Skeletal element abundances in archaeofaunal assemblages: economic utility,sample size,and assessment of carcass transport strategies

Economic utility indices provide a means of interpreting butchery and transport decisions reflected in the relative abundance of skeletal elements. Because of destructive taphonomic processes, interpreting skeletal element abundances in terms of carcass transport strategies requires that faunal analysts consider only those elements which accurately reflect their original abundances following human discard. In this study we use resampling techniques to examine the impact of sample size on correlations between high-survival skeletal element frequencies and economic utility in four simulated population assemblages reflecting distinct carcass transport strategies. Correlations alone do not accurately reflect the true relationship between bone abundance and economic utility as particular transport strategies have a tendency to generate high frequencies of Type II errors as sample size decreases. We show that the Shannon evenness index can be used as a quantitative means of distinguishing between bone assemblages characterized by subtle variations in skeletal element abundances. The evenness index can also be used to evaluate whether observed correlations reflect sampling error. Results from our simulations are applied to three published faunal assemblages to evaluate likely carcass transport strategies.     

Bone survival: The effects of sedimentary abrasion and trampling on fresh and cooked bone

It is commonly assumed that, at least when considering similar sized animals, the bones from all taxa stand an equal chance of preservation. This paper summarizes one aspect of a larger study undertaken in order to assess whether this assumption is true, based on the results of experiments and observations into the effects of a range of pre-depositional processes. The rates of bone destruction by sedimentary abrasion and by trampling are determined for small mammal, fish and frog bones. Patterns of bone loss and fragmentation are examined both between species and within the skeleton, for fresh and boiled bone. It is shown that there is considerable interspecies variation in the ability of bones to withstand these physical forces. Frog bone proved particularly resistant, while within the fish, bone from the Gadidae was less resilient than might be expected, given its predominance in British Medieval archaeological sites and coastal sites of all periods. Within the skeleton, bone shape appears to be a very important determinant of relative survival. Boiling dramatically reduces bone's resistence to destruction. The physical properties of fresh, boiled and burnt bone are compared mechanically, and the dramatic loss of strength induced by heating is demonstrated. The often voiced assumption that fish bone is more prone to destruction than mammal bone is shown to have some validity. The results add more evidence to support the view that comparison of species abundance by fragment counts may not always be appropriate, and that interpretation of skeletal element frequencies should be approached with caution.     

Tracking changes in bone fracture morphology over time: environment, taphonomy, and the archaeological record

Zooarchaeologists have often employed studies of bone fracture morphology as a means of understanding past human cultural activity, and various methodological approaches have been developed for analyzing archaeological broken bone assemblages. It is widely understood that bones degrade over time, however, few studies have attempted to define and quantify the rate at which bones degrade and fracture morphologies change. This study examines degradation in frozen bones (−20 °C) and bones exposed to hot (40 °C) dry conditions. These two simulated environmental conditions represent extreme real-world climates, and allow for an actualistic understanding of the rates of degradation that bones experience in nature. When frozen, bones degrade slowly but significantly, and demonstrate measurable differences in samples frozen for 1, 10, 20, 40, and 60 weeks. In hot, dry conditions, bones degrade very quickly, and demonstrate measurable differences after 1, 3, 7, 14, and 21 days. These data allow for a more detailed understanding of the relationship between the cultural and natural processes that result in bone fracture, and the time period during which bones can be expected to maintain fresh fracture characteristics. This research also has implications for understanding human subsistence and survival strategies and for interpreting the archaeological record.     

Avian taphonomy: observations at two Magellanic penguin (Spheniscus magellanicus) breeding colonies and their implications for the fossil record

Actualistic studies on vertebrate taphonomy have centred on mammals, and to a much lesser extent on flying birds. Members of the Spheniscidae are anatomically specialized making it problematic to make direct inferences from previous taphonomic work. Modern bone assemblages from two Spheniscus magellanicus breeding colonies on the southern Atlantic coast of continental Patagonia, Argentina, were surveyed on foot along linear transects, and features were determined that are useful in interpreting the fossil record. Present day bone accumulations have specific properties resulting from penguin anatomy and osteology as well as from the composition of the vertebrate community and regional environmental conditions. Most salient are the high spatial density of bones, the dominance of Spheniscidae remains over those of other vertebrates, the high percentage of disarticulated bones, the predominance of limb bones, the low frequencies of carnivore bone modifications, and the abundance of fractured bones. Many of these features observed in the modern assemblages can be identified in fossil avian bone deposits.     

Destruction of microstructure in archaeological bone: a case study from Portugal

Sampling of archaeological human bone may not be justified, contrary to former high expectations regarding adult age assessment based on histomorphometry. The alterations in buried bone as a result of bacterial action are readily visible in the scanning electron microscope (SEM). An understanding of the chemical and structural changes to cortical bone requires work at the level of a few microns. This paper reports on problems encountered during analyses of samples of human bone from Mesolithic (ca. 8000 calbp) shell midden sites at Muge in central Portugal, and the methods used to try and overcome these problems. We believe we have shown that these Mesolithic bones are partly comprised of bacterially reprecipitated mineral, which has had collagen removed, with consequent obliteration of bone microstructure. We conclude that microbial destruction of the structure of archaeological bone can be a serious impediment to analysis of the characteristics of the population represented by those skeletal remains. Copyright © 2001 John Wiley & Sons, Ltd.     

Actualistic research into dynamic impact and its implications for understanding differential bone fragmentation and survivorship

The relationship between bone mineral density and archaeological bone survivorship has played a critical role in zooarchaeological and taphonomic studies in recent decades. Numerous studies have suggested that higher-density skeletal element portions survive more frequently than lower-density element portions when archaeological assemblages are affected by some taphonomic processes. Interpretations of density mediated destruction have become commonplace in the archaeological literature, and are often used to explain the absence of certain bone elements and element parts in zooarchaeological assemblages. This study explores the effects of rockfall on bovid elements in varied environmental conditions and the differential survivorship of their element parts, and has implications for understanding the taphonomic processes through which bones are subjected to dynamic loading. Actualistic rockfall experiments conducted on twelve samples of frozen, fresh, and semi-dried bovid bones reveal that the generally low-density epiphyseal ends of bone elements resist fracture and analytical deletion with more frequency than the higher-density diaphyses. This evidence suggests that bone density does not correlate with likelihood of breakage or effective archaeological “destruction” when rockfall and other processes that result in dynamic impact are in action. While this research does not question the relationship between bone mineral density and the likelihood for archaeological survivorship as the result of some taphonomic processes, it presents one specific set of taphonomic processes that result in the differential survivorship of low density bone elements parts and the fragmentation and destruction of higher density element parts. This research presents evidence that shows that dynamic impact is a process capable of fragmenting and sometimes destroying high-density elements while low-density elements survive.     

Fluvial dispersal potential of guanaco bones (Lama guanicoe) under controlled experimental conditions: the influence of age classes to the hydrodynamic behavior

Hydrodynamic sorting is a taphonomic process able to transport and scatter bones deposited in archaeological and paleontological sites. This study presents the results of experimentation performed in an artificial flume with guanaco (Lama guanicoe) bones of different ontogenetic development, dry and saturated in water, in hydric flows velocities of 15 and 30 cm/s. The obtained results show that bone global density, the age of the individual, the dry or wet bone state, and the hydric flow velocity influence significantly bone dispersion. In this way, bones from immature individuals with unfused secondary growth centers and relatively low bulk density have better possibility of being transported than fused bones from adult individuals. Taking into account the results obtained in this experimentation and the feasibility of discriminating age categories in fossil assemblages, two bone groups with differential potential transport are presented in this paper. These transport groups constitute a methodological tool to evaluate the role hydric current may had played in the formation of a fossil assemblage.     

Comparative human and deer (Odocoileus virginianus) taphonomy at the Richards site,Ohio

The Richards site is attributed to the Philo phase of the Fort Ancient tradition of the Ohio Valley area. Human skeletal material from the site shows evidence of peri‐ and post‐mortem taphonomic changes, including cut marks, burning and fracturing. Previous analyses have discussed explanations for these changes, including secondary burial, ritual destruction and cannibalism. Researchers have theorised that, allowing for differences in anatomy among species, humans and animals butchered for the same purpose (consumption) will show similar patterns of taphonomic changes associated with butchery. The human remains at the Richards Site were disposed in general midden pits containing mixed cultural debris and faunal remains. White‐tailed deer (Odocoileus virginianus) constitutes approximately 60% of all the faunal bone, indicating that it was a major food resource. To test a cannibalism explanation, a comparative analysis of human‐induced taphonomy in human and deer skeletal remains was performed, using chi‐square and odds ratio tests. If humans were being used as a food resource, the pattern of butchery seen would mirror that of the deer. The analysis described here compares the patterns of treatment and disposal of human and deer skeletal elements at the Richards site, to test whether both species were used as food resources. Similar types of evidence for human‐induced taphonomic changes, including cutting, chopping, burning and breakage, can be seen in both species. However, results indicate that, in general, human remains show much more evidence of perimortem treatment than do deer remains. In fact, the common odds ratio for perimortem treatment in all bones is 3.25, indicating that a human bone is 3.25 times as likely as a deer bone to be affected by burning, cutting or chopping. This probably indicates that perimortem treatment of humans was greater than that necessary simply for butchering for consumption. Copyright © 2005 John Wiley & Sons, Ltd.     

Necropoli of Pill'e Matta Quartucciu (Cagliari,Sardinia): wild bee and solitary wasp activity and bone diagenetic factors

During the excavation at the necropolis and the laboratory studies, a variety of damage was found in the human bone remains. This damage included round holes, irregular bone destruction and irregular etching. This can be found especially in the skulls and in the long bones, and sometimes in the vertebrae and on the hands and feet. The exceptionality of this demanded meticulous study in order to define whether it was a diagenetic phenomenon of biological origin. Further studies revealed that the damage to the bones was produced by three kinds of Hymenoptera that build galleries: one of these belongs to the Sphecidae family, the other two to the Halictidae family. During the excavation of a grave it had been observed that a Halictidae had invaded the burial context and consequently contributed to the taphonomic and diagenetic process. The laboratory activities were directed towards the measurement of the damage to the human bone remains in 45 tombs. A histogram shows that the holes are not the result of accidental lesions, and the more frequent percentage values show similarities with the dimensions of holes built by the insects. The observations and the results of the study at the archaeological site enabled me to establish how significant the role of the insects had been, in particular of the Hymenoptera, in modifying the condition of the bone remains. Copyright © 2008 John Wiley & Sons, Ltd.     

Bone Degradation and Environment: Understanding,Assessing and Conducting Archaeological Experiments Using Modern Animal Bones

Archaeological experiments that use modern bones to replicate past animal bone assemblages have often failed to consider the effects of environment, storage and preparation on modern bones. Often, these experiments make little mention of the conditions to which bones were subject during their storage and preparation for use in experiments. In other instances, these variables are reported but not considered as factors that contribute to the nature of the results obtained. This study considers previously reported data concerning the degradation of frozen bones (−20°C), and bones exposed to hot, dry conditions (40°C), and presents new data for bones exposed to room temperature environments (22°C) and refrigerated environments (2°C), and bones that are frozen (−20°C) and then thawed (22°C). These conditions are all relevant to understanding the nature of bone degradation and the use of bones in modern archaeological experimentation. This article also surveys a range of previously reported experiments that utilise modern bones to create analogies to the past and considers different methodological approaches and their relationship to the condition of bones at the time of their fracture and fragmentation. The longitudinal data presented in this study demonstrate differential rates of bone degradation over time in various environmental conditions. This degradation results in dramatic changes in bone fracture morphology, bone strength and utility for bone tool production. These observations have significant implications for experiments that utilise modern bones, especially when experimental data are used to create analogies to the archaeological past. Copyright © 2012 John Wiley & Sons, Ltd.     

Bone surface modifications in zooarchaeology

Cutmarks made by stone tools, conchoidal flake scars from hammerstone percussion, carnivore tooth marks, striations from sedimentary abrasion, and other surface modifications on bones from archaeological sites constitute a crucial body of evidence for investigating the role of human behaviors and of nonhuman taphonomic processes in site formation. This paper describes the various kinds of bone surface modifications produced by humans and by nonhuman processes and assesses the current status of bone surface modification studies with regard to such issues as the need for greater analytical standardization, the selection of instruments for examining bone specimens, tactics for identifying the origins of marks on bones, and strategies for inferring human behaviors.     

Carnivore competition, bone destruction, and bone density

In carnivore-modified archaeofaunal assemblages it is important to evaluate the degree to which carnivores have overprinted hominin behavioral signals. To examine the signals of increased competition for discarded bone, we present controlled experimental data on 33 simulated archaeological sites subjected to secondary consumption by spotted hyenas. We examine the relationship between competition, as measured by controlled numbers of hyenas and limb bones, and resultant levels of destruction and correlations between long-bone portion survivorship and bone density. Our results indicate that levels of destruction are equivalent regardless of the numbers of hyenas or long-bones included in the experimental assemblages. Correlations between long-bone epiphyseal and near-epiphyseal portions and bone density, however, do provide an indication of the level of competition. Results from the experimental study are used to highlight divergent levels of carnivore competition for hominin-discarded bone at the Plio-Pleistocene localities FLKN-Zinjanthropus and FLKN levels 1–2 from Olduvai Gorge, Tanzania.     

The strange case of Apigliano: early ‘fossilization’ of medieval bone in southern Italy

The preservation of the osteological material at the medieval site of Apigliano, in southern Italy, is characterized by bones with highly crystalline, and altered, mineral phases. In addition to this, some material retains perfect histological preservation, with the exception of small microfissures present throughout this structure. Diagenetic porosity is indicative of collagen loss via chemical degradation. The levels of residual collagen in these bones are much lower than is predicted from simple models of gelatinization, and thus a more complex explanation for the state of preservation must be sought. Possible explanations for the rapid loss of bone collagen are considered, including a high–temperature event, the acceleration of hydrolysis due to liming and extreme wetting and drying cycles.     

“Numbers of individuals” in faunal analysis: the decay of fish bone in archaeological sites

Although quantifying animal remains in archaeological sites is best done by way of bone counts, there are several mechanisms that can cause distortions in the relative frequencies of different species. Some of these problems can be avoided by relatively minor modifications to standard methods, but the situation where bones have decayed since deposition cannot be controlled by methods currently in use.To overcome this a new technique is proposed. This involves comparing the relative frequencies of different anatomical elements across a number of sites, so that the extent of the dispersion of the frequencies of different bone classes at a site can be used as a guide to the extent of attrition there. This approach is illustrated by application to fish bones from sites in New Zealand.     

Implications of heat-induced changes in bone on the interpretation of funerary behaviour and practice

Bones submitted to heat experience structural and chromatic modifications. In particular, heat-induced bone warping and thumbnail fractures have been linked to the burning of fleshed and green bones – where the soft tissues have been removed from the bones soon after death – in contrast to dry bones. Those have been suggested as indicators of the state of the individual before being burned thus allowing inferences about the funerary behaviour of archaeological populations. A large sample of 61 skeletons submitted to cremation has been examined for the presence of both of these heat-induced features. Although uncommon, bone warping and thumbnail fractures were present in some of the skeletons demonstrating that its presence is not restricted to the burning of non-dried bones as generally believed. Rather than being an indicator of the presence of bones with soft tissues, bone warping seems to be more of an indicator of the preservation of collagen–apatite links which can be maintained on dry bones with low collagen deterioration. In addition, our results also do not confirm thumbnail fractures as an exclusive sign of the burning of bones with soft tissues. As a result, these heat-induced changes should be used with caution when trying to infer about the pre-burning state of an individual.     

Experimental effects of bone size and temperature on bone diagenesis

In the ground, bone undergoes chemical and physical changes which affect its preservation. This fact has important implications for dating and other analytical procedures involving bone, as well as faunal analysis where differential preservation of bones of different species may affect conclusions regarding the relative significance of an animal to the economy of a given society. The diagenic processes in bone range from minor changes in the bone protein to complete structural and chemical breakdown.Using fresh cow bone, we conducted laboratory experiments which simulate the effect of temperature and bone size on the rate and nature of bone disintegration in archaeological sites. Temperature influences the rate of chemical change, and bone size and density affect the accessibility of the molecular constituents of bone to extrinsic chemical reactions. These findings clarify the importance of two well-known concepts in bone taphonomy. (1) The rate of chemical breakdown in bone tissues is related to the proximity of a given unit of tissue to the bone surface. This means that, in archaeological bone samples, tissue near the surface may be different chemically from tissue away from the surface and great care is necessary in choosing and preparing bone samples for analytical procedures. (2) In general, small bones are not as well preserved as large bones, therefore small animals are likely to be underrepresented in faunal assemblages.     

FOCUS: on the use of the petrous bone for estimating cranial abundance in fossil assemblages

Low representation of braincase bones in zooarchaeological assemblages suggests that skulls have been intensively processed by Levantine Epipalaeolithic foragers; most cranial elements are often unidentifiable and are considered poor candidates for quantifying crania. In contrast, the petrous bone is usually found complete, and was found to be easily identifiable to body size category. Use of the petrous bone in fossil assemblages analyses leads to better estimation of the occurrence of cranial elements, and thus of skeletal part representation. We therefore suggest use of the petrous bone for detecting bone destruction and selective transport in faunal assemblages.     

Arsenic in Danish and Swedish Mesolithic and Neolithic human bones – diet or diagenesis?

Arsenic has previously been measured in a bone sample of a c. 5-year-old Mesolithic child from Nivaagaard in Denmark yielding an anomalously high value of 13 μg/g. In the present work we show that other individuals at a nearby site also exhibit elevated arsenic levels, whereas individuals from other Mesolithic sites in Denmark are found to have quite low As-concentrations. Several attempts to reveal the source of the arsenic are reported: A railway track near the site, where the railway sleepers were suspected to have been impregnated with As leading to transport or diffusion of As into the adjacent soil; Several food items, the remains of which were found at the site, and one food item not preserved in the excavation, i.e. seaweed. Finally, it is shown that the most likely explanation of the elevated arsenic levels in human bones at Nivaa is diagenesis.     

Was He Murdered or Was He Not?—Part II: Multi‐Elemental Analyses of Hair and Bone Samples from Tycho Brahe and Histopathology of His Bones

Hair and bone samples procured from the remains of Tycho Brahe were analysed by several analytical techniques. In segmented hair samples, concentrations of Fe, As, Ag and Au at the tips exceeded values for the contemporary population; however, they decreased towards the hair bulbs, similarly to Hg, indicating that recent exposure that was discontinued ~2 months prior to Brahe's death. Several other elements did not follow this pattern. Analyses of bones revealed signs of long‐term exposure to Au, while many other elements were within expected ranges. Histopathological examination of bone sections yielded no signs of severe bone metabolic disorders.     

Changes in reindeer body part representation at Grotte XVI, Dordogne, France

Foraging theory models are used to examine changes in reindeer body part representation in the Middle and Upper Paleolithic ungulate assemblages at Grotte XVI (Dordogne, France). Previous research suggests that climate change resulted in progressive increases in reindeer abundances throughout the region. If increased forager encounter rates with reindeer resulted in decreased transport distances and search times, central-place forager models predict that field processing at the kill site will decline and reindeer body part transport will become less selective. This prediction is supported, and reindeer skeletal element abundances are shown to become increasingly even and incorporate higher frequencies of low utility elements through time. The progressive shift in reindeer transport strategies operates across technological and hominin species boundaries including the Middle-to-Upper Paleolithic transition.