The Incredible Human Journey

by Alice Roberts

  ‘No – it’s all dental picks and hand drills; it’s very, very difficult stuff to dig. This small pit took about four excavation seasons to dig. But it was well worth the effort.’

  The lowest layer was the least cemented, and still quite sandy. It contained streaks of burnt material, possibly ancient hearths, as well as lithics and animal bones. Optically stimulated luminescence (or OSL) dating of this layer placed it at around 164,000 years ago. At that time, during OIS 6, the sea level was somewhat lower than today: the cliffs would not have been on the coast, but set back some 5 to 10km from it. Above those very ancient sediments was a layer containing hearths, but with fewer artefacts, dating to about 132,000 years ago. Sitting on top of that was a heavily cemented layer containing another layer of shells dating to about 120,000 years, and topped off with cemented dune sand and flowstone that had sealed the cave, and kept all that archaeology intact, building up from between 90,000 and 40,000 years ago. ‘These are some of the oldest archaeological deposits associated with early modern humans,’ said Kyle, quite proudly.

  Kyle brought out a selection of stone tools that had been discovered in the excavations. ‘These are very typical of the stone tools we find in this cave: blades and points made of quartzite, locally available on the beach down here. And alongside those larger tools, we find these very small bladelets.’ They were indeed tiny, less than 1cm in width and perhaps 2cm long.

  The stone tools from Pinnacle Point are a mixed bag of MSA and bladelets – like Howiesons Poort. In fact, more than half of the stone tools from Pinnacle Point are bladelets.7 It looked like these people were using composite tools. ‘It’s hard to see how these tiny blades would have been used without hafting them, setting them in a handle. So these suggest advanced tool-making techniques,’ said Kyle.

  The shells found in the upper cemented layer are also interesting. They include all sorts of edible shellfish, types that still thrive along this rocky shore, including many brown mussels (Perna perna), limpets (Patella spp.) and giant periwinkles (Turbo sarmaticus). There was also a fragment of whale barnacle, which may have been scavenged from the skin of a beached whale.

  Kyle told me that the giant periwinkles provided extra information about past climate. While the shells themselves were often quite smashed up, the operculum, or trap door of the periwinkles was usually very well preserved. He showed me some: they were like small, white, slightly domed buttons, with a spiral on the flat side, and easily visible growth layers. Sampling oxygen isotopes from these opercula gave the archaeologists an idea of the ocean temperature and more general climate at the time the sea snail had been alive. Before they started on the ancient shells, the archaeologists wanted to check their calculations comparing modern shells against recent climate records. For two years, they had collected giant periwinkles from the shore to study their opercula. And Kyle said that they were delicious.

  It might seem unremarkable that these hunting and gathering ancestors of ours were eating shellfish. But this is the first example of any human species exploiting marine resources. For millions of years, australopithecines and earlier Homo species had been restricted to eating land plants and animals. But it seemed that Homo sapiens developed a taste for fish and shellfish: exploitation of coastal resources is seen as another type of definitively modern human behaviour. From the evidence from other South African sites, it had been thought that this adaptation to coastal living came along perhaps 70,000 years ago. Archaeologists had argued that this development set the stage for the coastal expansion of modern humans out of Africa and into Asia. But once again, Pinnacle Point pushed the dates back – this time to about 120,000 years ago. Marean and his team suggested, based on the Pinnacle Point evidence, that shellfish may have become an important food source during OIS 6. During this glacial period, between 190,000 and 130,000 years ago, the environment became terribly dry, and humans would have struggled to find food. Turning to the resources on the coast may have been crucial to the survival of those early hunter-gatherers.

  But the evidence for modern behaviour at Pinnacle Point didn’t stop there. In the lowest layer of the excavation, the archaeologists also found lots of pieces of red ochre: fifty-seven in total. And these weren’t just natural pebbles. They had been scratched and scraped. Kyle handed me one of the pieces of ochre that had been found in the cave. It was clearly faceted where it had been ground down, and scratched on one side. I had seen photographs of the ochre pieces, but it was so much more convincing when I held one and looked at it. There was no way that the marks and shaping of this lump of pigment could have happened naturally. So there it was, sitting in my hand, the earliest evidence for pigment use in the world: 164,000 years ago, the people of Pinnacle Point had been painting something.

  ‘We really have very little to go on,’ said Kyle. ‘But this ochre is our best evidence that these people were practising some kind of symbolic communication.’ The red ochre from Pinnacle Point is certainly suitable for body painting, but we’ll never know for sure what it was – the cave walls, or some object, or themselves – that they were covering in this colour, or what it meant to them. But I couldn’t help thinking of the Kibish women with their braided hair, faces, necklaces and breasts painted in deep, rich, red ochre.

  Mellars6 cautions against assuming that South Africa was where modern human behaviour appeared, because the preponderance of sites may simply reflect the fact that extensive investigation has been carried out there. And in fact there are similar sites in Tanzania and Kenya, although the dating of these has proved problematic. As we have seen, it is difficult to know exactly when our ancestors became, anatomically, modern human – but we know they had pretty much ‘got there’ by the time of the Omo fossils, 195,000 years ago. The genetic evidence also suggests an origin of our species around 200,000 years ago.

  The evidence emerging from Pinnacle Point pushes back the date for the emergence of modern behaviour much closer to the earliest dates we have for the emergence of modern human anatomy.7 Like the anatomical features, it is likely that behavioural traits we consider as modern appeared one by one, gradually coming together to form a mosaic, a ‘package’ of modern features. But what Pinnacle Point shows is that by 160,000 to 120,000 years ago the people living there had a fairly comprehensive portfolio of dietary (shellfish), technological (bladelets) and cultural (pigment use) behaviours that all shout out ‘modern!’.

  The First Exodus: Skhul, Israel

  It is difficult to trace population expansions within Africa: there has been a great deal of time for populations to move around, over several glacial cycles. Both archaeological and genetic investigation have been biased towards more developed and politically stable countries, meaning that there is very little evidence about early modern humans across great swathes of Africa. Nevertheless, genetic studies provide clues about the geographic origins of modern human populations in Africa. The most ancient mitochondrial lineage, L1, is found in the Bushmen of South Africa and the Biaka pygmies from the Central African Republic. The most ancient Y chromosome haplogroup is found in East Africa, among Sudanese and Ethiopians, as well as among the Bushmen and other Khoisan populations. Genetic lineages appear to have expanded from East Africa to the south and north, as well as out of Africa. African genes also record a much later expansion, of Bantu speakers, from a homeland in West Africa, towards the east and the south, some 3000 years ago.1

  So when – and from where – did humans expand out of Africa? Migrations out of Africa may have depended on our ancestors being able to usefully exploit marine resources and spread along coastlines. But those migrations were also constrained and determined by geographic and climatic factors, factors that vacillated with the changing environment of the Pleistocene.2

  Geographically, at least four routes from Africa to Eurasia seem possible: from Morocco, across the Strait of Gibraltar; from Tunisia to Sicily to Italy; a northern route from Egypt into the Sinai Peninsula, and up into the Levant; and a southern route from Eritrea, across
Bab al Mandab (the ‘Gate of Tears’) at the southern end of the Red Sea. All would have involved sea crossings apart from the Sinai route, but, as we have seen, the occupation of Australia, by perhaps 60,000 years ago, would have required a sea crossing.3 So which of these routes may have been used, given the genetic and archaeological evidence?

  As many of these routes suppose a spread out of North Africa, what is the evidence for the earliest modern human presence in that area? In the 1960s the fossil remains of four hominins were discovered in Jebel Irhoud cave, along with Middle Palaeolithic Mousterian tools, in a quarry in Morocco. Animal fossils suggested that these might date to the end of the Pleistocene. Recent uranium series and ESR (electron spin resonance) dates on a juvenile mandible from Jebel Irhoud place the fossil around 160,000 years old.4 Some researchers claimed that the skulls were Neanderthals, but recent analyses have concluded that, though certainly robust, these people were early modern humans.5 There are some sites, like Dar-es-Soltane in Morocco, where early modern human fossils were found associated with Aterian tools, and there’s other evidence of modern behaviour, with pierced shell beads found alongside Aterian points at the site of Taforalt in eastern Morocco, dating to around 82,000 years ago.5,6

  Routes out of Africa. The trails of footprints indicate the northern and southern routes at either end of the Red Sea.The dune texture shows the maximum extent of deserts – during glaciations.

  There is, however, no actual evidence of any spread of modern humans from North Africa into Europe: it seems that the Mediterranean was a major barrier to expansion and colonisation. The dates of archaeological sites in Europe, as well as genetic studies of modern Europeans, suggest an east-to-west spread, making an exit from East Africa most likely.7 So that leaves the two routes out of East Africa: a northern route via Sinai, and a southern route across Bab al Mandab. The navigability of these routes would have varied during glacial cycles.

  In his book Out of Eden, Stephen Oppenheimer discussed the likelihood of each of these routes as an exit point for modern humans from Africa, taking into account the climate and environment at the time.8 For most of the Pleistocene the northern route out of Africa would have been ‘shut’: the climate would have been cold and dry, and both the Sahara and Sinai deserts would have been impassable. But the Ice Age was punctuated by interglacials, about one every 100,000 years, when the climate temporarily warmed up and the monsoon returned. During these periods, some of what had previously been desert would have turned green. Oppenheimer vividly describes this event as being like a ‘science-fiction stargate’. Sub-Saharan animals would have been able to move into areas that had previously been desert, expanding their range from equatorial regions into temperate zones. African fauna could move up into the Levant through a green ‘environmental corridor’ right through the Sinai Peninsula.9

  We are enjoying an interglacial at this moment: a nicely warm phase that started 13,000 years ago. The last interglacial before this one, the Eemian or Ipswichian, corresponding with OIS 5, started about 130,000 years ago: it seems that the climate was particularly warm and wet between 130,000 and 120,000 years ago.10 It is also around this time that the first traces of modern humans appear outside Africa, in the form of fossils from the caves of Skhul and Qafzeh, in Israel. It seems likely that the ancestors of these people left Africa by that newly green northern route. We are somewhat trapped here by our own appreciation of geography, our ideas of where continents begin and end. In fact, rather than thinking of these humans as having ‘left Africa’, it is probably better to think of the Levant of 125,000 years ago as an extension of north-east Africa: it was essentially part of the same environment, with the same range of animals, and modern humans were part of that African fauna.7,11

  So I made my way to Israel, to visit Skhul Cave. From Tel Aviv, I drove north and followed directions to the place, leaving the main road to enter a canyon called Nahal Mearot (or Wadi el-Mughareh), near Mount Carmel. The valley was framed by great limestone ridges on each side, and there was a series of caves on the southern escarpment. Still following directions, I headed up the valley a little way on foot, and then up the hillside to Skhul Cave. It was an unprepossessing place: small and short, opening on to a flat terrace in front. I could see where spoil from excavations had been piled in mounds, now covered in thorn bushes, just in front of it. I noticed lots of tiny pieces of flint debitage (debris from making stone tools), scattered on the ground in front of the cave.

  I sat on the rocks outside the cave and waited for Professor Yoel Rak to arrive. Yoel Rak was an anatomist at Tel Aviv University and a distinguished palaeoanthropologist. As well as working on Pleistocene sites in Israel, he had also worked with Don Johanson and William Kimbel in Ethiopia, finding the first, almost complete, skull of the early hominin Australopithecus afarensis.

  Yoel told me about the discoveries at the Mount Carmel caves. As with so many sites, the Mount Carmel caves had been found by accident, by British geologists planning a new road and port at Haifa in what was then British Mandate of Palestine. Archaeologist Dorothy Garrod, who later became the first female professor at Cambridge University,12 arrived to direct excavations, accompanied by palaeontologist Dorothea Bate, from the Natural History Museum in London. The excavations continued from 1924 to 1934. Yoel said that Dorothy was quite a feminist, and that the excavation team had consisted almost entirely of women from the nearby Arab village, but apparently some men had been drafted in when it came to the strenuous job of hand-drilling and lifting slabs of limestone breccia. Yoel pointed out the marks left by the drills on the terrace in front of Skhul Cave. The archaeologists found thousands of Mousterian stone tools in the cemented sediments, and in the lowest layer they discovered ten burials of modern humans.

  Just around the corner of the canyon from Skhul, the archaeologists discovered Neanderthal remains in Tabun Cave. Garrod thought that the modern human remains probably dated to around 40,000 years ago, while the Neanderthal bones were more than 50,000 years old. This fitted with the idea at the time that Neanderthals were predecessors to modern humans.

  But when absolute dating techniques were applied to the site in the 1980s the modern human burials were found to be much older. ESR dating of bovine teeth from the same layer as the burials produced a date of around 90,000 years.13 Even more recent dating, using uranium series and ESR on fossil human bone and teeth, and on two animal teeth associated with the burials, indicate that the Skhul burials date to some time between 100 and 130 thousand years ago.14

  After visiting Skhul Cave, I went to see some of the human remains themselves, in the Rockefeller Museum in Jerusalem. To reach them I walked through echoing galleries full of classical sarcophagi, Bronze Age burials and ossuaries, but the bones I was going to see were much more ancient.

  There were two of the Skhul individuals in the museum: the bones of a four-year-old child (Skhul I) and those of an adult male (Skhul IV). Both skeletons were incredibly well preserved: more complete and in better condition than many medieval skeletons I have looked at in the bone lab at Bristol – and so much older. Soils on limestone generally make for good preservation of bone, but these bones wouldn’t have survived had they not been buried.

  The bones of Skhul IV were arranged just as they had been found by the archaeologists. The body was not carefully laid out as in later burials, straight or bound into a crouched position. The skeleton lay awkwardly, with the legs bent at the hips and knees, and the torso twisted on to its front, with the skull resting higher up, and the arms bent to bring the hands close to the face. There was a flint scraper between the hands. It’s very difficult to know if this was placed in the grave deliberately or whether it was just in the soil that had been heaped on top of the body at burial.

  But there were other objects with the Skhul burials that definitely appear to have been associated with the burials, to have been placed in the ground at the same time as the bodies. Skhul V was buried with a boar’s mandible clasped in its arms, and there were also
two shell beads in the same layer as the burials.15

  Later in the 1930s, more modern human remains turned up in a cave near Nazareth, called Qafzeh. Initially, seven individuals were found, but when the cave was reinvestigated in the sixties and seventies the remains of a further fourteen individuals were uncovered.16 One of these, an adolescent, was buried holding deer antlers in its arms, and there were also pieces of worked ochre in the ground with the burials.14

  The two sites at Skhul and Qafzeh represent the earliest evidence anywhere of burial. Placing grave goods in the ground with the body is further evidence of ritual, and a spiritual dimension to these people’s lives. Like the traces of art and ornamentation from South Africa, we seem to be seeing something here which implies modern ways of thinking and behaving: an approach to life and death that seems somehow familiar to us. Although we can’t know what these objects signified, we can assume they meant something to the people who placed them in those graves around Mount Carmel all that time ago. It is tempting to imagine that the inclusion of personal ornaments and animal remains might even imply some kind of belief in an afterlife.

  But after those burials at Skhul and Qafzeh, traces of modern humans in the Levant disappear, for around 50,000 years. I asked Yoel Rak what he thought had happened. He said it was difficult to prove that people had actually disappeared from the region. They might have stopped burying their dead. There are no more anatomically modern bones, and no more pierced shells, for a long time. And as the stone tools at Skhul were very basic, Mousterian tools, in fact exactly the same as Neanderthal technology, the presence of modern humans could not be demonstrated through tools alone, that is, until more sophisticated technology appeared in the Levant, around 45,000 years ago. Perhaps the evidence is there but hasn’t been found yet. But maybe that absence is real, and Yoel believed that the disappearance of modern humans from the Levant, perhaps 90,000 years ago, could be explained by looking at what was happening to the climate and the environment at the time.