Modern Reference Samples Research Articles

The estimation and evolution of hominin body mass.

Body mass is a critical variable in many hominin evolutionary studies, with implications for reconstructing relative brain size, diet, locomotion, subsistence strategy, and social organization. We review methods that have been proposed for estimating body mass from true and trace fossils, consider their applicability in different contexts, and the appropriateness of different modern reference samples. Recently developed techniques based on a wider range of modern populations hold promise for providing more accurate estimates in earlier hominins, although uncertainties remain, particularly in non-Homo taxa. When these methods are applied to almost 300 Late Miocene through Late Pleistocene specimens, the resulting body mass estimates fall within a 25-60 kg range for early non-Homo taxa, increase in early Homo to about 50-90 kg, then remain constant until the Terminal Pleistocene, when they decline.

A protocol for identifying archaeological parenchyma using microCT: Steps towards a virtual reference collection

The investigation of archaeological parenchyma derived from underground storage organs (USOs) is under-represented in archaeobotany globally. Although some regional reference collections have been assembled and applied to archaeobotanical materials, these are not generally accessible to researchers. Here, the initial steps in the development of a virtual database for archaeological parenchyma are detailed. Foremost, a protocol for the microCT scanning and virtual reconstruction of modern reference material and also of archaeological parenchyma is detailed. The protocol enables a 3D virtual representation of scanned materials to be reconstructed at high resolution (the highest resolution typically being between 2 and 3 µm), which can be interrogated qualitatively (user-defined) and quantitatively (using automated segmentation, algorithms and eventually deep learning neural networks) to enable taxonomic differentiation and comparability. The protocol is presented to enable replicability of analysis and also to ensure standardization in the future development of an online, open access and editable, 3D virtual database of modern reference samples and archaeological parenchyma.

Bayesian mixing models as a tool to explore Bronze Age bitumen trade from Tell Lashkir (Erbil, Iraq)

Bitumen from north-eastern Mesopotamian seeps was exchanged across the Tigris and the Euphrates in antiquity. Nonetheless, recent research proposed a decline in its trade during the Bronze Age alongside the boost of central Mesopotamian (Hit) seeps trade. This paper presents new provenance studies from ancient bitumen recovered at Tell Lashkir, a 4th-2nd millennium BC settlement between the lower and upper Zab Tigris tributaries. The novel application of Bayesian mixing models to biomarker and isotopic data has narrowed down the identification of the bitumen putative sources and improved the apportionment of mixtures. This placed Tell Lashkir within the pathway of bitumen active trade routes in the Bronze Age. Thus, the population inhabiting Tell Lashkir participated in exchange networks which reached southern Mesopotamia, and traded with natural resources most probably originating from central and north-eastern Mesopotamia. From a methodological standpoint, the appraisal of the Bayesian mixing models in our study with modern and archaeological reference samples has provided a better understanding of the strengths and limitations of such an approach to apportion bitumen sources from several Bronze age territories.

The need to incorporate human variation and evolutionary theory in forensic anthropology: A call for reform.

In 1992, Norm Sauer called for a language shift in which practitioners would move away from the socially loaded term "race" and replace it with the less provocative term "ancestry." While many heeded the call and moved towards ancestry in their research and reports, the actual approach to research and analysis did not change. In response to this change, there was a large growth in ancestry estimation method development in the early decade of the 2000s. However, the practice of ancestry estimation did not adequately incorporate evolutionary theory in interpretation or trait selection and continued with little critical reflection. In the past decade, there has been an increase in ancestry validation methods with little critique of the "race" concept or discussion of modern human variation or reference samples. To advance, forensic anthropologists need to reckon with the practice of ancestry estimation as it is currently practiced. We are calling for another reform in the axiom focusing on evolutionary theory, population history, trait selection, and population-level reference samples. The practice needs to abandon the terms ancestry and race completely and recalibrate to an analysis of population affinity. Population affinity is a statistical approach based on the underlying population structure that would allow the understanding of how microevolutionary forces act in concert with historical events (e.g., colonization, the Transatlantic Slave Trade, etc.) to shape modern human variation. This is not to be confused with geographic ancestry that all too often can be perceived as interchangeable with social race and as an affirmation of the biological concept of race. It is time to critically evaluate the social and scientific implications of the current practice of ancestry estimation, and re-frame our approach to studying and analyzing modern human variation through a population structure approach.

Mire plant diversity change over the last 10,000 years: Importance of isostatic land uplift, climate and local conditions

Abstract Mires or peatlands host unique biodiversity and provide many valuable ecosystem services. Mires often undergo different development phases during their evolution. Two mire phases that have clearly divergent hydrological regimes and characteristic biotas are minerotrophic fen and ombrotrophic bog. Open mires can be overgrown by trees and develop into peatland forests. Mire development trajectories are expected to be associated with three major factors—post‐glacial isostatic uplift, autogenic succession and climate‐induced changes. Understanding long‐term mire development is important for the conservation planning of these threatened habitats. We use data from modern pollen samples to characterize differences between the pollen signal and to identify indicator pollen taxa for three mire development phases—open fens, forested fens and bogs. The modern reference samples are then used to support the interpretation of the sediment records in terms of mire development phases and related biodiversity changes in six mires within a 20 × 30 km area in western Saaremaa, Estonia. Palynological richness and phylogenetic diversity (PD) as well as Ellenberg indicator values are compared throughout the 10,000‐year history of the Saaremaa mires. Pollen of herbaceous taxa discriminates between open fens, forested fens and bogs, and indicator pollen taxa can be associated with each mire phase. In general, the fen phases of the mires show higher richness and PD than the bog phases but there is considerable variation between the sites. The mire diversity peaks are often associated with transitional periods when high local community heterogeneity allows the coexistence of high numbers of taxa from different phylogenetic lineages. Synthesis. When the initiation of mires in isostatic land uplift areas is closely related to water‐level changes and the position of the sites in relation to the sea, the development of mires and their biodiversity in the late Holocene is associated with local conditions but mediated by climate. The ongoing rapid climate change is likely to accelerate changes in existing mires, and while the transitional periods are characterized by high diversity, these periods are temporary, and the overall diversity of mires can be expected to decrease.

Recovering Plant Microfossils from Archaeological and other Palaeoenvironmental Deposits: A Practical Guide Developed from Pacific Region Experience

Presented are revised procedures for recovering pollen and spores, phytoliths, and starch and other plant material from archaeological and other palaeoenvironmental deposits for microscopic analysis. The procedures are based on lengthy experience of preparing numerous samples of deposits from Malesia, Melanesia, Micronesia, and Polynesia. The procedures are designed as a simple laboratory guide, outlined in detail and summarized to provide a practical, time-efficient, step-by-step method. The method has been carried out successfully on many types of soils and other deposits from Pacific Islands, including: clays, silts, and sands; waterlogged, porous, peaty, volcanic, and coralline soils; and sediment cores, tools, pot sherds, dental calculus, and coprolites from a range of environmental settings in tropical, sub-tropical, and temperate climates. Also included in the procedures are mounting recovered microfossils on microscope slides and preparing and mounting modern reference samples.

Analysis of grooved ceramic vessels from the early Chinese Bronze Age site of Yanshi Shangcheng: Preliminary evidence of food preparation methods through starch analysis

A non-destructive method is used to recover starch from kecaopen grooved vessel sherds from the early Bronze Age site of Yanshi Shangcheng (“Shang city at Yan­shi”), located in the Yellow River valley of northern China (Shang Dynsaty/Erligang period). A taxonomic method using morphological and morphometric characteristics identifies extracted starch as millets, Job's tears, snakegourd root, and Triticeae grasses, such as wheat and barley. A few starch grains identified as acorn and tuber (such as lily or yam) were also identified. Damaged starch grains from the ancient starch assemblage share similarities with ground modern reference samples. This suggests that grooved vessels were used to mill plant elements and grind foodstuffs, perhaps to dehusk seeds and make flour from dried roots and acorns in the same way that grinding-stones were used in preceding periods. This hypothesis is supported by the form of the kecaopen vessel, the texture of its inner surface, and modern-use analogy. Plant taxa identified from kecaopen scrapings at Yanshi Shangcheng are similar to economically important taxa identified from scrapings of grinding-stones from preceding periods. This suggests a long continuity in plant processing methods and a long tradition of food preparation based on grinding plant elements, such as seeds, roots, tubers, and acorns.

Provenance discrimination of fine sediments by mid‐infrared spectroscopy: Calibration and application to fluvial palaeo‐environmental reconstruction

AbstractDetermining sediment provenance allows a better understanding of fluvial palaeo‐dynamics, and identifying involved watersheds, at broad spatio‐temporal scales. Conventional approaches for source identification are usually based on the physical, mineralogical, geochemical, magnetic or isotopic properties of sediments. Rapid, non‐destructive and, in well‐established contexts, highly accurate, mid‐infrared spectroscopy is an alternative method for investigating sediment sources. The present research objectives are: (i) to use the mid‐infrared spectroscopy method to discriminate the provenance of fine sediments, by applying discriminant analysis on a large set of reference samples from three different watersheds in the Upper Rhine area (associated with the Rhine, Ill and Vosges tributaries); (ii) to clarify whether the provenance spectra signatures are influenced by riverine depositional contexts (bars versus banks) and, to some extent, by grain size and/or high organic matter content; and (iii) to apply the mid‐infrared spectroscopy – discriminant analysis method to a study of fluvial palaeo‐dynamics and determine the provenance of palaeo‐channel infillings. Three main sedimentary sources, divided into eight sub‐categories, have been characterized by 196 modern reference samples from 78 collecting sites. Discriminant analysis displayed a strong separating power by classifying correctly the origin of samples without any inter‐group overlap, independently from the geomorphological context (bar or bank) and associated slight changes in organic matter contents or grain size. Mid‐infrared spectroscopy – discriminant analysis investigations of the palaeo‐channel infill, complemented by radiocarbon dates and mineralogical data, allowed reconstructing general trends for the local morpho‐sedimentary dynamics over the last ca 12 millennia.

Specular Reflection FTIR: A Non-Contact Method for Analyzing Coatings on Photographs and Other Cultural Materials

ABSTRACTCultural heritage objects present a special set of challenges to analyze chemically. Often micro-sampling or even contacting the object is not appropriate or deemed too risky for fragile surfaces. Fourier Transform Infrared (FTIR) spectroscopy is a commonly used analytical technique for organic compound identification, either in a micro-sampling or Attenuated Total Reflection (ATR) mode, both of which inherently require some measure of contact with the sample. Presented here is a case study of the use of specular reflection FTIR spectroscopy, an FTIR collection mode that allows positive chemical identifications in a non-sampling and non-contact way. Although this paper focuses on the case study of coatings on 19th century photographs, the specular reflection FTIR mode is applicable to surface coatings on any artifact where molecular composition identification is needed but micro-sampling or physical contact with the sample have been ruled out. The main limitation of the specular reflection mode has traditionally been the lack of specular reflection FTIR reference libraries. As a result, the analytical project presented here first required generation of a specular reflection FTIR spectral library for historical coating materials used on 19th century prints by creating modern reference samples. The project is a result of collaboration between conservators at the Weissman Preservation Center at Harvard Library and materials scientists at Harvard’s Center for Nanoscale Systems to analyze original coatings on 19th century salted paper photographs in the collection of the Harvard University Archives.

Histological age assessment in a prehispanic Maya sample from Xcambó, Yucatan, Mexico: Benefits and limitations

The present study explores four different regression formulae for the histological assessment of age at death in ribs and their performance in a prehispanic Classic Maya population sample consisting of 57 individuals from Xcambó, Yucatan, Mexico. Regressions employed include the original age regression formula by Stout and Paine (1992), Cho et al.'s (2002) two formulae for samples of indeterminate ethnicity, as well as a formula published by Valencia et al. (2010) adjusted specifically for populations of Maya descent. In addition to applying these methods, we report histomorphometric variables (total cortical area (TA), cortical area (CA), relative cortical area (CA/TA%), osteon population density (OPD), and osteon cross-sectional area (On.Ar.)) from the 6th rib and compare these variables across groups within our sample defined by macroscopic age and sex, as well as with results reported for modern reference samples used by Cho et al. and Valencia and colleagues. Our study shows mean CA and CA/TA% are relatively high across all ages in the prehispanic Maya sample, especially in females, indicating a high degree of robusticity. OPD is high when compared with samples used by Cho et al., but similar to the modern Maya reference sample. Comparison of histological age at death estimates reveals interesting patterns of deviation; specifically Cho et al.'s formulae both deviate strongly from all other age estimates. Calculated mean net difference between Cho et al.'s and macroscopic age estimates, for example, is nearly 16 years. Both, Stout and Paine, and Valencia et al., result in age reconstructions more similar to macroscopic estimates (mean net difference around 8 years). Since Cho et al.'s formulae are unique in employing On.Ar., CA, and TA, in addition to OPD, OPD-based regression formulae may perform better in archaeological samples. However, some of the deviation observed could result from differences in histomorphometric variables between modern reference and archaeological samples, the outcome of complex biocultural processes. Continued analyses of histomorphological variation between differing reference and archaeological samples will be necessary to improve histological assessments of age at death in archaeological contexts.

Reporting atmospheric CO2 pressure corrected results of stable carbon isotope analyses of cereals remains from the archaeological site of Peñalosa (SE Iberian Peninsula): agricultural and social implications

The practice of agriculture across the Mediterranean basin has had significant social and economic consequences, including the development of social inequalities. To inform on plant water status and thus on agricultural management techniques and environmental conditions during the first half of the second millennium BCE, we measured stable carbon isotopes in a set of 280 seeds of Hordeum vulgare L. and Pisum sativum from the archaeological site of Penalosa (Banos de la Encina, southern Iberian Peninsula). The ranges in stable carbon isotope values for archaeological samples were wider than those observed for modern reference samples collected in 2014 and 2015, suggesting that archaeological samples experienced more varied water status conditions. This variability was associated with the location of the seeds within the site and could be a consequence of the cultivation of different plots and/or from temporal variations in local environmental conditions. For absolute comparisons of water status between modern and past samples, we introduced a novel correction to account for temporal changes in the concentration of atmospheric CO2 in addition to the usual adjustment that accounts for the variability in atmospheric CO2 stable carbon isotope values. This comparison showed that past samples had greater water availability than modern references, and thus, irrigation or intentional selection of naturally irrigated soils was practiced at the site.

Osseous Frame Index calculations of the early medieval South-West Germany.

The proper description of former populations is one of the most difficult tasks in anthropology. Archaeological material is often limited due to fragmented and sometimes poorly preserved bone material resulting in incomplete data. Published skeletal raw data are available from the past, but much of this data is either unavailable or not used for scientific studies. The authors seek to elicit more information about prehistoric times by using this dataset to introduce a new method. The purpose is to provide an approach to reconstruct a former population in respect to robusticity and health status. For this in the pilot study the Body Mass Index (BMI) and Frame Index (FI) of early medieval South-West Germany have been analysed. The FI, in contrast to the BMI, has not yet been used for robusticity analysis utilizing only skeletal remains. As far as we know, this is the first time that the FI has been calculated using archaeological material. Due to unknown soft-tissue thickness we introduce the Osseous Frame Index (OFI). The measured OFI reveals new insights in (pre-)historic populations and allows comparisons with modern reference samples. Our OFI calculations are relatively similar to modern calculations. Males have a higher robusticity than females, slightly increasing during life-time compared to females. These calculations provide a better historical understanding of human body composition.

Beyond size: The potential of a geometric morphometric analysis of shape and form for the assessment of sex in hand stencils in rock art

Hand stencils are some of the most enduring images in Upper Palaeolithic rock art sites across the world; the earliest have been dated to over 40 Kya in Sulawesi and 37 Kya in Europe. The analysis of these marks may permit us to know more about who was involved in the making the of prehistoric images as well as expanding the literature on the evolution of human behaviour. A number of researchers have previously attempted to identify the sex of the makers of Upper Palaeolithic hand stencils using methods based on hand size and digit length ratios obtained from digital or photo-based images of modern reference samples. Some analyses report that it was males who were responsible for the majority of hand stencils, whilst the most recent analysis determined that females produced the majority of hand stencils. Taken together, however, these studies generate contrasting and incompatible interpretations. In this study we critically review where we currently stand with methods of sexing the makers of hand stencils and the problems for the interpretation of hand markings of Palaeolithic age. We then present the results of a new method of predicting the sex of individuals from their hand stencils using a geometric morphometric approach that detects sexual differences in hand shape and hand form (size and shape). The method has the additional advantage of being able to detect these differences in both complete, as well as partial hand stencils. Finally we urge researchers to test this method on other ethnic groups and populations and consider ways of combining efforts towards a common goal of developing a robust, predictive methodology based on diverse modern samples before it is applied to Upper Palaeolithic hand stencils.

Cortical bone loss in a sample of human skeletons from the Muge Shell middens

The Muge shell middens of Cabeco da Arruda, Cabeco da Amoreira and Moita do Sebastiao (central Portugal) have been key sites of archaeological research for 150 years, possibly working as residential sites occupied by semi-sedentary communities during the final Mesolithic. The purposes of this article include the biocultural assessment of metacarpal cortical bone fragility and its associations with age at death, sex and osteoporotic fractures in the Portuguese Mesolithic, as well as a diachronic comparison of cortical bone health in Mesolithic (N = 34) and modern reference (N = 219) samples. Cortical bone at the Muge shell middens displays age and sex-specific trajectories of periosteal apposition and endosteal bone loss, most likely associated with hormonal and behavioural/cultural influences. Metacarpal endocortical bone loss seems to increase with age at death in females, with a simultaneous expansion of the diaphysis. The overall pattern of cortical bone health is similar to the pattern observed in a reference skeletal collection, but elderly women from Muge seem to lose less cortical bone than late twentieth century counterparts from Coimbra. Two older males exhibited vertebral compression fractures, but only one is possibly related with bone fragility.

Buried in ashes: Site formation processes at Lapa do Santo rockshelter, east-central Brazil

Few archaeological sites in the Americas contain high concentrations of human burials dating back to the early Holocene. The tropical karstic region of Lagoa Santa, in central Brazil (state of Minas Gerais) is one of the richest bioanthropological records available to study the behaviors and funerary practices of early Holocene South Americans, with more than 200 skeletons found so far. One of the key locations to examine the history of human settlement in Lagoa Santa is the site of Lapa do Santo, a rockshelter known to contain the oldest rock art and the earliest evidence of funerary complexity in the continent. In this geoarchaeological investigation we focus on the early Holocene settlement at Lapa do Santo (7.9–12.7 cal kyBP) applying high-resolution geoarchaeological techniques, such as micromorphology, organic petrology and μFTIR, on both archaeological, modern reference and experimental samples. This is the first time that a micro-contextual approach integrated with experimental geoarchaeology has been applied to study the formation of rockshelter deposits in a tropical setting. Our results show that the stratigraphic sequence formed under the dual influence of anthropogenic sedimentation—through continuous combustion activities—and geogenic sedimentation in the form of oxisol aggregates which fell from above the limestone cliff into the rockshelter. Intact hearths and remobilized combustion debris, possibly hearth rake-out, are close to the graves suggesting repeated burning activities as part of the ritual behavior of early Holocene South Americans. Large amounts of ash are intermixed with heated and unheated oxisol aggregates. Heated termite mound fragments were also found mixed within the sediments. Post-depositional alteration of the site includes limited bioturbation and localized, low energy surface water and sub-surface concentrations of moisture, leading to precipitation of dense, secondary carbonates. The age inversions can be attributed to the human action of reworking the ashy sediments and not to post-abandonment processes. Despite this, the overall preservation of the sediments is good and most human burials can be considered to be in primary context.

Identification of beeswax excavated from the Han Period Mausoleum M1 of the King of Jiangdu, Jiangsu, China

Two amorphous lumps of a black material with a combined weight of c. 1kg were recovered during rescue excavations at the Mausoleum M1 of the King of Jiangdu, located at Dayun Hill, Jiangsu Province, China, and dated to the Western Han Period (202 BC–8AD). This paper reports the analysis of this material by Fourier-transform infrared spectroscopy, gas chromatography and gas chromatography–mass spectrometry. Through comparison with modern reference samples, the archaeological material is identified as beeswax. Based on archaeological and documentary evidence, it is argued that this provides direct evidence for the early use of beeswax and could constitute the earliest use of beeswax as fuel for lamps in China.

Body mass estimates of hominin fossils and the evolution of human body size

Body size directly influences an animal's place in the natural world, including its energy requirements, home range size, relative brain size, locomotion, diet, life history, and behavior. Thus, an understanding of the biology of extinct organisms, including species in our own lineage, requires accurate estimates of body size. Since the last major review of hominin body size based on postcranial morphology over 20 years ago, new fossils have been discovered, species attributions have been clarified, and methods improved.Here, we present the most comprehensive and thoroughly vetted set of individual fossil hominin body mass predictions to date, and estimation equations based on a large (n = 220) sample of modern humans of known body masses. We also present species averages based exclusively on fossils with reliable taxonomic attributions, estimates of species averages by sex, and a metric for levels of sexual dimorphism. Finally, we identify individual traits that appear to be the most reliable for mass estimation for each fossil species, for use when only one measurement is available for a fossil.Our results show that many early hominins were generally smaller-bodied than previously thought, an outcome likely due to larger estimates in previous studies resulting from the use of large-bodied modern human reference samples. Current evidence indicates that modern human-like large size first appeared by at least 3–3.5 Ma in some Australopithecus afarensis individuals. Our results challenge an evolutionary model arguing that body size increased from Australopithecus to early Homo. Instead, we show that there is no reliable evidence that the body size of non-erectus early Homo differed from that of australopiths, and confirm that Homo erectus evolved larger average body size than earlier hominins.

Differentiating dietary and non-dietary microfossils extracted from human dental calculus: the importance of sweet potato to ancient diet on Rapa Nui

Human dental calculus is an excellent target for examining the plant component of ancient diets. Microfossils become imbedded within dental calculus throughout life, providing an overall picture of plant foods available (at least those that produce recoverable microfossils). Here we evaluate previous phytolith results (Dudgeon and Tromp, 2012) by examining starch grains from 30 human dental calculus samples from 10 archaeological sites throughout Rapa Nui (Easter Island), dating between AD 1330–1900. The unobscured starch grains recovered are consistent with descriptions of modern reference samples of sweet potato (Ipomoea batatas). These results indicate the importance of sweet potato to the Rapanui diet prior to European contact in 1722. The analysis of modern sweet potato skins show that they incorporate phytoliths as they grow in phytolith rich sediment, and we argue that the high frequency of palm phytoliths recovered from dental calculus, in conjunction with our starch results points to the consumption of sweet potato.

Identification of Carbonized Breadfruit (Artocarpus altilis) Skin: Refining Site Function and Site Specialization in the Society Islands, East Polynesia

Using systematic flotation, we recovered small carbonized fragments of breadfruit skin (exocarp) from a house site dated to the late prehistoric period on the island of Mo'orea in the Society Islands archipelago (East Polynesia). Our find is the first record of the fruit of breadfruit from Oceanic archaeobotanical material. Utilizing direct ethnographic analogy, our analysis of the archaeological breadfruit remains, including their context and morphology, and their comparison with experimentally charred modern reference samples of breadfruit exocarp, suggests that these remains resulted from the practice of roasting breadfruit. Taken as a whole, these data provide evidence for the practice of breadfruit roasting in the past. More importantly, the evidence contributes new information on site function in the context of a larger study concerning late prehistoric household variability. The case study broadly supports how paleoethnobotanical data can provide supporting evidence for inferring site function and site specialization.

Discovery of a Remnant Population of Sierra Nevada Red Fox (Vulpes Vulpes Necator)

The Sierra Nevada red fox (Vulpes vulpes necator) occurred historically throughout the high elevations of California's Sierra Nevada and southern Cascade Mountains. Before this study, the only known remaining population in California consisted of ≤ 20 individuals restricted to the Lassen Peak region in the southern Cascades. In August 2010, we photographed a red fox in the Sonora Pass area of the Sierra Nevada, > 100 km from the Lassen Peak region. To determine if multiple individuals were present and were indigenous, we set up additional camera stations, collected genetic samples (saliva, scat, hair, and a carcass), and conducted a comparative genetic analysis between these individuals and historical and modern reference samples. Photo-detections identified at least three individuals based on pelage characteristics. Genetic analyses identified two females and one male, whose microsatellite profiles suggested they were closely related. A genetic assignment analysis indicated that all three individuals clustered most closely (> 95%) with historical samples from the Sierra Nevada, and were distinct from those in the Lassen Peak region. Additionally, mtDNA and microsatellite alleles unique to each population confirmed that the Sonora Pass individuals represent a second remnant California population of Sierra Nevada red fox. Reduced genetic diversity relative to historical levels in both remnant populations was consistent with small populations. Follow-up surveys are needed to determine the abundance and distributional extent of the Sonora Pass population, combined with research on both populations to assess demographic trajectories, determine threats, and to inform conservation efforts.