Orbital controls on eastern African hydroclimate in the Pleistocene

Understanding eastern African paleoclimate is critical for contextualizing early human evolution, adaptation, and dispersal, yet Pleistocene climate of this region and its governing mechanisms remain poorly understood due to the lack of long, orbitally-resolved, terrestrial paleoclimate records. Here we present leaf wax hydrogen isotope records of rainfall from paleolake sediment cores from key time windows that resolve long-term trends, variations, and high-latitude effects on tropical African precipitation. Eastern African rainfall was dominantly controlled by variations in low-latitude summer insolation during most of the early and middle Pleistocene, with little evidence that glacial–interglacial cycles impacted rainfall until the late Pleistocene. We observe the influence of high-latitude-driven climate processes emerging from the last interglacial (Marine Isotope Stage 5) to the present, an interval when glacial–interglacial cycles were strong and insolation forcing was weak. Our results demonstrate a variable response of eastern African rainfall to low-latitude insolation forcing and high-latitude-driven climate change, likely related to the relative strengths of these forcings through time and a threshold in monsoon sensitivity. We observe little difference in mean rainfall between the early, middle, and late Pleistocene, which suggests that orbitally-driven climate variations likely played a more significant role than gradual change in the relationship between early humans and their environment

Measuring well-being in aphasia: The GHQ-28 versus the NHP

This study aimed to get the opinions of people with aphasia on two subjective well-being measures: the General Health Questionnaire 28-item version (GHQ-28) (Goldberg & Hillier, 1979) and the Nottingham Health Profile (NHP) (Hunt, McKenna, McEwen, Williams, & Papp, 1981). Twelve persons with moderate to mild aphasia of at least 2-years duration completed the GHQ-28 and the NHP. In a semistructured intenriew, they gave their feedback on the two questionnaires. All participants were able to complete both instruments. Nine out of 12 participants showed high psychological distress (> 5/28) in the GHQ-28. The NHP (part 1 less the physical abilities section) had a correlation of 0.78 (p < .01) with the GHQ-28. The social dysfunction subscale of the NHP identified more problems in the participants with aphasia than the social isolation subscale of the GHQ-28. The majority of the participants (10 out of 12) preferred the NHP, as they found it easier to understand and respond to. This small-scale study indicated that both the GHQ-28 and the NHP can be administered to people with moderate to mild aphasia and provide useful information on their well-being. Participants reported that the NHP was easier to do, and it asked questions more relevant to their situation

Preserving the impossible: conservation of soft-sediment hominin footprint sites and strategies for three-dimensional digital data capture.

Human footprints provide some of the most publically emotive and tangible evidence of our ancestors. To the scientific community they provide evidence of stature, presence, behaviour and in the case of early hominins potential evidence with respect to the evolution of gait. While rare in the geological record the number of footprint sites has increased in recent years along with the analytical tools available for their study. Many of these sites are at risk from rapid erosion, including the Ileret footprints in northern Kenya which are second only in age to those at Laetoli (Tanzania). Unlithified, soft-sediment footprint sites such these pose a significant geoconservation challenge. In the first part of this paper conservation and preservation options are explored leading to the conclusion that to 'record and digitally rescue' provides the only viable approach. Key to such strategies is the increasing availability of three-dimensional data capture either via optical laser scanning and/or digital photogrammetry. Within the discipline there is a developing schism between those that favour one approach over the other and a requirement from geoconservationists and the scientific community for some form of objective appraisal of these alternatives is necessary. Consequently in the second part of this paper we evaluate these alternative approaches and the role they can play in a 'record and digitally rescue' conservation strategy. Using modern footprint data, digital models created via optical laser scanning are compared to those generated by state-of-the-art photogrammetry. Both methods give comparable although subtly different results. This data is evaluated alongside a review of field deployment issues to provide guidance to the community with respect to the factors which need to be considered in digital conservation of human/hominin footprints

Lucy's Flat Feet: The Relationship between the Ankle and Rearfoot Arching in Early Hominins

BACKGROUND. In the Plio-Pleistocene, the hominin foot evolved from a grasping appendage to a stiff, propulsive lever. Central to this transition was the development of the longitudinal arch, a structure that helps store elastic energy and stiffen the foot during bipedal locomotion. Direct evidence for arch evolution, however, has been somewhat elusive given the failure of soft-tissue to fossilize. Paleoanthropologists have relied on footprints and bony correlates of arch development, though little consensus has emerged as to when the arch evolved. METHODOLOGY/PRINCIPAL FINDINGS. Here, we present evidence from radiographs of modern humans (n=261) that the set of the distal tibia in the sagittal plane, henceforth referred to as the tibial arch angle, is related to rearfoot arching. Non-human primates have a posteriorly directed tibial arch angle, while most humans have an anteriorly directed tibial arch angle. Those humans with a posteriorly directed tibial arch angle (8%) have significantly lower talocalcaneal and talar declination angles, both measures of an asymptomatic flatfoot. Application of these results to the hominin fossil record reveals that a well developed rearfoot arch had evolved in Australopithecus afarensis. However, as in humans today, Australopithecus populations exhibited individual variation in foot morphology and arch development, and "Lucy" (A.L. 288-1), a 3.18 Myr-old female Australopithecus, likely possessed asymptomatic flat feet. Additional distal tibiae from the Plio-Pleistocene show variation in tibial arch angles, including two early Homo tibiae that also have slightly posteriorly directed tibial arch angles. CONCLUSIONS/SIGNIFICANCE. This study finds that the rearfoot arch was present in the genus Australopithecus. However, the female Australopithecus afarensis "Lucy" has an ankle morphology consistent with non-pathological flat-footedness. This study suggests that, as in humans today, there was variation in arch development in Plio-Pleistocene hominins.Leakey Foundatio

The Hominin Sites and Paleolakes Drilling Project:High-Resolution Paleoclimate Records from the East African Rift System and Their Implications for Understanding the Environmental Context of Hominin Evolution

The possibility of a causal relationship between Earth history processes and hominin evolution in Africa has been the subject of intensive paleoanthropological research for the last 25 years. One fundamental question is: can any geohistorical processes, in particular, climatic ones, be characterized with sufficient precision to enable temporal correlation with events in hominin evolution and provide support for a possible causal mechanism for evolutionary changes? Previous attempts to link paleoclimate and hominin evolution have centered on evidence from the outcrops where the hominin fossils are found, as understanding whether and how hominin populations responded to habitat change must be examined at the local basinal scale. However, these outcrop records typically provide incomplete, low-resolution climate and environmental histories, and surface weathering often precludes the application of highly sensitive, state-of-the-art paleoenvironmental methods. Continuous and well-preserved deep-sea drill core records have provided an alternative approach to reconstructing the context of hominin evolution, but have been collected at great distances from hominin sites and typically integrate information over vast spatial scales. The goal of the Hominin Sites and Paleolakes Drilling Project (HSPDP) is to analyze climate and other Earth system dynamics using detailed paleoenvironmental data acquired through scientific drilling of lacustrine depocenters at or near six key paleoanthropological sites in Kenya and Ethiopia. This review provides an overview of a unique collaboration of paleoanthropologists and earth scientists who have joined together to explicitly explore key hypotheses linking environmental history and mammalian (including hominin) evolution and potentially develop new testable hypotheses. With a focus on continuous, high-resolution proxies at timescales relevant to both biological and cultural evolution, the HSPDP aims to dramatically expand our understanding of the environmental history of eastern Africa during a significant portion of the Late Neogene and Quaternary, and to generate useful models of long-term environmental dynamics in the regionpublishersversionPeer reviewe

The Hominin Sites and Paleolakes Drilling Project:Inferring the environmental context of human evolution from eastern African rift lake deposits

Funding for the HSPDP has been provided by ICDP, NSF (grants EAR-1123942, BCS-1241859, and EAR-1338553), NERC (grant NE/K014560/1), DFG priority program SPP 1006, DFG-CRC-806 “Our way to Europe”, the University of Cologne (Germany), the Hong Kong Research Grants Council (grant no. HKBU201912), the Peter Buck Fund for Human Origins Research (Smithsonian), the William H. Donner Foundation, the Ruth and Vernon Taylor Foundation, Whitney and Betty MacMillan, and the Smithsonian’s Human Origins Program.The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012–2014 HSPDP coring campaign.Publisher PDFPeer reviewe

Forced, not voluntary, exercise effectively induces neuroprotection in stroke

Previous treadmill exercise studies showing neuroprotective effects have raised questions as to whether exercise or the stress related to it may be key etiologic factors. In this study, we examined different exercise regimens (forced and voluntary exercise) and compared them with the effect of stress-only on stroke protection. Adult male Sprague-Dawley rats (n = 65) were randomly assigned to treatment groups for 3 weeks. These groups included control, treadmill exercise, voluntary running wheel exercise, restraint, and electric shock. Levels of the stress hormone, corticosterone, were measured in the different groups using ELISA. Animals from each group were then subjected to stroke induced by a 2-h middle cerebral artery (MCA) occlusion followed by 48-h reperfusion. Infarct volume was determined in each group, while changes in gene expression of stress-induced heat shock proteins (Hsp) 27 and 70 were compared using real-time PCR between voluntary and treadmill exercise groups. The level of corticosterone was significantly higher in both stress (P < 0.05) and treadmill exercise (P < 0.05) groups, but not in the voluntary exercise group. Infarct volume was significantly reduced (P < 0.01) following stroke in rats exercised on a treadmill. However, the amelioration of damage was not duplicated in voluntary exercise, even though running distance in the voluntary exercise group was significantly (P < 0.01) longer than that of the forced exercise group (4,828 vs. 900 m). Furthermore, rats in the electric shock group displayed a significantly increased (P < 0.01) infarct volume. Expression of both Hsp 27 and Hsp 70 mRNA was significantly increased (P < 0.01) in the treadmill exercise group as compared with that in the voluntary exercise group. These results suggest that exercise with a stressful component, rather than either voluntary exercise or stress alone, is better able to reduce infarct volume. This exercise-induced neuroprotection may be attributable to up-regulation of stress-induced heat shock proteins 27 and 70

The Age of the 20 Meter Solo River Terrace, Java, Indonesia and the Survival of Homo erectus in Asia

Homo erectus was the first human lineage to disperse widely throughout the Old World, the only hominin in Asia through much of the Pleistocene, and was likely ancestral to H. sapiens. The demise of this taxon remains obscure because of uncertainties regarding the geological age of its youngest populations. In 1996, some of us co-published electron spin resonance (ESR) and uranium series (U-series) results indicating an age as young as 35–50 ka for the late H. erectus sites of Ngandong and Sambungmacan and the faunal site of Jigar (Indonesia). If correct, these ages favor an African origin for recent humans who would overlap with H. erectus in time and space. Here, we report 40Ar/39Ar incremental heating analyses and new ESR/U-series age estimates from the “20 m terrace" at Ngandong and Jigar. Both data sets are internally consistent and provide no evidence for reworking, yet they are inconsistent with one another. The 40Ar/39Ar analyses give an average age of 546±12 ka (sd±5 se) for both sites, the first reliable radiometric indications of a middle Pleistocene component for the terrace. Given the technical accuracy and consistency of the analyses, the argon ages represent either the actual age or the maximum age for the terrace and are significantly older than previous estimates. Most of the ESR/U-series results are older as well, but the oldest that meets all modeling criteria is 143 ka+20/−17. Most samples indicated leaching of uranium and likely represent either the actual or the minimum age of the terrace. Given known sources of error, the U-series results could be consistent with a middle Pleistocene age. However, the ESR and 40Ar/39Ar ages preclude one another. Regardless, the age of the sites and hominins is at least bracketed between these estimates and is older than currently accepted

A Spatial Distribution Study of Faunal Remains from Two Lower Magdalenian Occupation Levels in El Mirón Cave, Cantabria, Spain

Abstract: Human behaviour can be reconstructed by analysing specific activities and campsite organization using spatial analysis. The dense occupation layers of the Lower Cantabrian Magdalenian in the Northern Spain reveal varied aspects of Upper Palaeolithic lifeways, including evidence of specific localized activities. The outer vestibule of El Mirón cave has a particularly rich and intact Lower Magdalenian occupation horizon, Levels 15–17. The excavations in the outer vestibule “Cabin” area of the site revealed excellent bone preservation. Artefacts and faunal remains were individually recorded and sediments water-screened to yield a large sample of archaeological finds and spatial data. Zooarchaeological analysis provided the taxonomic, anatomic and taphonomic determination of the faunal individual finds. Smaller animal remains were categorized and counted; special attention was given to the identification of anthropogenic modifications such as burnt bones or bone flakes. These small refuse items are considered to be useful, in situ indicators of localized activities. The spatial distribution analysis of this dense and complex palimpsest of El Mirón Lower Cantabrian Magdalenian layers required GIS based methods including density analysis, heatmaps and cluster analysis. Based on the spatial distribution of Level 15 and 16 faunal remains, different activity areas were identified comprising hearth, working and dropping zones. These results imply the deliberately segregated use of space within the Lower Cantabrian Magdalenian site area, in which bone-processing activities played a central rol