The Dawn of Human Culture (26 page)
Dar es Soltan
Skhul & Qafzeh
Irhoud
Singa
Bodo
Omo-Kibish
Equator
Enkapune Ya Muto
Katanda
Lake Ndutu
estern Rift
W
Atlantic
Eastern Rift
Kabwe
Ocean
Cave of Hearths
Florisbad
Boegoeberg
Elands Bay
Indian
Kasteelberg, Sea Harvest & Hoedjiespunt
Boomplaas
Ocean
Elandsfontein
Klasies River Mouth
Ysterfontein
Nelson Bay
Die Kelders & Byneskranskop
Blombos
FIGURE 7.2
The locations of the sites mentioned in this chapter.
the Middle Awash Valley of Ethiopia, Lake Ndutu near the western end of the main Olduvai Gorge in northern Tanzania, and Elandsfontein (also known as Hopefield or Saldanha) in the Western Cape Province of South Africa. At each site, the age range has been gauged mainly from associated mammal species, stratigraphic position, or both, and it is confirmed at Bodo by a potassium/argon date of about 600,000 years ago.
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The Kabwe skull and its probable contemporaries each combine primitive characters that occur in
Homo ergaster
and
Homo erectus
with advanced characters that typify both the Neanderthals and modern humans. The primitive features include large browridges, a low, flattened forehead, great breadth across the base of the skull, and thick skull walls. The most striking advanced features are the large size of the braincase (averaging more than 1200 cubic centimeters [cc] compared to 1000 cc in classic
erectus
) and a tendency for the braincase to be relatively broad at the front, expanded at the sides, and rounded at the back. At Bodo, Lake Ndutu, and Elandsfontein, the skulls are associated with late Acheulean hand axes, and the people may have been related to those Africans whose descendants brought the Acheulean Tradition to Europe about 500,000 years ago. An Out-of-Africa movement at this time could explain why the African skulls resemble European specimens that are probably about the same age or a bit younger. For the sake of convenience, we have referred the joint African/European population to
Homo heidelbergensis,
and we have suggested that
heidelbergensis
was the last shared ancestor of the Neanderthals and modern humans. The more important point here is that in form and probable geologic age, the Kabwe, Bodo, Lake Ndutu, and Elandsfontein skulls comprise a plausible link between
Homo ergaster
before 600,000 years ago and more modern-looking Africans after 400,000 years ago.
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Bloemfontein, South Africa. The spring owner had encountered animal fossils and stone tools when he enlarged baths for a spa, but he feared losing his investment if the baths were temporarily drained. Dreyer thus had to wade and grope for bones. The story goes that he stuck his hand underwater into the spring deposits and pulled out part of a human skull—his fingers lodged in the eye sockets.
The Florisbad skull comprises the right side of the face, most of the forehead, portions of the roof and sidewalls, and an isolated upper right wisdom tooth (third molar) that probably goes with it. It bears tooth marks from a hyena or other large carnivore that may reveal the cause of death. By modern standards, the skull walls are very thick and the face is remarkably broad (Figure 7.3). Nonetheless, despite conspicuous thickening above the eye sockets, there is no true browridge (no interruption or inflection between the region immediately above the sockets and the forehead above), the forehead rises relatively steeply, and the face is short, flat, and tucked in beneath the front of the braincase. In these last important respects, Florisbad differs not only from Kabwe and its allies but also from the Neanderthals, and it approaches the condition in modern humans.
The single tooth associated with the Florisbad skull has been dated to about 260,000 years ago by the Electron Spin Resonance (ESR) method.
We noted previously that this method often provides only tentative results, mainly because it depends on site-specific assumptions about the history of uranium uptake and loss in a tooth. Still, even if the Florisbad ESR result is placed aside, geologic context and associated mammal species indicate that the skull is younger than those from Elandsfontein, Lake Ndutu, and Bodo and that it is older than more fully modern fossils known from African sites that postdate 130,000 years ago.
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relatively steep
forehead
thickened bone above
the orbits, but no
true browridge
thick skull walls
puncture from
0
5 cm
carnivore tooth
broad, massive, but
relatively flat face
0
2 in
tucked in below the
front part of the
brain
Florisbad
FIGURE 7.3
The partial skull from Florisbad, South Africa (drawn by Kathryn Cruz-Uribe from a photograph) (Copyright Kathryn Cruz-Uribe).
Sites at Singa, Sudan, and Irhoud, Morocco, have provided fossil skulls that probably fall in the same time span as Florisbad, between roughly 300,000 and 130,000 years ago, and the specimens exhibit a similar mix of primitive and essentially modern characters. Collectively then, the Florisbad, Singa, and Irhoud skulls document the transition from more archaic to modern humans in Africa in broadly the same way that the Sima de los Huesos fossils document the transition from more archaic humans to Neanderthals in Europe.
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security of their dating, or both include Dar es Soltan Cave 2 in Atlantic Morocco, the Omo-Kibish river margin locality in southern Ethiopia, and the Klasies River Mouth Cave complex on the southern coast of South Africa (Figure 7.2). To the African sites proper we can also add the famous Skhul and Qafzeh caves in Israel. To explain their inclusion, we stress two facts. First, anyone migrating from Africa to southwestern Asia would encounter Israel first, and it is outside of Africa only by technical, historic geopolitical definition. Second, recall that during the long time span of human evolution, global climate has repeatedly fluctuated between glacial and interglacial intervals. On average, the glacial intervals were not only cooler, they were also drier, while the interglacial intervals tended to be both warmer and moister. The changes in temperature and precipitation often caused redistributions of plants and animals, and zoologist Eitan Tchernov of the Hebrew University in Jerusalem has shown that climatic conditions during past interglacial periods repeatedly enabled African animals to expand into what is now Israel. During the especially warm earlier part of the Last Interglacial, between roughly 125,000 and 90,000 years ago, the African invaders included early modern humans. The Israeli fossils are in fact the most numerous and most complete early modern human specimens yet discovered.
The African fossils from between 130,000 and 50,000 years ago are mostly fragments and isolated teeth, but even these are often adequate to show that the people were not Neanderthals, and they make it abundantly clear that the Neanderthals never penetrated Africa. Where lower jaws are available, they are sometimes large and rugged, but where the appropriate parts are preserved, they uniformly lack retromolar spaces (the gap that Neanderthal jaws have between the third molar and the part of the jaw that rises to articulate with the skull), and 07 Body before Behavior.r.qxd 1/29/02 5:06 PM Page 225
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they usually have well-defined chins like those of living people.
Together with other facial bones, the lower jaws show that unlike the Neanderthals, their African contemporaries generally had short, flat, modern-looking faces. Where skulls are known, they are sometimes ruggedly built, but the braincases tend to be short and high as in living people, rather than long and low as in Neanderthals (Figure 7.4).
Where the internal capacity of the braincases can be estimated, it ranges between roughly 1370 cc and 1510 cc, comfortably within the range of both Neanderthals and living humans.
Limb bones show that like the Neanderthals, their African contemporaries were well muscled, but the especially abundant bones from Skhul and Qafzeh caves also show that the Africans lacked the squat body form and short limbs that are a Neanderthal hallmark (Figure 7.5). Instead, the people were long and linear like most historic people living near the Equator. Since both early modern Africans and the Neanderthals were highly mobile hunter-gatherers, the difference in bodily proportions probably does not reflect a significant difference in activity levels, and it reinforces the conclusion that Neanderthal body form was primarily an adaptation to cold climate. This adaptation was extreme by modern standards, probably because it was less strongly mediated by culture or technology.
It is possible to overemphasize the modernity of Africans after 130,000 years ago, and the fossils vary significantly both between and within sites. As a group, the Skhul-Qafzeh skulls, for example, are highly variable in their expression of a chin, in the extent to which their foreheads rise vertically, and even in basic braincase shape. In some respects, such as well-developed browridges, large teeth, and a tendency for the jaws to protrude far forwards, they often recall more 07 Body before Behavior.r.qxd 1/29/02 5:06 PM Page 226
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steeply rising
forehead
short, high
braincase
rear of skull
smoothly
rounded
face retracted
below the forepart
of the braincase
near-modern African
forwardly
(Qafzeh 9)
projecting jaws
with large
teeth
0
5 cm
0
2 in
chin
receding
long, low
forehead
braincase
bun-like
backwards
projection
of skull rear
face projects
far forwards
along the
midline
juxtamastoid
crest
Neanderthal
retromolar
no chin (jaw
(Shanidar 1)
space
bone recedes
below incisor
teeth)
FIGURE 7.4
A modern or near-modern skull from Qafzeh Cave, Israel, compared to a Neanderthal skull from Shanidar Cave, Iraq (drawn by Kathryn Cruz-Uribe from casts and photographs) (Copyright Kathryn Cruz-Uribe).
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narrow
trunk
long forearm
long lower leg
early modern
European
African
Neanderthal
(Skhul IV)
(La Ferrassie I)
FIGURE 7.5
Contrasting body proportions of an early modern African and a Neanderthal (redrawn after O. M. Pearson 2000,
Evolutionary Anthropology
9, p. 241).
archaic humans. The much less numerous and more fragmentary Klasies River Mouth fossils, which date from basically the same interval between 120,000 and 90,000 years ago, differ from the Skhul-Qafzeh fossils in detail, and they are also remarkably variable among themselves. One of the Klasies River Mouth lower jaws is among the smallest human specimens ever found (Figure 7.6), and some isolated 07 Body before Behavior.r.qxd 1/29/02 5:06 PM Page 228
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KRM 41815
small
true chin
chin region
KRM 16424
not preserved
tiny
0
5 cm
0
2 in
true chin
1st molar
2nd molar
3rd molar
congenitally absent
chin region
not preserved
KRM 41815
1st molar
2nd molar
KRM 16424
3rd molar
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teeth suggest that other jaws were equally tiny. At the same time, the Klasies River Mouth human fossils include jaws and other bones from significantly larger people, and the degree of size variation is striking.
It may indicate a level of sexual difference (dimorphism) that has never been documented in any other “modern” human population.
The bottom line is that the Skhul-Qafzeh people and their Klasies River Mouth contemporaries are perhaps best characterized as
“near modern.” Neither group is likely to have been ancestral to anyone after 50,000 years ago, if only because each probably disappeared long before that. The Skhul-Qafzeh people were apparently replaced by Neanderthals when climate turned cooler after 80,000 years ago, while the Klasies River Mouth people and other near-modern southern Africans experienced a population crash when southern Africa turned mostly very dry in the middle of the last glaciation, about 60,000 years ago. When all the facts are considered, the Skhul-Qafzeh and Klasies River Mouth fossils are significant not because they represent the lineal ancestors of later modern people (they almost certainly do not), but because they pinpoint Africa as the place where modern anatomy evolved. The precise birthplace of the later modern humans is uncertain, but on present evidence, it probably lay in equatorial eastern Africa. Climatic conditions remained favorable there for human occupation throughout the last 130,000 years, and eastern Africa has provided some of the earliest evidence for the behavioral advance that allowed modern Africans to spread to Eurasia.