Problem Of Equifinality Research Articles

Between space and time. Naturalist taphonomic observations of lesser rhea (Rhea pennata pennata) remains in southern patagonia and its archaeological implications

The results of taphonomic observations of modern bones of lesser rhea, a large flightless bird, endemic to South America, are presented. The aim was to know the sequence of disarticulation and destruction of bone elements of this species, as a means to interpret and understand the anatomical frequencies in zooarcheological assemblages. The results obtained in a wide spatial or landscape scale are combined with those of longitudinal or long-term observations of naturally deposited lesser rhea carcasses. These bird remains are scarce in the archaeological deposits of the region, while exhibiting an anatomical representation in which the elements of the hindlimbs predominate. Actualistic observations showed a similar representation in modern natural assemblages, in which the joints that last longer include the pelvis/sacrum-hindlimbs, and hindlimbs elements from each other. The latter are the last to be destroyed. That is to say that two different processes, natural recycling and the human action of selective transport, can result in the same representation pattern of skeletal parts of Rhea pennata pennata, which poses a problem of equifinality that is difficult to solve.

Reply to “very human bears” by Rosell et al., 2019 Quaternary International

Rosell et al. (2019) warn about potential equifinality problems between human and bear tooth marks in their type, morphology, and measurements. They also note the possibility that both agents generate peeling on some bones, such as ribs and apophyses of vertebrae. However, we think that from an epistemological point of view, the authors fail to turn specific experimental models into general ones. Moreover, from a technical point of view, Rosell and colleagues make mistakes in the measurement of tooth marks and their comparative application. These two issues allow us to argue that their results are not sufficient to invalidate the inferences of human tooth marks in assemblages of anthropogenic origin, such as the TD6.2 level of Gran Dolina (Atapuerca).

Sensitivity Assessment of a Runoff Formation Model in the Mozhaisk Reservoir River Basin

The physically based model of river runoff formation with a daily resolution ECOMAG was adapted for the Mozhaisk Reservoir with an area of 1360 km2. A large series of numerical experiments were carried out in order to investigate the sensitivity of the model to the spatial resolution of land surface characteristics and the size of calculation cells. Digital elevation models (DEMs) of three different spatial resolutions (50, 100 m, and 2 km) were used along with model schematizations of the catchment area and river network with varying detail. In addition, the model sensitivity to sets of calibration parameters when modelling genetic runoff components was studied, as a part of the approaches to mitigating the problem of equifinality. The importance of incorporating additional hydrochemical information for a correct description of the spatial and temporal genetic structure of river runoff is shown.

Parameter uncertainty estimation of transient storage model using Bayesian inference with formal likelihood based on breakthrough curve segmentation

The transient storage model (TSM) for the analysis of pollutant mixing in rivers has been hampered by parameter uncertainties due to the equifinality problem. The generalized uncertainty estimation method, which was frequently used to quantify the parameter uncertainty of TSM, has been criticized because this method uses informal likelihood which can cause overestimation of the uncertainty. Thus, in this study, we suggest a Bayesian inference method using a segment mixture (SM) likelihood, which is a formal likelihood based on the mixture distribution of the segmented breakthrough curve. The uncertainty estimation was conducted using three synthetic data and the real tracer test data achieved from Uvas Creek in the USA. The results show that the SM likelihood estimated uncertainties of TSM appropriately by correctly representing the error distribution of the TSM and identifying the behavioral parameters.

Very human bears: Wild brown bear neo-taphonomic signature and its equifinality problems in archaeological contexts

Different agents can lead to similar damage patterns, and different causes can result in the same type of modification. This phenomenon was defined by Lyman (1987) as a problem of equifinality, with which the researcher warned about the risks of making direct systematic correlations. The fact that a specific type of damage cannot be linked to a single actor, behaviour or ecological context is primarily applicable to damage associated with the direct consumption of carcasses. Some carnivores show physical and dental characteristics that could lead to bone modifications potentially like those generated by humans. For example, bears have a bunodont dentition and plantigrade locomotion –the latter allows them to frequently release and use their claws as “hands”. Here, we present the neo-taphonomical study of 17 ungulate carcasses eaten by wild brown bears (Ursus arctos arctos) in the Spanish Pyrenees. Our observations express this equifinal problem due to the similarities between tooth marks and peeling generated by both bears and humans. This fact is especially significant, given that peeling and the combination of this damage with visible tooth marks were primarily associated with the feeding activities of humans and chimpanzees (Pan troglodytes) and only anecdotally with other taphonomic agents, such as spotted hyenas. With this research, we try to show some equifinal phenomena that could occur in Pleistocene faunal assemblages as well, where the presence of both hominids and bears is documented.

Who ate OH80 (Olduvai Gorge, Tanzania)? A geometric-morphometric analysis of surface bone modifications of a Paranthropus boisei skeleton

Olduvai Gorge (Tanzania) is one of the key areas for the study of human origins, given the sheer abundance of archaeological and paleontological sites discovered. Several of these archaeological sites have yielded numerous hominin fossils and traces of their activities, thus offering invaluable insights into the nature and origins of human behavior. Nevertheless, certain taphonomic discussions that have been of great importance for the study of the South African cave sites have remained unnoticed in East Africa. One of these issues revolves around the interpretation of Paranthropus as a common prey of predators. In this paper, we analyze the postcranial remains of OH80, a partial skeleton of a Paranthropus boisei discovered at the BK site (Bell Korongo, Bed II of Olduvai Gorge, Tanzania) in 2010. Some of the specimens of this skeleton have been reported to show surface modifications tentatively associated to the action of carnivores. Here, several pits observed on OH80-12, the Paranthropus boisei femur, were digitally reconstructed and analyzed through geometric morphometrics to determine the nature of the marks. The OH80-12 marks are compared with a modern sample of percussion marks and several carnivore tooth pits, since the action of both agents has previously been identified at the site and can sometimes result in equifinality problems. Alongside already published geometric morphometric tests, here we present a very newly developed approach based on the combination of geometric morphometric data and the training of machine learning algorithms. Both methodologies highlight that OH80 was consumed by carnivores, being a felid the most likely modifying agent.

Characterising leopard as taphonomic agent through the use of micro-photogrammetric reconstruction of tooth marks and pit to score ratio

ABSTRACT Leopards have been the focus of taphonomic research due to their capacity to create bone accumulations, prey on some hominin groups or potentially provide scavenging opportunities to early hominins. Some of the variables explored to characterise felids as taphonomic agents have presented problems of equifinality, such as the frequency of tooth marks on long bone shafts or the dimensions of tooth pits and scores. Recently, new methodologies based on microphotogrammetry and geometric morphometrics have been developed for the morphologic analysis of taphonomic marks, such as tooth marks. Through a review of Bob Brain’s neotaphonomic collection, the present study applies these new techniques to reconstruct leopard tooth marks and compare these with tooth marks from lions and spotted hyenas. Along with this, the ratio pit to score, a taphonomic variable previously characterised in lions and spotted hyenas, has been analysed. Results show that tooth marks inflicted by leopards, spotted hyenas and lions can be statistically differentiated based on their morphology. On the other hand, the ratio pit to score inflicted by the leopard is closer to hyenas.

Parameter sensitivity analysis of a root system architecture model based on virtual field sampling

Traits of the plant root system architecture (RSA) play a key role in crop performance. Therefore, architectural root traits are becoming increasingly important in plant phenotyping. In this study, we use a mathematical model to investigate the sensitivity of characteristic root system measures, obtained from different classical field root sampling schemes, to RSA parameters. Root systems of wheat and maize were simulated and sampled virtually to mimic real field experiments using the root system architecture (RSA) model CRootBox. By means of a sensitivity analysis, we found RSA parameters that significantly influenced the virtual field sampling results. To identify correlations between sensitivities, we carried out a principal component analysis. We found that the parameters of zero order roots are the most sensitive, and parameters of higher order roots are less sensitive. Moreover, different characteristic root system measures showed different sensitivity to RSA parameters. RSA parameters that could be derived independently from different types of field observations were identified. Selection of characteristic root system measures and parameters is essential to reduce the problem of parameter equifinality in inverse modeling with multi-parameter models and is an important step in the characterization of root traits from field observations.

Economic anatomy of Rheidae and its implication for the archeological record

The economic anatomy for Rheidae (Class: Birds) which includes the calculation of the Modified General Utility Index (MGUI) and its component indexes: Meat Utility Index (MUI), Marrow Index (MI), White Grease Index (WGI), and General Utility Index (GUI) are presented in this paper. In addition, I describe the methodology implemented to generate each index and discuss these results, applying them to an archeofaunal setting. The results show net values of meat utility, which are associated to the anatomical portions of the appendicular skeleton; a high grease index, which is associated to the axial portions (mainly pelvis, sacrum, and sternum); and a high marrow index in the tibiotarsus and tarsometatarsus. The correlation that exists between the Economic Utility Index and the Structural Bone Density Index shows an equifinality problem. Finally, I compare the Utility Index for other ratites built with the purpose of giving an analogy for all the species that constitute this group of birds.

Differentiating percussion pits and carnivore tooth pits using 3D reconstructions and geometric morphometrics.

During the end of the 20th century and the beginning of the 21st century the discussion on early human behavioral patterns revolved around the hunting versus scavenging debate. The correct identification of bone modifications, including percussion, cut and tooth marks, is a key issue within this debate. While many authors have shown that carnivore and human modifications can be easily distinguished, it is true that sometimes percussion marks without associated microstriations and tooth pits overlap morphologically, causing confusion, especially when unmodified hammerstones are used. In order to solve this equifinality problem, many investigations have focused their efforts on other pieces of evidence such as the identification of notches, fragmentation patterns and frequencies, among others. These studies, however, cannot be considered as fully conclusive. Within this paper we address the problem of equifinality when identifying percussion marks produced with unmodified hammerstones and tooth pits created by carnivores using new methodologies based on the 3D reconstruction of marks and their statistical multivariate analysis. For the purpose of this study a total of 128 marks– 39 percussion marks produced with an unmodified quartzite hammerstone, and 89 pits generated by different carnivores–were virtually modelled with the aid of a DAVID structured-light scanner SLS-2 and later analyzed by means of geometric morphometrics. Our results show that percussion marks not associated with striae fields and the pits generated by the carnivores studied here can be successfully distinguished.

Generative inference for cultural evolution.

One of the major challenges in cultural evolution is to understand why and how various forms of social learning are used in human populations, both now and in the past. To date, much of the theoretical work on social learning has been done in isolation of data, and consequently many insights focus on revealing the learning processes or the distributions of cultural variants that are expected to have evolved in human populations. In population genetics, recent methodological advances have allowed a greater understanding of the explicit demographic and/or selection mechanisms that underlie observed allele frequency distributions across the globe, and their change through time. In particular, generative frameworks-often using coalescent-based simulation coupled with approximate Bayesian computation (ABC)-have provided robust inferences on the human past, with no reliance on a priori assumptions of equilibrium. Here, we demonstrate the applicability and utility of generative inference approaches to the field of cultural evolution. The framework advocated here uses observed population-level frequency data directly to establish the likely presence or absence of particular hypothesized learning strategies. In this context, we discuss the problem of equifinality and argue that, in the light of sparse cultural data and the multiplicity of possible social learning processes, the exclusion of those processes inconsistent with the observed data might be the most instructive outcome. Finally, we summarize the findings of generative inference approaches applied to a number of case studies.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

Improving drought simulations within the Murray-Darling Basin by combined calibration/assimilation of GRACE data into the WaterGAP Global Hydrology Model

Simulating hydrological processes within the (semi-)arid region of the Murray-Darling Basin (MDB), Australia, is very challenging specially during droughts. In this study, we investigate whether integrating remotely sensed terrestrial water storage changes (TWSC) from the Gravity Recovery And Climate Experiment (GRACE) mission into a global water resources and use model enables a more realistic representation of the basin hydrology during droughts. For our study, the WaterGAP Global Hydrology Model (WGHM), which simulates the impact of human water abstractions on surface water and groundwater storage, has been chosen for simulating compartmental water storages and river discharge during the so-called ‘Millennium Drought’ (2001–2009). In particular, we test the ability of a parameter calibration and data assimilation (C/DA) approach to introduce long-term trends into WGHM, which are poorly represented due to errors in forcing, model structure and calibration. For the first time, the impact of the parameter equifinality problem on the C/DA results is evaluated. We also investigate the influence of selecting a specific GRACE data product and filtering method on the final C/DA results. Integrating GRACE data into WGHM does not only improve simulation of seasonality and trend of TWSC, but also it improves the simulation of individual water storage components. For example, after the C/DA, correlations between simulated groundwater storage changes and independent in-situ well data increase (up to 0.82) in three out of four sub-basins. Declining groundwater storage trends - found mainly in the south, i.e. Murray Basin, at in-situ wells - have been introduced while simulated soil water and surface water storage do not show trends, which is in agreement with existing literature. Although GRACE C/DA in MDB does not improve river discharge simulations, the correlation between river storage simulations and gauge-based river levels increases significantly from 0.15 to 0.52. By adapting the C/DA settings to the basin-specific characteristics and reducing the number of calibration parameters, their convergence is improved and their uncertainty is reduced. The time-variable parameter values resulting from C/DA allow WGHM to better react to the very wet Australian summer 2009/10. Using solutions from different GRACE data providers produces slightly different C/DA results. We conclude that a rigorous evaluation of GRACE errors is required to realistically account for the spread of the differences in the results.

Abrupt cooling events during the Early Holocene and their potential impact on the environment and human behaviour along the southern North Sea basin (NW Europe)

ABSTRACTIn this paper the potential impact of the 9.3k cal a BP cooling event on the environment and human occupation in the Rhine–Meuse–Scheldt region of NW Europe is investigated. Although various environmental (decreased fluvial activity, increased wildfires and changing vegetation) and cultural changes (lithic technology, raw material circulation, decreasing site density) can be identified in the (late) Boreal, a serious problem of equifinality remains. Lacking a high‐resolution chronology for these events, it is still difficult to separate the impact of gradual from punctuated climatic changes. However, at present it seems that (some) environmental and cultural changes were already ongoing before the 9.3k cal a BP event but were accelerated by the latter. To gain a better understanding of these processes, it is necessary to take a holistic, multidisciplinary approach towards the Early Holocene in the southern North Sea basin.

Parameter estimation and uncertainty analysis of the Spatial Agro Hydro Salinity Model (SAHYSMOD) in the semi-arid climate of Rechna Doab, Pakistan

Manual calibration of distributed models with many unknown parameters can result in problems of equifinality and high uncertainty. In this study, the Generalized Likelihood Uncertainty Estimation (GLUE) technique was used to address these issues through uncertainty and sensitivity analysis of a distributed watershed scale model (SAHYSMOD) for predicting changes in the groundwater levels of the Rechna Doab basin, Pakistan. The study proposes and then describes a stepwise methodology for SAHYSMOD uncertainty analysis that has not been explored in any study before. One thousand input data files created through Monte Carlo simulations were classified as behavior and non-behavior sets using threshold likelihood values. The model was calibrated (1983–1988) and validated (1998–2003) through satisfactory agreement between simulated and observed data. Acceptable values were observed in the statistical performance indices. Approximately 70% of the observed groundwater level values fell within uncertainty bounds. Groundwater pumping (Gw) and hydraulic conductivity (Kaq) were found to be highly sensitive parameters affecting groundwater recharge.

Identification of the dominant hydrological process and appropriate model structure of a karst catchment through stepwise simplification of a complex conceptual model

Conceptual models often suffer from the over-parameterization problem due to limited available data for the calibration. This leads to the problem of parameter nonuniqueness and equifinality, which may bring much uncertainty of the simulation result. How to find out the appropriate model structure supported by the available data to simulate the catchment is still a big challenge in the hydrological research. In this paper, we adopt a multi-model framework to identify the dominant hydrological process and appropriate model structure of a karst spring, located in Guilin city, China. For this catchment, the spring discharge is the only available data for the model calibration. This framework starts with a relative complex conceptual model according to the perception of the catchment and then this complex is simplified into several different models by gradually removing the model component. The multi-objective approach is used to compare the performance of these different models and the regional sensitivity analysis (RSA) is used to investigate the parameter identifiability. The results show this karst spring is mainly controlled by two different hydrological processes and one of the processes is threshold-driven which is consistent with the fieldwork investigation. However, the appropriate model structure to simulate the discharge of this spring is much simpler than the actual aquifer structure and hydrological processes understanding from the fieldwork investigation. A simple linear reservoir with two different outlets is enough to simulate this spring discharge. The detail runoff process in the catchment is not needed in the conceptual model to simulate the spring discharge. More complex model should need more other additional data to avoid serious deterioration of model predictions.

NEW CRITERIA FOR THE ARCHAEOLOGICAL IDENTIFICATION OF BONE GREASE PROCESSING

Bone grease processing is frequently used in archaeology to investigate human diet breadth because it constitutes a costly mode of lipid procurement. However, problems of equifinality often complicate the identification of this activity. This paper develops new criteria focused on morphology, the presence of micro-inclusions, and forms of damage that were derived from a bone grease rendering experiment that involved red deer(Cervus elaphus)long bones. Because they are poorly represented in a distinct experiment focused exclusively on marrow extraction, the criteria presented here appear to provide robust signatures of bone grease processing. A survey of the actualistic literature shows that certain bone processing activities, such as stewing and soup making, mostly involve coarse spongy fragments. Because these fragments are too large to be ingested, grease can be extracted from them only through heating or boiling. In contrast, bones ingested in bone meal or as flour necessitate pulverization. A high percentage of coarse fragments may therefore provide a proxy for cooking technology or, minimally, the use of fire, if other patterns are consistent with grease extraction. Given the evolutionary significance of these innovations, the criteria presented here may help to strengthen arguments about dietary shifts during the Paleolithic and later periods.

Reliability of Genotype-Specific Parameter Estimation for Crop Models: Insights from a Markov Chain Monte-Carlo Estimation Approach

Abstract. Parameter estimation is a critical step in successful application of dynamic crop models to simulate crop growth and yield under various climatic and management scenarios. Although inverse modeling parameterization techniques significantly improve the predictive capabilities of models, whether these approaches can recover the true parameter values of a specific genotype or cultivar is seldom investigated. In this study, we applied a Markov Chain Monte-Carlo (MCMC) method to the DSSAT dry bean model to estimate (recover) the genotype-specific parameters (GSPs) of 150 synthetic recombinant inbred lines (RILs) of dry bean. The synthetic parents of the population were assigned contrasting GSP values obtained from a database, and each of these GSPs was associated with several quantitative trait loci. A standard inverse modeling approach that simultaneously estimated all GSPs generated a set of values that could reproduce the original synthetic observations, but many of the estimated GSP values significantly differed from the original values. However, when parameter estimation was carried out sequentially in a stepwise manner, according to the genetically controlled plant development process, most of the estimated parameters had values similar to the original values. Developmental parameters were more accurately estimated than those related to dry mass accumulation. This new approach appears to reduce the problem of equifinality in parameter estimation, and it is especially relevant if attempts are made to relate parameter values to individual genes. Keywords: Crop models, Equifinality, Genotype-specific parameters, Markov chain Monte-Carlo, Parameterization.

Mammal bone surface alteration during human consumption: An experimental approach

The study of human tooth marks on bones remains constitutes a promising line of research of high archaeological interest. Most taphonomic studies assume that tooth marks in bones are evidences of carnivore intervention. However, human beings, regardless of the use of lithic artifacts, access to animal nutrients through their masticatory system producing bite marks. In order to solve equifinality problems of the marks left during consumption, a study with volunteers has been carried out. Ten volunteers ate meat from the scapulae, radii and phalanges of Ovis aries, trying to bite the bones and extract the meat as much as possible. Each piece was consumed raw, roasted and boiled by the same people in order to differentiate marks according to bone and the type of cooking treatment. A significant number of marks were observed including types, morphologies and metric values. Differences between raw and cooked bones were also detected. These results may contribute to identify human bite marks and cooking treatment in the archaeological record.

Using Computational Modeling for Building Theory: A Double Edged Sword

Computational modeling is a powerful method for building theory. However, to construct a computational model, researchers need to operationalize their cognitive or verbal theory into the specific terms demanded by the simulation’s language. This requires the researcher to make a series of reasonable assumptions to fill unanticipated “specificity gaps.†The problem is that many other reasonable assumptions could also have been made, and many of those resulting models would also match the conceptual theory. This is the problem of equifinality. We demonstrate the power and the dangers of computational modeling by building a simulation of a classic small group study. The results demonstrate that reasonable assumptions and equifinality are straightforward (but often overlooked) problems at the core of genuinely useful methodology. We offer recommendations and hope to open a dialog on other perspectives and solutions.

The demography of the Upper Palaeolithic hunter–gatherers of Southwestern France: A multi-proxy approach using archaeological data

Demographic change is increasingly cited as an explanation for many of the patterns seen in the Palaeolithic archaeological record, following the assumption of a relationship between population size and material culture espoused by dual inheritance theory. However, the empirical testing of this relationship relies on the ability to extract information about past population patterns from the archaeological record. Using the extensive and well-studied record of the Upper Palaeolithic (∼39,500–11,500calBP) hunter–gatherers of Southwestern France as a case-study, this paper compares the evidence for changes in relative population size as seen in three popular archaeological proxies for demographic change (site counts, site sizes, and occupation intensity estimates). These proxies present conflicting results across the sequence; a finding which is explored through the impact of taphonomic biases and past research agendas. Numbers of sheltered sites and quantities of retouched stone tools are suggested to be the most reliable demographic proxies. The problem of equifinality of interpretation in archaeological proxies for demography is examined for the Aurignacian and Gravettian periods in the region, with changes in lithic raw material, faunal acquisition strategies, and hunter–gatherer mobility all potentially contributing to the patterns documented.