by Paul Jordan
Remains, often very fragmentary, of ergaster/erectus types have been found in parts of Africa other than the East African homeland of the species where dates run from about 1.8 mya to 560,000 BP; in South Africa ergaster/erectus dates from about 1.6 mya down to perhaps 700,000 BP, while in North Africa finds made so far seem to cover a range between about 750,000 and 500,000 BP. By this time, the Acheulian tradition had appeared in Europe and the story of human evolution we have been telling in this chapter links up here with the ancestry of the Neanderthalers that we reviewed in Chapter 8. Whether the feat of ocean crossing seemingly achieved by erectus in the Java Sea was emulated by ergaster/erectus across the Mediterranean is not presently known. It has not generally been thought that a crossing was made into Europe via Gibraltar (any more than a passage to Madagascar was ever accomplished); the early dates of Developed Oldowan or early Acheulian in the Jordan Valley (to say nothing of the finds in Georgia) have tended to suggest that humanity and technology spread into Europe at the eastern end of the Mediterranean rather than crossing the Mediterranean in the west, though affinities between the tool types of the North African Acheulian and the Acheulian of Spain have been noted. At all events, with the appearance of the Acheulian tradition in Europe and of the fragmentary human remains, which may be classified as Homo heidelbergensis or late Homo ergaster (or late Homo erectus, for that matter), discovered as we have seen at places like Gran Dolina in the Atapuerca Mountains of Spain, our story has brought evolving humanity to the point at which the very distant ancestry of Neanderthal Man and his Mousterian culture can be discerned in Europe – at about 700,000 BP where the Acheulian tools are concerned and perhaps as far back as 800,000 BP with the skull and skeleton fragments. Arrived in Europe, evolving Homo ergaster (on his way to Homo heidelbergensis) faced in short order by the standards of geological time a climatic deterioration that would set the huge challenge of much colder times (if interspersed with milder ones) to which the Neanderthalers rose so doggedly, even heroically, in the end.
The Emergence of Homo sapiens sapiens
By about half a million years ago human evolution had put on earth, in places as far apart as South Africa and northern China, a form of human being with – whatever regional and even perhaps species variations – a postcranial skeleton to all intents and purposes like our own and a brain about twice the size of the first hominids of two million years or so before. Brain size remained rather stable among ergaster and erectus populations for many hundreds of thousands of years, and with it there went a long conservatism in toolmaking habits and, we may presume, in any use of language too, which was probably still almost entirely restricted to social relations and unable to admit much ‘discussion’ of other topics, even potentially vital ones that related to observation of the natural world and to technical matters like toolmaking and food procuring and processing. In so far as these creatures could be thought to have possessed consciousness at all, it must have been a consciousness dedicated to the social realm, to awareness of oneself as a social agent, to guessing of others’ ‘intentions’ and prediction of their likely actions, to dissembling and deceiving for advantage, to forging and dissolving of alliances, to wriggling out of trouble and smoothing one’s path through social life. For the rest, the same old tools were to be made in the same old ways, without ‘thought’ of innovation, and nature’s rewards were to be gathered (and threats avoided) in the same old instinctive ways, without much in the way of reflection and conjecture as to how to do it better. Perhaps there was a trickle of other considerations into social consciousness, with some slight improvements in tools, language and hunting skills, but not very much. Of symbolic imagination there appears to have been nothing at all.
After a million years of Homo erectus/ergaster, the fossil record starts to show some clear-cut novelties at around 500,000 years ago, with further brain enlargement and skull changes to go with it. Because much of the fossil evidence is fragmentary, it is not possible to say exactly when the changes first appeared, and no doubt they happened at different times in different places among the small populations that were strung out across the inhabited world. In Europe, for example, the Atapuerca fragments (about 800,000 BP), the Mauer jaw (perhaps 500,000 BP) and the Boxgrove leg bone (also about 500,000 BP) have all been classified as Homo heidelbergensis to mark their sufficient evolution out of Homo ergaster/erectus. In the Far East Homo erectus was flourishing without any detectable evolution towards later forms at the same dates. In Africa the scientific classification Homo heidelbergensis has been given to a massive skull found at a place called Bodo (Ethiopia) which convincingly combines ergaster/erectus features with others foreshadowing Homo sapiens in just the way that we would expect the skulls, if we had them, of Mauer and Boxgrove to do: all this at an estimated date of 600,000 BP. Bodo has the biggest face of all known human fossils, with a very prominent ridge over the eyes (which extends as a single bar, though rounded over each eye) and a midline keel on the skull top which hark back most emphatically to ergaster/erectus, and cranial capacity is not much larger. But the nasal area of the face and the frontal area rising over the brow-ridge look forward to Homo sapiens, as do the places on the skull’s underside where the jaw articulated. The skull represents a clear advance over even late erectus types with whom it is, if its early date is correct, contemporaneous. Interestingly, there are cut marks round the eyes, on the cheeks and forehead, at the top and back of the skull that – being never healed – point to defleshing of the Bodo skull at the end of the individual’s life; cannibalism or some postmortem ritual treatment suggest themselves, with implications for some glimmering of symbol-driven behaviour to do with the dead. The tools found in association with the Bodo skull show a surprising mixture of Acheulian with Oldowan items, reminding us that simpler tools of the Oldowan style did not altogether disappear with the start of the long career of the Acheulian even in Africa (and Europe), while they went on as the mainstay of stone technology in the Far East to the end.
The face from Bodo.
The Kabwe skull.
The jaw fragment and skullcap from Elandsfontein in the Cape Province of South Africa (also known by the names Saldanha and Hopefield), found in apparent association with faunal remains suggesting a date between 500,000 and 200,000 BP, are also very much like ergaster/erectus but with a significantly greater cranial capacity at an estimated 1200 ml. Acheulian axes were also found in association. At Broken Hill in the old Rhodesia, a site now called Kabwe, a skull was unearthed that looks very much like a progression from Bodo in its very massive brow-ridge construction. When it was found, before the Second World War, its superficially Neanderthal features caused it to be called in the state of knowledge at the time an African Neanderthal Man or at least a ‘Neanderthaloid’, but the skull shape as a whole more closely resembles that of modern Homo sapiens sapiens than the distinctive lines of the Neanderthalers’ skulls. Faunal associations suggest a date of at least 125,000 BP and very probably older, perhaps as old as 300,000 BP. Brain size is estimated at 1300 ml, with a skull shape considerably evolved beyond ergaster/erectus in its loaf-shaped aspect seen from the back and its fullness in the occipital area where there is a steeper rise to the skull top. (The Kabwe skull is essentially rather like the Petralona skull from Greece, and both stand at a similar point in the evolution of sapiens out of heidelbergensis traits.) The Kabwe skull lacks any distinctively Neanderthal characteristics (like the pulled forward face and the bun at the back) and limb bone fragments found at the same time look rather modern in form, though with very thick outer bone in the manner of ergaster/erectus. Their association with the skull may be doubted. The teeth, incidentally, are unique in the fossil record of early man in showing a degree of dental caries with abscesses not seen again till the times of the first farmers after about 10,000 years ago. A hole near the left ear may be the result of affray involving some sharp instrument or of the attentions of some carnivore. The arrangement of the voice-box, as inferred from the basal flexin
g of the Kabwe skull, has been deemed to suggest a better capacity for forming a wide range of sounds for potential use in speech than is seen in the Eurasian Neanderthalers. A maxillary (upper jaw) fragment from the same site at Broken Hill seems to reveal a less ruggedly built individual who may not belong with the Kabwe specimen in time and indeed resembles the Ngaloba remains mentioned below. Meanwhile, the Ndutu find from Olduvai may represent a more lightly made female of the same general sort as the Kabwe male.
Omo II.
Two skulls from Omo on the banks of the River Kibish in Ethiopia may take the story on from Kabwe, if they truly belong to the levels in which they were found. That they might not is, unfortunately, suggested by the marked differences between them which raises the possibility that one or the other is intrusive, perhaps both. Omo II shows a relatively heavily made skull with a receding forehead but at the same time a loaf-like breadth between the parietals and a cranial capacity of some 1400 ml. At a date of about 130,000 BP, judging by dating of mollusc shells from the levels in which it was found, Omo II makes a plausible descendant of Kabwe. The fragmentary Omo I, from the same levels on the other side of the river, reconstructs as very modern looking with parietal breadth, high forehead, a short face, brow-ridges not outside the range of rugged individuals today, and a jaw with a chin. Brain capacity was up to modern standards. There were bones from the shoulder, arm, hand, spine, ribcage, leg and foot areas that suggest a tall and lightly built body of a modern sort. It has been hard for some anthropologists to conclude that Omo I could really date to some 130,000 BP or that Omo I and II might together represent some very variable population on its way to Homo sapiens sapiens. Omo I might be the remains of a much later individual whose bones have got mixed into the dated levels of his discovery; unfortunately, the same might be true of Omo II, though his features would not perhaps be out of place in 130,000 BP. Kabwe, at over 125,000 BP, and Omo II, at perhaps 130,000 BP, can be seen to represent a stage of evolution out of an ergaster/erectus ancestry via heidelbergensis (Bodo) that roughly equates with the early Neanderthalers of Europe, similarly derived via European heidelbergensis from ergaster/erectus, but the African specimens do lack the distinctive traits of the Neanderthalers and their differences from their European cousins impress many anthropologists as looking forward to modern Homo sapiens sapiens better than do the characteristics of the Neanderthal folk.
The Ngaloba skull.
In Africa it is possible to list a few more finds that seem to take on the line of incipient modernity. The remains from Singa in the Sudan (at about 150,000 BP and from Ngaloba in Tanzania (at some 130,000 BP), together with those from Florisbad in South Africa have a borderline modern look about them but are really too enigmatic to make much of. The fragments of five individuals from Jebel Ihroud in Morocco do, however, show clear signs of evolving modernity at perhaps as early as 150,000 BP. A femur fragment is robust and teeth are large, but a rather delicate jaw has signs of a chin. The skull shape looks ‘primitive’ at the back but more ‘modern’ at the front, being broad and flat-faced with hollowed cheeks in marked contrast to the inflated cheek appearance of the Neanderthalers who were to flourish later on the north side of the Mediterranean. All the same, the Jebel Ihroud type shows rugged brow-ridges. The remains from Border Cave in South Africa, including an adult’s skull and two broken mandibles along with some postcranial bones and the skeleton of an infant, are very modern in character but cannot be confidently dated since they were found in uncontrolled circumstances (by guano shovellers in the 1940s) and are not in the same condition as some animal bones from the site that might otherwise help to date them to perhaps 100,000 BP. Much more useful are the bones from the site called Klasies River Mouth in South Africa. Five fragmentary mandibles, a maxilla, several small cranial pieces, a few teeth and a few postcranial bones paint a picture of a population in which individuals might have no primitive-looking continuous bar of brow-ridges over their eyes, some real chin development on their jaws, and slender limb bones. Floral and faunal evidence and some date determinations by physics put the Klasies River Mouth remains at between 115,000 and 75,000 BP. For all that, some of the jaws are rather robust with big teeth (and one of them has no chin) in a way we should not expect to find among fully modern populations. Traces of burning on some of the bones and cut marks on the frontal fragment have been seen as suggestive of cannibalism at this site. Fragmentary though the Klasies pieces are, they are consistent with the notion of an emerging constellation of modern Homo sapiens sapiens physical traits not seen outside Africa as early as 115,000 BP, and certainly not among the contemporaneous Neanderthalers of Europe. Even so, the rather skimpy array of African evidence, not always well dated, could scarcely support any firm conclusion that fully modern human beings evolved first in Africa around 100,000 years ago without the addition of some other line of argument – and a powerful one at that. After all, we might only be fortuitously picking up in Africa stray hints that modern humanity was evolving in the sapiens sapiens direction in more than one part of the inhabited world (excluding Europe).
A reconstruction of the Florisbad skull fragments.
Rear view of the Jebel Ihroud skull.
The face of Jebel Ihroud.
Jaw from Klasies River Mouth; with thanks to University of Chicago Press.
It was first suggested in the 1970s by geneticists that comparisons of blood groups, enzymes and proteins in modern populations across the world might make it possible to estimate the lengths of time that have ensued since some of the major peoples of the world separated into largely non-interbreeding groups with ‘racial’ characteristics. Of course, all sorts of human beings all over the world remain completely interfertile, constituting a single species that looks superficially quite variable but, in genetic terms, is tremendously homogenous – more so than are the chimpanzees or gorillas within their own species. This suggests either that no populations in the long history of evolving humanity have ever been so isolated as to lose genetic interchange with other populations however distant, or that all human beings in the world today have only rather recently descended from a common source in a single small population ancestral to every one of us. The first proponents of this latter view, arguing from the evidence of blood group and protein variation, estimated that the Mongoloid peoples of today became effectively separated from the Caucasoids at about 40,000 years ago and their joint common stock split from African peoples at about 110,000 BP. The coincidence of this latter date with the dates arrived at for the early African appearances of fossil men with modern traits in places like Klasies River Mouth is unmissable. Since the 1970s genetic studies of modern human variability have made great strides and, on their basis, schemes of human evolution have been vigorously argued that have all human beings in the world today descended from a small population of Homo sapiens sapiens evolved in Africa at some time not so very long before 100,000 years ago. Many anthropologists have welcomed ideas along these lines but some have steadfastly opposed them, standing by the scheme of human evolution expressed by Weidenreich before the Second World War that sees mankind as evolving all over the world through the broad stages represented by such creatures as Homo erectus, Homo heidelbergensis and Homo sapiens (neanderthalensis and modern sapiens) without large-scale extinctions of local populations in the face of expansionist invaders from Africa (or anywhere else). In this view it is genetic interchange across group borders that has kept evolving humanity genetically homogenous all over the world.
Genetic and related studies have not only been brought to bear on questions like the degree of closeness between modern human populations (taking in, as we have seen, certain Neanderthal specimens, too), but also on the problem of dating the stages of human evolution in terms of real, if approximate, years on the geological time-scale. These genetic dates rest ultimately on agreed dates for genetic events (like, for example, the divergence of the orang-utan line from the rest of ape evolution) that have been determined by dating methods based on
physics, but they go on to handle the dating framework of human evolution in a novel way. Before exploring that field, it is worth reviewing the means by which fossils have been sorted and above all dated before the development of the genetic approach. Physical anthropologists have traditionally ordered human fossils by noting their distinctive features, mainly of the skull and jaw, and comparing these with other fossils to build up a scheme of evolutionary relationships on a framework of dates for the fossils in question where such dates may be available and reliable. In the course of the century-and-a-half of anthropological enquiry, dating methods have run from quite speculative estimates of geological dates for events like ice ages to modern tests based on physics for age determination. Dates come in two basic sorts: relative and absolute. Relative datings allow us to judge only on grounds of, say, stratigraphy and faunal associations, that one fossil or hand-axe is older or younger than another, by a bit or a lot, without knowing exactly when any particular fossil man lived or any tool was knapped, or how long a bit or a lot really was. Absolute dating methods aspire to tell us, in terms of real years elapsed, just how old a fossil or an archaeological find might be. Some methods really are absolute, in principle at least, such as counting tree rings or annual varve deposits in northern lake beds. But these methods are of very limited application in general, covering a period back to 8,000 and 12,000 years ago respectively, and of no use at all with fossil man. All the worthwhile methods of absolute chronology are related to radioactive processes in nature and their ‘absoluteness’ is tempered with more or less wide margins of error in practice. The dates we have been assigning in the past chapters to the fossils of Australopithecines or of Homo erectus or the remains from Klasies River Mouth and so on are all ultimately dependent on determinations made by means of physics in connection with radioactive processes. Not all datings by any means have been directly arrived at from the fossils themselves, but many rely on dating of associated materials (like shells and flint) or on faunal associations and climatic indicators known at other sites to date to such and such a time. All the methods result in individual dates quoted with plus-and-minus ranges (sometimes of tens of thousands of years) and all suffer from the complications and uncertainties inherent in the physics on which they depend. The best dating situations are ones in which several different determinations can be made, preferably by different methods, so that statistical clusters emerge with greater likelihood that the date sought after lies within a narrow margin of possibilities. The most famous of the methods uses the decay of radiocarbon in organic materials to measure time elapsed, but C14 dates are unreliable in absolute terms beyond about 30,000 BP (though they can still provide relative chronology) and effectively unobtainable beyond about 40,000 BP, which means that only the latest, for example, of the Neanderthalers fall within the scope of radiocarbon dating. Of application to much remoter epochs are the methods called Potassium/Argon and Argon/Argon which can date materials like lava and volcanic ash by measuring relative quantities of isotopes of these elements in rock samples. The same rocks, volcanically reheated in the past, can also entrap palaeomagnetic patterns that log the changes in the Earth’s magnetic polarity over long periods of time – before about 730,000 years ago (within the times of Homo erectus) magnetic polarity was reversed by reference to today’s and so, even without Potassium/Argon dating, magnetic polarity in volcanic rock can help to assign dates to fossil and archaeological finds. Previously heated materials like volcanic glasses may also contain the tracks of particles emitted by uranium within them since erasure of any former tracks at the time of heating; Fission-Track dating relies on this circumstance to arrive at age determinations, by counting tracks, for geological events reflected in stratigraphies containing fossil remains and artefacts. The gap between the very old dates afforded by such methods and the comparatively recent dates supplied by C14 is closed in part by the dating procedure called Uranium Series, which depends on the precipitation, out of water-soluble uranium, of the decay products thorium and protactinium over time. This method can be used to date shells and coral and carbonate precipitations like stalagmites, stalactites and travertines (spring limestones), covering a very useful range between about 350,000 and 150,000 BP.
