by Paul Jordan
The remains of the ‘Nariokotome Boy’.
All of the teeth of ergaster/erectus are smaller than those of his ancestors, with the molars particularly reduced in proportion to the incisors and canines. It is likely that much more in the way of meat eating lies behind this development, with a premium on biting and tearing at the front of the mouth rather than (vegetable) chewing at the back. The whole skull architecture of ergaster/erectus, and of many of his successors until the appearance of fully modern Homo sapiens sapiens, points to the need for hefty and securely anchored musculature to work the front teeth; the heavy brow-ridges, pronounced occipital tori and sagittal crests along the top mid-lines of some skulls attest to the presence in life of this powerful musculature. Teeth were doing a meat-handling job that only the eventual development of much better tools could finally render redundant in wholly modern people.
The skeleton from Nariokotome.
Postcranially, the ergaster/erectus skeleton as seen at Nariokotome is basically very like that of a modern human being, with a fully evolved bipedal status and limb proportions like our own. (It may be that full bipedalism in itself, with its high requirements for nervous control of balance and motion on two legs, benefited from brain enlargement.) Where he differs from modern youths, it is in details like the longer spines on some of his vertebrae and the constricted aperture of the spinal canal through them, together with the elongated ‘neck’ leading to the ball of the femur and the narrowness of the pelvis. The constriction of the spinal canal has been held as of some significance for the speech-producing powers of the Nariokotome Boy, limiting as it might the nerve provision for control of the thoracic region in subtle breath production for utterance. At worst, this might only point to an inferior capacity for speech relative to ourselves, not an absence of it. Certainly, the Nariokotome specimen exhibits for the first time in human evolution the barrel-chested configuration in marked contrast to the tapered chest shapes of apes, Australopithecines and habilis specimens. All in all, we can say that – provided that the Nariokotome Boy was not some freak of his time who has perversely come down to us as the best preserved of his kind – then Homo ergaster/erectus had more or less acquired by 1.6 mya the modern sort of postcranial skeleton and stature that would serve our ancestors from his time to ours.
The ergaster/erectus skulls of Africa are really very like those of the erectus specimens from Asia in their strong brow-ridges and reduced faces vis-à-vis Homo habilis, their low vaults, keeling along their mid-line tops, rounded occipital areas and cranial bases wider than what comes above (in keeping with their small cranial capacities by comparison with ourselves). Like all erectus specimens (and all human fossils until the first intimations of really modern types) the jaws are chinless, though the African ergaster/erectus examples tend to be smaller than those of Asian erectus and the cheek teeth in particular are small by comparison with those of their Asian counterparts. It is details like these that incline some anthropologists to place them in the species ergaster rather than lumping them in with erectus, and to discern in them a more direct line to later human types like Homo heidelbergensis that we saw in an earlier chapter were likely candidates for the ancestry of the Neanderthalers (and, as we shall also see in due course, of ourselves, too). Some African fossils, be it said, are even more like Asian erectus than those dubbed ergaster are, and it suffices for our purposes to see in the worldwide phenomenon of Homo ergaster/erectus a definite stage of human evolution in which brain size was significantly enlarged over everything that had gone before and the postcranial skeleton achieved more or less its modern form, whatever variability may be identified in detail in different parts of the world.
A specimen of Homo ergaster.
It was H. erectus, or just possibly his immediate ancestors in the form of a version of H. habilis with strong erectus foreshadowings, that spread over much of the Old World after millions of years of Australopithecine and hominid evolution that had been confined to Africa. The stone tools that erectus carried out of Africa into Europe and the Middle East were initially of the simple Oldowan variety but in due course Developed Oldowan and more particularly Acheulian tool kits were largely adopted over most of the inhabited world, with the clear-cut exception of those parts of the Far East like China and Java that never went Acheulian. The Acheulian centred upon the making of hand-axes, though the flakes produced in their manufacture were also much used and, in some circumstances, favoured to the exclusion of hand-axes – a process that accelerated into the Tayacian and Mousterian traditions later on. Wood was no doubt in regular use too, and perhaps it furnished the digging sticks of foraging mothers in search of plant food that did as much to keep erectus populations alive as the stone axes of hunting and scavenging males did. Even bone, though not recovered to any significant extent in the archaeological record, may have been employed to some degree. Sites like Olduvai in East Africa and Swartkrans in South Africa have yielded bone pieces polished by use to cut meat and perhaps to dig up plants, but bone tools as known from the archaeological record go on to show no distinct typography through hundreds of thousands of years. (Until, that is, a spectacular and, to date, rather isolated instance in Equatorial Africa at going on for 100,000 BP, if the date holds up, long after the career of erectus was over, but also long before the appearance of the Upper Palaeolithic worked bone pieces; we shall return to this intriguing evidence in a later chapter.)
An Acheulian hand-axe.
Microwear studies of Acheulian material reveal marks consistent with meat cutting, woodworking and the cutting of stemmed plants. As with the ancestors of Homo erectus, the gathering of plant food must have remained an important element in subsistence, but erectus no doubt ate more meat than his predecessors and animal bones bearing the cut marks of his tools attest to this. Meat eating remained the means by which brain enlargement could be maintained alongside gut reduction in an active and energetic creature, fully bipedal in posture and locomotion. Acheulian tools are found in Africa among the bones of pig, zebra, hippo and elephant; when it came to spreading out of Africa into potentially cooler climes, meat eating very likely became even more important as a convenient way to acquire and transport a much needed source of energy. The relatively large size of the incisors and canines of erectus jaws point to their use in biting and tearing meat just as surely as the stone tools indicate butchery.
To what extent Homo erectus hunted rather than scavenged and established any sort of home bases rather than simply wandered through his world remain contentious questions. Sites in Africa and in Spain do show instances of Acheulian tools in association with animal bones that carry no signs of carnivore gnawing; in warm environments scavenging holds little appeal for modern foraging peoples, not only because of the high risk of confrontation with the jealous killers of the prey and with other scavenging carnivores, but also because the micro-organisms that feed on carrion have equipped themselves with toxins to deter their bigger competitors. It may be that scavenging, of the sort that many anthropologists believe the Neanderthalers to have practised, was a development suited to more northerly and cooler regions as mankind spread out of Africa and the world’s climate took a turn for the colder and more antiseptic.
As the erectus type of humanity began to people the globe, travelling out of warm Africa at the same time as the cooler epoch of the ice ages set in, fire became a crucial component of the technological armoury of evolving mankind. There are indications of the first use of fire in East Africa at a very early date in the career of ergaster/erectus. At Koobi Fora tools of the Developed Oldowan type (on their way to Acheulian) have been found in association with deposits of baked earth to which a date of about 1.6 mya is assigned; the form of the baking, as soil oxidized in a bowl formation, and the evident high temperatures involved indicate that the fires that baked the earth were more intense than those that result from accidental grassland conflagrations and so were probably deliberately tended by human agency. In another East African instance lumps of b
urnt clay were found in association with stone tools and animal bones at a date of about 1.5 mya, the largest lumps – in a reportedly hearth-like arrangement of stones – having been heated to an estimated 400–600 °C, beyond the expected range of natural fires. At Swartkrans in South Africa burnt bones (including those of robust Australopithecines) of about 1 mya have been deemed to have suffered temperatures associated with camp fires rather than wild fires. (The robusts’ bones would represent the victims of ergaster/erectus in this case, while the ergaster fragments from the site, with heavy brow-ridges, would represent the fire-users who perhaps ate them.) Whether any means of starting fires were available to these presumed pioneers of the use of fire is not known – it is likely that materials kept alight from grassland fires as a result of lightning strikes were carefully conserved for continued use. And whether the camps that went with the ‘camp fires’ were worthy of the name of ‘home bases’ is similarly hard to determine. Evidence for home bases, in the shape of patterns of large stones with empty areas where perhaps wind-breaks or protective walls of thorn bush were piled up, has been proposed even for sites of human occupation predating the appearance of ergaster/erectus, but scholarly opinion has been divided about such instances, for natural causes and animal activity could have generated the evidence. Regular use of fire, especially perhaps out of Africa in colder zones where cave shelter became more desirable, increases the likelihood that home bases were a feature of the erectus way of life. The fireside provided not only a source of warmth and a deterrence against foes, along with heat to thaw, cook and smoke food, but also light to prolong some of the activities of life (like toolmaking, for example) beyond the time allotted by the natural cycles of the days and seasons; and above all perhaps it promoted social life after the day’s labours and social grooming in the form of ‘conversation’, as we might a bit prematurely call it. ‘Home’ was also potentially the scene of food sharing, of proto-familial relationships, of care and provision for the young. The long process of maturation seen in human beings today from infancy through adolescence to adulthood was probably not entirely in operation in erectus populations (as it probably was not, either, among Neanderthalers), but the pelvis of the Nariokotome Boy strongly argues that erectus babies were born in a similar state of development to that of our own, even if the age indications of his teeth versus his general skeletal status point to a noticeably more rapid postnatal development than we know today. Erectus firesides may have been centrepieces of home bases in which children matured more slowly, played their educative games and generally went on learning more extensively, both about their social world and the wide world about them, than any non-human animal ever does. It is very interesting to note that, with the arrival of ergaster/erectus, there is for the first time in human evolution no question but that sexual dimorphism was markedly reduced, a situation indicating a relative absence of competition between males for females, which further suggests that more or less monogamous pair-bonding may possibly have been a feature of ergaster/erectus society, with greater likelihood of investment on the part of both parents in the upbringing of their offspring.
With their sophisticated tools (by comparison with what had gone before), their use of fire, their greater reliance on meat eating in competition with rival predators and scavengers in the animal world, the people of the erectus stage of evolution needed not just the intelligence and awareness of their ancestors in the social field, but also a growing technical and environmental application of intelligence to handle the business of toolmaking and tool use, of identifying and going after their food, of outwitting their competitors. From the Australopithecines to Homo ergaster/erectus, the size of the brain doubled to some 900 ml and then, in keeping with the slow progress of toolmaking innovation that we see in the archaeological record, brain enlargement rather stalled; evidently the erectus brain was good enough to facilitate the spread of its carriers over much of the temperate world beyond Africa. The really cold areas that were to be found in the world as the era of the ice ages came on remained beyond the scope of Homo erectus, who probably sallied out of Africa into Europe and Asia via the region of the Levant and its hinterland. The spread to the Far East probably followed the coastal areas adjacent to the Arabian Sea and the Bay of Bengal and then north into China and south to Sumatra and Java. As we saw, if the very early dates for archaeological material and human remains in Java stand the test of time, then it is just possible that a sort of late Homo habilis evolving into early Homo erectus reached the Far East by 1.8 mya, without its carriers’ and their ancestors’ participation in the development of the Acheulian, which is not found in China and Java. Homo erectus was to enjoy a very long career in the East, lasting until perhaps some 300,000 BP, and among his accomplishments in those parts is apparently to be counted the crossing of seas on at least one occasion by means of rafts, for there is an island in the Java Sea with erectus remains which was never connected to the mainland (unlike Java itself) during any fluctuation of sea level during erectus times. Some 19 km of open sea needed to be crossed to reach Flores, apparently in about 800,000 BP!
In China Homo erectus remains have been found in contexts dated back to about 1 mya (and even half as much again according to some determinations), but the best known of the Chinese erectus finds came from the cave site near Beijing (one of the few caves to have lasted from so long ago) that is now called Zhoukoudian. The climatic indicators at the site, taken together with evidence of ancient patterns of the Earth’s magnetic polarity, suggest a date going back to some 450,000 BP for erectus at Zhoukoudian, which puts Pekin Man into one of the interglacial periods of the ice age era, at a time when the climate was about as cool in northern China as it is nowadays. There is evidence of the use of fire on the site (in the form of thin lenses of ash with concentrations of charred bones and seeds) and stone tools in coarse quartz and quartzite are found in some abundance, but they are of the sort that would be called ‘Oldowan’ in Africa, where the Acheulian was a million years old by the time of Zhoukoudian. The remains of about forty erectus individuals have been discovered at Zhoukoudian, including fragments whose damage hints at cannibalism, but, of course, the original finds from before the Second World War vanished in the 1940s and are known today only by the excellent casts made by Franz Weidenreich in the years after their discovery. (Weidenreich believed, it is interesting to recall, that Pekin Man already displayed certain proto-Mongoloid traits – among other things in details of cheeks and teeth – that persuaded him that some broad racial differentiations appeared early in the human story and were maintained through the successive stages of evolution driven by gene flow between population borders over long distances and by convergent evolution under the same pressures of natural selection in different parts of the world.) The Zhoukoudian people were big-faced with heavy jaws, but their brow-ridges were a little smaller than those of other erectus types. At just over 1000 ml, their average brain sizes are large for an erectus population. Their Java contemporaries (later than the fragmentary pieces claimed to date from as far back as 1.8 mya) were more ruggedly made in their skulls and of slightly lower average brain size. In both Java and China the massive build of the skulls with many indications of strong muscle attachments to work the bulky jaws points to a diet dependent on heavy tearing and chewing capacities. No tools are known from the Java sites.
Skullcap from Zhoukoudian.
Skullcap from Java.
All the East Asian erectus skulls are thicker, more brow-ridged and more sloping from brow to skull top than those of their African counterparts, with pronounced keeling along their tops and incidence of occipital torus at the back. Their cheek teeth are larger. Many of them, moreover, are younger than the African examples and the tools associated with them are quite different. If we are justified in making two distinct species out of all these remains, then the East Asian people must retain their long assigned species name erectus and the African (and other) finds must own another one – ergaster, on the precedent
of the name already applied by some anthropologists to the Nariokotome Boy and others. Where erectus and ergaster differ, it is ergaster that foreshadows Homo sapiens rather more than erectus does, and so it is tempting to see a line of descent from the African ergaster populations that leads on to archaic Homo sapiens (with Homo sapiens neanderthalensis and Homo sapiens sapiens) without the erectus populations of the East. The situation in which erectus went on thriving in the East until about 300,000 BP (in Java certainly and perhaps also in China) while archaic Homo sapiens arose and flourished in Africa and Europe is deemed by some anthropologists to mirror the similar situation they believe to have obtained when Neanderthalers enjoyed their heyday in Europe at the same time as fully modern forms of Homo sapiens were evolving elsewhere.
