Brain expansion in early hominins predicts carnivore extinctions in East Africa

While the anthropogenic impact on ecosystems today is evident, it remains unclear if the detrimental effect of hominins on co‐occurring biodiversity is a recent phenomenon or has also been the pattern for earlier hominin species. We test this using the East African carnivore fossil record. We analyse the diversity of carnivores over the last four million years and investigate whether any decline is related to an increase in hominin cognitive capacity, vegetation changes or climatic changes. We find that extinction rates in large carnivores correlate with increased hominin brain size and with vegetation changes, but not with precipitation or temperature changes. While temporal analyses cannot distinguish between the effects of vegetation changes and hominins, we show through spatial analyses of contemporary carnivores in Africa that only hominin causation is plausible. Our results suggest that substantial anthropogenic influence on biodiversity started millions of years earlier than currently assumed.     

Hominin occupations at the Dmanisi site, Georgia, Southern Caucasus: raw materials and technical behaviours of Europe's first hominins

Dmanisi is the oldest site outside of Africa that records unquestioned hominin occupations as well as the dispersal of hominins in Europe and Asia. The site has yielded large numbers of artefacts from several periods of hominin occupation. This analysis of Dmanisi stone tool technology includes a review of all the pieces recovered during the last 15 years of excavations. This lithic assemblage gives insights into the hominin behaviour at 1.7-1.8 Ma in Eurasia. Dmanisi hominins exploited local rocks derived from either nearby riverbeds or outcrops, and petrographic study provides data on patterns of stone procurement. Recent geological surveys and technological studies of the artefacts illustrate the roles of hominins in composing the assemblage. Dmanisi hominins selected two types of blanks, including cobbles and angular blocks, of basalt, andesite, and tuffs. Many complete cobbles, pebbles, and rolled blocks in basalt were unmodified, and geological analyses and surveys indicate that hominins brought manuports back to the site, suggesting a complex procurement strategy. Cores, flakes and debris show that all stages of flaking activity took place at the site. Numerous unifacial cores suggest that knapping was not very elaborate. Centripetal knapping is observed on some flake-cores. Knapping was influenced by the blank shape and natural angles. Most flaked objects were either cores or chopper-cores. Flakes predominate while flake tools are rare. The Dmanisi lithic assemblage is comparable to Oldowan sites in Africa in terms of reduction sequence, organisation of the removals, platform types, and the lack of retouched flakes. Dmanisi artefacts and may have been produced by the original hominins in Europe and Asia.     

Quantifying Oldowan Stone Tool Production at Olduvai Gorge,Tanzania

Recent research suggests that variation exists among and between Oldowan stone tool assemblages. Oldowan variation might represent differential constraints on raw materials used to produce these stone implements. Alternatively, variation among Oldowan assemblages could represent different methods that Oldowan producing hominins utilized to produce these lithic implements. Identifying differential patterns of stone tool production within the Oldowan has implications for assessing how stone tool technology evolved, how traditions of lithic production might have been culturally transmitted, and for defining the timing and scope of these evolutionary events. At present there is no null model to predict what morphological variation in the Oldowan should look like. Without such a model, quantifying whether Oldowan assemblages vary due to raw material constraints or whether they vary due to differences in production technique is not possible. This research establishes a null model for Oldowan lithic artifact morphological variation. To establish these expectations this research 1) models the expected range of variation through large scale reduction experiments, 2) develops an algorithm to categorize archaeological flakes based on how they are produced, and 3) statistically assesses the methods of production behavior used by Oldowan producing hominins at the site of DK from Olduvai Gorge, Tanzania via the experimental model. Results indicate that a subset of quartzite flakes deviate from the null expectations in a manner that demonstrates efficiency in flake manufacture, while some basalt flakes deviate from null expectations in a manner that demonstrates inefficiency in flake manufacture. The simultaneous presence of efficiency in stone tool production for one raw material (quartzite) and inefficiency in stone tool production for another raw material (basalt) suggests that Oldowan producing hominins at DK were able to mediate the economic costs associated with stone tool procurement by utilizing high-cost materials more efficiently than is expected and low-cost materials in an inefficient manner.     

泥河湾盆地东谷坨遗址6A2层的形成过程

东谷坨遗址是泥河湾盆地内重要的旧石器时代早期遗址,其文化层以河湖相堆积为主,大量的文化遗物在埋藏过程中会受到流水等自然作用的影响,明确遗址的形成过程、了解遗物在埋藏过程中被改造的程度是我们开展其他各项研究的基础。2016-2020年,中国科学院古脊椎动物与古人类研究所和河北省文物考古研究院对东谷坨遗址T1区域开展了新的发掘,通过此次发掘,我们将原6A文化层划分为2个亚层。其中6A2为粗砂砾石堆积,显示水动力较强的沉积环境,但该层出土的多数石制品表面新鲜,并未显示出受高能水流的改造或被长距离搬运的特征。鉴于此,我们以探讨搬运改造石制品所形成破损特点为目的设计并实施了模拟搬运试验,开展了遗址内沉积物、石制品特征等多指标分析探讨遗址的形成过程。结果表明,6A2层的多数石制品并非由高能水流搬运而来,而是粗砂砾石堆积在遗址形成后,古人类活动于其上所遗留,此层石制品显示了原地埋藏的特点。     

The First Hominins and the Origins of Bipedalism

Molecular and paleontological evidence now point to the last common ancestor between chimpanzees and modern humans living between five and seven million years ago. Any species considered to be more closely related to humans than chimpanzees we call hominins. Traditionally, early hominins have been conspicuous by their absence in the fossil record, but discoveries in the last 20 years have finally provided us with a number of very important finds. We currently have three described genera, Ardipithecus, Orrorin and Sahelanthropus, of which Ardipithecus is extremely well represented by cranial, dental, and postcranial remains. All three genera are argued to be hominins based on reduced canine size and an increased capacity for bipedal locomotion. The evolutionary relationships between these taxa and both earlier hominoids and later hominins are somewhat disputed, but this is to be expected for any species thought to be close to the root of the hominin lineage.     

Early Origin for Human-Like Precision Grasping: A Comparative Study of Pollical Distal Phalanges in Fossil Hominins

Background

The morphology of human pollical distal phalanges (PDP) closely reflects the adaptation of human hands for refined precision grip with pad-to-pad contact. The presence of these precision grip-related traits in the PDP of fossil hominins has been related to human-like hand proportions (i.e. short hands with a long thumb) enabling the thumb and finger pads to contact. Although this has been traditionally linked to the appearance of stone tool-making, the alternative hypothesis of an earlier origin—related to the freeing of the hands thanks to the advent of terrestrial bipedalism—is also possible given the human-like intrinsic hand proportion found in australopiths.

Methodology/Principal Findings

We perform morphofunctional and morphometric (bivariate and multivariate) analyses of most available hominin pollical distal phalanges, including Orrorin, Australopithecus, Paranthropous and fossil Homo, in order to investigate their morphological affinities. Our results indicate that the thumb morphology of the early biped Orrorin is more human-like than that of australopiths, in spite of its ancient chronology (ca. 6 Ma). Moreover, Orrorin already displays typical human-like features related to precision grasping.

Conclusions

These results reinforce previous hypotheses relating the origin of refined manipulation of natural objects–not stone tool-making–with the relaxation of locomotor selection pressures on the forelimbs. This suggests that human hand length proportions are largely plesiomorphic, in the sense that they more closely resemble the relatively short-handed Miocene apes than the elongated hand pattern of extant hominoids. With the advent of terrestrial bipedalism, these hand proportions may have been co-opted by early hominins for enhanced manipulative capabilities that, in turn, would have been later co-opted for stone tool-making in the genus Homo, more encephalized than the previous australopiths. This hypothesis remains may be further tested by the finding of more complete hands of unequivocally biped early hominins.     

Cool birds: facultative use by an introduced species of mechanical air conditioning systems during extremely hot outdoor conditions

Rapid climate change across the globe is having dramatic effects on wildlife. Responses of organisms to shifting thermal conditions often include physiological and behavioural accommodations, but to date these have been largely viewed and studied as naturally evolved phenomena (e.g. heat avoidance, sweating, panting) and not necessarily as strategies where animals exploit other anthropogenic conditions or resources. Moreover, the degree to which native versus introduced species show thermal plasticity has generated much conservation and ecological interest. We previously have observed introduced rosy-faced lovebirds (Agapornis roseicollis) perching in the relief-air vents on building faces in the Phoenix, Arizona, USA, metropolitan area, but doing so only during summer. Here, we show that such vent-perching events are significantly associated with extreme outdoor summer temperatures (when daily local highs routinely exceed 40°C). In fact, the temperature threshold at which we detected lovebirds starting to perch in cool air vents mirrors the upper range of the thermoneutral zone for this species. These results implicate novel, facultative use of an anthropogenic resource—industrial air-conditioning systems—by a recently introduced species (within the last 35 years) to cool down and survive extremely hot conditions in this urban ‘heat-island'' environment.     

人为热排放对城市热环境的影响研究展望

全球范围的城市扩张和能源消耗,导致人为热在不同时间和空间尺度上影响地表热环境,人为热排放与城市热岛的关系受到广泛关注。通过国内外文献总结源清单法、数值模拟法和能量平衡方程等3种人为热估算方法的优缺点,评价人为热研究在城市、区域和全球尺度的主要进展和区别,归纳出现有研究在城市尺度多关注人为热的时间动态变化,区域和全球尺度研究则更关注人为热的空间差异,以及人为热对于全球变暖的贡献和人类的适应对策。从中发现人为热研究中存在的问题和不足,包括研究尺度和研究方法匹配性、研究结果的验证和比较、人为热排放与景观功能的联系、人为热排放强度和周期对气温的影响机制等。根据现存问题提出多学科集成、人为热与景观功能耦合、时空尺度选择、数据获取等4个方面的建议,有助于在理论和方法方面深化和拓展城市人为热研究。     

Operationalizing niche construction theory with stone tools

One of the greatest difficulties with evolutionary approaches in the study of stone tools (lithics) has been finding a mechanism for tying culture and biology in a way that preserves human agency and operates at scales that are visible in the archaeological record. The concept of niche construction, whereby organisms actively construct their environments and change the conditions for selection, could provide a solution to this problem. In this review, we evaluate the utility of niche construction theory (NCT) for stone tool archaeology. We apply NCT to lithics both as part of the “extended phenotype” and as residuals or precipitates of other niche‐constructing activities, suggesting ways in which archaeologists can employ niche construction feedbacks to generate testable hypotheses about stone tool use. Finally, we conclude that, as far as its applicability to lithic archaeology, NCT compares favorably to other prominent evolutionary approaches, such as human behavioral ecology and dual‐inheritance theory.     

生态旅游区的景观生态问题及其调控

目前,在生态旅游开发过程中存在着许多生态破坏现象,严重影响生态旅游的可持续发展,是生态旅游区建设中亟待重视的问题。本文总结了当前我国生态旅游区在发展生态旅游过程中存在的生态破坏问题,并运用景观生态学、旅游生态学的原理和方法提出了解决生态旅游区生态问题的景观生态调控对策和措施,包括进行旅游景观生态规划、设计合理的旅游生态管理容量、对旅游景观结构进行生态化设计、构建景观生态安全格局、加强旅游生态教育和旅游环境监测等方面。     

Locomotor anatomy and biomechanics of the Dmanisi hominins

The Dmanisi hominins inhabited a northern temperate habitat in the southern Caucasus, approximately 1.8 million years ago. This is the oldest population of hominins known outside of Africa. Understanding the set of anatomical and behavioral traits that equipped this population to exploit their seasonal habitat successfully may shed light on the selection pressures shaping early members of the genus Homo and the ecological strategies that permitted the expansion of their range outside of the African subtropics. The abundant stone tools at the site, as well as taphonomic evidence for butchery, suggest that the Dmanisi hominins were active hunters or scavengers. In this study, we examine the locomotor mechanics of the Dmanisi hind limb to test the hypothesis that the inclusion of meat in the diet is associated with an increase in walking and running economy and endurance. Using comparative data from modern humans, chimpanzees, and gorillas, as well as other fossil hominins, we show that the Dmanisi hind limb was functionally similar to modern humans, with a longitudinal plantar arch, increased limb length, and human-like ankle morphology. Other aspects of the foot, specifically metatarsal morphology and tibial torsion, are less derived and similar to earlier hominins. These results are consistent with hypotheses linking hunting and scavenging to improved walking and running performance in early Homo. Primitive retentions in the Dmanisi foot suggest that locomotor evolution continued through the early Pleistocene.     

Speciation, diversity, and Mode 1 technologies: the impact of variability selection

Over geological timescales, organisms encounter periodic shifts in selective conditions driven by environmental change. The variability selection hypothesis suggests that increases in environmental fluctuation have led to the evolution of complex, flexible behaviours able to respond to novel and unpredictable adaptive settings. This hypothesis is tested via the framework of a single locus genetic model in which an invading ‘versatilist’ allele competes with two opposed specialists in a selection regime driven by a fluctuating environment, modelled initially as a sine wave and subsequently as an empirical climate curve covering the past 5 million years. Results demonstrate that generalist alleles achieve fixation in the sine wave environment, whilst versatilist alleles do so in the empirical environment, even at a range of very low fitness advantages over the basic generalist template. Variability selection is found to be a particularly strong force between approximately 2.5 and 1.2 Ma (millions of years ago). These results are discussed in relation to the spread of Oldowan lithics and the patterns of speciation and extinction documented in the hominin fossil record. It is suggested that the flexibility required for survival in a variable climatic regime may have been a stimulus to the development of the first stone tool technologies, whilst the ecological opportunities provided by heightened variability may have been a factor in prompting the hominin adaptive radiation evidenced during this period.     

Movement Pattern Variability in Stone Knapping: Implications for the Development of Percussive Traditions

The earliest direct evidence for tool-use by our ancestors are 2.6 million year old stone tools from Africa. These earliest artifacts show that, already, early hominins had developed the required advanced movement skills and cognitive capacities to manufacture stone tools. Currently, it is not well understood, however, which specific movement skills are required for successful stone knapping and accordingly it is unknown how these skills emerged during early hominin evolution. In particular, it is not clear which striking movements are indicative of skilled performance, how striking movement patterns vary with task and environmental constraints, and how movement patterns are passed on within social groups. The present study addresses these questions by investigating striking movement patterns and striking variability in 18 modern stone knappers (nine experienced and nine novices). The results suggest that no single movement pattern characterizes successful stone knapping. Participants showed large inter-individual movement variability of the elementary knapping action irrespective of knapping experience and knapping performance. Changes in task- and environmental constraints led knappers to adapt their elementary striking actions using a combination of individual and common strategies. Investigation of striking pattern similarities within social groups showed only partial overlap of striking patterns across related individuals. The results therefore suggest that striking movement patterns in modern stone knappers are largely specific to the individual and movement variability is not indicative of knapping performance. The implications of these results for the development of percussive traditions are discussed.     

Adaptive Landscape by Environment Interactions Dictate Evolutionary Dynamics in Models of Drug Resistance

The adaptive landscape analogy has found practical use in recent years, as many have explored how their understanding can inform therapeutic strategies that subvert the evolution of drug resistance. A major barrier to applications of these concepts is a lack of detail concerning how the environment affects adaptive landscape topography, and consequently, the outcome of drug treatment. Here we combine empirical data, evolutionary theory, and computer simulations towards dissecting adaptive landscape by environment interactions for the evolution of drug resistance in two dimensions—drug concentration and drug type. We do so by studying the resistance mediated by Plasmodium falciparum dihydrofolate reductase (DHFR) to two related inhibitors—pyrimethamine and cycloguanil—across a breadth of drug concentrations. We first examine whether the adaptive landscapes for the two drugs are consistent with common definitions of cross-resistance. We then reconstruct all accessible pathways across the landscape, observing how their structure changes with drug environment. We offer a mechanism for non-linearity in the topography of accessible pathways by calculating of the interaction between mutation effects and drug environment, which reveals rampant patterns of epistasis. We then simulate evolution in several different drug environments to observe how these individual mutation effects (and patterns of epistasis) influence paths taken at evolutionary “forks in the road” that dictate adaptive dynamics in silico. In doing so, we reveal how classic metrics like the IC₅₀ and minimal inhibitory concentration (MIC) are dubious proxies for understanding how evolution will occur across drug environments. We also consider how the findings reveal ambiguities in the cross-resistance concept, as subtle differences in adaptive landscape topography between otherwise equivalent drugs can drive drastically different evolutionary outcomes. Summarizing, we discuss the results with regards to their basic contribution to the study of empirical adaptive landscapes, and in terms of how they inform new models for the evolution of drug resistance.     

Estimated impact of RTS,S/AS01 malaria vaccine allocation strategies in sub-Saharan Africa: A modelling study

BackgroundThe RTS,S/AS01 vaccine against Plasmodium falciparum malaria infection completed phase III trials in 2014 and demonstrated efficacy against clinical malaria of approximately 36% over 4 years for a 4-dose schedule in children aged 5–17 months. Pilot vaccine implementation has recently begun in 3 African countries. If the pilots demonstrate both a positive health impact and resolve remaining safety concerns, wider roll-out could be recommended from 2021 onwards. Vaccine demand may, however, outstrip initial supply. We sought to identify where vaccine introduction should be prioritised to maximise public health impact under a range of supply constraints using mathematical modelling.Methods and findingsUsing a mathematical model of P. falciparum malaria transmission and RTS,S vaccine impact, we estimated the clinical cases and deaths averted in children aged 0–5 years in sub-Saharan Africa under 2 scenarios for vaccine coverage (100% and realistic) and 2 scenarios for other interventions (current coverage and World Health Organization [WHO] Global Technical Strategy targets). We used a prioritisation algorithm to identify potential allocative efficiency gains from prioritising vaccine allocation among countries or administrative units to maximise cases or deaths averted. If malaria burden at introduction is similar to current levels—assuming realistic vaccine coverage and country-level prioritisation in areas with parasite prevalence >10%—we estimate that 4.3 million malaria cases (95% credible interval [CrI] 2.8–6.8 million) and 22,000 deaths (95% CrI 11,000–35,000) in children younger than 5 years could be averted annually at a dose constraint of 30 million. This decreases to 3.0 million cases (95% CrI 2.0–4.7 million) and 14,000 deaths (95% CrI 7,000–23,000) at a dose constraint of 20 million, and increases to 6.6 million cases (95% CrI 4.2–10.8 million) and 38,000 deaths (95% CrI 18,000–61,000) at a dose constraint of 60 million. At 100% vaccine coverage, these impact estimates increase to 5.2 million cases (95% CrI 3.5–8.2 million) and 27,000 deaths (95% CrI 14,000–43,000), 3.9 million cases (95% CrI 2.7–6.0 million) and 19,000 deaths (95% CrI 10,000–30,000), and 10.0 million cases (95% CrI 6.7–15.7 million) and 51,000 deaths (95% CrI 25,000–82,000), respectively. Under realistic vaccine coverage, if the vaccine is prioritised sub-nationally, 5.3 million cases (95% CrI 3.5–8.2 million) and 24,000 deaths (95% CrI 12,000–38,000) could be averted at a dose constraint of 30 million. Furthermore, sub-national prioritisation would allow introduction in almost double the number of countries compared to national prioritisation (21 versus 11). If vaccine introduction is prioritised in the 3 pilot countries (Ghana, Kenya, and Malawi), health impact would be reduced, but this effect becomes less substantial (change of <5%) if 50 million or more doses are available. We did not account for within-country variation in vaccine coverage, and the optimisation was based on a single outcome measure, therefore this study should be used to understand overall trends rather than guide country-specific allocation.ConclusionsThese results suggest that the impact of constraints in vaccine supply on the public health impact of the RTS,S malaria vaccine could be reduced by introducing the vaccine at the sub-national level and prioritising countries with the highest malaria incidence.

Alexandra Hogan and colleagues explore strategies to optimize vaccine allocation for maximum public health benefit in the face of potential supply constraints.     

Inside the “African Cattle Complex”: Animal Burials in the Holocene Central Sahara

Cattle pastoralism is an important trait of African cultures. Ethnographic studies describe the central role played by domestic cattle within many societies, highlighting its social and ideological value well beyond its mere function as ‘walking larder’. Historical depth of this African legacy has been repeatedly assessed in an archaeological perspective, mostly emphasizing a continental vision. Nevertheless, in-depth site-specific studies, with a few exceptions, are lacking. Despite the long tradition of a multi-disciplinary approach to the analysis of pastoral systems in Africa, rarely do early and middle Holocene archaeological contexts feature in the same area the combination of settlement, ceremonial and rock art features so as to be multi-dimensionally explored: the Messak plateau in the Libyan central Sahara represents an outstanding exception. Known for its rich Pleistocene occupation and abundant Holocene rock art, the region, through our research, has also shown to preserve the material evidence of a complex ritual dated to the Middle Pastoral (6080–5120 BP or 5200–3800 BC). This was centred on the frequent deposition in stone monuments of disarticulated animal remains, mostly cattle. Animal burials are known also from other African contexts, but regional extent of the phenomenon, state of preservation of monuments, and associated rock art make the Messak case unique. GIS analysis, excavation data, radiocarbon dating, zooarchaeological and isotopic (Sr, C, O) analyses of animal remains, and botanical information are used to explore this highly formalized ritual and the lifeways of a pastoral community in the Holocene Sahara.     

北京香山公园自然景观价值二十年变迁

自然景观是由自然环境、物质和景象构成,具有观赏、游览、休闲、疗养等效用和价值的风景综合体或景物。然而,人们在开发利用自然资源时,并没有将自然景观的价值纳入到费用效益分析中,这种对自然景观价值的忽略和低估导致了各种不可逆转的环境问题。如果赋予自然景观合适的经济价值并探究其价值变化,能为其开发利用提供决策支持。以北京香山公园为例,构建了价值评估的指标体系:即自然景观价值为使用价值与非使用价值之和。并对这两种价值分别运用个体旅行费用法和条件价值法进行评估,得出2012年香山公园的使用价值为19.25亿元,非使用价值为3.46亿元。对香山公园在1992—2012年20年间的自然景观价值变化进行深入的研究发现,其景观价值由1992年的0.175亿元增长到2012年的22.71亿元,增长近130倍,速率为1.13亿元/a,游客量的加倍增长、人们游览支出的提高,以及支付意愿的增长是产生该变化的主要原因。随着环境污染和生态破坏的日益加剧以及人们对健康生活的迫切向往,香山公园自然景观价值仍将持续增长,景区当局应全面认识香山公园所承载的价值,在发展旅游的同时也要积极探索解决现有生态环境问题的新思路。     

Degraded temperature sensitivity of a stone pine chronology explained by dendrochemical evidences

Fluctuations in sulphur (S) content in tree rings were analysed for a 93 years long period (1915–2007) by laser ablation system coupled to an inductively coupled plasma mass spectrometer from three Swiss stone pine (Pinus cembra L.) trees grown in the Rachitis Cirque, Calimani Mts, Eastern Carpathians. Investigated domain envelops the period of degraded climatic sensitivity of pines’ growth. Chemical data were standardized for sapwood and heartwood separately. The averaged sulphur record calculated from the three individual records unequivocally presents anomalously high S content for the tree rings dated to 1970s and 1980s. Ring-width fluctuation portrays changes of summer temperature but from 1966 to 1986 pines produced apparently larger rings than the corresponding summer temperatures can explain. This deviating interval coincides with the period of exploitation in the nearby sulphur mine. The elevated S content in tree rings refers probably to the dispersion of S-rich dust around the mine owing to the opencast type of exploitation. The divergent growth trend and degraded climatic signal likely due to the anthropogenic altered nutritional status of the site, as residues from nitrogen fertilizer, applied as a compound of explosive in the opencast sulphur exploitation, could be deposited on the surrounding forest.     

景观生态学在土地整治中的应用研究进展

在土地整治中融入景观生态学理念是推动土地整治生态建设的必然要求。阐述了土地整治中的景观生态学原理,分析了相关文献变化和研究重点,总结了中国土地整治中的景观生态学研究现状,提出了土地整治中的景观生态学研究展望:(1)重视土地整治中景观生态学的基础理论研究,构建土地整治的景观生态学理论与技术体系;(2)加强土地整治的景观动态与生态效应机制研究,建立适用土地整治景观生态影响的方法和模型;(3)强化土地整治的多尺度和长序列景观生态研究,揭示土地整治过程中的尺度效应和多尺度耦合机制;(4)加强土地整治中多种生态系统服务的集成与优化,强化用于指导土地整治生态规划设计与管理工作,以期为深化土地整治中的景观生态学研究提供借鉴和启示。