Chapter 18
Humans had established their physical form with the emergence of long-legged, large-brained Homo ergaster/erectus by 1.7 Ma in the early Pleistocene. Apart from a modest expansion in brain volume (Figure 18.1),1 little further change in morphology occurred over almost the next million years. Then, after 0.9 Ma, a marked surge in cranial capacity towards modern levels took place, accompanied by changes in the shape of the skull, in Europe as well as in Africa. This was around the time when the period between glacial peaks lengthened to ~100 kyr, producing even greater extremes of cold and aridity. A new species name was applied, shared between the two continents: H. heidelbergensis. The European lineage evolved into the stockily built Neanderthal people (H. neanderthalensis), with a brain volume matching that of modern humans. In Africa, the skull had assumed almost modern form by ~200 ka. While the brain vault of the Neanderthals extended backwards from a sloping forehead, that of the early modern humans domed upwards above a flattened face with reduced brow ridges. For whatever reasons, modern humans also developed a protruding chin.
Figure 18.1
Progressive expansion in brain volume of hominins through the Pleistocene.
(chart by Nick Matzke at www.ncseweb.org from phylo.wikidot.com/fun-with-hominin-cranial-capacity-through-time)
While there are few fossils to document changes in human skulls, the products of mental competence in the form of stone artefacts are abundant throughout Africa. Hence the focus of this chapter shifts from paleoanthropology to archaeology – the study of evolving forms of the cultural material left behind by people, rather than their bones and teeth. In some places worked stones are accompanied by fossilised bones of ungulates, indicating how these artefacts had been used as tools to process herbivore remains for consumption of marrow within and meat attached. A new form of tool use emerged around 70 ka when geometric scratches on stones suggest artistic expression. Changes in the shape of some stone flakes indicate a cultural advance with more profound consequences: the hafting of stone points onto spears and later arrows.
People left Africa, in two waves. A minor one preceding 100 ka took humans only as far as the Levant in the Middle East. The second major dispersal, beginning around 60 ka, spread H. sapiens through other continents, replacing the Neanderthals and other earlier human inhabitants. Later, some descendants of these people returned to Africa, bringing domesticated ungulates and cultivated plants. Herding and farming lifestyles spread through eastern and southern Africa, displacing stone-age hunter-gatherers. Genetic markers indicate some of the movements of various groups of people within Africa.
In this chapter, I will outline the adaptive shifts in cultural expression in the form of stone tools, rock art, and lifestyles that took place within savanna regions of Africa. These cultural advances enabled humans to persist and expand in numbers through times when several animal forms that had survived prior climatic oscillations faded into extinction.
From Earlier to Later Stone-working Technology
The earliest generally accepted stone artefacts come from the Awash valley in north-eastern Ethiopia, dated to 2.6 Ma,2 slightly pre-dating other worked stones found nearby.3 This dating follows shortly after the appearance of the earliest fossil assigned to Homo, a mandible found in the same region of Ethiopia from 2.83 Ma.4 These early stone artefacts take the form of unretouched flakes with sharp edges struck from large cores (Figure 18.2A).5 This form of stone working was first discovered in association with fossils assigned to Homo habilis in the lowest beds at Olduvai Gorge dated to ~2 Ma and accordingly named the Oldowan technology. Stone tools of similar antiquity have been found in the Cradle of Humankind as well as in Wonderwerk Cave in South Africa6,7 and as far north as Algeria.8
Figure 18.2
Stone tool industries. (A) Oldowan core and flakes; (B) Acheulian tools bifacially shaped; (C) Middle Stone Age finely crafted blades and points.
(images supplied by Human Origins Program, NMNH, Smithsonian Institution)
A date of 3.3 Ma has been claimed for stones discovered west of Lake Turkana in Kenya, proposed to represent an even earlier ‘Lomekwian’ culture.9 These stones, some as heavy as 15 kg, were accompanied by large flakes broken from them. However, this exceptionally early date 700 kyr before the next most recent artefacts has been challenged, questioning whether they were really found ‘in situ’.10,11 Animal bones found nearby do not show signs of percussion, reinforcing doubt about their use as tools by hominins who were still in the ape-man stage. No stone tools have been found in association with Au. africanus in South Africa dated earlier than 2.2 Ma.7 Nevertheless, early ape-men probably did use unworked stones to pound tough plant parts and, at some stage, to break open animal bones to extract the marrow.12 Chimpanzees and capuchin monkeys employ stones to pound nuts.13 Unworked stones applied for such purposes would not be distinguishable from other rocks lying around. The deployment of stones to soften plant and perhaps animal food resources would have contributed to the trend towards less-robust dentition diverging the lineage evolving into Homo from that giving rise to Paranthropus around 2.9 Ma.
The inferred use of the Oldowan flakes was to scrape the flesh from the bones of animals scavenged, while cores (cobblestones) were probably used to crack open limb bones so as to extract the marrow. Although robust-jawed ape-men were around at that time, it is doubtful that they were the makers of the stone flakes. A stick or a bone would rather be used to dig up underground plant parts. Bones with wear indicating that they were used for digging have been found in Kromdraai Cave in South Africa where the only hominin fossils present were Paranthropus, dated shortly after 2.0 Ma.14
Around 1.7 Ma, a distinct technology named the Acheulian appeared almost synchronously in the West Turkana region of Kenya, at Olduvai and in South Africa.15,16,17 This was associated with the appearance of H. ergaster in Africa and H. erectus in Eurasia.18 Acheulian stone artefacts feature cores shaped bifacially (on both sides) to serve as large cutting tools, like handaxes, cleavers or picks. Large flakes knapped from the cores were modified for additional functions (Figure 18.2B). At Olduvai Gorge and elsewhere, the Acheulian technology made its appearance quite abruptly, alongside Oldowan tools, without intermediate forms, suggesting ingress by the tool makers.19 Oldowan tools tend to be concentrated at sites together with aggregations of large herbivore fossils, while Acheulian tools are generally more widely scattered.20 The presence of cut marks beneath tooth marks on limb bones of ungulates has been interpreted to mean that carcasses were processed intact and thus had been obtained by hunting rather than scavenged.21 Hence the appearance of the Acheulian tool assemblages suggests a shift towards hunting as the primary means of obtaining meat in the diet. Both stone cultures coexisted for several thousand years before the Oldowan faded out. Together, the Oldowan and Acheulian industries define the Earlier Stone Age (ESA) of Africa.
Between 600 and 200 ka, flakes became more finely shaped for a greater variety of uses, defining the progressive transition into the Middle Stone Age (MSA; Figure 18.2C).17 During this period, humans attained almost fully modern appearance. Faunal assemblages were consistently dominated by medium–large ungulates, from wildebeest to buffalo size.22 The frequency of human cut marks on bones relative to marks inflicted by carnivore teeth increased. In the south-western Cape, animals butchered included prime-aged wildebeest while old and young animals predominated among buffalo, suggesting that the latter had been scavenged from predator kills.
The crucial period between 500 and 320 ka leading towards modern humans is missing from sedimentary layers both at Olorgesaile and Lake Baringo in Kenya.23 This included a time of extreme aridity around 440 ka followed by a rapid transition into an interglacial peaking around 400 ka (Figure 19.1). A sediment core drilled from a lake basin south of Olorgesaile documents heightened environmental variability after 500 ka with chloridoid grasses present near a shallow saline lake during the glacial maximum.24 The herbivore fauna had shifted towards smaller species with more browsers and mixed feeders. MSA sites dated earlier than 195 ka are scarce in eastern Africa and mostly situated on the margins of rivers or lakes in rift valley settings.25 After 130 ka, when milder interglacial conditions ensued, sites with tools become more widely spread on hillsides and in caves and tools became more varied.26 Artefacts representing MSA technology have been found north of the Sahara fringing the Mediterranean Sea.27 The earliest stone tools assigned to the Later Stone Age (LSA) of eastern Africa come from Munga Cave, dated before 50 ka.28 By 25 ka, when the most recent glacial advance neared its maximum, LSA technology had become widely established across numerous sites in eastern Africa.29
In South Africa, the transition into the MSA is represented by the ‘Fauresmith’ industry, including finely worked flakes and points but fewer large cutting tools.30 Blades with sharp cutting edges were hafted onto wooden shafts to serve as spear points, an innovation recorded as early as ~500 ka at Kathu Pan in north-western South Africa.31 The Florisbad skull dated roughly to 260 Ma confirms the presence of early modern humans in interior South Africa during this period. However, very few archaeological sites in South Africa, and none in neighbouring Botswana,32 document the period between 200 and 130 ka when glacial conditions generated extreme aridity. However, this time span is represented at Makapansgat, located in the warmer northern bushveld and at Border Cave on the southern Swaziland border, not far inland from the coast.33
Along the southern Cape coast, various cave sites preserve a rich archaeological record. At Pinnacle Point this goes back as early as 160 ka,34,35 but elsewhere it spans only the period after 130 ka when conditions were warming. The lowering of sea level during the cold extreme prior to 130 ka had exposed the grassy Agulhas plain stretching up to 100 km beyond the current shoreline and supporting concentrations of grazing ungulates. The caves provided shelter from the local winter wetness and a reliable protein source year-round in the form of shellfish plus seals either scavenged or hunted.35,36,37 Deposits within these caves have yielded bone tools, as well as geometric engravings on soft stones of ochre, dated earlier than 70 ka. Other artefacts include shells strung into necklaces, beads and patterns carved on bones. Finely constructed (‘microlith’) projectile points made of flint or bone became prominent in deposits dated to 71 ka. By 65 ka, ostrich eggs became used as vessels to carry water. Lower deposits contain the remains of numerous large antelope, while upper layers show a shift towards more medium- or small-sized ungulates, as the coastal plain contracted.38 The relative representation of browsers also increased.39 The surrounding vegetation includes numerous plants with underground storage organs and there are signs that such starchy foods were cooked.40 Following submergence of the coastal plain by rising sea levels after 15 ka during the Holocene interglacial, the meat component of the diet of the cave inhabitants consisted mainly of shellfish along with tortoises.35
In South Africa, stone artefacts representing the later MSA have been assigned to successive stages labelled Klasies River (115–80 ka), Still Bay (80–65 ka) and Howieson’s Poort (70–65 ka) industries.41 At Border Cave, MSA technology continued to be in use after 130 ka. In Sibudu Cave located close to the KwaZulu-Natal coast, arrow points made of stone or bone are dated earlier than 60 ka and show signs that poison was applied to their tips.42,43 Similarly daubed bone points have been identified at Pinnacle Point dated 71 ka.44 The earliest record for the thin blades initiating the LSA come from Border Cave, dated to 45 ka.45,46 Digging sticks, bone points and a poison applicator are also preserved there.47 Warthog and bushpig bones predominate at this and other cave sites, replacing the preceding abundance of bones of larger mammals such as eland and hartebeest.48 After ~45 ka, stone tool assemblages representing the LSA become widely distributed through inland sites across South Africa.32,46 During the most extreme phase of the LGM around 20 ka, large mammals increased markedly in their representation at archaeological sites, suggesting that humans concentrated their hunting on them. This deviates from the pattern shown during the previous glacial maximum, when evidence of human habitation was mostly missing from the interior.
In central Africa, the cultural transition from the ESA into the MSA is represented by industries labelled the Sangoan, from a bay in Lake Victoria, and the Lupemban, from a site in eastern Congo DRC.33 Hand axes fade out and small flake tools become common. Deposits from northern Zambia dated to ~265 ka are affiliated technologically with the transitional period. Numerous sites in Zambia exhibit abundant backed flakes and scrapers used for hunting, exemplifying the Nachikufan industry. The prominence of these tool designs emphasises the continued dependence of modern humans on meat.49 Cave assemblages from south-western Zimbabwe exhibit similar features of MSA technology, but have not been dated.33 In Malawi, few sites, if any, show human presence between 135 and 75 ka, when the mega-drought that prevailed through this region of south-central Africa reduced Lake Malawi to puddles.
Stone tools found in the Ogooue River valley in south-west Gabon, where grassland–forest mosaics currently prevail, date back as far as 400 ka and retain technology typical of the ESA.33 MSA artefacts have been found in the Congo basin and as far west as Senegal, dated later than 130 ka. They also occur in eastern regions of the Sahara, which were well vegetated and contained lakes around that time. Associations between stone tools and the processing of large herbivore remains are widely evident there between 130 and 60 ka.
Modern humans with MSA culture appeared in the Levant region of Israel around 100 ka at a time when the Sahara as well as Arabia were quite green. Settlement sites spread further into the Arabian Peninsula, only to fade out after drier conditions took hold around 75 ka. It is possible that some people moved further into Asia along the coast.50 However, the main exodus of humans from Africa took place later, around 60 ka. This movement continued along a coastal route to reach Australia by 55 ka or soon thereafter.
Bow Wave Out of Africa
Much emphasis has been placed on the cultural innovations documented in the southern Cape around 70 ka and what they reveal about human cognition. These include body adornments with ochre and shell beads, the beginnings of art and widening of tool kits to include bone as well as stone substrates. This timing, shortly before the wave of movement took people beyond Africa around 60 ka, has founded speculation that the people who colonised Eurasia originated from the Cape coastal region.36,51 Klein52 suggests that some revolutionary gene enabled a major cognitive advance, perhaps by facilitating language capabilities. However, I suspect that the key innovation had profound ecological implications: the advent of hunting by bow and arrow (Figure 18.3). Recent findings have pushed the appearance of arrow points made of bone or stone earlier than 60 ka at Klasies River and Pinnacle Point in the Cape plus Sibudu Cave in KwaZulu-Natal.53 These arrow tips show signs of the application of poison, as employed by San hunters historically, making them lethal without needing to penetrate deeply between the ribs of their prey. Stone shaped for projectiles launched as spears were recognised in MSA assemblages at Kathu Pan somewhat earlier at 500 ka,31 but many thrusts with a spear from close quarters would be needed to draw a lethal amount of blood from prey perhaps chased to exhaustion. A single prick from a poison-tipped arrow inflicted by a lone hunter could be sufficient to cause death, although the prey may need to be tracked for a few hours, until the poison did its job. The implications for food security are huge – a healthy animal as large as a giraffe could be killed by a single hunter. Following the use of poison-tipped arrows, ungulates of all sizes and ages were almost equally vulnerable to being hunted.
Figure 18.3
Modern hunter-gatherers. (A) San men hunting with bow-and-arrow in Botswana (photo: Ariadne Van Zandbergen); (B) hunters returning with an antelope carcass (photo: GreatStock); (C) San women on a foraging excursion seeking plant resources (photo: Alamy); (D) Hadza hunters searching for animals, holding their large bows.
(photo: Brian Wood)
This advanced capability would have facilitated the dispersal of people from Africa’s southern coast to culturally infiltrate regions of south-central Africa that had been de-populated during the mega-drought preceding 70 ka.54,55 Empowered as hunters by the use of bows and arrows, people then dispersed onward through the Horn of Africa, crossing the Red Sea into Arabia and beyond. When they eventually encountered the Neanderthals, or the Denisovans, the short thrusting spears that the latter possessed were no match for arrows launched from a distance by the human ingressors. This enabled H. sapiens to replace H. neanderthalensis throughout Europe within a few thousand years.56 But if poison for arrow tips could not be procured in Europe, such projectiles would be less effective for hunting large animals.
Archaeological sites in eastern Africa have not yielded recognisable arrow points dated earlier than 13 ka, but bows don’t preserve and bone points are easily overlooked.57,58 People with a sophisticated armoury of projectile weapons remained present through the southern African interior as the LGM advanced towards its coldest extreme ~20 ka. While food resourced from plants became extremely meagre, there was relatively little shortage of animals to hunt, perhaps concentrated in habitat refugia.
Several large herbivores that had persisted through previous glacial extremes went extinct during or shortly after the LGM in Africa (Chapter 14) as well as in Europe. While it seems difficult to credit predation by humans as playing a role in Africa,59 some contribution from hunters recently armed with poison-tipped arrows cannot be ruled out. During times of extreme aridity, the dependence of humans on hunting for subsistence would have been amplified. Large herbivores would also have become restricted in their distribution to ecological islands of favourable vegetation. Similar spatial contexts may have fostered the demise of other large mammals worldwide during the late Pleistocene, following colonisation by humans.60
The implications of projectile weapons for the success of hunting are profound. They explain why white rhinos became so vulnerable to human hunters, despite their huge size. This mega-grazer disappeared from the broad extent of savanna Africa between the Zambezi and Nile rivers (Chapter 14), while remaining hugely abundant south of the Zambezi River into historic times.61,62 White rhinos were present as recently as 50 ka at the archaeological site of Mumba in northern Tanzania, but not later.63 Nevertheless, they are depicted in rock art at Konda in central Tanzania ascribed to Sandawe hunter-gatherers.64 The rhinos that survived historically in the south are acutely fearful of the slightest whiff of human odour, even though these individuals had never experienced hunting (before the recent poaching wave). Indeed, fear of humans is deeply engraved in the nature of all of Africa’s large mammals, even the carnivores.
Nevertheless, it does seem incredible that humans could have been responsible for the extinctions of large herbivores that did take place across Africa, from its southern to northern extremities, during the late Pleistocene, including a species as large and thick-skinned as Reck’s elephant. The timing of the extinctions coincides with the advancement of glacial extremes, as discussed in Chapter 14, but it is too glib to dismiss human hunters as having made no contribution to the demise of animals that had long been their prey, at a time when their capability to deploy poison-tipped arrows had emerged and was most needed. Some interaction between accentuated human predation and worsening nutritional stress cannot be excluded as a factor contributing to these large mammal extinctions.
Genomic Evolution
Continuing genetic mutations enable connections among populations to be tracked through time, thereby identifying approximately when populations separated and thus no longer shared new mutations. Genetic information may be obtained from mitochondrial DNA (mtDNA), inherited solely from the mother; Y-chromosome DNA, inherited patrilinearly; or from fragments of autosomal DNA subject to single nucleotide polymorphisms (SNPs). Under tropical conditions, opportunities to extract complete genomes from ancient DNA preserved in organic matter are rare. In order to place genetic changes in a time context, assumptions must be made about the rate at which mutations accumulate. Estimates differ, by a factor of two, depending on whether derived from new mutations appearing between recent human generations or, as earlier, calibrated from the fossil record of time since divergence of gene pools.65 Recent findings based on accurate dating of specimens established by radioactive 14C decay are congruent with the fossil-calibrated estimates.66 Accordingly, I will adjust reported times of divergence based on recent nucleotide mutations between parents and offspring downward.
The metapopulation structure revealed from mitochondrial gene mutations is largely consistent with the distinct language groups identified among Africa’s people. Greatest genetic diversity is retained by the Khoe-San click-speakers, indicating that they are closest to the ancestral population that gave rise to all modern humans.67 Nevertheless, they are less diverse genetically than the great apes. This suggests that the lineage leading to modern humans underwent one or more population bottlenecks, during which numbers were low enough for genes to be lost.25,36,68 It seems that, at some stage, humans were reduced to as few as 15,000–40,000 individuals dispersed in small, somewhat separated, subpopulation units.69
The groupings of people affiliated by language today became isolated at various times back in the past. The earliest separation was between people of Khoe-San affiliation found in the south and groups living further north in Africa. This became effective around 160 ka or even earlier, shortly after humans had attained their modern cranial form.67,70 Technologically, it came after the transition into the MSA.70 However, a genetic connection remained between the Khoe-San and the forest-inhabiting ‘pygmy’ or Batwa grouping, as well as with the remnant Hadza and Sandawe people inhabiting central Tanzania, until around 100–120 ka. The Hadza and Sandawe are allied with Bantu speakers physically as well as genetically, but retain a language incorporating click consonants along with forms of rock art resembling those of the San. They seem to be a cultural relict of hunter-gatherers who merged genetically with the Bantu-speaking immigrants into eastern Africa after 5 ka. Genetic isolation of the Batwa people from Bantu-language speakers originating in western Africa developed after 75 ka, while Bantu speakers had diverged from their common ancestor shared with Nilotic and Cushitic speakers by 34 ka. Eastern Africa has become particularly mixed genetically because of the ingress of Bantu people from the west plus Cushitic and Nilotic people from the north over the past several thousand years, absorbing the original hunter-gatherers genetically.67
It has been suggested, from changes in mtDNA haplotypes, that all modern humans further north originated from a subpopulation of Khoe-San people living near the vast Makgadikgadi–Okavango wetland that existed in Botswana around 200 ka.71 This region evidently remained a relatively moist oasis while extreme glacial conditions prevailed between 190 and 130 ka. The relatively few number of archaeological sites suggests that people had mostly vacated the interiors of both southern and eastern Africa during this time. Moreover, the area to the north extending from Malawi through southern Tanzania had become depopulated during the ‘mega-drought’ conditions experienced there from 130 until 75 ka,72 opening space for recolonisation. Some movement of people from the south into this region is signalled by the appearance there of a mtDNA haplotype typical of the Khoe-San close to 70 ka, shortly preceding the time of great exodus into Eurasia,55,73 but the genetic profile of the people who continued moving onward beyond Africa does not resemble that of the southerners. Rather, it seems that they had taken up some of the cultural innovations introduced from the south, in body adornment, decorated artefacts, microlith stone and bone tools and, I contend, also hafted arrow points.58 These technological advancements propelled the continued northward dispersal into Arabia and onward during the unusually moist conditions that prevailed in the Horn of Africa for a while after 70 ka. The intercontinental expansion was facilitated by the newfound capacity to hunt more effectively by launching poisoned arrows from bows. The material evidence for this advancement is lacking, but not surprisingly.
In summary, the genetic findings indicate that groups of people underwent spatial shuffling during the MSA while humans assumed their modern physical form and developed distinct language groups. There is evidence of a population bottleneck between 190 and 130 ka when extremes of glacial aridity took hold through both southern and eastern Africa. While there might have been previous bottlenecks during earlier glacial advances, there was not one during the most recent one, after humans had become armed with highly effective projectile weapons for hunting. The population segment that obtained refuge in caves along the southern Cape coast may have contributed culturally to the great exodus from Africa, but not their specific genomes.
How Do Modern Hunter-Gatherers Subsist Year-round?
Fortunately, the hunter-gatherer lifestyle persisted into modern times in two regions of Africa. Case studies there illustrate how effectively hunting overcomes food shortages potentially arising during the dry season. The San people were formerly widely present throughout southern Africa south of the Zambezi and Kunene rivers, as testified by their rock art on cave walls and other substrates. Following European settlement and, indeed, active extermination, they became restricted to arid savanna regions of Botswana and Namibia, where studies were undertaken. The arrow-tips and other tools that they had formerly made from stone or bone had been replaced by tools made of iron co-opted from the Bantu pastoralists who had settled among them by that time. The Hadza people persist in a small region of Tanzania south of Olduvai not far from the Serengeti plains. Although they likewise incorporate click sounds in their language, they are only distantly related genetically to the San, and quite distinct physically. Wild ungulates are no longer as abundant in the places where they occurred in the past, partly due to the activities of the herders living alongside the hunter-gatherers in this region.
Studies on the San were focused on both the !Kung or Ju/’hoansi groups (the extra symbols represent various click consonants) living in western Botswana at a time when these people still depended largely on hunting and gathering.74 Male hunters brought back mainly smallish animals like warthogs, duikers, porcupines and springhares. Larger ungulates were hunted opportunistically when they appeared nearby, using bows equipped with poison-tipped arrows (Figure 18.3A). The poison mix did not kill instantly, meaning that a wounded animal had to be followed by its tracks until it came to a standstill and could be killed with spears. While a video vividly shows endurance hunting of an unwounded kudu until it could run no further, this method is no longer used today. Dogs may assist with the hunt, and snares are also deployed. Kill rates of large antelope amounted to merely two animals per hunter per year. Women gathered a mix of fruits, nuts, tubers and bulbs. Meat from various sources provided about 30 percent of the diet, underground plant tissues around 25 percent, and other plant parts formed the remainder. Nuts produced by mongongo trees (Schinziophyton rautanenii) were especially sought because they could be stored for consumption during the dry season. Rodents smaller than springhares and insects were not eaten.
Hunting success was best during the late dry season when edible plant parts were scarce, because animals were weaker. Nevertheless, base camps were shifted every few weeks as local plant resources became depleted. Groups occupying temporary camps typically comprised 10–30 individuals moving over annual ranges covering about 150 km2. This is 5–10 times larger than the home ranges typically traversed by chimpanzee and gorilla groups (Table 16.1). Foraging excursions covered round-trip distances increasing seasonally from 3 to 19 km, vastly further than apes move daily. Time taken up by foraging was similar for women gathering plant foods and men hunting for animals, amounting to less than 20 h per week (8 h per day over 2.5 days per week). Additional time was taken up by chores at camp. People usually slept in the open in front of temporary huts, lighting fires as a deterrent against carnivores.
The Hadza people (Figure 18.3D) live south-east of the Serengeti plains near Lake Eyasi. At the time of the studies their population density was low, with around 1000 people occupying a range of 4000 km2.75,76 Only about 350 of them still operated exclusively as hunter-gatherers. Base camps occupied by about 30 people were moved every 1–2 months over an annual home range of about 120 km2. Foraging activities took up about 4 h per day for women and 6 h per day for men on average, while daily travel distances averaged 5.5 and 8.3 km, respectively. Women sought both large fruits (especially those of baobab trees) and berries of wild raisins and dug for tubers using sharpened sticks. Men hunted using bows with poison-tipped arrows, capable of killing an animal as large as a giraffe. They also scavenged from carcasses of large animals killed by lions when opportunities were presented. After the lions appeared satiated, they were driven off by firing an arrow. Unguarded leopard kills were retrieved from trees. During the dry season, men waited at waterholes for animals coming to drink at night. Hunters returned with carcasses of large ungulates only about once per month, but secured smaller prey like springhares more frequently. Hunting of large mammals would have been more successful in the past when wild animals were more plentiful. Meat provided about 25 percent of the diet, greater for men and less for women. Dry-season conditions were not particularly harsh, because berries remained available and animals were easier to ambush near waterholes. Lions seemed to pose little threat, although people had been killed and eaten by lions at night in the past.
Studies on both of these groups have emphasised their leisurely lifestyles, with much less time spent on securing food than the 40+ hour week devoted to work by modern people in the developed world. However, this contrast is somewhat exaggerated. Maintenance work around camp by the hunter-gatherers is inadequately taken into account, and not all of the 40-hour working week of modern people is taken up by actual work. Today, people also spend time outside of work hours on home maintenance and on excursions to stores to purchase food and other needs. Nevertheless, the hunting and gathering groups that were observed did seem to have more time available for socialising and sleeping than those studying them recall having back in their home places.
Foraging excursions by women were lengthened during the dry season when less food was sourced from plants, but easier access to animals for meat meant less time pressure for men. However, studies were obviously conducted where people had survived, which means places having adequate supplies of fruits or nuts that could be stored plus ready access to animals that could be hunted. They do not represent extreme drought conditions when people might starve. Locating animals of whatever size to hunt during such times would be of crucial importance for survival. Neither the San nor the Hadza groups that were studied lived in places where they could expect to encounter many carcasses of animals that had died besides those killed by carnivores.
Selection pressures imposed by times of starvation are evident from the seemingly superfluous amounts of body fat stored by modern humans, both hunter-gatherers and modern city dwellers.77 Mean body fat levels average 13 percent for men and 25 percent for woman, compared with merely 3 percent for baboons. Even human babies carry much fat. This is obviously a legacy of past times when women were unable to nurture the survival and growth of their offspring without these body reserves. Fat deposits around the buttocks feature prominently among women of both the Khoe herders and San gatherers, located where they least compromise thermoregulation under hot conditions. Frequent famines must have featured in the ecology of at least this region of Africa.
Rock Art
Cave paintings and rock engravings made by hunter-gatherers are widespread throughout savanna regions of Africa, but styles vary.78 The earliest rock art, found on loose stones within caves on the southern Cape coast, took the form of geometric scratches, dated to 77 ka.79 The earliest animal images preserved in Africa come from stones in Apollo Cave in southern Namibia, dated to 27 ka. This is later than the earliest cave paintings in France, dated at 33 ka, but rock paintings made under shallow overhangs in Africa are much less likely to be preserved than those made deep within limestone caves in Europe. Dates for rock art in northern Africa range from 12 to 2.5 ka, after the last glacial advance, when the Sahara region was green and thronged with animals and people. Paintings on rock walls in southern Africa have yielded an earliest date of 6 ka, from sites in Botswana. Cave paintings in the Drakensberg/Maloti region of South Africa gave earliest dates of 2.5 ka, although human habitation in caves there goes back as far as 80 ka.80 Rock engravings are more durable and probably have earlier origins than cave paintings, but seem impossible to date.
Geometric shapes painted using fingers predominate in the region broadly surrounding the Central African rainforest.78 They contain some animal depictions, but these are relatively crude. This art form has been ascribed to ancestors of the Batwa people, represented today by groups living in rainforest regions, but who were more widespread prior to the expansion of Bantu speakers. In the south, this style of rock art occurs across a broad region extending from southern Tanzania, Malawi, northern Mozambique and parts of northern Botswana into Angola. Paintings locally depicting either geometric shapes or antelope are scattered through Zambia. Where human remains have been associated with the geometric art, they show features typical of people inhabiting west-central Africa rather than Khoe-San. The Hadza/Sandawe people exhibit cultural connections with the Khoe-San in art and language, but physically resemble neighbouring Bantu-speakers. The original language of the Batwa peoples is unknown, because everywhere they have adopted the language of local Bantu-speakers. Also enigmatic are the Damara people inhabiting northern Namibia, who are dark-skinned like the neighbouring Himba/Herero people but speak a click language, and lack cultural affinities with any local ethnic group. Genetically, they are allied with western Bantu immigrants represented by the Himba and Herrero.81 Thus languages, cultures and genes can become reassorted partially independently.
The rock art ascribed to San hunter-gatherers south of the Zambezi and Kunene rivers features particularly human figures finely painted with brushes.82 Many cave paintings depict ‘anthropomorphs’, combining animal and human features, plus imagery potentially visualised during trance dances. Among the animal depictions, antelope and other large herbivores are most common, with different species prominent in particular regions (Figure 18.4). Eland feature especially in the Drakensberg, replaced by hartebeest or kudu along with giraffe in South Africa’s northern bushveld. Giraffe and kudu along with elephants are especially common in south-western Zimbabwe and springbok in Namibia. Animal depictions found near Konda in central Tanzania, with giraffe once again conspicuous, followed by hartebeest and elephant, are ascribed to Sandawe people, neighbours of the Hadza who no longer live as hunter-gatherers.64 Black rhinos are especially prominent among rock engravings in southern Africa. The most recent paintings in South Africa depict the arrival of European people, often on horseback, along with their livestock.
Figure 18.4
Large ungulates depicted in rock art in southern Africa. (A) Eland in Drakensberg; (B) kudu in Zimbabwe; (C) giraffe and zebra in Zimbabwe; (D) reedbuck in Drakensberg; (E) hartebeest in Drakensberg; (F) roan antelope petroglyph in northern Cape.
Naturalistic paintings and engravings, some of them huge, also occur widely through northern Africa inland from the Mediterranean coast, particularly in Libya and Algeria. They are intriguingly similar in style to the art produced by the San people, despite the geographic separation. Animals commonly depicted there include giraffe, elephant, hippo, white rhino, and various unidentified antelope, along with the long-horned buffalo that became extinct 5000 years ago. People are shown hunting with bows and arrows and also standing among evidently domesticated cattle.
Assemblages of rock paintings are notable not only for the animal species shown, but also for those absent. In southern Africa, wildebeest and blesbok are rarely depicted, although among the most common ungulates there until quite recently. Bones of wildebeest are well represented in some fossil assemblages, with signs of butchery.83 Perhaps wildebeest and blesbok attracted less attention because they are found in open grassland providing little cover for stalking hunters.
The San rock art emphasises the cultural importance of Africa’s large herbivores in the lives of their human compatriots, especially their eminence as a food resource, but why do animals feature so much less among the geometric images associated with the Batwa or their affiliates? The Mbuti pygmies hunt forest-inhabiting duikers using nets, but perhaps none of these species is sufficiently prominent to be given ritual significance.
Pastoralism and Cultivation
Humans who spread from Africa through Eurasia had established a hunter-gatherer lifestyle in their continent of origin. Their hunting prowess with arrows as well as thrown spears enabled them to replace the Neanderthal people, who were dependent on mortally wounding large mammals and rivals using short stabbing spears. The fascination that the strange herbivores found in northern climates provided to the African immigrants is evident on cave walls through the limestone regions of Spain and France. Eventually, descendants of these people underwent a radical change in lifestyle in the ‘Fertile Crescent’ of the Middle East around 10 ka, when conditions had warmed considerably following the LGM. People established settlements, domesticated animals and cultivated crops. Aspects of this lifestyle soon filtered from there back into Africa.
Rock paintings show the presence of aurochs (ancestors of cattle) in southern Egypt around 10,500 years ago, but these animals were evidently hunted and not yet domesticated.84 Domestic caprines (sheep and/or goats) first appeared in the Mediterranean region of northern Africa around 8000 years ago, as shown by rock engravings and paintings at various sites.85 They were followed shortly after by cattle, representing the taurus form domesticated in Europe rather than the indicus (or zebu) originating in India. These domesticated ungulates became spread through the western Sahara region, which remained well vegetated until around 4500 years ago. Intensifying desert conditions then forced people with livestock to move southwards into the Sahel region of western Africa. The domesticated herbivores supplied a year-round source of food and liquid, in the form of milk. Plants were first cultivated in western Africa shortly after herding had spread. The first crop plant, pearl millet, appeared in western Africa around 3500 years ago, followed by sorghum, wild rice and finger millet.86
A separate southward movement of people with livestock took place in the north-east ~5000 years ago. These herders followed the Nile valley through present-day Sudan and settled near Lake Turkana in northern Kenya, where they incorporated fish in their diet.87,88 There they mixed genetically with the indigenous foraging people. A thousand years passed before herding appeared further south in the vicinity of Lake Victoria, initially only with sheep and goats (Figure 18.5A), and expanded from there into southern Kenya and northern Tanzania shortly after 3000 years ago. The susceptibility of cattle to diseases acquired from wild ungulates may have inhibited movement by these herders southwards into moister savanna regions.89 Back then the herding people still used stone implements. Starting between 3000 and 2500 years ago, people representing the Bantu language group migrated eastwards from the highlands located near Cross River close to the current Cameroon–Nigeria border into Uganda, following the northern rim of the Congo Basin, and onwards.90 They brought pottery, grindstones, and later iron-working. How they integrated among the local hunter-gatherers remains unclear. The rock art found in eastern Africa does not depict the appearance of the domesticated ungulates, contrary to the images portrayed in the far north and south of the continent. Nilotic pastoralists, represented today by the Maasai and related groups, are the most recent indigenous immigrants, entering eastern Africa from the north only around 250 years ago.
Figure 18.5
Herding livestock. (A) Sheep in Kenya; (B) cattle in Uganda.
Domestic livestock, in the form of sheep, appeared in Namibia around 2300 years ago.91,92 The herding people, affiliated physically and linguistically with the Khoe-San, apparently acquired livestock from people living to the north of Angola. Cultural links between them and the Batwa hunter-gatherers are suggested by the presence of geometric rock art through this region. The Khoe herders, still with LSA implements, expanded their presence southwards, either by moving or cultural infiltration among the San, as far as the Western Cape, acquiring cattle at some stage. Cattle-herders with Khoe affiliations were evidently present in northern Botswana around 1700 years ago.49 The Khoe settlers in the Cape had acquired the genes for lactose tolerance in adulthood, probably from close contacts with herders further north, enabling them to digest milk.93
In the east, a southwards movement of Bantu-speaking herders got underway before 2000 years ago, probably following a route through the grassy highlands so as to avoid the miombo woodland belt where tsetse flies transmitted sleeping sickness (trypanosomiasis) to cattle and humans.89 This was during a period when cooler and hence more arid conditions were associated with an expansion in C4 grasses in the diets of wild and domestic ungulates.94 Bones of caprines accompanied by pottery have been found in Zimbabwe and northern Mozambique dated to around 2250 years ago, closely synchronous with the dispersal in the west.92 Crops were grown and metal-working took place in Zimbabwe around 1800 years ago, while cattle were present in Malawi shortly after.
By around 1650 years ago, farming people had arrived in South Africa, bringing iron-working33 and accompanied by sheep and goats, and later by cattle (Figure 18.5B). They settled in river valleys where soils were most easily worked. By 1250 years ago, farmers accompanied by livestock had reached the Fish River in the Eastern Cape. There they came into contact with Khoe herders, who had occupied this transitional zone between summer- and winter-dominant rainfall, providing both grass for cattle and shrublets for sheep plus goats. A further influx by agro-pastoral people along with abundant cattle took place around 1050 years ago. Those settling in the north established stone-walled structures at Mapungubwe alongside the Limpopo River and later built more elaborate stone constructions at Great Zimbabwe and elsewhere. The Mapungubwe settlement disintegrated around 700 years ago when conditions became too dry, while the Zimbabwe structures were abandoned around 500 years ago, supposedly because the local concentration of people exceeded what environmental resources could support.
In parts of Africa too dry to enable cultivation, such as northern Kenya and most of Botswana and Namibia, people subsisted on livestock products in the form of meat, blood and milk, supplemented by plants harvested from the wild. In wetter savannas, crops of sorghum, millet, and later maize formed the main basis of sustenance, augmented by meat and milk from livestock. Although wild ungulates were no longer hunted routinely, ceremonial drives took place and people turned to wildlife as a food buffer during severe droughts after livestock had died. In Botswana, people dug pits to trap animals as large as elephants. No wild animals were domesticated in Africa, probably because the indigenous ungulates were wary of close contact with humans, storing long experience with these meat-seeking primates in their genes. As time continued, more of Africa’s grasslands became consumed by domestic ungulates rather than by all of the surviving wild ungulates combined.
European explorers and hunters entered Africa in increasing numbers during the eighteenth and nineteenth centuries. They found abundant wildlife present alongside indigenous people from Maasailand in eastern Africa through much of Zimbabwe, Botswana, Namibia and Zululand to the Eastern Cape.61,62 Herders avoided infections of their animals with sleeping sickness transmitted by tsetse flies by keeping their cattle away from densely wooded localities. Populations of wild ungulates were decimated only after the introduction of firearms and their deployment for commercial trading as well as sport hunting. Humans no longer lived so accommodatingly along with the wild animals that they had earlier hunted merely for subsistence.
Overview
The adaptions in physical features that led to the establishment of Homo ergaster by ~1.7 Ma were accompanied by cultural innovations consolidating its ecological niche as facultative scavenger and later as active hunter. While hyenas developed powerful jaw muscles to access the marrow within bones of carcasses abandoned by, or stolen from, feline carnivores, hominins employed stones as percussion tools to crack them. Stones that were probably used to bash open nuts and tubers by australopithecine ape-men became co-opted for this new task. Flakes that had been waste became deployed to scrape off the scraps of flesh remaining on the outside of the bones. But these hominins did not become obligate carnivores. Their staple food dependency surely remained plant parts, especially those secured from underground by digging. The robust ape-men remained solely dependent on a plant resource base. Early humans diverged by adding the flesh component particularly during the dry season when plant parts became scarce and what remained required much effort to extract. Meanwhile, during this time of the year the carcass remains of animals that had starved or been killed by sabretooth cats and hunting hyenas became more abundant, awaiting picking. To access this food source sufficiently safely, the human scavengers needed to be active during the heat of midday, when other carnivores dozed. Hence this must have been the time in evolutionary development when body hair became reduced to a crown on the head plus a few other patches. This partly scavenging lifestyle apparently persisted from when constructed rocks and flakes made their appearance during the climatic transition into the Pleistocene ice ages, until the shift to more specifically shaped stone artefacts characterising the Acheulian technology accompanied the appearance of H. ergaster during the next major climatic transition, for around a million years.
Progressively cooling glacial conditions made plant resources even more scarce during the dry seasons when grazing ungulates became increasingly concentrated around remaining water sources at the time of the year when they were most weakened. The trophic (food-related) niche of the early humans thus expanded to incorporate hunting by pursuit as well as scavenging, building on their capabilities to tolerate heat loads that could prove fatal for animals unable to shed their fur coats. Stone tools became used to butcher the abundant meat secured by own kills in addition to what could be scavenged, requiring more substantial pieces than flakes. The weapons used to kill weakened or exhausted ungulates must have taken the form of sharpened sticks used as thrown or thrust spears, not preserved in fossil accumulations. The group coordination needed for hunting excursions from home bases by males promoted further but small increases in cranial capacity, but little further advancement in tool technology, over a further million years. Of course, females also needed to coordinate their excursions from shared home bases plus the management of infants at different stages.
The onset of widened oscillations between glacial and interglacial cold initiating the Middle Pleistocene ~0.8 Ma prompted a surge in cranial capacity, probably reflecting even greater dependency on hunting and perhaps not solely during dry seasons. Tool kits became even more finely crafted and lighter for greater mobility. Artefacts shaped for body penetration became hafted onto the tips of spears. Then a crucial next step in hunting technology occurred: the launching of sharp-tipped arrows from bows over greater distances than spears could cover, accompanied by the application of poisons to enhance their lethality. But the prey targeted did not die instantly, and the ability of the hunters to follow tracks through the heat of midday until animals could be dispatched with spears was a supporting physiological adaptation. Furthermore, arrows could be launched by hunters lying in ambush to kill even healthy ungulates, so that hunting was no longer mainly a dry-season activity. Other cultural innovations also emerged, including decorative beads and body adornments and the beginnings of art. These expressions took place near the coastline of southern Africa during a period when it seems that most of the subcontinental interior had been abandoned due to the severity of the preceding glacial maximum. When language capabilities emerged can only be conjectured. I envisage a progressive advancement of communication initiated by sounds and gestures facilitating social coordination when australopiths launched into open savannas to seek predator kills, progressively refined into the shaped vibrations that define languages. The cultural advances surely contributed to the population surge that carried a group of people beyond Africa and throughout the rest of the world.
Their increased hunting prowess allowed African inhabitants to survive more successfully during the LGM than people had through previous ones. It may have contributed to the demise of several large grazers clustered locally in places where food and water still remained. The advances inaugurating LSA tool technology were retained into modern times by some groups of people.
Meanwhile, a back-migration took place of people dependent on herding domesticated animals in place of hunting wild ones, supported by the cultivation of crop plants in place of those harvested from the wild. Notably, the domestic animals brought into Africa were mainly grazers and the crop plants grown mainly grasses. The agro-pastoralists spread through Africa, displacing the hunter-gatherers while incorporating their genes. People discovered how to smelt iron ore to obtain metal to make even more robust tools, notably including hoes as well as spear and arrow tips. Having acquired greater subsistence security from their livestock and cultivars, hunting pressure on wild ungulates became alleviated, although these animals remained a fallback resource during severe droughts and disease outbreaks. Wild herbivores living in grassy savannas remained a central feature of human subsistence and culture from when the earliest humans added scavenged carcass remains to their diets until the present time. Africa retains most of its Pleistocene diversity of large mammals because these animals had evolved along with humans while the latter honed their skill as hunters. African animals learnt early on not to become too familiar with upright apes, so none of them became domesticated. Once people living in Africa had gained the food security conferred by herding domestic ungulates, they tolerated, and even revered, the wild ungulates that coexisted in savanna grasslands.
Today, cerebral humans gape at the big mammals that Africa still possesses, which featured so centrally in our ecological trajectory from forest-inhabiting, fruit-eating apes to bipedal hunters. In the next chapter, I will explore more fundamentally how evolutionary transitions among the plethora of candidate hominins eventually led to modern humans in Africa. The final chapter will look ahead to the place of wild herbivores in evolving human culture.
SUGGESTED FURTHER READING
Barham, L; Mitchell, P. (2008) The First Africans. African Archaeology from the Earliest Toolmakers to the Most Recent Foragers. Cambridge University Press, Cambridge.
Plummer, T. (2004) Flaked stones and old bones. Biological and cultural evolution at the dawn of technology. Yearbook of Physical Anthropology 47:118–164.
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