Modern humans stayed anatomically unchanged at least for the past 80,000 years. On the evolutionary level of organization, anatomically fixed things are expected to stay (nearly) fixed in behavior. Our (anatomically) modern ancestors lived up to this rule for the first half, or slightly more, of their tenure on earth. All hell broke loose in the second. The extraordinary changes in the archeological record starting around 40,000 to 30,000 years ago, and carrying through the height of the last ice age to the onset of the Holocene (some 10,000 years ago), suggest remarkable refinements in behavioral structures unexpected of a morphologically fixed organism. Changes in the record further suggest a remarkable increase in regional and temporal diversity of material structures that up to that point varied little through time and space. The Middle to Upper Paleolithic transition, or the creative explosion as this episode has sometimes been labeled (e.g., Pfeiffer, 1982), is most vividly evident in wall paintings preserved in caves, in portable art, personal ornamentation, and in elaborate burials. More subtle are the sudden refinements in tools, and the rapid expansion into new geographic areas, indeed, into two new continents (Australia and the Americas). Underlying all of this is an authentic economic expansion reminiscent of various mercantile and industrial revolutions in recorded history.

The key question, from an evolutionary viewpoint, is how could such remarkable changes take place in functional behavior without apparent change in morphology. One possible explanation ascribes this turn of events to some neurological change that led to an evolution in behavior without an apparent change in anatomical form (e.g., Klein 1992).

The incredible shrinking gut

Laboratories under sail

Among the sailors who crisscrossed the oceans during the sixteenth century few knew how to swim. It was pointless. A sailboat at sea could not be stopped or turned to rescue a shipmate washed or fallen overboard. The hazards of the occupation could not escape the attention of sailors struggling to lash unruly sails in unpredictable gale-force winds. One slip on the upper yards meant almost certain death. Given the state of the art and the perils of the sea, casualties from accidents and disease were exceedingly high even by the standards of the time. As to comforts and niceties of life – nobody could ask for, nor possibly be granted, accommodations beyond the bare minimum.

With lives aboard more expendable than cargo, one can wonder why skippers and ship stewards paid meticulous attention to supplies of food-stuff. A typical list of ship supplies for a journey across the Atlantic around 1577, the year Sir Francis Drake set out to circumnavigate the world, included such diverse items as hardtack, flour, pickled beef and pork, dried peas and codfish, butter, cheese, oatmeal, rice, honey, and vinegar, as well as about eight tons of beer. The selection seems to compare quite favorably even today with any decent hospital or school cafeteria – not counting the beer. Careful attention to an adequate bulk of food supplies before embarking on unpredictably long trips such as the one undertaken by the Mayflower (66 days across the Atlantic in 1620) is perfectly understandable. But why overburden the already hard-pressed logistics of a ship on high seas with a wide variety of food items?

Darwin and the Scottish economists: The first point of junction

The fundamental economic problem of human evolution

In view of the discussion thus far, the issue is no longer the mere existence of a human predisposition to exchange, but its evolutionary origin. Unsure of this origin, Adam Smith himself acknowledged (and deflected) in passing an intriguing question:

The inception of modern economics was thus accompanied (in 1776) by an evolutionary question preceding by nearly a century the Darwinian notion of evolution itself. Adam Smith probably agonized over this question, though as it seems, had the good sense to abort it in due course. Neither he nor his pre-Darwinian readers could fully comprehend the question, let alone conceive a sensible answer to it. With the advantage of hindsight, however, the question seems to present a challenge of the highest order to the modern study of human evolution: Was exchange an early agent of human evolution, or was it merely a late by-product of previously evolved “faculties of reason and speech”?

With the publication of The Descent of Man a century or so later, Darwin had at his disposal a fairly mature notion of evolution applicable to human affairs.

The first appearance of manufactured stone tools in widespread systematic human use, about 2 million years ago, in combination with other evidence (e.g., food sharing), suggests the possibility that some form of exchange, however primitive, was already practiced by traders with brains half the size of a modern human being. If true, the implication is that exchange could have played an important facilitating role already in the first major economic transition in human (or protohuman) history – the transition from the feed-as-you-go strategy of primate feeding to hunting-gathering. The discussion in this chapter will consider these possibilities in light of the available paleoarcheological data, starting with a preliminary review of the physical environment.

The physical environment

The single most important factor that describes the theater of events in evolution, certainly in human evolution, is climate. The global climate in which civilization flourished is the wrong environmental model for understanding human evolution not only throughout the long ice ages (nearly 90% of the time humans walk the earth) but, in all likelihood, also in the course of the short spikes of interglacial periods (the remaining 10%). The climate observed today and enjoyed by (anatomically) modern people over the past 10,000 years is a placidly warmand, arguably, all too brief interval in a long process of falling temperatures starting about 3.2 million years ago (and greatly intensifying roughly 2.4 million years ago and then again about 900,000 years ago).

If market exchange evolved from some preadaptation observable in humans or animals, then a careful examination of analogies with nepotistic exchange (such as courtship feeding in birds) or symbiotic exchange (such as pollination) is a logical course of action to pursue. In following this approach the first part of this chapter demonstrates the existence of some tempting analogies of market exchange drawn from the behavior of certain animals and plants, as well as from the nonmarket sphere of human affairs. It also demonstrates the risk of drawing premature, if not fanciful, explanations from such analogies.

Alternatively, if market exchange evolved de novo, then the major thrust in the inquiry is best directed toward the mechanisms of the market and the deep structures of exchange itself. This approach is undertaken in the second part of this chapter with the hope that intricacies of market exchange as we know them could provide a clue to their origin. At issue is a catalyst in the form of an activity, or perhaps a single commodity, with the power of spurring exchange between exceedingly reluctant traders at some remote point in antiquity.

Bateman's syndrome

There are certain parallels between the choice of mating partners and the choice of trading partners – chief among them is asymmetry. The asymmetry in the case of sexual selection is due to adaptive pressures that for a widely recognized reason – known as Bateman's principle – act differently on the reproductive behavior of males and females. In a pattern that cuts across nearly all the species of higher organisms, as already noted by Darwin (1874), females are more selective.

Without really being aware of it, human beings economically interact under two distinct routines – nepotistic exchange and market exchange – effortlessly switching back and forth between the two regimes. The tendency to turn on and off two separate processes of decision-making (with implications in action and in demeanor) could have been readily diagnosed as some sort of split-personality disorder had it not been so predictable – repeating itself in nearly the same manner in almost any member of the species. The fundamental difference between the market and the nepotistic (or domestic) routines of human activities was examined in the foregoing discussion (especially in Chapter 2) on the grounds of practical considerations and, so far, only with a secondary emphasis on evolutionary ones. The main implication suggests nothing in the way of a behavioral disorder. What it suggests is the coexistence of two distinct adaptations. The main attempts to trace these two adaptations to their separate evolutionary origins are relegated to two chapters in this volume. The present chapter is primarily concerned with the origins of nepotistic exchange. (Chapter 9 will be similarly concerned with the origins of market exchange.)

Primordial exchange at the lowest levels of organization

Certain advantages of division of labor, supported by exchange, occurred at fairly early stages of life on earth. Consider, for instance, the evolution of one of the most comprehensive and amazing systems of exchange and division of labor in nature: a single body of a multicelled organism. Finely tuned exchange among specialized cells, tissues, and organs is inherent in the physiology of such an organism.

The propensity and capacity to exchange one thing for another between two traders – however unrelated to each other – is a profound distinguishing feature of human subsistence. Human beings are endowed with remarkable skills of trade which they deploy spontaneously when confronted with favorable opportunities; skills that lie dormant in the absence of such opportunities. As is true of other innate human abilities – such as the mastery of spoken language – basic skills of trade are taken for granted precisely because they are either inborn or acquired at a young age without conscious effort. Such skills are not as trivial as they may seem to a casual observer or, for that matter, to their very practitioners. Exchange requires certain levels of dexterity in communication, quantification, abstraction, and orientation in time and space – all of which depend (i.e., put selection pressure) on the lingual, mathematical, and even artistic faculties of the human mind. Moreover, exchange relies on mutual trust: predictable codes of conduct agreeable to the human sense of morality. Exchange, therefore, is a pervasive human predisposition with obvious evolutionary implications. The root cause of this predisposition and its evolutionary consequences in history, and prehistory, are the central concerns of this book.

Was exchange an early agent of human evolution, or is it a mere de novo artifact of modern civilization? The evolutionary literature treats the question with great caution. Many authors, starting with Charles Darwin and Alfred Russel Wallace, preferred to avoid the issue altogether. When the issue comes to the fore, the importance of exchange in recent industrialized societies is readily acknowledged.

Calorie for calorie, fuel is less expensive than food. This is, fundamentally, the only explanation for the close tie of humans to fire – an unexpected reliance of a carbon based life form on an unruly combustive chemical reaction. The impact of fire on civilization from the hearth to the microwave oven is fairly well recorded. Yet, by comparison, the bearing of fire on human evolution prior to civilization is still poorly understood and far more speculative. Given its antiquity in human use, from 300,000 years according to fairly conservative indications, up to 1.5 million years according to others, it is hard to escape the conclusion that fire had a role to play not only as an agent of civilization but also as an agent of evolution promoting hardwired adaptations – not in the least, incitement to trade. Human use of fire, I will argue in this chapter, both facilitated, and was facilitated, by early forms of market exchange.

Nonhuman use of fire

Before we examine the use of fire by humans, it would be appropriate to examine its exploitation by certain forms of life other than human. However opportunistic and passive, the practice is apparent in plants more than in animals for a good reason. Unable to flee fire but, making a virtue of a necessity, plants developed elaborated safeguards against it and, occasionally, use its deadly reaches to their own advantage. Plants protect themselves from fire by various means (e.g., by sheltering storage and vital tissues underground) and, consequently, are fireproof to different degrees.

Upton Sinclair's novel, The Jungle (1906), is a brutally graphic account of the ruthless competition in the stockyards and slaughterhouses of Chicago at the turn of the nineteenth century. Literary observers like Sinclair, and social observers in general, have often appealed to an imaginary animal-like struggle for survival in search of analogies that describe human conduct in the marketplace. The analogy is unfair to humans as much as to animals. In reality, the essential pattern of market activities, perhaps more than any other pattern of human behavior, is marked by the lack of analogy with animals.

Exchange, or apparent exchange, among living organisms other than humans is largely confined to the realms of symbiosis and nepotism (i.e., transfers among members of separate species and transfers among related conspecifics, respectively). For human beings these two patterns of exchange are only part of a wider repertoire that includes a remarkable addition in the form of mercantile exchange (transfers among conspecifics at large). A preliminary survey of these three patterns of exchange will be given in this chapter.

Adam Smith's zoological digression

Adam Smith was a younger contemporary and, it is told, a great admirer of Linnaeus (Schabas, 1994:332). The Linnaean version of the “economy of nature” had already acquired some enthusiastic following among English-speaking readers like Erasmus Darwin, another contemporary of Linnaeus (and grandfather of Charles), who cast the Linnaean system into verse under the title The Botanic Garden (1789). Smith's main concern, however, was the man-made “political economy.”

The specialization–diversification dichotomy

Our life as productive agents is incredibly narrow in scope. Most people, when asked to list the types of products (commodities or services) they help produce in a course of a working day, if not a lifetime, would be hard pressed to point to more than one item. On the other hand, with the exception of the most devoted ascetics, almost everybody can easily list a dozen or more distinct products they help to consume before breakfast is over, and dozens more by the end of the day. Strictly in scope, though not necessarily in craftiness or subtlety, our life as consumers seems to be exceedingly richer than our life as producers.

The pattern is of great antiquity – as old, in fact, as hunting-gathering (when the act of procurement was first set apart from the act of consumption). This state of affairs reflects a fundamental dichotomy in the principles of human production and consumption. In production, the central organizing principle is specialization. In consumption, quite the opposite, the central organizing principle is diversification. By their very nature, these two principles are at constant variance with each other. The conflict can be reconciled only by redistribution and that is, in the final analysis, the primary function of exchange.

Agriculture rose in the face of this conflict. The transition from one-step acquisition to multi-stage production of food greatly intensified the tension between the expediency of specialization and the necessity of diversification in diet. This worked to put great demand on the system of redistribution and, by extension, on exchange.

Against all odds, agriculture was not part of the “creative explosion.” The Upper Paleolithic people, completely obsessed with wildlife – especially with grazing animals (as evident, for instance, from their art) – strangely enough found no interest in domesticating any of them. Food production would have been, it seems, the logical conclusion of the Middle to Upper Paleolithic transition, yet for no immediately apparent reason it was never attempted. This failure to act defied for a long time any explanation, although such an explanation is key to any attempt to understand the transition to agriculture, if not to civilization itself.

In 1993 a promising clue was discovered in unexpected quarters. Of all places, it was extracted from a deep hole in the ice-cap over a remote mountaintop thousands of miles away from the nearest site that could conceivably have served as a cradle of early agriculture. It came in the form of a three-page report published that year in Nature (364: 218–220) by a group of scientists from the Ice-core Project Summit (GRIP) of Greenland (a country with a land area 99% unfit for agriculture). I will come back to this report shortly, but first we have to establish the necessary environmental and economic connections.

Five unexplained remarkable facts

The first humans who relied on agriculture left more traces in the archaeological record than any culture that preceded them; so much so, that they are a mystery to us primarily because of what we know about them, rather than what we don't.

Division of labor can evolve (i.e., be selected for) only if all its structures and partaking entities are properly exposed to natural selection. By implication, division of labor can be anticipated to readily evolve only if it occurs at a level of organization strictly below the unit of selection. For instance, the division of labor among cells and organs of a single healthy organism is possible largely because the unit of selection typically rests at the level of the organism, if not above it. By its very nature, division of labor is an interaction among two or more partly independent entities that have to share, somehow, the costs and benefits of their common endeavor. They need a system of redistribution. This is provided and best regulated by the designated unit of selection on behalf (and from above) all its constituents. For the same reason, division of labor can evolve only with great difficulty at or above the level of organization of the unit of selection. Ordinarily it does not successfully occur at such levels, and those rare instances where it does are invariably associated with evolutionary innovations of great interest. These innovations are the main subject to be discussed in the present chapter.

Some aspects of division of labor are transitory. They may rise in one generation only to fade away in another depending on the changing environment and, in human society, on the rise and fall of contemporaneous technologies (an example is provided by the ever-changing sexual division of labor in human society – to be discussed in a subsequent section).

The chimpanzee is our closest nonhuman relative and, on the whole, is probably the best animal model of human individual behavior. A society of chimpanzees, however, is not necessarily the best model of human society. Strictly in terms of group behavior, humans may bear – perhaps uncomfortably – a closer resemblance to a society of baboons. In fact, of all the animals that live in groups, only the baboons provide a model of group formation (known as the fusion-fission system, after Kummer, 1997) that defines the very concept of a group in a sense applicable to human society. Ironically, the baboon is a quadruped dog-snouted primate that on a phylogenetic scale occupies a place nowhere as nearly related to humans or chimpanzees as both are related to each other. Darwin was keenly aware of this fact but, nonetheless, made nearly twice as many separate references to baboons than to chimpanzees in the Descent of Man (see Box 7.1). Almost a century later the importance of the baboon's ecology and society to the study of human evolution (especially in its Australopithecine stage) was recognized in the literature following an influential paper by DeVore and Washburn (1963). The present discussion further follows the evolution of the baboons in an attempt to better understand some conceivable early indications for the existence of human exchange. On this issue and a few others (e.g., sex-roles and warfare) I have found the insights gained from the natural history and social structures of the baboon to be more helpful than comparable insights gained from the chimpanzee or other apes. Perhaps we have something in common with a monkey that we do not share with an ape.