Retrospect on Carl Ortwin Sauer

ABSTRACT. Carl Ortwin Sauer (1889-1975) is widely regarded as one of the most influential geographers of the twentieth century, admired particularly for his studies in cultural and historical geography. His contribution to the study of prehistory is less widely acknowledged, but, between 1944 and 1962, he published a series of speculative yet scholarly papers that contain many prescient insights into humanity’s remote past and the relationships of our ancestors to the environments they occupied-and modified. In this essay, based on the Carl O. Sauer Memorial Lecture given at the University of California, Berkeley, in October 2001, I reflect on Sauer’s contribution to the science of prehistory by examining, in the light of recent advances in knowledge, two major themes of Sauer’s work: the early dispersal of Homo sapiens in the Old World, and the origins and prehistoric spread of agriculture. Keywords: agriculture, archaeology, domestication, fire, prehistory, Carl Sauer.

Looking back over the years since 1976, when John Leighly delivered the inaugural Carl O. Sauer Memorial Lecture, I am impressed by how widely my predecessors have ranged in time and space, as befits the celebration of a man whose scholarship was as broad and deep as Carl Sauer’s. Some chose topics only tangentially linked to Sauer’s own work, but most spoke about aspects of their research that were inspired, directly or indirectly, by his unique geographical and historical vision. On this occasion, I want to follow a somewhat different path by offering a critique of one part of that vision: Sauer’s contributions to the study of prehistory. I count myself very fortunate to have been one of those who came directly under Mr. Sauer’s influence (Figure 1). Encountering him, and others in the Berkeley Department of Geography in the mid- 1950s, was for me a liberating and defining experience. Under Sauer’s inspirational tutelage, and responding to the diverse talents of his remarkable departmental colleagues-Clarence Glacken, John Kesseli, John Leighly, Jim Parsons, and Erhard Rostlund-I discovered a new kind of geography, unrestricted in its exploration of time as well as space.

Since then I have strayed beyond the institutional bounds of geography into archaeology but, happily, have found the boundary between them to be a comfortably permeable one. In his well-known poem The Road Not Taken, the New England poet Robert Frost regretted, when faced by two roads diverging in a yellow wood, that he “could not travel both And be one traveller” (1955, 78). I have found the geographical and archaeological roads to be so intimately intertwined that it has been possible to make one journey along them, and for me, echoing Frost, “that has made all the difference.” That journey started for me on the Berkeley campus, where the discovery of Sauer’s kind of geography, intellectually unconfined by the conventional disciplinary boundaries of academia, came as a revelation, especially his bold explorations of the “farther reaches of human time.”1

FIG. 1-Carl O. Sauer, photographed by Dorothea Lange in her garden in Berkeley in the 1940s. (Photograph courtesy of Mrs. Elizabeth Fitzsimmons, Carl O. Sauer’s daughter)

So for this lecture I have chosen to focus on two aspects of humanity’s remote past that fascinated Sauer and have shaped our own world. They transformed mankind’s relationship to the planet and can be seen in retrospect as major transitions on Homo sapiens’ pathway to what Sauer characterized as “man’s ecological dominance.”2 They are, first, the initial dispersal of humans, aided by fire, out of Africa and into Eurasia and, second, the origins and prehistoric spread of agriculture. Sauer made farsighted contributions to both topics, and my purpose is to comment on how our knowledge of each has changed since his time-for today they are subjects of much new research, and not a little controversy.

Before turning to the first topic, I want to draw attention to Sauer’s attitude toward the interplay of human geography with prehistoric archaeology. This is most explicitly expressed in his presidential address to the Association of American Geographers in 1940, “Foreword to Historical Geography” (1941). There, in the section entitled “The Relevance of All Human Time,” he points to archaeology’s “specifically geographic dimension,” commends geographers who have “concerned themselves with prehistoric settlements and culture,” suggests that the remit of historical geographers is to study “human origins and changes throughout all human time,” and concludes-with some asperity-”Let no one think, therefore, that we are in any sense off-side from the main theme [of human geography] if we work at the farthest reaches of time” (p. 13). He himself did just that, in a series of scholarly and speculative essays, most of which were published between 1944 and 1962 and provide the background to this lecture.3

OUT OF AFRICA, INTO EURASIA: THE EARLY DISPERSAL OF HOMO SAPIENS

From 1925, when Raymond Dart announced his discovery of the first fossil Australopithecine or “southern ape man,” Sauer followed with keen interest the reports of further finds of hominid fossils in South Africa and subsequently East Africa, but he did not concern himself with the details of their classification. We do not find in his essays any discussion of the complexities of hominid evolution. Instead, in a typically evocative phrase, he speaks just of “the primate groundling who was becoming man” (1961, 401); and, when he wrote about the spread of humans out of Africa into Asia, he did not distinguish between the earliest dispersals of Homo erectus populations, represented in his time by the so-called Java Man and Peking Man fossils, and the later spread of anatomically and behaviorally modern humans, Homo sapiens. The picture he painted of a coastwise spread of humans along the shores of the Indian Ocean could be applied to either. But it is the spread of Homo sapiens that particularly attracts scientific attention and public interest today, and it is here that Sauer’s ideas have proved most prescient- as exemplified by two quotations from “Seashore-Primitive Home of Man?” (1962).

The dispersal of early man took place most readily by following along the seashore. The coasts ahead presented familiar foods and habitats. . . . Coastwise there was scarcely a barrier to the spread . . . through tropical and subtropical latitudes. . . . Even when the zone of winter cold was reached the supply of food was less altered or seasonally restricted than was that of the land. (p. 47)

The Indian Ocean, likeliest sea of earliest human occupation, exhibits to a large extent . . . inviting articulation of shoreline, from Africa to the Sunda Islands, (p. 46)

In recent decades geneticists have added a new dimension to the study of past human migrations. They have done so by analyzing genetic markers in living humans, particularly those from the male Y chromosome and from mitochondrial DNA (which is passed down the female line), and then tracing them back to their geographical origins (Hedges 2000; Ingman and others 2000; Gibbons 2001; Underbill and others 2001; Templeton 2002). This research has strongly reinforced the hypothesis, based on the fossil evidence, that Africa was the homeland of all hominids, including our own species, which current estimates suggest originated there between 200,000 and 130,000 years ago. Thus, although some palaeoanthropologists continue to support the multiregional hypothesis (Thorne and Wolpoff 1992, for example), which envisages Homo sapiens evolving from Homo erectus populations independently in Asia as well as in Africa, most now subscribe to the “Out of Africa” model (Wilson and Cann 1992; Stringer and McKie 1996).

But investigation of the timing and direction of the dispersal of Homo sapiens from Africa into Asia has been hampered by a lack of archaeological evidence. It used to be thought that there had been only one major migration from northeastern Africa to the Levant after 50,000 years ago, followed by the rapid spread of people westward across Europe and eastward across Asia. However, when remains of Homo sapiens found at the sites of Qafzeh and Skhul in Israel were dated to circa 100,000 ago (Schwarcz and others 1988; Valladas and others 1988; Stringer and others 1989; Mercier and others 1993), it became clear that the process of dispersal had begun much earlier-although it was still assumed that it had taken place through the interiors of the continents.

The first body of archaeological evidence seriously to challenge this assumption came not from within Europe or Asia but from the more remote continent of Australia. There, the discovery in the 1980s and 1990s of several Pleistocene sites that were occupied by humans between 50,000 and 60,000 years ago stimulated renewed speculation about how, and by what routes, people first reached the continent (Jones 1989; Smith and Sharp 1993; Allen 1994; Harris 1994, 6-8; Roberts, Jones, and Smith 1994; Stringer 1999; Thorne and others 1999). At times of lowered sea level during the Pleistocene, Australia, Tasmania, and New Guinea formed the continent of Sahul, and most of island Southeast Asia was part of the Sundaland extension of the Asian landmass; but humans still had to cross several stretches of open sea 60-80 kilometers wide before they reached the northwestern shores of Sahul (Figure 2). That a few individuals might have accidentally drifted across these ocean barriers on mats of floating vegetation and become the founding population of Sahul is wholly improbable. The crossing-aptly described by one prehistorian as a “remarkable and precocious maritime adventure” (Groube 1989, 292)-can only have been accomplished with a seagoing craft, probably some form of raft made of logs or bamboo.

From the archaeological proof of human presence in Australia more than 50,000 years ago has come a radical reappraisal of the antiquity of seafaring and, in turn, examination anew of the routes that may first have led people from Africa to Southeast Asia and on to Australia. The idea that the earliest dispersals were coastal, along the shores of the Indian Ocean, as Sauer suggested, is increasingly regarded as tenable hypothesis rather than unfounded speculation, and it has recently gained credence from discoveries at Abdur, a site on the southwestern coast of the Red Sea (Figure 2). There, Middle Palaeolithic stone hand axes and obsidian flake and blade tools, associated with the remains of shellfish and large mammals, have been found on a coral-reef terrace that has been dated (by the Uranium-Thorium method) to circa 125,000 years ago, indicating that the site was occupied during the last interglacial period, almost certainly by early modern humans (Walter and others 2000).

Fossil remains of Homo sapiens dating to the same period have been found at several sites in eastern Africa and in Israel (at Qafzeh and Skhul), but no equivalently early sites have yet been discovered along the 175,000 kilometers of present-day coastline between the Red Sea and Australia (Figure 2). It is probable that most early coastal sites were inundated long ago by rising postglacial sea levels, but if any can be found they will help track and date the migrations of early modern humans around the northern shores of the Indian Ocean. Few archaeologists have deliberately looked for them in likely locations, such as raised marine terraces, let alone underwater offshore. One such location that invites close scrutiny is the southern rim of Arabia, which Sauer nominated as possibly “a great lost corridor of mankind” (1952, 36).

FIG. 2-The Indian Ocean, showing (in gray) the approximate extent of the continental landmasses exposed at times of lowered sea level during the Pleistocene period, the location of the Middle Palaeolithic archaeological sites of Abdur, Qafzeh, and Skhul, and suggested directions (arrows) of Pleistocene coastal dispersals of Homo sapiens.

Forty years after Sauer speculated about the significance of the seashore in general, and of the Indian Ocean in particular, as habitat and routeway for early humans, the idea is at last being taken seriously by some palaeoanthropologists. Chris Stringer, head of human origins research at the British Museum, recently published a note in Nature that included a map showing a “putative route for coastal migration of modern humans from Africa to Asia” (2000, 25); and Marta Lahr and Robert Foley likewise favor the hypothesis of eastward dispersal along the coasts of the Indian Ocean (1994, 1998, 167-168).

Doubtless Sauer would have relished learning of these new discoveries in Australia and the Red Sea, notwithstanding the fact that the reports of them contain no references to any of his publications. He was a prophet yes, but in this case one without honor!

Thus the picture Sauer conjured forty years ago of people spreading coastwise out of Africa and following the warm, resource- rich shorelines of the Indian Ocean eastward is beginning to be substantiated by archaeological and palaeoenvironmental research. But human dispersal beyond the Tropics, especially away from the coasts into the winter-cold continental interiors of Asia and Europe, was dependent on another aspect of their behavior that preoccupied Sauer: the use of fire. Over many years he repeatedly argued, notably in “Grassland Climax, Fire, and Man” (1950), that the deliberate burning of vegetation by hunters, gatherers, and cultivators, rather than climate, was primarily responsible for the creation and maintenance of temperate grasslands and tropical savannas. Later he gave more attention to the question of how humans first added fire to their cultural repertoire. His thoughts on this theme are summed up in “Fire and Early Man” (1961), in which he proposes that “primordial man” in the “volcanic lands of East Africa” was the earliest fire user, and he goes on to evoke, in characteristically eloquent prose, the circumstances and consequences of this “great innovation”:

The step from watching the effects of fire to using fire was bound to be taken. . . . It may have taken time, perhaps a long time, before someone picked up a brand, carried it, and set a fire. It may have taken more time before someone carried fire back home and fed it there. . . . Trial was followed by imitation, act led to desired effect, a new way of living was started. Man had broken the limitations of environment that had previously confined him. Henceforth he could make warmth where it was cold; he could scare away predators and drive creatures to their destruction; he could prepare food. We speak of mankind as masculine collectively, but the great innovation was mainly done by woman, keeper of the hearth and provider of food. The early capture of fire was from the hot insides of the Earth; Prometheus came late, too late, to be anything but a romantic myth. (p. 404)

Sauer cited little direct evidence of very early fire use in support of this persuasive picture, although he did refer to “Choukoutien inhabited by Peking Man [as the] “earliest generally admitted site of fire-using man” (p. 403). But we may ask how his interpretation stands up to scrutiny today. What have we learned in the intervening forty years about how, where, and when humans began to use fire?

Despite a great increase in the archaeological investigation of early hominid sites since the 1950s, well-attested evidence of early fire use remains elusive. This is due partly to the difficulty of discriminating in the sedimentary record between natural and humanmade fires and partly to a general lack of evidence of burning in early hominid sites. An exception is the East African site of Chesowanja, in Kenya, where lumps of baked clay, which undoubtedly represent burned material and may derive from a campfire hearth, have been tentatively dated to between 1.3 and 1.5 million years ago. These finds were first reported by John Gowlett and his colleagues in 1981 and further discussed in a more recent work (Gowlett and others 1981; Gowlett 1999). The identity of the hominids who made the stone tools found at Chesowanja is uncertain- Gowlett favors Homo erectus-but the finds long predate the emergence of Homo sapiens and raise the possibility that premodern humans in East Africa were capable of some controlled use of fire prior to 1 million years ago.

Regardless of whether early hominids living in African savanna environments in the Pleistocene were fire users, as seems probable, we can assume-as did Sauer-that the ability to control and use fire, for warmth, light, the procurement and preparation of food, tool making, communication, and protection, was a prerequisite for the spread of humans into temperate and polar latitudes in Eurasia. It has long been thought that the earliest reliable evidence for fire use in temperate Eurasia came from Locality 1 at Zhoukoudian (Choukoutien), China, which was occupied during the Middle Pleistocene by a Homo erectus population. The evidence consisted of burned bones and sediments in the earliest archaeological horizon (Layer 10), and it was later inferred that some of the ashlike deposits represented the remains of hearths. This interpretation has been questioned, most recently by Steve Weiner and others (1998), who acknowledge that the co-occurrence of burned bones and quartz artifacts in Layers 10 and 4 is suggestive of fire use by hominids but point out that their samples offer no evidence of ash or in situ hearth features. In a subsequent on-line exchange with Weiner and others, Xinzhi Wu reasserted the case for in situ fire use (1999). So the evidence remains inconclusive, although it is consistent with fire use by Homo erectus at the site.

Evidence for fire use in the Middle Pleistocene, in the form of hearthlike features, has also been reported from Lower Palaeolithic sites in Europe, such as Vertesszollos in Hungary, Terra Amata in France, and Beeches Pit in eastern England. At the latter, excavations by Gowlett and colleagues since 1992 have revealed scatters of burned flints and discrete patches of burned sediment that probably represent hearths (Gowlett and others 1998). The site was occupied between about 400,000 and 360,000 years ago, during a fully temperate part of the Cromerian interglacial period, probably by an archaic population of Homo sapiens or Homo heidelbergensis who controlled and used fire but may not have known how to make it.

More indirect evidence of fire comes from other Lower Palaeolithic sites in southeastern England during the subsequent Hoxnian interglacial period. In the sedimentary sequences in the type site of Hoxne (in Suffolk), at Marks Tey (in Essex), and at Barnfield Pit, Swanscombe (in Kent), charcoal occurs abundantly together with pollen that indicates a grassland phase estimated to have lasted about 300 years (Evans 1975, 14-15; Bell and Walker 1992, 155). At Swanscombe flints reddened by fire were also found (Evans 1975, 9), but whether all this evidence derives from natural fires or deliberate burning by humans remains unresolved.

Not until the late Pleistocene in Europe do we encounter conclusive evidence of fire use in the form of abundant deposi s of ash, charcoal, and burned bones in cave and open sites occupied by Neandertal and Homo sapiens populations during the Middle and Upper Palaeolithic. The widespread occurrence of such evidence strongly suggests that the occupants of these sites knew how to make as well as maintain fire. However, built hearths are rare on Middle Palaeolithic Neandertal sites and only become common after the beginning of the Upper Palaeolithic, around 40,000 years ago.

From this still-meager evidence we can conclude that the ability to make fire, and use it in manifold ways, became part of the complex of skills that enabled Homo sapiens to spread through the temperate and polar regions of eastern Eurasia and eventually into the Americas across what is today Bering Strait but which was, at times of lowered sea level in the Pleistocene, the land bridge of Beringia (Hoffecker, Powers, and Gobel 1993, 46).

Tantalizingly little archaeological evidence exists of the initial spread of humans into and across the vast expanse of northernmost Eurasia to the threshold of North America. It has generally been supposed that the region remained unoccupied until after the Last Glacial Maximum, circa 20,000 years ago. But recently discovered evidence suggests otherwise. That evidence consists of stone tools associated with numerous mammoth bones excavated at a site on the Arctic Circle: Mamontovaya Kurya, on the Usa River at the northern end of the Urals (Pavlov, Svendsen, and Indrelid 2001). Several of the mammoth bones and a tusk with cut marks made by stone tools have been radiocarbon dated to circa 36,000 years ago. The occupants of the site were probably Homo sapiens (rather than Neandertals), and the finds support the inference from the Upper Palaeolithic sites farther west in Europe that humans were habitually making and using fire by 40,000 years ago. Pollen analysis of deposits associated with the bones found at Mamontovaya Kurya indicates that grassy steppe surrounded the site, which was probably occupied during a relatively mild interlude in the last glacial period. This raises the possibility that people may have reached western Beringia across the steppe before the setting in of the extreme cold of the Last Glacial Maximum.

Such new evidence adds fuel to the fire of the long-running and sometimes acrimonious debate between the advocates of a late and of an early entry of people into the Americas. In the 1940s Sauer was already arguing (1944, 1948) that people first entered North America (via Beringia) early in or even prior to the last deglaciation, well before the time interval of circa 15,000-12,000 years ago favored then-and still today-by most American archaeologists who have studied the evidence closely (Bonnichsen and Schneider 1999; Bonnichsen and Turnmire 1999; Fiedel 1999, 2000; Anderson and Gillam 2000; Adams, Foote, and Otte 2001; Dixon 2001). It is not part of my purpose to go further into this contentious question here, beyond noting that arguments continue over the true age of several sites in North and South America that are claimed to be substantially older than 12,000 years, such as Meadowcroft in Pennsylvania (Adovasio and others 1999) and Monte Verde in Chile (Dillehay 1984, 1997; Lynch 2001). The jury is still out, and it remains to be seen whether Sauer’s speculations about when this great step in the human colonization of the continents occurred will eventually be confirmed by further research.

No such uncertainty attaches to the crucial importance of fire in the initial human occupation of Eurasia (and subsequently the Americas), despite the difficulty of reconstructing early fire use from the sparse and often ambiguous archaeological and palaeoenvironmental records. And, although we still have much to learn about when humans first began to use, and later to make, fire, Sauer’s views on the antiquity and cultural importance of this “first great force employed by man” have largely been vindicated by subsequent research (Stewart 1956).

THE ORIGINS AND PREHISTORIC SPREAD OF AGRICULTURE

Carl Sauer’s ideas about the origins and prehistoric spread of agriculture have, in my view, stood the test of time less well than his essays on fire and early human dispersals. This is a difficult judgment for one who has-as I did on the Berkeley campus in 1955- come under the spell of what is probably Sauer’s most widely known publication: the slender and captivatingly readable Agricultural Origins and Dispersals of 1952. However, rather than launch directly into a critique of the assumptions on which the book is based, we should see it first as part of Sauer’s contributions to the larger theme of the changing relationships, through time, of people, plants, and animals. It is in these contributions, particularly “Early Relations of Man to Plants” (1947) and “Environment and Culture during the East Deglaciation” (1948) that his insights into these relationships are most convincingly stated.

In these offerings from the 1940s we find the seeds of the grand synthesis that was to become Agricultural Origins and Dispersals. Indeed, in 1948 Sauer suggested that “microliths, bow and arrow, fishing gear, boats, adze and axe, grinding slabs, pottery, and domesticated dog are sufficient parts of a mosaic to venture a preliminary hypothesis as to the nature of Mesolithic culture, its general place of origin, and its age,” and “to see in this period the trial arrangements and finally the full prelude to the Neolithic” (p. 73). Here too we meet for the first time the notion of “progressive fishing people who initiated the basic steps in plant and animal domestication” (p. 74) and who lived in permanent villages close to rivers and lakes. This “transformation of culture . . . out of which came the Neolithic modes of life . . . perhaps was pioneered only in one area, which most probably lay in Southeastern Asia” (p. 77). Also by 1948 Sauer was rejecting Southwestern Asia as a hearth of earliest agriculture, “largely because I do not see that the things it contributed, such as small grains and other economic annuals and the larger domesticated animals, belong to the earlier stages of the sequence that led to agriculture” (p. 75).

By 1952 Sauer was ready to state his assumptions about the beginnings of agriculture more explicitly. In the first chapter of Agricultural Origins and Dispersals he enunciates the concept of “progressive cultures” that occupied “creative culture hearths” or “centers of innovation” in “physically favored areas.” He also states his conviction that few such centers existed and that the spread of innovations from them, rather than independent, parallel invention, was the main mode of cultural change. And at the outset of the second chapter, under the heading “Antecedents of Domestication,” he lists the following six “basic premises” concerning how agriculture arose. There is no need to consider each of them, but I will return later to the first and the last.

1. Agriculture did not originate from a growing or chronic shortage of food.

2. The hearths of domestication are to be sought in areas of marked diversity of plants or animals. . . .

3. Primitive cultivators could not establish themselves in large river valleys. . . .

4. Agriculture began in wooded lands.

5. The inventors of agriculture had previously acquired special skills . . . that predisposed them to agricultural experiments.

6. Above all, the founders of agriculture were sedentary folk. (1952, 20-22, here abbreviated)

In the second chapter too Sauer proposes mainland Southeastern Asia as “the cradle of earliest agriculture” and suggests that “[n]o other area is equally well situated or equally well furnished for the rise of a fishing-farming culture” (pp. 24-25), from which putative source he goes on to derive, by diffusion, the beginnings of agriculture throughout the Old World. It is this aspect of his synthesis-the assumption of a single center and the reliance on diffusion to explain the origins of agriculture everywhere else- that has attracted the most criticism and has led many of his critics to overlook the original insights into the early relationships among people, plants, and animals that the book, and his earlier writings, contain.

It is beyond the scope of this essay to assess Sauer’s opinions on the origins of individual domesticated plants and animals against new evidence, but the validity of several of his main propositions can be examined in the light of what we now know about the beginnings of agriculture in the Old World. The first point to stress is that his contention that mainland Southeastern Asia was the single “cradle of earliest agriculture” in the Old World is not borne out. It is not among the regions where current archaeological and biological evidence suggests that independent transitions to agriculture occurred. In the Old World there were probably three core regions where agriculture developed independently-western Southwest Asia (the Levant), China, and northern tropical Africa (the southern Sahara and the Sahel)-and there is some evidence too for independent origins in other regions, such as southern India (Fuller, Korisettar, and Venkatasubbiah 2001) and New Guinea (Golson 1977, 1989; Groube 1989; Yen 1991, 1998, 163-170; Gosden 1995; Harris 1995; Spriggs 1996).

The most compelling evidence on how and when agriculture began comes from the Levant, but archaeological research in China now points strongly to an independent origin of cereal cultivation there (based on rice and millets) slightly later than the beginnings of grain agriculture (based on barley, wheat, and pulses) in the Levant, both transitions having taken place very slowly during Late Pleistocene and Early Holocene times between circa 11,000 and circa 8,000 years ago (Bar-Yosef and Meadow 1995; Higham 1995; Cohen 1998; Crawford and Chen 1998; Harris 19983; Zhao 1998; Garrard 1999; Moore, Hillman, and Legge 2000). There is less archaeological evidence for agricultural origins in the southern Sahara and Sahel, but the circumstantial case is strong for native crops such as sorghum and other millets, tree crops and yams having come into cultivation there independently of external influences by circa 3,500 years ago (Stahl 1993; Neumann 1999; D’Andrea, Klee, and Casey 2001); and archaeological and genetic evidence suggests the possibility that native cattle may also have been domesticated there independently of their domestication in Southwest Asia (Smith 1986; Grigson 1991; Wendorf and Schild 1994, 1998; Bradley and others 1996; Bradley and Loftus 2000; Gautier 2001; Marshall and Hildebrand 2002, 109-114).

This last point brings me to a second way in which subsequent research has undermined some of the assumptions on which Sauer’s hypothesis rests. His proposition that agriculture developed throughout the Old World as a result of diffusion from Southeast Asia depends in part on the assumption that the plants and animals of early agriculture were each domesticated, once only, in the areas where their wild progenitors lived in recent times.

This is now being seriously challenged by the results of both palaeoenvironmental and biomolecular research. The rapidly accruing body of palaeoenvironmental data, principally from ice-core and sediment studies, is revealing frequent and extreme climatic and vegetational changes in the Late Pleistocene and Early Holocene (Peteet 1993; Roberts 1998, 62-126). Such events profoundly affected the ranges of plants and animals and, thus, cast doubt on inferences based on modern biogeographical distributions. At the same time, studies of variations in the modern and ancient dna of domesticated species are indicating that many may have been domesticated several times in different areas. That evidence relates both to secondary domesticates, incorporated after agriculture was well established, such as horses (Vila and others 2001), and to some of the so-called founder crops and animals associated with the beginnings of agriculture in the core regions of the Old World, such as barley (Holwerda, Jana, and Crasby 1986,1287), emmer wheat (Brown and others 1993), rice (Sato 1997), cattle (Loftus and others 1994; Bailey and others 1996; Bradley and others 1996; Hanotte and others 2002), and perhaps goats (Takada and others 1997; Mannen, Nagata, and Tsuji 2001). These two new sources of data suggest that much received wisdom about the homelands of crops and domestic animals, which derive from Nikolai Vavilov, Sauer, and other early students of domestication, may have to be radically revised (Harris 1990; Blumler 1992; Jones and Brown 2000).

A third general point of contention relates to Sauer’s ideas about the precedence of root-crop cultivation over seed-crop cultivation, in the humid Tropics in general and in Southeast Asia in particular. Here we encounter a major difficulty because seed crops, particularly cereals, are more likely to be preserved in archaeological contexts, usually as a result of charring, than are root crops, and the recovery of seeds and chaff by the flotation method is now routine practice. So evidence of their early cultivation is more likely to be found than is evidence of root crops, which are only rarely preserved in macroscopically recognizable form, in very dry or in waterlogged sites. To counter this bias in favor of the grains, at the Institute of Archaeology in London we pioneered a novel microanatomical method for identifying charred fragments of the soft tissues of roots and tubers (known as “parenchyma”) preserved in archaeological deposits. My colleague Jon Hather developed the method (1991, 1994, 2000) and was, for example, able to prove, with Pat Kirch (1991), that the sweet potato, of South American origin, was introduced to the Cook Islands in central Polynesia by circa a.d. 1000-a result that supports Sauer’s acceptance of the pre-Columbian transpacific carriage of the crop (1952, 60). But the technique has not yet been widely applied in areas of the Tropics where root-crop cultivation may be of great antiquity, so Sauer’s more general inference that tuberous plants were domesticated long before grain crops remains untested.

In Southeast Asia archaeological evidence exists of intrusive rice farmers moving south from China during the third millennium B.C. into areas occupied by fisher-hunter-gatherers rather than by people already practicing some form of agriculture (Glover and Higham 1996, 419-426); and, even if root-crop cultivation is very ancient in Southeast Asia, it is unlikely to have expanded into China, India, and eventually tropical Africa, as Sauer proposed. It did not, on its own, provide a nutritionally adequate diet that freed farmers from dependence on wild sources of protein and fat, obtained mainly from fish and terrestrial mammals in their natural habitats. In contrast, systems of grain cultivation, especially the Southwest Asian variant, which integrated domestic herd animals with crop cultivation, provided a more balanced diet and were inherently expansive, and it is they that spread extensively during Neolithic times (Harris 2003a).

Perhaps it is surprising that Sauer’s model of the spread of agriculture outward from Southeast Asia did not distinguish between the expansion of agricultural populations (often referred to as “demie diffusion” or “colonization”) and the adoption of agricultural crops, animals, and techniques by foragers (“cultural diffusion” or “technology transfer”). In recent years this distinction has come to the fore in debates on the spread of agriculture, especially in Neolithic Europe, where it has become clear that the sedentary foragers of the northern margins of the continent, who occupied riverine and coastal areas rich in aquatic and terrestrial foods, adopted Neolithic agriculture only slowly and in a piecemeal fashion (Price 1996, 2000; Zvelebil 1996; Woodman 2000). From this we can infer that Sauer’s putative Southeast Asian “sedentary freshwater fishing communities” are unlikely begetters of systems of agriculture that subsequently spread (as his model assumes), although they may have domesticated some indigenous plants and cultivated them on a small scale.

This leads us to what I believe to be another flaw in Sauer’s position: his assumption that agriculture began in conditions of plenty, where people “lived at a comfortable margin above the level of want” and had “the leisure for reflection, experimentation and discussion” (Sauer 1952, 21). This may be true of the smallscale tending of useful plants by sedentary foragers within or near their settlements, but it overlooks the fact that once fields began to be systematically tilled, vegetation cleared, and agricultural products processed and stored, agriculture became unremitting hard work, more demanding of energy and time than were fishing, hunting, and gathering. The great advantage of farming over foraging is that it produces more food per unit area and can sustain more people in permanent settlements. I think it most unlikely that foragers would voluntarily have made the transition to the new, more laborious way of life unless their old way of life were subjected to some sustained stress-and the most probable source of stress sufficient to bring about such a fundamental socioeconomic shift is an environmental change that reduced the wild foods on which the foragers depended.

This idea is by no means new, but it has recently found strong support in the most detailed archaeological study we have of a transition to agriculture from anywhere in the world. It was undertaken at the Late Palaeolithic / Neolithic site of Tell Abu Hureyra on the Euphrates in Syria (Moore, Hillman, and Legge 2000). My colleague Gordon Hillman, who led the archaeobotanical investigation of the abundant plant remains recovered from the site, has been able to demonstrate a progressive decline in the grass seeds and other wild seed foods gathered by the Late Palaeolithic inhabitants, from the less to the more drought-tolerant species, which coincided with the interval of much colder and drier conditions known as the Younger Dryas stadial (Roberts 1998, 70- 76), which occurred between circa 11,000 and 10,000 years ago (13,000-11,500 calibrated years before present) (Hillman 1996, 2000,375-377; Hillman and others 2001). Remains of domesticated cereals and pulses first appear in the archaeobotanical record at Abu Hureyra toward the end of the Younger Dryas, and at the same time weeds typical of dryland rain-fed cultivation increase in abundance (Hillman 2000, 363-393). In the subsequent earliest Neolithic period (the Pre-Pottery Neolithic A) the climate became warmer and wetter, and the cultivation of cereals and pulses began to expand at several other Levantine sites. During the following Pre- Pottery Neolithic B period, which lasted some 2,000 years, grain agriculture and livestock herding became widely established throughout the region and began to radiate outward toward Europe, central and southern Asia, and northeastern Africa (Bar-Yosef and Meadow 1995, 73-93; Harris 1998b).

It is significant for this critique of Sauer’s model that Abu Hureyra was a large sedentary settlement in the Late Palaeolithic and that its inhabitants intensified their exploitation of the wild plants on which they depended as the impact of the Younger Dryas increased, eventually turning to the cultivation of this diminishing resource. The case study of Abu Hureyra clearly implicates environmental stress in the transition to agriculture in the Levant, and the preliminary results of research on rice remains recently found at Late Palaeolithic / Neolithic sites in the Yangzi Basin suggest that the transition to agriculture in China may likewise be related to the impact of the Younger Dryas (Zhao 1998; Harris 2003b).

With these two examples in mind we can return to two of Sauer’s “basic premises.” The first-that “[agriculture did not originate from a growing or chronic shortage of food”-appears to be contradicted by the evidence now coming to light on how cereal agriculture began in the Levant and China, whereas the second-that “the founders of agriculture were sedentary folk”-is borne out and, indeed, has long been widely accepted by students of agricultural origins.

The final point to make in this brief critique is that we now try to differentiate more sharply than did Sauer between evidence for the development of agricultural systems, which incorporated different suites of crops and domestic animals, and the ways in which many foragers engaged in the small-scale planting and raising of morphologically undomesticated plants and animals for food and other purposes. This distinction allows us to formulate research questions more precisely and interpret evidence more critically, although, in reality, the ways in which humans have intervened over the millennia in the ecology of the organisms they have exploited comprise a continuum of people, plant, and animal relationships, from complete dependence on wild organisms to almost complete dependence on domesticated ones (Harris 1989, 1996).

It is not my intention to try to draw up a balance sheet of what, with hindsight, we can say Sauer got right and what he got wrong about the origins and spread of agriculture. Instead, I salute his ecological and cultural insights into how, far back in prehistory, humans began to domesticate the wild world around them. Ironically, had he not woven his ideas into a single story-of agriculture emanating from Southeast Asia and diffusing through the Old World and, perhaps, into the Americas-but had instead continued to present them in scholarly journals, as he had up to 1952, his influence on later workers might have been greater. Agricultural Origins and Dispersals, with its frankly speculative style, its global scope, and its general disregard of archaeological evidence, was too easy a target for narrower specialists, who could quickly point to the lack of “hard” evidence in support of Sauer’s grand scheme. It was easy for them to overlook his disarming remark, at the end of the book: “If this be exaggeration of the processes of diffusion of learning, the proposed thesis may be taken as an invitation to study the various lines of evidence as to the growth of the agricultural arts” (1952, 103-104).

For me personally, it was an invitation I could not resist, and of which I have never tired, as Sauer’s “lines of evidence” have come to include numerous new methods of scientific investigation, from the ams technique of radiocarbon dating that now permits us to date a single charred cereal grain, to the analysis of modern and ancient dna that is helping us to unravel the evolutionary histories of our domesticated plants and animals.

And so we come to the end of these reflections on Carl Sauer as prehistorian. By focusing on two great themes in the global history of humanity, to which he brought broad scholarship and innovative imagination, I have tried to assess how his ideas on the early spread of humans and the origins of agriculture stand up to contemporary scrutiny. I have also sought to show how much remains in his writings to stimulate and inform today’s research agendas. His role as a prophet of the modern ecological movement has been widely celebrated by others. I hope this essay will help to increase awareness of his more obscure role as an intellectual pioneer in the study of world prehistory-a study that is, I believe, relevant to our world, besieged as it is by fears and conflicts. For prehistory teaches us to think of humankind as a whole, however ethnically diverse we may be, and it encourages us to focus on what unites rather than divides us. Sauer expressed much the same idea more than sixty years ago, and I shall give him the last word (1941, 24): “From all the earth and in all the time of human existence, we build a retrospective science, that out of this experience acquires an ability to look ahead.”

It is neither accident nor escape that thoughtful human geographers have given much attention to primitive groups and remote time.

-Carl Ortwin Sauer, 1944

* I thank Betty (Mrs. James J.) Parsons for her unfailingly generous hospitality over the years, especially while my wife and I were in Berkeley in October 2001, and David Hooson and his colleagues for inviting me to give the Carl O. Sauer Memorial Lecture.

NOTES

1. This phrase is the title that Leighly gave to part 4 of Land and Life, his edited selection of nineteen of Sauer’s publications (Leighly 1965). It echoes Sauer’s reference to “the farthest reaches of time” in his “Foreword to Historical Geography” (1941, 13).

2. This is a frequent theme in Sauer’s writings, exemplified by the title of chapter 1 of Agricultural Origins and Dispersals: “Man- Ecologic Dominant” (1952, 1).

3. Six of Sauer’s principal essays on aspects of early human prehistory were republished in Land and Life: “A Geographic Sketch of Early Man in America” (1944), “Early Relations of Man to Plants” (1947), “Environment and Culture during the Last Deglaciation” (1948), “The End of the Ice Age and Its Witnesses” (1957), “Fire and Early Man” (1961), and “Seashore-Primitive Home of Man?” (1962) (Leighly 1965).

REFERENCES

Adams, J. M., G. R. Foote, and M. Otte. 2001. Could Pre-Last Glacial Maximum Humans Have Existed in North America Undetected? An Interregional Approach to the Question. Current Anthropology 42 (4): 563-566.

Adovasio, J. M., D. Pedler, J. Donahue, and R. Stuckenrath. 1999. No Vestige of a Beginning nor Prospect for an End: Two Decades of Debate on Meadowcroft Rockshelter. In Ice Age People of North America, edited by R. Bonnichsen and K. L. Turnmire, 416-431. Corvallis: Oregon State University Press for the Center for the Study of the First Americans.

Allen, J. 1994. Radiocarbon Determinations, Luminescence Dating and Australian Archaeology. Antiquity 68 (259): 339-343.

Anderson, D. G., and J. C. Gillam. 2000. Paleoindian Colonization of the Americas: Implications from an Examination of Physiography, Demography, and Artifact Distribution. American Antiquity 65 (1): 43- 66.

Bailey, J. E, M. B. Richards, V. A. Macauley, I. B. Colson, I. T. James, D. G. Bradley, R. E. M. Hedges, and B. C. Sykes. 1996. Ancient DNA Suggests a Recent Expansion of European Cattle from a Diverse Wild Progenitor Species. Proceedings of the Royal Society London Series B: Biological Sciences 263 (1376): 1467-1473.

Bar-Yosef, O., and R. H. Meadow. 1995. The Origins of Agriculture in the Near East. In Last Hunters, First Farmers: New Perspectives on the Prehistoric Transition to Agriculture, edited by T. D. Price and A. B. Gebauer, 39-94. Santa Fe, N.Mex.: School of American Research Press.

Bell, M., and M. J. C. Walker. 1992. Late Quaternary Environmental Change: Physical and Human Perspectives. Harlow, England: Longman Scientific and Technical; New York: J. Wiley.

Blumler, M. A. 1992. Independent Inventionism and Recent Genetic Evidence on Plant Domestication. Economic Botany 46 (1): 98-111.

Bonnichsen, R., and A. L. Schneider. 1999. Breaking the Impasse on the Peopling of the Americas. In Ice Age People of North America, edited by R. Bonnichsen and K. L. Turnmire, 497-519. Corvallis: Oregon State University Press for the Center for the Study of the First Americans.

Bonnichsen, R., and K. L. Turnmire. 1999. An Introduction to the Peopling of the Americas. In Ice Age People of North America: Environments, Origins, and Adaptations, edited by R. Bonnichsen and K. L. Turnmire, 1-26. Corvallis, Oregon: Oregon State University Press and Center for the Study of the First Americans.

Bradley, D. G., and R. T. Loftus. 2000. Two Eves for Taurus? Bovine Mitochondrial DNA and African Cattle Domestication. In The Origins and Development of African Livestock: Archaeology, Genetics, Linguistics, and Ethnography, edited by R. M. Blench and K. C. MacDonald, 244-250. London: UCL Press.

Bradley, D. G., D. E. MacHugh, P. Cunningham, and R. T. Loftus. 1996. Mitochondrial Diversity and the Origins of African and European Cattle. Proceedings of the National Academy of Sciences of the United States of America 93 (10): 5131-5135.

Brown, T. A., R. G. Allaby, K. A. Brown, and M. K. Jones. 1993. Biomolecular Archaeology of Wheat: Past, Present, and Future. World Archaeology 25 (1): 64-73.

Cohen, D. J. 1998. The Origins of Domesticated Cereals and the Pleistocene-Holocene Transition in East Asia. Review of Archaeology 19 (2): 22-29.

Crawford, G. W., and S. Chen. 1998. The Origins of Rice Agriculture: Recent Progress in East Asia. Antiquity 72 (278): 858- 866.

D’Andrea, A. C., M. Klee, and J. Casey. 2001. Archaeobotanical Evidence for Pearl Millet (Pennisetum glaucum) in Sub-Saharan West Africa. Antiquity 75 (288): 341-348.

Dillehay, T. D. 1984. A Late Ice-Age Settlement in Southern Chile. Scientific American 251 (4): 106-117.

_____. 1997- Monte Verde: A Late-Pleistocene Settlement in Chile. Vol. 2, The Archaeological Context and Interpretation. Smithsonian Series in Archaeological Inquiry. Washington, D.C.: Smithsonian Institution Press.

Dixon, E. J. 2001. Human Colonization of the Americas: Timing, Technology, and Process. Quaternary Science Reviews 20 (1-3): 277- 299.

Evans, J. G. 1975. The Environment of Early Man in the British Isles. Berkeley: University of California Press.

Fiedel, S. J. 1999. Older Than We Thought: Implications of Corrected Dates for Paleoindians. American Antiquity 64 (1): 95- 115.

_____. 2000. The Peopling of the New World: Present Evidence, New Theories, and Future Directions. Journal of Archaeological Research 8 (1): 39-103.

Frost, R. 1955. Selected Poems. Harmondsworth, England: Penguin Books.

Fuller, D. Q., R. Korisettar, and P. C. Venkatasubbiah. 2001. Southern Neolithic Cultivation Systems: A Reconstruction Based on Archaeobotanical Evidence. South Asian Studies 17:171-187.

Garrard, A. 1999. Charting the Emergence of Cereal and Pulse Domestication in South-West Asia. Environmental Archaeology 4: 67- 86.

Gautier, A. 2001. The Early to Late Neolithic Archaeofaunas from Nabta and Bir Kiseiba. In Holocene Settlement of the Egyptian Sahara. Vol. 1, The Archaeology of Nab