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Critical Thinking Questions
- Why is the nearly complete skeleton from Nariokotome so important? What kinds of evidence does it provide?
- Assume that you’re in the laboratory and have the Nariokotome skeleton, as well as a skeleton of a modern human. First, given a choice, what age and sex would you choose for the comparative human skeleton, and why? Second, what similarities and differences do the two skeletons show?
- What fundamental questions of interpretation do the fossil hominins from Dmanisi raise? Does this evidence completely overturn the earlier views (hypotheses) concerning H. erectus dispersal from Africa? Explain why or why not.
- What are the main differences between Acheulian and Oldowan tool industries? What do these differences tell us about the evolution of human culture? Why did Lower Paleolithic culture change so slowly?
- Describe the geographical distribution of the earliest Homo erectus finds and compare the dating for these discoveries in Africa, Asia, and Europe.
- Describe the most important anatomical features found in Homo erectus and compare them with early Homo and Homo sapiens.
- Discuss the biocultural evidence (both anatomical and archaeological) that might explain how early hominins dispersed from Africa to other regions of the Old World.
A New Kind of Hominin
The discovery of fossils now referred to as Homo erectus began in the nineteenth century. Later in this chapter, we’ll discuss the historical background of these earliest discoveries in Java and the somewhat later discoveries in China. For these fossils, as well as several from Europe and North Africa, a variety of taxonomic names were suggested.
It’s important to realize that such taxonomic splitting was quite common in the early years of paleoanthropology. More systematic biological thinking came to the fore only after World War II and with the incorporation of the Modern Synthesis into paleontology.
Most of the fossils that were given these varied names are now placed in the species Homo erectus—or at least they’ve all been lumped into one genus (Homo). In the last few decades, discoveries of firmly dated East African fossils have established the clear presence of Homo erectus by 1.7 mya. Some researchers see several anatomical differences between these African representatives of an erectus-like hominin and their Asian cousins (hominins that almost everybody refers to as Homo erectus). Thus, they place the African fossils into a separate species, one they call Homo ergaster (Andrews, 1984; Wood, 1991).
While there are some anatomical differences between the African specimens and those from Asia, they are all clearly closely related and quite possibly represent geographical varieties of a single species. We’ll thus refer to them collectively as Homo erectus.
Most analyses show that H. erectus represents a type of hominin that is quite different from its more ancient African predecessors. Increase in body size and robustness, changes in limb proportions, and greater encephalization all indicate that these hominins were more like modern humans in their adaptive pattern than their African ancestors were. It’s clear from most of the fossils usually classified as Homo erectus that a major adaptive shift had taken place— one setting hominin evolution in a distinctly more human direction.
We mentioned that there is considerable variation among different regional populations defined as Homo erectus. New discoveries show even more dramatic variation, suggesting that some of these hominins may not fit closely with this general adaptive pattern (more on this presently). For the moment, however, let’s review what most of these fossils look like.
Body Size
Anthropologists estimate that some H. erectus adults weighed well over 100 pounds, with an average adult height of about 5 feet 6 inches (McHenry, 1992; Ruff and Walker, 1993; Walker and Leakey, 1993). Another point to keep in mind is that H. erectus was quite sexually dimorphic—at least as indicated by the East African specimens. Some adult males may have weighed considerably more than 100 pounds.
Increased height and weight in H. erectus are also associated with a dramatic increase in robusticity. In fact, a heavily built body was to dominate hominin evolution not just during H. erectus times, but through the long transitional era of premodern forms as well. Only with the appearance of anatomically modern H. sapiens did a more gracile skeletal structure emerge, one that still characterizes most modern populations.
Brain Size
While Homo erectus differs in several respects from both early Homo and Homo sapiens, the most obvious feature is cranial size—which is closely related to brain size. Early Homo had cranial capacities ranging from as small as 500 cm3 to as large as 800 cm3 . H. erectus, on the other hand, shows considerable brain enlargement, with a cranial capacity of about 700* to 1,250 cm3 (and a mean of approximately 900 cm3 ). As we’ve discussed, brain size is closely linked to overall body size. So it’s important to note that along with an increase in brain size, H. erectus was also considerably larger than earlier members of the genus Homo. In fact, when we compare H. erectus with the larger bodied early Homo individuals, relative brain size is about the same (Walker, 1991). What’s more, when we compare the relative brain size of H. erectus with that of H. sapiens, we see that H. erectus was considerably less encephalized than later members of the genus Homo.
Cranial Shape
Homo erectus crania display a highly distinctive shape, partly because of increased brain size, but probably more correlated with increased body size. The ramifications of this heavily built cranium are reflected in thick cranial bone (in most specimens), large browridges (supraorbital tori) above the eyes, and a projecting nuchal torus at the back of the skull .
The braincase is long and low, receding from the large browridges with little forehead development. Also, the cranium is wider at the base compared with earlier and later species of genus Homo. The maximum cranial breadth is below the ear opening, giving the cranium a pentagonal shape (when viewed from behind). In contrast, the skulls of early Homo and H. sapiens have more vertical sides, and the maximum width is above the ear openings.
Most specimens also have a sagittal keel running along the midline of the skull. Very different from a sagittal crest, the keel is a small ridge that runs front to back along the sagittal suture. The sagittal keel, browridges, and nuchal torus don’t seem to have served an obvious function, but most likely reflect bone buttressing in a very robust skull.
The First Homo erectus: Homo erectus from Africa.
Where did Homo erectus first appear? The answer seems fairly simple: Most likely, this species initially evolved in Africa. Two important pieces of evidence help confirm this hypothesis. First, all of the earlier hominins prior to the appearance of H. erectus come from Africa. What’s more, by 1.7 mya, there are well-dated fossils of this species at East Turkana, in Kenya, and not long after that at other sites in East Africa.
But there’s a small wrinkle in this neat view. We now know that at about 1.8 mya, similar populations were already living far away in southeastern Europe, and by 1.6 mya, in Indonesia. So, adding these pieces to our puzzle, it seems likely that H. erectus first arose in East Africa and then very quickly migrated to other continents; nevertheless, as we’ll see shortly, the dating of sites from Africa and elsewhere does not yet clearly confirm this hypothesis. Let’s first review the African H. erectus specimens dated at 1.7–1 mya, and then we’ll discuss those populations that emigrated to Europe and Asia.
The earliest of the East African H. erectus fossils come from East Turkana, from the same area where earlier australopith and early Homo fossils have been found. Indeed, it seems likely that in East Africa around 2–1.8 mya, some form of early Homo evolved into H. erectus. The most significant H. erectus fossil from East Turkana is a nearly complete skull (ER 3733;). Recently redated at 1.7 mya, this fossil is about the same age (or even a little younger) as some other fossils outside of Africa; nevertheless, for now, it certainly is the oldest known member of this species from Africa (Lepre and Kent, 2010). The cranial capacity is estimated at 848 cm3 , in the lower range for H. erectus (700 to 1,250 cm3 ), which isn’t surprising considering its early date. A second very significant new find from East Turkana is notable because it has the smallest cranium of any H. erectus specimen from anywhere in Africa. Dated to around 1.5 mya, the skull has a cranial capacity of only 691 cm3 .
As we’ll see shortly, there are a couple of crania from southeastern Europe that are even smaller. The small skull from East Turkana also shows more gracile features (such as smaller browridges) than do other East African H. erectus individuals, but it preserves the overall H. erectus vault shape.
It’s been proposed that perhaps this new find is a female and that the variation indicates a very high degree of sexual dimorphism in this species (Spoor et al., 2007).
Another remarkable discovery was made in 1984 by Kamoya Kimeu, a member of Richard Leakey’s team known widely as an outstanding fossil hunter. Kimeu discovered a small piece of skull on the west side of Lake Turkana at a site known as Nariokotome. Excavations produced the most complete H. erectus skeleton ever found . Known properly as WT 15000, the almost complete skeleton includes facial bones, a pelvis, and most of the limb bones, ribs, and vertebrae and is chronometrically dated to about 1.6 mya. Such well-preserved postcranial elements make for a very unusual and highly useful discovery, because these elements are scarce at other H. erectus sites. The skeleton is that of an adolescent about 8 years of age with an estimated height of about 5 feet 3 inches (Walker and Leakey, 1993; Dean and Smith, 2009). Some estimates have hypothesized that the adult height of this individual could have been about 6 feet. However, this conclusion is contentious, since it assumes that the growth pattern of this species was similar to that of modern humans. More recent and more detailed analyses find the developmental pattern in this and other H. erectus individuals to actually be more like that of an ape (Dean and Smith, 2009).
Nevertheless, the postcranial bones look very similar, though not quite identical, to those of modern humans. The cranial capacity of WT 15000 is estimated at 880 cm3 ; brain growth was nearly complete, and the adult cranial capacity would have been approximately 909 cm3 (Begun and Walker, 1993). Other important H. erectus finds have come from Olduvai Gorge, in Tanzania, and they include a very robust skull discovered there by Louis Leakey back in 1960. The skull is dated at 1.4 mya and has a well-preserved cranial vault with just a small part of the upper face. Estimated at 1,067 cm3 , the cranial capacity is the largest of all the African H. erectus specimens. The browridge is huge, the largest known for any hominin, but the walls of the braincase are thin. This latter characteristic is seen in most East African H. erectus specimens; in this respect, they differ from Asian H. erectus, in which cranial bones are thick.
Three other sites from Ethiopia have yielded H. erectus fossils, the most noteworthy coming from the Gona area and the Daka locale, both in the Awash River region of eastern Africa (Gilbert and Asfaw, 2008). As you’ve seen, numerous remains of earlier hominins have come from this area. A recently discovered nearly complete female H. erectus pelvis comes from the Gona area in Ethiopia and is dated to approximately 1.3 mya (Simpson et al., 2008). This find is particularly interesting because H. erectus postcranial remains are so rare, and this is the first H. erectus female pelvis yet found. This fossil also reveals some tantalizing glimpses of likely H. erectus development. The pelvis has a very wide birth canal, indicating that quite large-brained infants could have developed in utero (before birth); in fact, it’s possible that a newborn H. erectus could have had a brain that was almost as large as what’s typical for modern human babies.
This evidence has led Scott Simpson and his colleagues to suggest that H. erectus prenatal brain growth was more like that of later humans and quite different from that found in apes or in australopiths such as Lucy. However, it’s also evident that H. erectus brain growth after birth was more rapid than in modern humans. This new pelvis is very different from that of the Nariokotome pelvis and may reflect considerable sexual dimorphism in skeletal anatomy linked to reproduction as well as body size. Another recent discovery from the Middle Awash of Ethiopia of a mostly complete cranium from Daka is also important because this individual (dated at approximately 1 mya) is more like Asian H. erectus than are most of the earlier East African remains we’ve discussed (Asfaw et al., 2002). Consequently, the suggestion by several researchers that East African fossils are a different species from (Asian) H. erectus isn’t supported by the morphology of the Daka cranium.
Who Were the Earliest African Emigrants?
The fossils from East Africa imply that a new adaptive pattern in human evolution appeared in Africa not long after 2 mya. Until recently, H. erectus sites outside Africa all have shown dates later than the earliest finds of this species in Africa, leading paleoanthropologists to assume that the hominins who migrated to Asia and Europe descended from earlier African ancestors. Also, these travelers look like Homo, with longer limbs and bigger brains. Since H. erectus originated in East Africa, they were close to land links to Eurasia (through the Middle East) and thus were probably the first to leave the continent. We can’t be sure why these hominins left— were they following animal migrations, or was it simply population growth and expansion?
What we do know is that we’re seeing a greater range of physical variation in the specimens outside of Africa and that the emigration out of Africa happened earlier than we had previously thought. Current evidence shows H. erectus in East Africa about 1.7 mya, while similar hominins were living in the Caucasus region of southeastern Europe even a little earlier, about 1.8 mya.* Eventually, hominins made it all the way to the island of Java, Indonesia, by 1.6 mya! It took H. erectus less than 200,000 years to travel from East Africa to Southeast Asia. Let’s look at this fascinating evidence. The site of Dmanisi, in the Republic of Georgia, has produced several individuals and an associated assemblage of Oldowan stone tools, giving us a unique look at these first possible travelers. The age of this crucial site has recently been radiometrically redated to 1.81 mya (Garcia et al., 2010). The Dmanisi crania are similar to those of H. erectus (for example, the long, low braincase, wide base, and sagittal keel; see especially.
However, other characteristics of the Dmanisi individuals are different from what is seen in other hominins outside Africa. In particular, the most complete fossil has a less robust and thinner browridge, a projecting lower face, and a relatively large upper canine. At least when viewed from the front, this skull is more reminiscent of the smaller early Homo specimens from East Africa than it is of H. erectus Also, specimen 2700’s cranial capacity is very small— estimated at only 600 cm3 , well within the range of early Homo. In fact, all four Dmanisi crania so far described have relatively small cranial capacities— the other three estimated at 630 cm3 , 650 cm3 , and 780 cm3 . Probably the most remarkable find from Dmanisi is the most recently discovered skull. This nearly complete cranium is of an older adult male; and surprisingly for such an ancient find, he died with only one tooth remaining in his jaws (Lordkipanidze et al., 2006). Because his jawbones show advanced bone loss (which occurs after tooth loss), it seems that he lived for several years without being able to efficiently chew his food . As a result, it probably would have been difficult for him to maintain an adequate diet. The newest evidence from Dmanisi includes several postcranial bones coming from at least four individuals (Lordkipanidze et al., 2007). This new evidence is especially important because it allows us to make comparisons with what is known of H. erectus from other areas. The Dmanisi fossils have an unusual combination of traits. They weren’t especially tall, having an estimated height ranging from about 4 feet 9 inches to 5 feet 5 inches.
Certainly, based on this evidence, they seem smaller than the full H. erectus specimens from East Africa or Asia. Yet, although short in stature, they still show body proportions (such as leg length) like that of H. erectus (and H. sapiens) and quite different from that seen in earlier hominins. Based on the evidence from Dmanisi, we can assume that Homo erectus was the first hominin to leave Africa. While the Dmanisi specimens are small in both stature and cranial capacity, they have specific characteristics that identify them as H. erectus (for example, a sagittal keel and low braincase). So, for now, the Dmanisi hominins are thought to be H. erectus, although an early and quite different variety from that found almost anywhere else.
While new and thus tentative, the recent evidence raises important and exciting possibilities. The Dmanisi findings suggest that the first hominins to leave Africa were quite possibly a smallbodied very early form of H. erectus, possessing smaller brains than later H. erec tus and carrying with them a typical African Oldowan stone tool culture. Also, the Dmanisi hominins had none of the adaptations hypothesized to be essential to hominin migration— that is, being tall and having relatively large brains. Another explanation may be that there were two migrations out of Africa at this time: one consisting of the small-brained, short-statured Dmanisi hominins and an almost immediate second migration that founded the wellrecognized H. erectus populations of Java and China. All this evidence is so new, however, that it’s too soon even to predict what further revisions may be required.
Homo erectus from Indonesia
After the publication of On the Origin of Species, debates about evolution were prevalent throughout Europe. While many theorists simply stayed home and debated the merits of natural selection and the likely course of human evolution, one young Dutch anatomist decided to go find evidence of it. Eugene Dubois (1858–1940) enlisted in the Dutch East Indian Army and was shipped to the island of Sumatra, Indonesia, to look for what he called “the missing link.” In October 1891, after moving his search to the neighboring island of Java, Dubois’ field crew unearthed a skullcap along the Solo River near the town of Trinil—a fossil that was to become internationally famous as the first recognized human ancestor . The following year, a human femur was recovered about 15 yards upstream in what Dubois claimed was the same level as the skullcap, and he assumed that the skullcap (with a cranial capacity of slightly over 900 cm3 ) and the femur belonged to the same individual.
Counting the initial find plus later discoveries, all the H. erectus fossil remains have so far come from six sites located in eastern Java. The dating of these fossils has been hampered by the complex nature of Javanese geology, but it’s generally accepted that most of the fossils belong to the Early to Middle Pleistocene and are between 1.6 and 1 million years old. What’s more, there was also a very late surviving H. erectus group in Java that apparently managed to survive there until after 100,000 years ago (ya).
These later fossils, from the Ngandong site, are by far the most recent group of H. erectus fossils from Java or anywhere else. At Ngandong, an excavation along an ancient river terrace produced 11 mostly complete hominin skulls. Some estimates put the age of the Ngandong H. erectus fossils at only 50,000– 25,000 ya. These dates have been controversial, but further evidence is establishing a late survival of H. erectus in Java (approximately 70,000–40,000 ya; Yokoyama et al., 2008). So these individuals would be contemporary with H. sapiens—which, by this time, had expanded widely throughout the Old World and into Australia around 60,000– 40,000 ya. Recent work on the old excavation site of Ngandong (first excavated in the early 1930s) has led to a rediscovery of the fossil bed where the H. erectus fossils had been found (Ciochon et al., 2009). New dating techniques and fossil identification will be undertaken to better understand site formation and taphonomy. As we’ll see in Chapter 12, even later—and very unusual—hominins have been found not far away, apparently evolving while isolated on another Indonesian island.
Homo erectus from China
The story of the first discoveries of Chinese H. erectus is another saga filled with excitement, hard work, luck, and misfortune. Europeans had known for a long time that “dragon bones,” used by the Chinese as medicine and aphrodisiacs, were actually ancient mammal bones. Scientists eventually located one of the sources of these bones near Beijing at a site called Zhoukoudian.
Serious excavations were begun there in the 1920s, and in 1929, a fossil skull was discovered. The skull turned out to be a juvenile’s, and although it was thick, low, and relatively small, there was no doubt that it belonged to an early hominin.
Zhoukoudian Homo erectus
The fossil remains of H. erectus discovered in the 1920s and 1930s, as well as some more recent excavations at Zhoukoudian , are by far the largest collection of H. erectus material found anywhere. This excellent sample includes 14 skullcaps , other cranial pieces, and more than 100 isolated teeth, but only a scattering of postcranial elements (Jia and Huang, 1990).
Various interpretations to account for this unusual pattern of preservation have been offered, ranging from ritualistic treatment or cannibalism to the more mundane suggestion that the H. erectus remains are simply the leftovers of the meals of giant hyenas. The hominin remains were studied, and casts were made immediately, which proved invaluable, since the original specimens were lost during the American evacuation of China at the start of World War II.
The hominin remains belong to upward of 40 adults and children and together provide a good overall picture of Chinese H. erectus. Like the materials from Java, they have typical H. erectus features, including a large browridge and nuchal torus. Also, the skull has thick bones, a sagittal keel, and a protruding face and is broadest near the bottom.
This site, along with others in China, has been difficult to date accurately. Although Zhoukoudian was previously dated to about 500,000 ya, a new radiometric dating technique that measures isotopes of aluminum and beryllium shows that Zhoukoudian is actually considerably older, with a dating estimate of approximately 780,000 ya (Ciochon and Bettis, 2009; Shen et al., 2009).
Cultural Remains from Zhoukoudian
More than 100,000 artifacts have been recovered from this vast site, which was occupied intermittently for many thousands of years. The earliest tools were generally crude and shapeless, but they became more refined over time.
Common tools at the site are choppers and chopping tools, but retouched flakes were fashioned into scrapers, points, burins, and awls . The way of life at Zhoukoudian has traditionally been described as that of hunter-gatherers who killed deer, horses, and other animals. Fragments of charred ostrich eggshells and abundant deposits of hackberry seeds unearthed in the cave suggest that these hominins supplemented their diet of meat by gathering herbs, wild fruits, tubers, and eggs. Layers of what has long been thought to be ash in the cave (over 18 feet deep at one point) have been interpreted as indicating the use of fire by H. erectus. More recently, several researchers have challenged this picture of Zhoukoudian life. Lewis Binford and colleagues (Binford and Ho, 1985; Binford and Stone, 1986a, 1986b) reject the description of H. erectus as hunters and argue that the evidence clearly points more accurately to scavenging. Using advanced archaeological analyses, Noel Boaz and colleagues have even questioned whether the H. erectus remains at Zhoukoudian represent evidence of hominin habitation of the cave. By comparing the types of bones, as well as the damage to the bones, with that seen in contemporary carnivore dens, Boaz and Ciochon (2001) have suggested that much of the material in the cave likely accumulated through the activities of extinct giant hyenas. In fact, they hypothesize that most of the H. erectus remains, too, are the leftovers of hyena meals. Boaz and his colleagues do recognize that the tools in the cave, and possibly the cut marks on some of the animal bones, provide evidence of hominin activities at Zhoukoudian.
Probably the most intriguing archaeological aspect of the presumed hominin behavior at Zhoukoudian has been the long-held assumption that H. erectus deliberately used fire inside the cave. Controlling fire was one of the major cultural breakthroughs of all prehistory. By providing warmth, a means of cooking, light to further modify tools, and protection, controlled fire would have been a giant technological innovation.
While some potential early African sites have yielded evidence that to some have suggested hominin control of fire, it’s long been assumed that the first definite evidence of hominin fire use comes from Zhoukoudian. Now even this assumption has been challenged. In the course of further excavations at Zhoukoudian during the 1990s, researchers carefully collected and analyzed soil samples for distinctive chemical signatures that would show whether fire had been present in the cave (Weiner et al., 1998). They determined that burnt bone was only rarely found in association with tools. And in most cases, the burning appeared to have taken place after fossilization—that is, the bones weren’t cooked. In fact, it turns out that the “ash” layers aren’t actually ash, but naturally accumulated organic sediment. This last conclusion was derived from chemical testing that showed absolutely no sign of wood having been burnt inside the cave. Finally, the “hearths” that have figured so prominently in archaeological reconstructions of presumed fire control at this site are apparently not hearths at all. They are simply round depressions formed in the past by water.
Another provisional interpretation of the cave’s geology suggests that the cave wasn’t open to the outside like a habitation site, but was accessed only through a vertical shaft. This theory has led archaeologist Alison Brooks to remark, “It wouldn’t have been a shelter, it would have been a trap” (quoted in Wuethrich, 1998). These serious doubts about control of fire, coupled with the suggestive evidence of bone accumulation by carnivores, have led anthropologists Boaz and Ciochon to conclude that “Zhoukoudian cave was neither hearth nor home” (Boaz and Ciochon, 2001).
Other Chinese Sites
More work has been done at Zhoukoudian than at any other Chinese site. Even so, there are other paleoanthropological sites worth mentioning. Three of the more important regions outside of Zhoukoudian are Lantian County (including two sites, often simply referred to as Lantian), Yunxian County, and several discoveries in Hexian County (usually referred to as the Hexian finds).
Dated to 1.15 mya, Lantian is older than Zhoukoudian (Zhu et al., 2003). From the Lantian sites, the cranial remains of two adult H. erectus females have been found in association with firetreated pebbles and flakes as well as ash (Woo, 1966; ). One of the specimens, an almost complete mandible containing several teeth, is quite similar to those from Zhoukoudian.
Two badly distorted crania were discovered in Yunxian County, Hubei Province, in 1989 and 1990 (Li and Etler, 1992). A combination of ESR and paleomagnetism dating methods gives us an average dating estimate of 800,000–580,000 ya. If the dates are correct, this would place Yunxian at a similar age to Zhoukoudian in the Chinese sequence. Due to extensive distortion of the crania from ground pressure, it was very difficult to compare these crania with other H. erectus fossils; recently, however, French paleoanthropologist Amélie Vialet has restored the crania using sophisticated imaging techniques (Vialet et al., 2005). And from a recent analysis of the fauna and paleoenvironment at Yunxian, the H. erectus inhabitants are thought to have had limited hunting capabilities, since they appear to have been restricted to the most vulnerable prey, namely, the young and old animals.
In 1980 and 1981, the remains of several individuals, all bearing some resemblance to similar fossils from Zhoukoudian, were recovered from Hexian County, in southern China (Wu and Poirier, 1995; A close relationship has been postulated between the H. erectus specimens from the Hexian finds and those from Zhoukoudian (Wu and Dong, 1985). Dating of the Hexian remains is sequence. Due to extensive distortion of the crania from ground pressure, it was very difficult to compare these crania with other H. erectus fossils; recently, however, French paleoanthropologist Amélie Vialet has restored the crania using sophisticated imaging techniques (Vialet et al., 2005). And from a recent analysis of the fauna and paleoenvironment at Yunxian, the H. erectus inhabitants are thought to have had limited hunting capabilities, since they appear to have been restricted to the most vulnerable prey, namely, the young and old animals.
In 1980 and 1981, the remains of several individuals, all bearing some resemblance to similar fossils from Zhoukoudian, were recovered from Hexian County, in southern China (Wu and Poirier, 1995; ). A close relationship has been postulated between the H. erectus specimens from the Hexian finds and those from Zhoukoudian (Wu and Dong, 1985). Dating of the Hexian remains is unclear, but they appear to be later than Zhoukoudian, perhaps by several hundred thousand years. The Asian crania from Java and China share many similar features, which could be explained by H. erectus migration from Java to China perhaps around 1 mya. Asia has a much longer H. erectus habitation than Africa (1.8 mya–40,000 or 70,000 ya versus 1.7–1 mya), and it’s important to understand the variation seen in this geographically dispersed species
Later Homo erectus from Europe
We’ve talked about H. erectus in Africa, the Caucasus region, and Asia, but there are European specimens as well, found in Spain and Italy. While not as old as the Dmanisi material, fossils from the Atapuerca region in northern Spain are significantly extending the antiquity of hominins in western Europe. There are several caves in the Atapuerca region, two of which (Sima del Elefante and Gran Dolina) have yielded hominin fossils contemporaneous with H. erectus. The earliest find from Atapuerca (from Sima del Elefante) has been recently discovered and dates to 1.2 mya, making it clearly the oldest hominin yet found in western Europe (Carbonell et al., 2008). So far, just one specimen has been found here, a partial jaw with a few teeth. Very provisional analysis suggests that it most closely resembles the Dmanisi fossils. There are also tools and animal bones from the site. As at the Dmanisi site, the implements are simple flake tools similar to that of the Oldowan. Some of the animal bones also bear the scars of hominin activity, with cut marks indicating butchering. Gran Dolina is a later site, and based on specialized techniques discussed in Chapter 8, it’s dated to approximately 850,000–780,000 ya (Parés and PérezGonzález, 1995; Falguères et al., 1999). Because all the remains so far identified from both these caves at Atapuerca are fragmentary, assigning these fossils to particular species poses something of a problem. Spanish paleoanthropologists who have studied the Atapuerca fossils have decided to place these hominins into another (separate) species, one they call Homo antecessor (Bermúdez de Castro et al., 1997; Arsuaga et al., 1999). However, it remains to be seen whether this newly proposed species will prove to be distinct from other species of Homo.
Finally, the southern European discovery of a well-preserved cranium from the Ceprano site in central Italy may be the best evidence yet of H. erectus in Europe (Ascenzi et al., 1996). Provisional dating of a partial cranium from this important site suggested a date between 900,000 and 800,000 ya, but more recent paleomagnetic studies have indicated a date of 450,000 ya (Muttoni et al., 2009). Philip Rightmire (1998) has concluded that cranial morphology places this specimen quite close to H. erectus. Italian researchers have proposed a different interpretation that classifies the Ceprano hominin as a species separate from H. erectus. For the moment, the exact relationship of the Ceprano find to H. erectus remains to be fully determined.
After about 400,000 ya, the European fossil hominin record becomes increasingly abundant. More fossils mean more variation, so it’s not surprising that interpretations regarding the proper taxonomic assessment of many of these remains have been debated, in some cases for decades. In recent years, several of these somewhat later “premodern” specimens have been regarded either as early representatives of H. sapiens or as a separate species, one immediately preceding H. sapiens. These enigmatic premodern humans.
Archaeology of Early Hominin Dispersal
The first hominins to leave Africa were tool-assisted scavenger-gatherers who carried with them the basic concepts and technological capabilities of the Oldowan tool industry (e.g., see Mgeladze et al., 2011). As such, they differed greatly from modern humans. They began their extraordinary journey without the benefit of language, the controlled use of fire, or projectile weapons and other killing tools. Nevertheless, their Lower Paleolithic ancestors’ biocultural flexibility to adapt to significant environmental changes (Potts and Teague, 2010) demonstrates that they were equally capable of successfully invading new habitats across the Old World, from the Atlantic to the Pacific.
Evidence of butchering is widespread in early H. erectus sites, and in the past, such evidence was cited in arguments for consistent hunting. Researchers formerly interpreted any association of bones and tools as evidence of hunting, but many studies now suggest that cut marks on bones from this period often overlay carnivore tooth marks. This means that hominins were gaining access to the carcasses after the carnivores and were therefore scavenging the meat, not hunting the animals. Wild plants, tubers, and fruits were also important foods, but these hominins, who were not fire using, had limited ability to deal with common plant toxins that cooking inactivates.
Just as with the fossil evidence, the stone tools and other artifacts found in the earliest sites are not the same everywhere. The stone tool assemblages of early sites such as Dmanisi in Georgia and Atapuerca in Spain resemble those of Oldowan sites in East Africa, which implies not only a similar grasp of technology but also the technological requirements for its use. By contrast, the assemblages of early East Asian sites in the Nihewan Basin in northern China exhibit patterned differences (for example, smaller artifacts and more artifacts that show evidence of pounding) that may reflect technological requirements and tool kits unlike African Oldowan assemblages (Braun et al., 2010; Potts and Teague, 2010). Equally interesting is the absence of unequivocal Oldowan archaeological evidence in South Asia, where Acheulian sites are known from most of the subcontinent after about 1.5–1.2 mya (Gaillard et al., 2010; Pappu et al., 2011). The problem, of course, is how to explain these important differences. Did stone tool industries other than Oldowan leave Africa with the earliest emigrants? Do differences in
these industries mainly reflect noncultural factors, such as local raw material availability or geomorphological conditions that inhibited the preservation of contemporaneous sediments (Chauhan 2010)? Or did new industries develop as early hominins adapted to new habitats and resources across the Old World? We have the questions, but finding good answers requires more research.
By 1.7–1.6 mya, a new stone tool industry called Acheulian is found in Africa and, soon after, at sites in the Near East, the Indian subcontinent, and parts of East Asia (Semaw et al., 2009). The Acheulian tool kit was both more diverse and more complex than the Oldowan. It represented several new concepts about making stone tools. First, Acheulian toolmakers invented the idea of a bifacial stone tool—one that has been worked to create two opposing faces. A notable example of an Acheulian bifacial tool is the hand axe , thousands of which have been found at Lower Paleolithic sites from Africa to Europe and eastward to India. Second, Acheulian toolmakers developed a new way to knock flakes from stone cores, which gave more predictable results than the “hard hammer” percussion method used by their Oldowan predecessors. “Soft hammer” percussion employs a hammer made of a somewhat flexible material, such as wood, bone, or antler. When struck against a core, the soft hammer absorbs some of the striking force, giving an experienced stone toolmaker greater control over the length, width, and thickness of the resulting flakes . While this may sound like a small change, it was an era during which such small technological changes could make big differences in how stone tools were made and how they looked when finished.
Finally, some kinds of Acheulian tools tend to reflect shared notions of form, or what they should look like. In other words, not only did Acheulian toolmakers create new stone tools and ways to make them; they were also capable of developing and communicating to each other ideas of form and design. For example, pretty much everything was a “Swiss Army knife” to an Oldowan toolmaker; but when an Acheulian toolmaker sat down to make, say, a hand axe, he or she clearly expected to end up with a stone tool that was bifacially worked, often about 6 to 8 inches long, and possessing a pear or teardrop shape with a point at one end and a rounded base at the other . Conceptualizing tools in this way was something new.
The most distinctive Acheulian artifacts are hand axes, which we just described, and cleavers, which are much like hand axes except that they end in a broad straight edge rather than a point. While we still don’t have a clear idea what cleavers were used for, hand axes show wear patterns and other evidence of having been used for many different kinds of tasks, especially cutting and chopping.
The Acheulian tool kit was not just hand axes and cleavers. It also included many kinds of flake tools , which were used for cutting, abrading, scraping, piercing, and other tasks, as well as hammer stones, cores, and other artifacts, many of which would also have been familiar to an Oldowan toolmaker.
Seeing the Big Picture: Interpretations of Homo erectus
Several aspects of the geographical, physical, and behavioral patterns shown by Homo erectus seem clear. But new discoveries and more in-depth analyses are helping us to reevaluate our prior ideas. The fascinating fossil hominins discovered at Dmanisi are perhaps the most challenging piece of this puzzle. Past theories suggest that H. erectus was able to emigrate from Africa owing to more advanced tools and a more modern anatomy (longer legs, larger brains) compared to earlier African predecessors. Yet, the Dmanisi cranial remains show that these very early Europeans still had small brains; and H. erectus in Dmanisi, Java, and Spain was still using Oldowan-style tools.
So it seems that some key parts of earlier hypotheses are not fully accurate. At least some of the earliest emigrants from Africa didn’t yet show the entire suite of H. erectus physical and behavioral traits. How different the Dmanisi hominins are from the full H. erectus pattern remains to be seen, and the discovery of more complete postcranial remains will be most illuminating.
Going a step further, the four crania from Dmanisi are extremely variable; one of them, in fact, does look more like H. erectus. It would be tempting to conclude that more than one type of hominin is represented here, but they’re all found in the same geological context.
The archaeologists who excavated the site conclude that all the fossils are closely associated with each other. The simplest hypothesis is that they’re all members of the same species. This degree of apparent intraspecific variation is biologically noteworthy, and it’s influencing how paleoanthropologists interpret all of these fossil samples.
This growing awareness of the broad intraspecific variation among some hominins brings us to our second consideration: Is Homo ergaster in Africa a separate species from Homo erectus, as strictly defined in Asia? While this interpretation was popular in the last decade, it’s now losing support. The finds from Dmanisi raise fundamental issues of interpretation. Among these four crania from one locality , we see more variation than between the African and Asian forms, which many researchers have interpreted as different species. Also, the new discovery from Daka (Ethiopia) of a young African specimen with Asian traits further weakens the separate-species interpretation of H. ergaster.
The separate-species status of the early European fossils from Spain (Sima del Elefante and Gran Dolina) is also not yet clearly established. We still don’t have much good fossil evidence from these two sites; but dates going back to 1.2 mya for the earlier site are well confirmed. Recall also that no other western European hominin fossils are known until at least 500,000 years later, and it remains to be seen if any of these European hominins dating prior to 500,000 ya are ancestors of any later hominin species. Nevertheless, it’s quite apparent that later in the Pleistocene, well-established hominin populations were widely dispersed in both Africa and Europe. These later premodern humans are the topic of the next chapter.
When looking back at the evolution of H. erectus, we realize how significant this early human was. H.erectus had greater limb length and thus more efficient bipedalism; was the first species with a cranial capacity approaching the range of H. sapiens; became a more efficient scavenger and exploited a wider range of nutrients, including meat; and ranged across the Old World, from Spain to Indonesia. In short, it
was H. erectus that transformed hominin evolution to human evolution. As Richard Foley states, “The appearance and expansion of H. erectus represented a major change in adaptive strategy that nfluenced the subsequent process and pattern of human evolution” (1991, p. 425).