The Home-base Theory Essay, Research Paper

Glynn Isaac Defines “the Homebase Hypothesis”

It has been argued since Darwin’s day that the great apes were man’s nearest living relatives, and as evidence emerged during the late 1960’s of the hunting propensities and simple tool use of chimpanzees (Goodall 1986), anthropologists found more and more reason to presume similarity of behavior between modern (e.g., Pan troglodytes or Pan panicus) and ancient varieties of hominids (Tanner 1981).

Still, modern humans are not chimps. Substantial differences of behavior exist between the great apes and hominids, and it was the late Glynn Isaac’s notion that these differences began early in our history.

Specifically, he noted that the modern human “habitually carries tools, food and other possessions either with his arms or in containers,” communicates with other humans by a spoken language, that the acquisition and sharing of food is “a corporate responsibility,” that modern human hunter-gathers conduct their foraging operations in the vicinity of communal gathering places or “home bases,” and that humans seek to acquire high-protein foodstuffs by hunting or fishing. None of these are common behavior among the apes or are practiced to the extent that they are among Homo sapiens sapiens. (Isaac 1978)

He also noted tool use both for gathering foods and for processing them for consumption, and different modes of social behavior, including long term pairing bonds (”marriage”) between male and female humans and complex rules of kinship and interpersonal behavior.

Many or all of these differences, Isaac felt, analyzing the archaeological data– primarily broken stones and bones and geological reconstructions of ancient landscapes– had been established at some point between 2.5 and 1.5 million years BP. Moreover, rather than being incidental, they were part of “a novel adaptive strategy” which led to modern Homo sapiens.

Earlier researchers had attempted to establish sequences for the appearance of modern human characteristics– movement to the savanna, bipedalism, tool use, hunting, brain enlargement, etc. (e.g., Campbell 1966) To Isaac, these “simple additive models” were untenable since some of the behavior to be accounted for was already present if only in primitive form in the repertoire of wild chimpanzees. As early as 1971, he argued in favor of integrated models.

“Integrated growth is a better analogue than chain reaction. Thus I would favor models involving concurrent development with mutual reinforcement of adaptive advantages by matching changes in all components, and from this stance I would argue that hunting, food sharing, division of labor, pair bonding, and operation from a home base or camp, form a functional complex, the components of which are more likely to have developed in concert than in succession. It is easy to see that tools, language, and social cooperation would fit into the functional complex as well, and very likely had equally long development histories within the overall system.” (Isaac 1972)

Isaac’s intuition was probably reinforced by his Ph. D. research at Olorgesaile, a Homo erectus site in Kenya. Olorgesaile, dated to between 900,000 and 400,000 years ago, almost certainly did function as a home base (Potts 1988:292). Moreover, it was discovered and first excavated by Louis and Mary Leakey, who saw evidence of home bases (”living floors”) at a number of hominid-formed sites in East Africa, including some in Olduvai Gorge. No doubt this common-sense interpretation, which in some respects goes back as far as 1933 to Solly Zuckerman (Potts 1988:251), had rubbed off on Isaac, but he had also become convinced that lower Paleolithic artifact assemblages were peculiarly difficult to interpret because of low sample densities which produced erratic and potentially misleading data. Discussing this in his 1972 paper, he went on to suggest that paleoarchaeologists were best employed searching “for regularities in the data that are indicative of widespread states and or major evolutionary trends,” and that “the study of occupation sites and their contents seems more promising than preoccupation merely with artifact assemblages.” (Isaac 1972:200)

He predicted a shift towards behavioral models.

Lewis Binford’s Initial Criticisms

In 1977 Isaac published a monograph on Olorgesailie. Lewis R. Binford, reviewing it that year in the Journal of Anthropological Research, was critical, later saying, “While Isaac was an innovator in considering the integrity of deposits yielding traces of early man, he never questioned that the associations among the items found in such modified deposits were all indicative of hominid behavior. He simply accepted the conventional ‘wisdom’ that they were present because hominids had caused the association.” (Binford, 1985:301)

The part of conventional wisdom that most annoyed Binford was evidently what another author called “the hunting hypothesis” (Ardrey 1976). Already skeptical about Neandertal’s abilities as a hunter, Binford was quite as willing to throw cold water on any too- human proclivity of Homo erectus, and firmly convinced that archaeological data would support him. As soon as reliable data and methods for interpreting it appeared, of course. His review called for a “frontal attack” on tool-fauna associations in the Lower Paleolithic.

The Koobi Fora “Homebases”

Meanwhile, that frontal attack was going on in East Africa, much of it under Isaac’s direction at the Koobi Fora research project, of which he had been co-leader (with Richard Leakey) since 1970. There seems to have been a graduate student uncovered with each and every artifact, and many of them produced dissertations on paleolithic taphonomy and went on to related careers– too many to name here.

Isaac, concentrating on the archaeology, categorized four types of sites at Koobi Fora: type A sites had artifacts (stone tools) without associated bone, type B combined artifacts with bones from a single large animal, type C had artifacts and a “conspicuous patch of broken- up bones” from several animals; type D sites were low density distributions of artifacts, what Isaac elsewhere called “the scatters between the patches.” Type C sites were probable home bases. Type D sites were not discussed in his report (but see Stern 1993).

As of 1975, seven major type A sites had been found, one type B, and five type C sites. The oldest of the latter is the “KBS” site, (somewhat redundantly titled, since KBS stands for Kay Behrensmeyer Site), where the archaeological material rests between two layers of volcanic tuff, the upper layer of which is in fact the infamous KBS tuff that so enlivened Richard Leakey’s existence. The age is about 1.9 million years, and the site can be attributed to habilines of one sort or another. (Day 1986). (Other type C sites at Koobi Fora are dated at between 1.5 million and 1.2 million years and were probably created by Homo erectus.)

The KBS site is a former stream bed; silt preserves the impression of tree leaves which fell into puddles. The patch was estimated at 12 to 15 meters in diameter; about half remained for excavation when it was found. The diggers uncovered about 200 stone tools and manuports and “a scatter” of broken bones from various animals: waterbuck, gazelle, porcupine, pig, and hippopotamus. For Isaac, there was “good circumstantial evidence for regarding it as a fossilized remnant of a hominid home base.” However, the summary noted that such conclusions were “tentative” and “speculative.” (Isaac and Harris 1978:85)

In his Scientific American article that year, using the same data, Isaac was much less tentative. “A study of the context of the early African artifacts yields unique clues,” he noted, “both to the ecological circumstances of the proto-human toolmakers and to aspects of their socio-economic organization.” And: “Excavation of these proto-human sites has revealed evidence suggesting that 2 million years ago some elements that now distinguish man from apes were already part of a novel adaptive strategy.” (Isaac 1978:290)

Despite this, he backed off from broader claims of hunting at Koobi Fora, with the remark that “Given the low level of stone technology in evidence, I am inclined to suspect scavenging….” It was even probable that “the first toolmakers lacked the highly developed mental and cultural abilities of more recent humans.”

Whether these reservations were noticed by the typical reader is doubtful. With the imprimatur of Scientific American (and frequent reprinting of the article in years to come) the home base hypothesis had jumped from beyond the archaeological and paleo- anthropological community to the general public. For the next ten years or so, it would be treated virtually as fact by popularizers, interested laymen, and more than a few professionals.

Second Generation Research on Homebases

At roughly the same time, a new generation of researchers, many of them trained by Isaac, were returning to Olorgesaile and Olduvai Gorge to confirm or refute the lessons learned at Koobi Fora. Some concentrated on the bones of hominids (Michael Day, Alan Walker), some on the dinner bones (Pat Shipman, Henry Bunn, Ellen Kroll), some on the sites themselves (Richard Potts). Others, seeking out modern day analogues of ancient hunter-gathers, went to Botswana to observe the !Kung San (R. B. Lee, I. Devor, J. E. Yellen). One apostate (Tim White) defected to the home base of Donald Johanson.

In general, no surprises emerged from the new work. (Sept 1992) However, in his 1982 dissertation, Potts developed an independent critique of the home base idea. Many of the animal bones at Type C sites, he noticed, showed signs of carnivore-inflicted damage. Evidently hominids and felines maintained an interest in the same food material; this “competitive milieu surrounding animal tissues” had probably “restricted” hominids from enjoying the sites for long. “The focusing of social life (in the sense of a hunter-gather home base) at these areas of bone and artifact accumulation was probably not a strategy adopted by the Olduvai hominids.” (Potts 1988:253-4)

Potts suggested that Level I Olduvai inhabitants (Homo habilis, presumably) had established caches of stone throughout their foraging range, to which animal remains could be brought for processing. These were not home bases per se, but may have served as a step towards such hundreds of thousands years later. At the time however, they were only intended for short term use, as a place where bones could be broken up and subsequently discarded. The accumulation of faunal remains over long periods of time created deposits that came to be interpreted as home bases. True home bases would be identified by the controlled use of fire, extensive processing of animal remains, and animal remains that showed modification only by hominids. Effectively, this postpones home bases to roughly 500,000 years ago or even later. (Potts 1988:291)

Binford was pleased to see new thinking, but noted (correctly, in my opinion) that “It is a classic post hoc accommodative argument” which could not be tested because it was designed to fit all the available evidence. (Binford 1985:313)

A more serious challenge to the home base idea emerges from the 1993 paper of Nicola Stern, who argues that the archaeological record is a “palimpset” of debris accumulated over tens of thousands of years. Patches of artifacts and faunal remains, in her view, are simply thicker assemblages of the same stones and bones– the scatter– that rest at sites less interesting to archaeologists. There is no special significance to Type C sites or any other; they are not records of particular events, but merely places where chance happened to preserve more objects, and much of what archaeologists think they perceive in the record is incorrect. (Stern 1993) This idea has not been greeted with enthusiasm; comments on her article variously argued that the record was not as imprecise as she claimed, and that various middle range methods— actualistic studies or “off site archaeolgy”– would come to the aid of future archaeologists. Since Stern’s research began as off site archaeology at Koobi Fora, this assurance has to be wondered at.

Scavenging Defeats the Homebase Hypothesis

Meanwhile, according to Binford, Glynn Isaac was still telling “just so” stories. And childish ones at that, about “a kind of middle-class genteel proto-human who shared his food, took care of his family, and was on his way to being emotionally and intellectually human.” (Binford 1981:295)

In Binford’s view of the data, hominids were the scavengers which came last to the feast, even behind the ants, and used casually found stones to break open marrow bones. There were no base camps. There was no evidence of food sharing. Even evidence of purposeful tool making was suspect before Homo erectus arose. Later on in his career, Binford decided that there was no reliable evidence for big game hunting until after the advent of modern humans; as predators Homo erectus and Homo neanderthalensis were no more to be feared in the field than a troop of modern cub scouts– which apparently they sometimes resembled. (Binford 1984, 1986)

Given this degree of doubt, it is not surprising that Binford was equally unimpressed by the work of Isaac’s students and associates. Potts, Shipman, Bunn, Behrensmeyer, Walker, Leakeys young and old– all had failed to be sufficiently stern and analytical. True, they’d learned over the years to speak soberly of proto-human scavenging rather than big game hunting and of the need for middle range theories and “actualistic” experiments. They had swiped– without attribution, of course– the best of his ideas. But they had not truly repented. With the partial exception of Potts, they still found home bases and tool making in the data. They saw the behavior of modern Kalahari bushmen re-enacted in the Pleistocene dust. They all had disgusting book contracts and speaking roles in PBS specials. There wasn’t a vegetarian among them.

Which is snide. Reviewing his contributions, Binford had undoubtably been correct in calling for more objective examination of the evidence and for studies of the processes which had created the archaeological record. He had put his principles into practice by studying hunting and settlement patterns among the Nunamuit Eskimos and his prediction that lower Pleistocene hominids were more scavengers than hunters has achieved the status of conquering orthodoxy. A cynic could argue his predictions owed as much to guess as theory but he had been right about as often as wrong– which was a respectable batting average.

And at the end, he had even beaten an admission out of Glynn Isaac that food-transport was not necessarily proof of food sharing and that “the hypotheses about early hominid behavior I have advanced in previous papers made the early hominids seem too human.” Henceforth, the term “home base” would be shunned in favor of “central-place- foraging.” (Isaac 1983)

Summing Up

But even in defeat, the points Isaac had made in 1972 held. Archaeological data from the far ends of the Old Stone Age is sparse, is incomplete, and is potentially misleading; most of it hasn’t been known very long, and there aren’t that many people to evaluate it. It is simply not realistic to ask that it all be analyzed as rigorously as late 20th century census statistics.

Moreover, most humans now live in urban environments. We do not live in splendid isolation and scatter when we hear the leopard’s cough. We are possessed of families and kin. We place communal meals and gatherings at the center of our social life. We are the product of greatly enlarged human gathering points. The home base is part of our heritage and the point at which it or “central place foraging” began to shape our existence still needs to be identified.

If not the Lower Paleolithic, when?

Ardrey, Robert 1976, The Hunting Hypothesis, New York, Bantam

Binford, Lewis R. 1981, Bones: Ancient Men and Modern Myths, New York, Academic Press

— 1984. Faunal Remains from Klasies River Mouth, New York, Academic Press.

— 1985, “Human ancestors: changing views of their behavior,” in Journal of Anthropological Archaeology, vol. 4, pp 292-327. Reprinted in Debating Archaeology, New York, Academic Press, 1989.

— 1986, “The Hunting Hypothesis, Archaeological Methods, and the Past,” American Association of Physical Anthropologists Annual Luncheon Address, Apr 1986, pp 1-9, Yearbook of Physical Anthropology vol 30 (1987) Reprinted in Debating Archaeology, New York, Academic Press, 1989.

Campbell, Bernard 1966, Human Evolution: An Introduction to Man’s Adaptations, Chicago, Aldine

Day, Michael H. 1986, Guide to Fossil Man, 4th Edition, Chicago, University of Chicago Press

Goodall, Jane. 1986, The Chimpanzees of Gombe: Patterns of Behavior, Cambridge, Harvard University Press

Isaac, Glynn Ll. 1972, “Early phases of human behavior: models in Lower Paleolithic archaeology,” in Models in Archaeology , David Clark (ed.) pp 167-200. London, Methuen & Company, 1972.

— 1978, “The food-sharing behavior of protohuman hominids,” in The Archaeology of Human Origins: Papers by Glynn Isaac, Barbara Isaac (ed.) pp 289-311. Cambridge, Cambridge University Press, 1989. (orig in Scientific American, vol. 238(4), pp 90-108)

— 1983, “Bones in contention: competing explanations for the juxtaposition of Early Pleistocene artifacts and faunal remains,” in The Archaeology of Human Origins: Papers by Glynn Isaac, Barbara Isaac (ed.) pp 325-335. Cambridge, Cambridge University Press, 1989.

Isaac, Glynn Ll. and John W. K. Harris. 1978, “Archaeology,” in Koobi Fora Research Project, volume 1, The Fossil Hominids and an Introduction to their Context, 1968-1974, Maeve Leakey and Richard Leakey (eds.), pp 47-76. Oxford, Clarendon Press.

Potts, Richard 1988, Early Hominid Activities at Olduvai, New York, Aldine de Gruyter.

Sept, Jeanne 1992, “Archaeological evidence and ecological perspectives for reconstructing early hominid subsistence behavior,” in Archaeological Method and Theory, vol 4., pp 1-56.

Stern, Nicola 1993, “The structure of the Lower Pleistocene archaeological record: a case study from the Koobi Fora formation,” in Current Anthropology, vol. 34, pp 201-225.

Tanner, Nancy M. 1981, On Becoming Human, Cambridge, Cambridge University Press.