The archeology of modern human origins

Two competing hypotheses have long dominated specialist thinking on modern human origins. The first posits that modern people emerged in a limited area and spread from there to replace archaic people elsewhere. Proponents of this view currently favor Africa as the modern human birthplace.^1–5 The second suggests that the evolution of modern humans was not geographically restricted, but invlved substantial continuity between archaic and modern populations in all major regions of the occupied world.^6–7 Based solely on the fossil record, both hypotheses are equally defensible, but the spread-and-replationships scenario is far more strongly supported by burgeoning data on the genetic relationships and diversity of living humans.^8–16 These data impy that there was a common ancestor for all living humans in Africa between 280,000 and 140,000 year ago, and that Neanderthals and other archaic humans who inhabited Eurasia during the same interval contributed few, if any, genes to living peiple. I argue here that the spread-and-replacement hypothesis is also more compatible with a third line of evidence: the spread-and-replacement hypothesis is also more compatible with a third line of evidence: the archeological record for human behavioral evolution.     

Morphometric cranial identity of prehistoric Malawians in the light of sub-Saharan African diversity

Little has been described of the Holocene populations of South‐Central Africa, despite the region demonstrating major subsistence shifts relating to dispersals of agriculturalists at least 2,000 years ago. Seven sites with associated human skeletal remains were selected. Hora, Chencherere, Fingura, and Mtuzi represent the Middle Holocene (2,000–5,000 years ago), and Phwadze, Mtemankhokwe, and Nkudzi Bay represent the Late Holocene and the arrival of agriculturalists between 500–2,000 years ago. Focusing on the identity of Hora and Chencherere specimens, two questions were addressed: are the various Holocene Malawians similar to each other, or do they suggest morphological change over time? What modern populations are closest to the prehistoric specimens? The archaeological sample was compared to modern sub‐Saharan Africans from four regions, plus a historic Khoi‐San foraging group. Factor analyses were performed in order to identify complex patterns of variation in metric traits of the skull. According to the results, prehistoric Malawians showed only slight differences between the Late and Middle Holocene, suggesting a population change without any major discontinuity. Later Stone Age skulls did not exclusively show similarities with the Khoi‐San, as they frequently fit well within the variation of modern Bantu‐speaking groups, especially West‐Central Africa. Therefore, we reject the hypothesis that Middle Holocene South‐Central Africans have an exclusively Khoi‐San ancestry, and support an alternative hypothesis that both Middle and Late Holocene groups share a common biological heritage originating in West‐Central Africa in earlier times. Am J Phys Anthropol, 2006. © 2005 Wiley‐Liss, Inc.     

Glacial cycling, large mammal community composition, and trophic adaptations in the Western Cape, South Africa

Some of the earliest evidence for modern human behavior has been recovered from the Western Cape Province, South Africa. Archaeological and paleontological sites in the Western Cape are typically described as “glacial” or “interglacial” in aspect based on the numbers of grazers found in the faunal assemblage, as glacial periods are often thought to have been characterized by spreading C₄ grasslands that replaced endemic C₃ shrubland vegetation found in the Western Cape today. Here, we test the hypothesis that glacial and interglacial time periods were associated with a predictable change in large mammal trophic adaptations by analyzing the proportions of grazing larger mammals from 118 levels of 15 Western Cape fossil assemblages sampling marine isotope stage (MIS) 6 to the present time to determine whether there is a change in composition in these communities that might reflect a shift in ecology and habitat. Our results indicate that trophic proportions did not significantly change over time in the Western Cape as a whole, and thus the hypothesis for habitat changes affecting the subsistence ecology of modern humans during the development of modern behavior is not supported. However, our results show that the southwestern subregion of the Western Cape was characterized by the presence of more grazing species through time than the western subregion. Thus, if ecological and population isolation during glacial periods were integral to catalyzing the development of modern behaviors in the Western Cape region of South Africa, then a complex model including the development of possible mosaic habitats is needed.     

Taphonomic and paleoecological change in the large mammal sequence from Boomplaas Cave,western Cape,South Africa

Excavations conducted by H.J. Deacon in the 1970s at Boomplaas Cave (BPA) uncovered a stratified sequence of Middle Stone Age (MSA) and Later Stone Age (LSA) deposits spanning the last >65,000 years. This study provides the first comprehensive and integrated taphonomic and paleoecological analysis of the BPA large mammals, with a focus on its implications for understanding human adaptations and environmental changes in southern Africa's Cape Floristic Region (CFR), an area that features prominently in understanding modern human origins. Taphonomic data indicate a complex history of human, carnivore, and raptor accumulation of the large mammal assemblage. The anthropogenic signal is largely absent from the bottom of the sequence (>65,000 years ago), intermediate in MSA and LSA assemblages from ∼50,000 to 20,000 years ago, and strong in LSA deposits post-dating the Last Glacial Maximum (LGM). When viewed in the broader CFR context, the inferred occupation history of BPA is consistent with the hypothesis that both MSA and LSA human populations were concentrated on the submerged coastline from ∼60,000 to ∼20,000 years ago. Intensive occupation following the LGM parallels an apparent increase in regional population densities, which may have been driven in part by rising sea levels. The BPA ungulate assemblage is characterized by the rise and decline of a taxonomically diverse grazing community, which peaks during the LGM. These changes are not correlated with taphonomic shifts, meaning that they are likely driven by environmental factors, namely the expansion and contraction of grassland habitats. Changes in ungulate diversity indicate that effective precipitation was highest during the LGM, corresponding with an intensified winter rainfall system. This is consistent with recent arguments that the LGM in this region may not have been extremely harsh and arid.     

Human skeletal remains from Mumba Rock Shelter,Northern Tanzania

During their expeditions in Northern Tanzania in 1934/38, Ludwig and Margit Kohl-Larsen (discoverer of Eyasi and Garusi hominids)excavated i. a. the Mumba Rock Shelter. This important excavation yielded human skeletal remains of 18 individuals. The most relevant results of the morphological analyses are presented here. According to the affinities and absolute dating (hominid IX, 3700 B. C. ), the present study supports recent indications of the presence of Negroid groups in East Africa at an early stage in Later Stone Age times.