The Dawn of Human Culture (2 page)
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DAWN AT TWILIGHT CAVE
High above the western shore of Lake Naivasha, a blue pool on the parched floor of East Africa’s Great Rift Valley, sits a small rock-shelter carved into the Mau Escarpment. Maasai pastoralists who once occupied this region in central Kenya called the place Enkapune Ya Muto, or “Twilight Cave.” People have long sought shelter there. The cave’s sediments record important cultural changes during the past few thousand years, including the first local experiments with agriculture and with sheep and goat domestication. Buried more than 3 meters (10
feet) deep in the sand, silt, and loam at Enkapune Ya Muto, however, lie the traces of an earlier and far more significant event in human prehistory. Tens of thousands of pieces of obsidian, a jet-black volcanic glass, were long ago fashioned into finger-length knives with scalpel-sharp edges, thumbnail-sized scrapers, and other stone tools, made on the spot at an ancient workshop. But what most impressed archeologist Stanley Ambrose were nearly six hundred fragments of ostrich 01 Twilight.r.qxd 1/29/02 5:03 PM Page 12
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eggshell, including thirteen that had been fashioned into disk-shaped beads, about 6 millimeters (0.25 inches) in diameter (Figure 1.1). Forty thousand years ago, a person or persons crouched near the mouth of Enkapune Ya Muto to drill holes through angular fragments of ostrich eggshell and to grind the edges of each piece until only a delicate ring remained. Many shell fragments snapped in half under pressure from the stone drill or from the edge-grinding that followed. The craftspeople discarded each broken piece and began again with a fresh fragment of shell.
Why did the occupants of Enkapune Ya Muto take so many hours from more essential activities like foraging just to make a handful of beads? The question is particularly appropriate, since they were not the only ones to pursue this seemingly esoteric activity. More than 30,000 years ago, the stone age people who occupied Mumba and Kisese II Rockshelters in Tanzania and Border and Boomplaas Caves in South Africa also produced carefully shaped ostrich eggshell beads.
Ambrose believes that these ancient beads played a key role in the survival strategy of the craftspeople and their families. In the Kalahari Desert of Botswana, !Kung San hunter-gatherers practice a system of gift exchange known as
hxaro
. Certain items, such as food, are readily shared among the !Kung but never exchanged as gifts. The most appropriate gifts for all occasions just happen to be strands of ostrich eggshell beads. The generic word for gift is synonymous with the !Kung word for sewn beadwork. Although the nomadic !Kung carry the barest minimum of personal possessions, they invest considerable time and energy in creating eggshell beads.
The beads serve as symbols. They represent reciprocity between neighboring or distant bands of people. Should a drought or other 01 Twilight.r.qxd 1/29/02 5:03 PM Page 13
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1 cm
Enkapune
Ya Muto
Equator
Atlantic
Ocean
Klasies River
Mouth
Indian
Ocean
Figure 1.1
The locations of Enkapune Ya Muto and Klasies River Mouth. Enkapune Ya Muto has provided ostrich eggshell beads and bead blanks or preforms dated to about 40,000 years ago.
Klasies River Mouth shows that between about 120,000 and 60,000 years ago human hunters preferred the docile eland to the more dangerous buffalo.
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sudden climatic or environmental change leave food in scarce supply, a group can move to another group’s territory, where they rely on aid and support from those with whom they have established
hxaro
ties.
For the !Kung, beads provide a lightweight, portable token of mutual obligations—the currency of a long-term, long-distance social security system. “They’re paying into their health insurance, in a sense,” says Ambrose, a professor at the University of Illinois in Urbana. “They’re paying insurance to each other.”
No one knows whether the toolmakers at Enkapune Ya Muto or the other ancient African sites intended their ostrich eggshell beads to be social gifts. But if these beads were invested with symbolic meaning similar to that of beads among the !Kung, then Twilight Cave may record the dawning of modern human behavior. Communicating with symbols provides an unambiguous signature of our modernity. Within the grand scope of human evolution, symbolic behavior was a very recent innovation. Once symbols appear in the archeological record, as enigmatic geometric designs, as human or animal figurines carved in ivory, or as beads and other ornaments, we know we’re dealing with people like us: people with advanced cognitive skills who could not only invent sophisticated tools and weapons and develop complex social networks for mutual security, but could also marvel at the intricacies of nature and their place in it; people who were self-aware.
The deep antiquity of the Enkapune Ya Muto beads is almost certain. Ambrose discovered that ostrich eggshell beads and beads-in-the-making (preforms) were ten times more numerous per cubic meter in the deepest part of the deposit than they were higher up. That could attest to the importance the early inhabitants placed on bead manufacture, but it also reduces the likelihood that the beads are simply 01 Twilight.r.qxd 1/29/02 5:03 PM Page 15
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younger artifacts that filtered down into deeper and older sediments with the passage of time and the burrowing of animals. Ambrose argues that the social value attached to eggshell beads by contemporary Kalahari people likewise attests to a deep-rooted symbolic meaning, carried across millennia from a time when far more ancient hunter-gatherer bands were scattered across southern and eastern Africa.
If, as Ambrose conjectures, the Enkapune Ya Muto beads helped to ensure survival during hard times, they may have emboldened early modern people to strike out into riskier environments—perhaps even some beyond Africa itself. “With this social safety net they could do better than people without symbolic means of establishing future permanent ties of reciprocity,” he surmises. “You could say it’s like weav-ing lifelines between people, and the lifelines are strings of beads.”
The other artifacts from Enkapune Ya Muto represent an initial form of the stone technology associated only with fully modern humans in Africa, after 50,000 years ago. More than any sophisticated stone tool, however, the simple beads, laboriously crafted from ostrich eggshell, suggest that people in eastern Africa at this time had achieved cognitive capacities beyond those of any preceding human population, in Africa or anywhere else. Thus, our evolutionary success and the rich array of cultures from later times may have depended not so much on physical qualities or intimidating weapons as on the intellectual capacity to conceive, create, and communicate in symbols. To understand why evidence from sites such as Enkapune Ya Muto bespeaks a significant departure from all previous human behavior, we must move a bit further back into our African past and travel to the southern tip of the continent.
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The roughly two dozen human fossils from the caves are admittedly few and fragmentary. Yet, they include key parts of the skull that reveal how anatomically modern these people were. A nearly complete lower jaw, for example, shows that the owner had an essentially modern, short, broad, flat face quite unlike the long, narrow, forwardly projecting faces of the Neanderthals who occupied Europe at the same time, about 100,000 years ago. And a fragment of bone from above one eye socket (orbit) lacks the brow ridge that marks the skulls of primitive members of the human genus. (This piece of bone also exhibits stone tool cutmarks suggesting that the skull was defleshed, perhaps for food. Other human fragments were slashed, bashed, and burned, implying that human parts were sometimes processed like those of antelopes and seals. This suggests to scientists that like some historic people, the Klasies people occasionally practiced cannibalism.)
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While the Klasies fossils do vary widely in size, in their basic form they are undeniably modern. The people are plausible ancestors for historic Africans, or for historic people everywhere, and their bones date from as much as 120,000 years ago. With brief interruptions, they lived at Klasies River Mouth from 120,000 years ago until about 60,000
years ago, when the onset of extreme aridity perhaps forced people to abandon the region for tens of thousands of years.
Excavated first by Ronald Singer and John Wymer from the University of Chicago and more recently by Hilary Deacon from the University of Stellenbosch, the Klasies caves preserve abundant kitchen debris of the occupants. These include the shells of mussels, limpets, and other mollusks that can still be collected at low tide nearby. They place the Klasies people among humanity’s oldest known shellfish gourmets.
The caves are equally rich in fragmentary animal bones and in stone tools that were often flaked from cobbles collected on the beach. Burnt shells and bones show that the people engaged in cooking, and their fireplaces are so common that it seems certain they could make fire at will. Deacon suggests that each fireplace marks the domestic hearth of an individual family and that the people therefore resembled modern hunter-gatherers in nuclear family structure. Yet none of the Klasies Caves has provided ostrich eggshell beads like those from Enkapune Ya Muto, nor have they provided any other object that is unambiguously symbolic.
The animal bones exhibit numerous cutmarks, and they were often broken for the extraction of marrow. The implication is that the Klasies people consumed a wide range of game, from small, grey-hound-size antelope like the Cape grysbok to more imposing quarry like buffalo and eland, as well as seals and penguins. The number and location of stone tool cutmarks and the rarity of carnivore tooth marks 01 Twilight.r.qxd 1/29/02 5:03 PM Page 18
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indicate that the people were not restricted to scavenging from lions or hyenas, and they often gained first access to the intact carcasses of even large mammals like buffalo and eland.
But the bones also show that the people tended to avoid confrontations with the more common—and more dangerous—buffalo to pursue a more docile but less common antelope, the eland. Both buffalo and eland are very large animals, but buffalo stand and resist potential predators, while eland panic and flee at signs of danger. The Klasies people did hunt buffalo, and a broken tip from a stone point is still imbedded in a neck vertebra of an extinct “giant” long-horned buffalo. The people focused, however, on the less threatening young or old members in buffalo herds. The stone points found at Klasies could have been used to arm thrusting spears, but there is nothing to suggest that the people had projectiles that could be launched from a distance, and they may thus have limited their personal risk by concentrating on eland herds that could be chased to exhaustion or driven into traps. The numerous eland bones in the Klasies layers represent roughly the same proportion of prime-age adults that would occur in a living herd. This pattern suggests the animals were not victims of accidents or endemic diseases which tend to selectively remove the very young and the old, but rather that they suffered a catastrophe that affected individuals of all ages equally. The deposits preserve no evidence of a great flood, volcanic eruption, or epidemic disease, and from an eland perspective, the catastrophe was probably the human ability to drive whole herds over nearby cliffs.
In contrast to Klasies River Mouth, other much younger archeological sites nearby such as Nelson Bay Cave contain many more bones of dangerous prey like buffalo and wild pigs and many fewer of 01 Twilight.r.qxd 1/29/02 5:03 PM Page 19
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eland. The reason is probably that by this time, around 20,000 years ago, people had developed projectile weapons like the bow and arrow that allowed them to attack dangerous prey from a distance and therefore to limit their personal risk. The advantage was considerable, because the ancient environment probably broadly resembled the historic one, in which buffalo and pigs greatly outnumbered eland nearby.
The Klasies people not only avoided the most dangerous game, they also failed to take full advantage of other widely available resources. The ages of seals in the Klasies deposits show that the people remained at the coast more or less throughout the year, including times when resources were probably more abundant in the interior. In contrast, much later people like those at Nelson Bay Cave timed their coastal visits to the late winter/early fall interval when they could literally harvest 9- to 11-month-old seals on the beach, and they moved inland when resources became more plentiful there. The ability of these later people to pursue an efficient seasonal strategy probably depended in part on their use of ostrich eggshells as canteens. Fragments of such canteens, with carefully positioned openings to allow water out and air in, have been found in their sites but not at Klasies River Mouth or other sites that are older than 50,000 years. The inability of the Klasies people to transport water may have forced them to remain near the river throughout the year.
