David W. Cameron

CHAPTER 7 – Human Evolution in the Middle Pleistocene

The earliest non- ergaster/georgicus/erectus hominins in Europe are the specimens from Gran Dolina Cave, Level TD-6, in the Atapuerca Hills of northern Spain, allocated to their own species, Homo antecessor and dating to around 780,000 years ago. It has been argued that the new species evolved from H. ergaster and represents the likely stem species that gave rise to the Neanderthal lineage and to modern humans. Given the fragmentary nature of the specimens from Gran Dolina, however, their specific distinction from the later European and African H. heidelbergensis remains debatable. The supposedly distinctive features of this H. antecessor , including increased cranial capacity, reduced facial prognathism, well-developed canine fossa, and angled inferior cheekbone, are also characteristic of H. heidelbergensis . Primitive features that H. antecessor shares with H. ergaster and H. erectus include the presence of male lower canine and premolar cingula, and asymmetry in the crowns of the lower third premolars. While it is currently not possible to ascertain the phylogenetic significance of H. antecessor , we can see that the pattern of human evolution from their first appearance in Europe is not as straightforward as previously thought, especially if we consider the implied H. erectus migration into Europe, as suggested by the Italian Ceprano H. erectus specimen at around the same time as the Gran Dolina hominins in Spain make their appearance, not to mention the earlier migration into far southeastern Europe of H. ergaster .

Morphometric evolutionary trends in the dental complex ofPongo

This paper examines whether there has been an overall reduction in the likely size ofPongo from the Pleistocene to the present day. It is concluded that the original suggestion byHooijer (1948) that the evolution ofPongo over the last half-million years was characterized by a reduction in dental size, corresponding to a reduction in overall body size, is likely. There were, however, fluctuations in dental size during the Pleistocene. Overall, in the Sundaic region a slight reduction in overall dental size continued from Late Pleistocene to the present day.

CHAPTER 5 – A Systematic Scheme for the Pliocene and Early Pleistocene Hominids

This chapter directly addresses issues of phylogeny and taxonomy by generating a number of phylogenetic analyses of the Miocene and Plio-/ Pleistocene hominids. Overall the chapter examines: (1) what the systematic significance of Sahelanthropus is in relation to the Miocene and Pliocene hominids; (2) how the inclusion of A. anamensis and A. garhi affects the often-commented-upon paraphyletic status of Australopithecus ; (3) what the phylogenetic relationship of Kenyanthropus is to other Pliocene hominids; and (4) how these relationships should be reflected in taxonomy.

CHAPTER 3 – The Later Miocene and Early Pliocene Hominids

The recent significant discovery and description of Sahelanthropus tchadensis from Chad by a joint French and Chadian paleoanthropological team, dating to between 6 and 7 million years ago, has done much to refocus our attention on the divergences of the hominins from other hominids. One of the key differences of the hominins from most other hominids is the development of a primitive form of bipedal locomotion, which would likely postdate the development of increased ability for uptight posture. Around 5–6 million years ago, the common human–chimpanzee ancestor had what we now think is the primitive hominid locomotion pattern, a quadrupedal, knuckle–walking ability. Shortly after the split from the last common ancestor with the chimpanzee, the hominins must have developed a more uptight gait, with some form of primitive bipedal walking. If Sahelanthropus was bipedal, either it was a hominin or, if it represents a common ancestor to the chimpanzee–human lineages, knuckle–walking must have developed independently in both Pan and Gorilla. For reasons to be discussed the latter is considered most unlikely. Associated with the development of these patterns of locomotion and positional behavior would be the development of numerous features of the skull and teeth.

CHAPTER 9 – The Second African Exodus: The Emergence of Modern Humans

The earliest evidence for the emergence of truly modern humans is from Africa, with the discoveries of H. sapiens from Herto in the Middle Awash of Ethiopia. These fossil specimens and stone artifacts have been dated to between 160,000 and 154,000 years ago by precise age determinations based on the argon isotope method. They are truly significant because they predate the classic Neanderthals and lack any of the Neanderthal derived features. Like some previous (and later) hominin populations, there is evidence of postmortem modification to the bones, that is, cut marks. These are best considered to be mortuary practices rather than cannibalism. Indeed, the morphological condition of these specimens is intermediate between the condition observed in the African deme of H. heidelbergensis and modern H. sapiens of today.

Chapter 6 – The First African Exodus: The Emergence of Early Homo in Europe and Asia

The dietary and behavioral shift to an increased focus on meat eating within the earliest representatives of Homo was not a simple matter. It probably required a major change in group dynamics involving cooperation and coordination of individuals, an increased dependence on tool technologies to help in meat acquisition and processing (specimens of H. ergaster are associated with the primitive Oldowan stone tool technology), and certainly a major reconfiguration in hominin gut morphology in order to process associated fat and meat fibers. It is likely that some proto-australopithecine species incorporated meat into their diet, but it was probably not an important component of their diet. Indeed, the major dietary focus of these hominids and the hominin species within Paranthropus is usually associated with a dependence on eating fruit with hard nuts and seeds. The degree to which Australopithecus incorporated meat into its diet is still debated, though the recent isotopic studies suggest that Australopithecus (specimens dating to around 2.5 Ma) consumed large quantities of animal tissues from large grazing animals. The studies conclude that it was how Australopithecus and Homo exploited their food sources, as much as the exact sources they used, that distinguished them: Stone tools, in particular, enabled Homo to disarticulate the skeletons and get at the marrow.

CHAPTER 4 – Our Kind of Hominins

The classic excavations at the Swartkrans cave locality, South Africa, have yielded a large number of hominin specimens, attributed mostly to Praeanthropus robustus . One of these, SK 54, is a young child with two very distinct puncture marks on its cranium. Kenyanthropus platyops originates from geological deposits dating to around 3.5 million years ago. Its discovery so recently, with its unique anatomical features so unexpected, sent shockwaves through the anthropological world and started a flurry of speculation. Indeed, recently it has been suggested that the cranium of the type specimen of Kenyanthropus platyops (specimen KNM-WT 40000) may actually represent a specimen of Praeanthropus , as it suggests that the distortion of the specimen has resulted in a misdiagnosis. While this suggestion deserves serious consideration, some derived features of Kenyanthropus, which are unlikely to be overtly influenced by the type of distortion, suggest otherwise. For example, K. platyops , unlike Pr. afarensis , does not have an occipitomarginal sinus or a compound temporonuchal crest; it has reduced incisor heteromorphy, the upper molars are also significantly reduced in size relative to Praeanthropus , and finally its enamel thickness is reduced. Therefore, Kenyanthropus can be recognized as a distinct taxon.

Chapter 10 – The Emergence of Modern Humans in Asia and Australia

Publisher Summary In the 1930s, an American anthropologist, Joseph Birdsell, traveled around Australia measuring Aboriginal people. He found that in the rainforests of the Atherton Tablelands, in far north Queensland, people are very short and have crisply curled sometimes “woolly” hair. In the southeast, people are comparatively light-skinned and bulkily built, and the men tend to be hairy and to go bald early. In the tropical north (outside the rain forests), people are very dark and of slender built. Instead of simply noting these variations and ascribing them to local adaptations, as we would today, Birdsell was convinced that three distinct races, which came in at different times and, in part, replaced each other, populated Australia. First, he argued, came the short people, who survive today in purest form in the Atherton rainforests; he called them Barrineans, after Lake Barrine, near Atherton. Next came the light-skinned people, whom he called the Murrayians because they survived in the purest form along the River Murray. Finally came the dark, lanky people; he called them Carpentarians, from the Gulf of Carpentaria. This is Birdsells Trihybrid hypothesis.

CHAPTER 8 – “The Grisly Folk”: The Emergence of the Neanderthals

In 1957, the skeleton of an elderly, crippled Neanderthal man was excavated from Shanidar, the cave in northern Iraq that had entombed him. This one cave was eventually to yield the remains of nine Neanderthals, some of them apparently buried—one, it is claimed, with a final gift of flowers placed in the grave. This area was just as unstable geologically in the recent past as it is today, and the roof fall was probably the result of an earthquake or major tremor. The chapter discusses the significance of the Shanidar excavations and their later interpretation.

CHAPTER 2 – Evolution of the Miocene Great Apes

During the Eocene, forest vegetation, increased rainfall, and hotter conditions spread from the equator to the poles. The earths ecology was relatively homogeneous. With the Eocene/Oligocene transition, however, ecological stability started to break down, and the world was thrown into the “big chill.” By 25 million years ago, the position and shape of the continents were beginning to look something like they do today, though North and South America remained separated, the Himalaya and the Tibetan Plateau had yet to develop, and Africa was still an island continent. At the Oligocene/Miocene transition, however, warmer climatic conditions returned. Even so, from the earliest Miocene, the rainforest belt, which had covered most of Africa, had been breaking up into a number of distinct ecological niches. Instead of the homogeneous tropical cover, ever-increasing patches of woodland and grassland could be seen interrupting the vast tracts of rainforest. The ongoing continental collisions had reached their zenith during the Miocene, with the major uplift of the Himalayas, the Tibetan Plateau, and the Ethiopian highlands, as continental plates crashed against each other, twisting and thrusting upward from the external land surface.