similarities). How did humans become the special kind of ape that we are? What accounts for the difference between us and other extant apes? Despite the considerable attention that has been devoted to that question, it is still not well understood.

The crucial role of the hand in producing and constituting human nature has long been recognized. Charles Bell published his classic text The Hand: Its Mechanism and Vital Endowments as Evincing Design in 1833, which argues that only a divine creator could have made something as wonderful and fitting as the human hand.³ In The Descent of Man (1871) Charles Darwin drew a different lesson from the marvels of the hand: “Man alone has become a biped; and we can, I think, partly see how he has come to assume his erect attitude, which forms one of the most conspicuous differences between him and his nearest allies. Man could not have attained his present dominant position in the world without the use of his hands, which are so admirably adapted to act in obedience to his will” (84). For Darwin, the anatomical adaptation that is the human hand is the chief engine of human emergence—it is what made us the remarkable creatures we are.⁴ The hand is the source of our biological success, our species ascendancy. This position was later developed in greater detail by John Napier, the physician and primatologist, in his books Hands (1980) and The Roots of Mankind (1970) and other works, drawing upon evidence unavailable in Darwin’s time. It is now something of a commonplace in paleoanthropological studies.⁵ Frank R. Wilson, in The Hand: How Its Use Shapes the Brain, Language, and Human Culture (1998), writes as follows: “It is genuinely startling to read Bell’s Hand now, because its singular message—that no serious account of human life can ignore the central importance of the human hand—remains as trenchant as when it was first published. This message deserves vigorous renewal as an admonition to cognitive science. Indeed, I would go further: I would argue that any theory of human intelligence which ignores the interdependence of hand and brain function, the historic origins of that relationship, or the impact of that history on developmental dynamics in modern humans, is grossly misleading and sterile.” In the present book, I too will sing the praises of the hand, though in a more philosophical key, finding an essential explanatory role for it in human evolution, particularly with respect to language. The central thesis of the book can then be very simply stated: it is the human hand that accounts for the Transition. It will turn out to be a little more complicated than that, to be sure, but the basic idea is that the hand made us what we are (indeed, that we are). The present author, like those preceding him, confesses to being enamored of the human hand, the often-neglected core of our humanity. The hand is what may have saved us from early extinction and what became the foundation of all our subsequent achievements. We owe it everything, quite literally. That, at any rate, is the general thesis, to be elaborated (and qualified) as we proceed.

I decided to call the book Prehension (not The Intelligent Hand or Hand and Mind or some such) for two reasons. One is that I wanted to fasten onto a particular function of the hand, namely gripping or grasping, which I regard as especially important. The other is that the hand is not the only prehensive organ in nature and I wanted to consider the role of prehension in evolution more generally (the mouth and the mind, in particular).⁶ The hand for humans is the dominant prehensive organ, but prehension itself is a much broader phenomenon. Still, the hand will play an absolutely central theoretical role in what follows, since we are concerned mainly with the human species.

I will not enter into elaborate justifications for the claims made by paleoanthropologists, nor worry too much about details, but simply accept the broad outlines of what they say. My main interests concern the interpretation and ramifications of the established science (insofar as this science can ever be regarded as established). I do, however, recommend some immersion in the scientific literature for my philosophical readers, if only to accustom them to the style of the field.⁷ I am interested in the philosophical consequences and uses of their findings and theories. I seek to bring their mode of thinking into the philosophical mainstream.⁸ This means that I fully accept the standard account of human evolution, even though it is incomplete in many ways. I will, however, allow myself much more freedom in describing early human life than scientists typically permit themselves—especially with regard to the psychological condition of early man. It won’t be all fossils and external behavior, but will also discuss what it must have felt like to undergo the kinds of transitions that we know occurred. I am concerned with the psychological evolution of man—the evolution of man’s soul, if you like—as well as with his anatomical and behavioral evolution.

Heuristically, we can picture the inquiry as retracing our ancestry back to prehuman times. Take your parents and then their parents and then their parents, and so on going back through hundreds and thousands of generations. As we travel further back in time, there is a more and more pronounced divergence between you and your ancestors: where they live, what size they are, their expected life span, their coloring, their technological condition, their social arrangements, their use of language, their mental sophistication. If we go back far enough, now finding ourselves on the African continent, some millions of years ago, we will find our apelike ancestors, occupying the copious tropical forests and looking and behaving a good deal like modern apes. What we want to know is how these successive generations—these sons and daughters of fathers and mothers—became modified over time to become the human being that you now are. We want to describe the contours and driving force of the Transition. What were the selective pressures, the resultant adaptations, the cognitive and affective modifications? In this long ancestral sequence we will keep our eye firmly on the hands of the successive generations—on their anatomy and activities.⁹