Hominin fossil evidence in the Turkana Basin in Kenya from ca. 4.1 to 1.4 Ma samples two archaic early hominin genera and records some of the early evolutionary history of Paranthropus and Homo. ...Stable carbon isotopes in fossil tooth enamel are used to estimate the fraction of diet derived from C₃ or C₄ resources in these hominin taxa. The earliest hominin species in the Turkana Basin, Australopithecus anamensis, derived nearly all of its diet from C₃ resources. Subsequently, by ca. 3.3 Ma, the later Kenyanthropus platyops had a very wide dietary range—from virtually a purely C₃ resource-based diet to one dominated by C₄ resources. By ca. 2 Ma, hominins in the Turkana Basin had split into two distinct groups: specimens attributable to the genus Homo provide evidence for a diet with a ca. 65/35 ratio of C₃- to C₄-based resources, whereas P. boisei had a higher fraction of C₄-based diet (ca. 25/75 ratio). Homo sp. increased the fraction of C₄-based resources in the diet through ca. 1.5 Ma, whereas P. boisei maintained its high dependency on C₄-derived resources.
Human evolutionary scholars have long supposed that the earliest stone tools were made by the genus Homo and that this technological development was directly linked to climate change and the spread ...of savannah grasslands. New fieldwork in West Turkana, Kenya, has identified evidence of much earlier hominin technological behaviour. We report the discovery of Lomekwi 3, a 3.3-million-year-old archaeological site where in situ stone artefacts occur in spatiotemporal association with Pliocene hominin fossils in a wooded palaeoenvironment. The Lomekwi 3 knappers, with a developing understanding of stone's fracture properties, combined core reduction with battering activities. Given the implications of the Lomekwi 3 assemblage for models aiming to converge environmental change, hominin evolution and technological origins, we propose for it the name 'Lomekwian', which predates the Oldowan by 700,000 years and marks a new beginning to the known archaeological record.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
An earlier origin for the Acheulian LEPRE, Christopher J; ROCHE, Hélène; KENT, Dennis V ...
Nature (London),
09/2011, Letnik:
477, Številka:
7362
Journal Article
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The Acheulian is one of the first defined prehistoric techno-complexes and is characterized by shaped bifacial stone tools. It probably originated in Africa, spreading to Europe and Asia perhaps as ...early as ∼1 million years (Myr) ago. The origin of the Acheulian is thought to have closely coincided with major changes in human brain evolution, allowing for further technological developments. Nonetheless, the emergence of the Acheulian remains unclear because well-dated sites older than 1.4 Myr ago are scarce. Here we report on the lithic assemblage and geological context for the Kokiselei 4 archaeological site from the Nachukui formation (West Turkana, Kenya) that bears characteristic early Acheulian tools and pushes the first appearance datum for this stone-age technology back to 1.76 Myr ago. Moreover, co-occurrence of Oldowan and Acheulian artefacts at the Kokiselei site complex indicates that the two technologies are not mutually exclusive time-successive components of an evolving cultural lineage, and suggests that the Acheulian was either imported from another location yet to be identified or originated from Oldowan hominins at this vicinity. In either case, the Acheulian did not accompany the first human dispersal from Africa despite being available at the time. This may indicate that multiple groups of hominins distinguished by separate stone-tool-making behaviours and dispersal strategies coexisted in Africa at 1.76 Myr ago.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Reconstructing vegetation at hominin fossil sites provides us critical information about hominin palaeoenvironments and the potential role of climate in their evolution. Here we reconstruct ...vegetation from carbon isotopes of plant wax biomarkers in sediments of the Nachukui Formation in the Turkana Basin. Plant wax biomarkers were extracted from samples from a wide range of lithologies that include fluvial–lacustrine sediments and palaeosols, and therefore provide a record of vegetation from diverse depositional environments. Carbon isotope ratios from biomarkers indicate a highly dynamic vegetation structure (ca 5–100% C4 vegetation) from 2.3 to 1.7 Ma, with an overall shift towards more C4 vegetation on the landscape after about 2.1 Ma. The biomarker isotope data indicate ca 25–30% more C4 vegetation on the landscape than carbon isotope data of pedogenic carbonates from the same sequence. Our data show that the environments of early Paranthropus and Homo in this part of the Turkana Basin were primarily mixed C3–C4 to C4-dominated ecosystems. The proportion of C4-based foods in the diet of Paranthropus increases through time, broadly paralleling the increase in C4 vegetation on the landscape, whereas the diet of Homo remains unchanged. Biomarker isotope data associated with the Kokiselei archaeological site complex, which includes the site where the oldest Acheulean stone tools to date were recovered, indicate 61–97% C4 vegetation on the landscape.
This article is part of the themed issue ‘Major transitions in human evolution’.
Background: Drug survival in a real-life setting is critical to long-term use of biologics for psoriasis.
Objective: We describe our 12-year experience with biologics in psoriasis patients.
Patients ...and Methods: All patients treated with biologics including infliximab, adalimumab (ADA), etanercept (ETA), and ustekinumab (UST) for psoriasis vulgaris between January 2005 and December 2016 were retrospectively analyzed.
Results: In total, 545 treatment series were administered to 269 patients, including 211 treatment series with ADA, 135 with ETA, 77 with infliximab, and 122 with UST. ADA and ETA were initiated most often as first-line therapy; 65.3% of treatment sequences were discontinued. UST had the highest drug survival. The major reason for treatment termination was a loss of efficacy (44.9%). Definitive discontinuation increased with the number of biologic therapy sequences.
Limitations: Subjects were not randomized to the different treatments.
Conclusions: In a long-term real-life setting, drug survival of UST is better than that of TNF-a inhibitors for both biologic-naive and biologic-experienced patients with psoriasis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
All modern humans use tools to overcome limitations of our anatomy and to make difficult tasks easier. However, if tool use is such an advantage, we may ask why it is not evolved to the same degree ...in other species. To answer this question, we need to bring a long-term perspective to the material record of other members of our own order, the Primates.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A review of the human–horse relationship Hausberger, Martine; Roche, Hélène; Henry, Séverine ...
Applied animal behaviour science,
January 2008, 2008, 2008-01-00, 20080101, 2008-01, Letnik:
109, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Despite a long history of human–horse relationship, horse-related incidents and accidents do occur amongst professional and non professional horse handlers. Recent studies show that their occurrence ...depend more on the frequency and amount of interactions with horses than on the level of competency, suggesting a strong need for specific research and training of individuals working with horses. In the present study, we review the current scientific knowledge on human–horse relationships. We distinguish here short occasional interactions with familiar or unfamiliar horses (e.g. veterinary inspection) and long-term bonds (e.g. horse–owner).
An important aspect of the horse–human relationship is to try and improve the development and maintenance of a strong positive relationship. Studies show that deficits in the management conditions (housing, feeding, possibilities for social contact, and training methods) may lead to relational problems between horses and humans. Different methods have been used to assess and improve the human–horse relation, especially at the young age. They reveal that the time and type of contact all play a role, while recent studies suggest that the use of familiarized social models might be a great help through social facilitation.
We argue that an important theoretical framework could be Hinde's Hinde, R., 1979. Towards Understanding Relationships. Academic Press, Londres definition of a relationship as an emerging bond from a series of interactions: partners have expectations on the next interaction on the basis of the previous ones. Understanding that a relationship is built up on the basis of a succession of interactions is an important step as it suggests that attention is being paid to the “positive” or “negative” valence of each interaction as a step for the next one. A better knowledge of learning rules is certainly necessary in this context not only to train the horse but also to counterbalance the unavoidable negative inputs that exist in routine procedures and reduce their impact on the relationship.
It appears clearly that research is needed in order to assess how to better and safely approach the horse (e.g. research in position, posture, gaze, etc.), what type of approaches and timing may help in developing a positive bond, what influence human management and care have on the relationship, and how this can be adapted to have a positive influence on the relationship. Also the interaction between rider and horse, the search for the optimal match between two individuals, is an aspect of the horse–human relationship that requires attention in order to decrease the number of horse-riding accidents and reduced states of welfare. On the other hand, adequate knowledge is readily available that may improve the present situation rapidly. Developing awareness and attention to behavioural cues given by horses would certainly help decreasing accidents among professionals when interacting. Scientists therefore should play a major role in transmitting not only elements of the current knowledge of the ethology of the horse but also by helping developing observational skills.
Abstract
The evaluation of the impact of plasma-facing components damage on subsequent plasma operation is an important issue for ITER. During the first phase of the operation of WEST, a few ...ITER-like divertor plasma-facing units (PFUs) have been installed on the lower divertor. One PFU was pre-damaged under electron beam gun thermal loading, before its installation in WEST, and the subsequent evolution of the damage was studied after the WEST plasma exposure. This paper presents the procedure followed to get the pre-damaged PFU. It consists of the characterization of the response of tungsten samples representative of WEST PFU under high heat flux (HHF) loading, the selection of damage (namely, small cracks, crack network, crack network, and W melt droplets). Finally, according to the WEST plasma loading conditions, the blocks with damage within the PFU and the position of the pre-damaged PFU on the WEST lower divertor are attributed. The first results obtained after an initial plasma exposure in WEST lead to the assessment, as expected with regard to the heat loading conditions, that no major surface aspect modification was found. This result emphasized the possibility of implementing as pre-damaged small droplets of melted tungsten in a high heat-loaded zone for a future WEST experimental campaign.
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