"To honor and remember": An ethical awakening to African American remains in museums

In 2021, amid surging activism in the Movement for Black Lives, the Smithsonian Institution's possession of the remains of thousands of African Americans drew widespread attention. In response, the Smithsonian and its National Museum of Natural History undertook a series of steps to assess these remains and to develop a policy for returning as many as possible to descendants and descendant communities, under changes that would apply to all non-Native American remains in Smithsonian collections. This paper reviews the actions taken to date and the work that is still in progress or planned. I contextualize these steps more broadly within an "ethical awakening" to African American remains that have long been present, studied, and displayed in collections across the museum community in the United States, where other institutions have faced similar challenges and changes.

Uncovering the Holocene roots of contemporary disease-scapes: bringing archaeology into One Health

The accelerating pace of emerging zoonotic diseases in the twenty-first century has motivated cross-disciplinary collaboration on One Health approaches, combining microbiology, veterinary and environmental sciences, and epidemiology for outbreak prevention and mitigation. Such outbreaks are often caused by spillovers attributed to human activities that encroach on wildlife habitats and ecosystems, such as land use change, industrialized food production, urbanization and animal trade. While the origin of anthropogenic effects on animal ecology and biogeography can be traced to the Late Pleistocene, the archaeological record-a long-term archive of human-animal-environmental interactions-has largely been untapped in these One Health approaches, thus limiting our understanding of these dynamics over time. In this review, we examine how humans, as niche constructors, have facilitated new host species and 'disease-scapes' from the Late Pleistocene to the Anthropocene, by viewing zooarchaeological, bioarchaeological and palaeoecological data with a One Health perspective. We also highlight how new biomolecular tools and advances in the '-omics' can be holistically coupled with archaeological and palaeoecological reconstructions in the service of studying zoonotic disease emergence and re-emergence.

Regaining creativity in science: insights from conversation

The 'early modern' (Renaissance) workshop was predicated on the idea that informal, open-ended cooperation enables participants to experience difference and develop new insights, which can lead to new ways of thinking and doing. This paper presents the insights that emerged from a conversation event that brought wide-ranging voices together from different domains in science, and across the arts and industry, to consider science leadership as we look to the future in a time of interlocking crises. The core theme identified was a need to regain creativity in science; in the methods of scientific endeavours, in the way science is produced and communicated, and in how science is experienced in society. Three key challenges for re-establishing a culture of creativity in science emerged: (i) how scientists communicate what science is and what it is for, (ii) what scientists value, and (iii) how scientists create and co-create science with and for society. Furthermore, the value of open-ended and ongoing conversation between different perspectives as a means of achieving this culture was identified and demonstrated.

Investigating factors of metabolic bone disease in baboons (Papio spp.) using museum collections

OBJECTIVES

To assess manifestations of metabolic bone disease (MBD) and their potential environmental and phenotypic factors in captive and non-captive baboon (Papio spp.) specimens.

MATERIALS AND METHODS

Our sample consisted of 160 baboon specimens at the Smithsonian's National Museum of Natural History accessioned from 1890 to 1971. Combining cranial indicators of MBD and the museum's historical data, we examined factors contributing to likely instances of MBD. We used binomial-family generalized linear models to assess differences in MBD frequency by environment (captive, non-captive), specimen accession year, and skin color (light, medium, dark).

RESULTS

Indicators of MBD were most frequently observed in captive baboons, with a decrease in MBD frequency over time. Fifteen non-captive individuals showed indicators of MBD, which are the first published cases of MBD in non-captive nonhuman primates (NHPs) to our knowledge. The most common MBD indicators were bone porosity (n = 35) and bone thickening/enlargement (n = 35). Fibrous osteodystrophy was observed frequently in our sample, likely relating to nutritional deficiencies. We found no association between exposed facial skin color variation and MBD.

CONCLUSIONS

Our findings are consistent with historical accounts of MBD prevalence in captive facilities, especially earlier in the 20th century. A decrease in MBD prevalence later in the 20th century likely reflects improvements in housing, diet, and veterinary care in captive settings. Causes of MBD development in non-captive baboons should be further explored, as understanding the potential health impacts that anthropogenic environments impose on NHPs is imperative as humans increasingly alter the natural world in the 21st century.

Forensic Tools for Species Identification of Skeletal Remains: Metrics, Statistics, and OsteoID

Although nonhuman remains constitute a significant portion of forensic anthropological casework, the potential use of bone metrics to assess the human origin and to classify species of skeletal remains has not been thoroughly investigated. This study aimed to assess the utility of quantitative methods in distinguishing human from nonhuman remains and present additional resources for species identification. Over 50,000 measurements were compiled from humans and 27 nonhuman (mostly North American) species. Decision trees developed from the long bone data can differentiate human from nonhuman remains with over 90% accuracy (>98% accuracy for the human sample), even if all long bones are pooled. Stepwise discriminant function results were slightly lower (>87.4% overall accuracy). The quantitative models can be used to support visual identifications or preliminarily assess forensic significance at scenes. For species classification, bone-specific discriminant functions returned accuracies between 77.7% and 89.1%, but classification results varied highly across species. From the study data, we developed a web tool, OsteoID, for users who can input measurements and be shown photographs of potential bones/species to aid in visual identification. OsteoID also includes supplementary images (e.g., 3D scans), creating an additional resource for forensic anthropologists and others involved in skeletal species identification and comparative osteology.

Amyotrophic Lateral Sclerosis After Exposure to Manganese from Traditional Medicine Procedures in Kenya

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron loss and widespread muscular atrophy. Despite intensive investigations on genetic and environmental factors, the cause of ALS remains unknown. Recent data suggest a role for metal exposures in ALS causation. In this study we present a patient who developed ALS after a traditional medical procedure in Kenya. The procedure involved insertion of a black metal powder into several subcutaneous cuts in the lower back. Four months later, general muscle weakness developed. Clinical and electrophysiological examinations detected widespread denervation consistent with ALS. The patient died from respiratory failure less than a year after the procedure. Scanning electron microscopy and X-ray diffraction analyses identified the black powder as potassium permanganate (KMnO4). A causative relationship between the systemic exposure to KMnO4 and ALS development can be suspected, especially as manganese is a well-known neurotoxicant previously found to be elevated in cerebrospinal fluid from ALS patients. Manganese neurotoxicity and exposure routes conveying this toxicity deserve further attention.

What does it mean to be wild? Assessing human influence on the environments of nonhuman primate specimens in museum collections

OBJECTIVES

Natural history collections are often thought to represent environments in a pristine natural state-free from human intervention-the so-called "wild." In this study, we aim to assess the level of human influence represented by natural history collections of wild-collected primates over 120 years at the Smithsonian Institution's National Museum of Natural History (NMNH).

MATERIALS AND METHODS

Our sample consisted of 875 catarrhine primate specimens in NMNH collections, representing 13 genera collected in 39 countries from 1882 to 2004. Using archival and accession information we determined the approximate locations from which specimens were collected. We then plotted location coordinates onto publicly available anthrome maps created by Ellis et al. (Global Ecology and Biogeography, 2010, 19, 589), which delineate terrestrial biomes of human population density and land use worldwide since the 1700s.

RESULTS

We found that among primates collected from their native ranges, 92% were from an environment that had some level of human impact, suggesting that the majority of presumed wild-collected primate specimens lived in an environment influenced by humans during their lifetimes.

DISCUSSION

The degree to which human-modified environments may have impacted the lives of primates currently held in museum collections has been historically ignored, implicating unforeseen consequences for collection-based research. While unique effects related to commensalism with humans remain understudied, effects currently attributed to natural phenomena may, in fact, be related to anthropogenic pressures on unmanaged populations of primates.

Sexual dimorphism in mastoid process volumes measured from 3D models of dry crania from mediaeval Croatia

3D analysis of skeletal volumes has become an important field in digital anthropology studies. The volume of the mastoid process has been proposed to display significant sexual dimorphism, but it has a complex shape and to date no study has quantified the full mastoid volume for sex estimation purposes. In this study we compared three different ways to isolate the volume of the mastoid process from digital 3D models of dry crania, and then evaluated the performance of the three different volume definitions for sex estimation purposes. A total of 170 crania (86 male, 84 females) excavated from five medieval Croatian sites were CT-scanned and used to produce 3D stereolitographic models. The three different isolation techniques were based on various anatomical landmarks and planes, as well as the anatomy of the mastoid process itself. Measurements of the three different mastoid volumes yielded different accuracies and precisions. Interestingly, anatomical structures were sometimes more useful than classical landmarks as demarcators of mastoid volume. For all three volume definitions, male mastoid volumes were significantly larger than female volumes, in both relative and absolute numbers. Sex estimation based on mastoid volume showed a slightly higher precision and better accuracy (71% correct classifications) than visual scoring techniques (67%) and linear distance measurements (69%) of the mastoid process. Sex estimation based on cranial size performed even better (78%), and multifactorial analysis (cranium size + mastoid volume) reached up to 81% accuracy. These results show that measurements of the mastoid volume represent a promising metric to be used in multifactorial approaches for sex estimation of human remains.

Lithium ions display weak interaction with amyloid-beta (Aβ) peptides and have minor effects on their aggregation

Alzheimer's disease (AD) is an incurable disease and the main cause of age-related dementia worldwide, despite decades of research. Treatment of AD with lithium (Li) has showed promising results, but the underlying mechanism is unclear. The pathological hallmark of AD brains is deposition of amyloid plaques, consisting mainly of amyloid-β (Aβ) peptides aggregated into amyloid fibrils. The plaques contain also metal ions of e.g. Cu, Fe, and Zn, and such ions are known to interact with Aβ peptides and modulate their aggregation and toxicity. The interactions between Aβ peptides and Li+ ions have however not been well investigated. Here, we use a range of biophysical techniques to characterize in vitro interactions between Aβ peptides and Li+ ions. We show that Li+ ions display weak and non-specific interactions with Aβ peptides, and have minor effects on Aβ aggregation. These results indicate that possible beneficial effects of Li on AD pathology are not likely caused by direct interactions between Aβ peptides and Li+ ions.

A chomped chimp: New evidence of tooth marks on an adult chimpanzee (Pan troglodytes verus)

OBJECTIVES

To describe and interpret previously unreported marks on the dry cranium of an adult chimpanzee (Pan troglodytes verus) from Côte d'Ivoire at the Smithsonian's National Museum of Natural History (USNM 450071).

MATERIALS AND METHODS

All marks on the cranium were documented and assessed through physical examination of the specimen, photography, micro-computed tomography (micro-CT), and 3D laser scanning. Pits and punctures were measured with digital calipers for comparison with published carnivore tooth mark measurements.

RESULTS

The cranium shows perimortem or postmortem damage to the temporal, occipital, and maxillary regions that is not recent. Size and color variation in the marks suggest two damage events, possibly involving chewing by different animals, at least one of which was a large-bodied mammal. The 22 tooth pits and punctures (0.89-8.75 mm in maximum length and 0.88-6.63 mm in breadth) overlap in size with those inflicted by wild leopards, the most significant predators of common chimpanzees due to their largely overlapping ecological distributions.

CONCLUSIONS

Based on qualitative and quantitative evidence, we conclude that leopards are the most likely cause of the most prominent marks on the cranium. However, we cannot rule out the additional possibility of other chimpanzees, although there are no published studies of chimpanzee tooth marks for direct comparison. This study is the most extensive documentation to date of a modern adult chimpanzee skull exhibiting tooth marks by a large mammal, thus providing new evidence to help identify and interpret other events of predation and scavenging of large-bodied apes in the modern and fossil records.

Mercury and Alzheimer's Disease: Hg(II) Ions Display Specific Binding to the Amyloid-β Peptide and Hinder Its Fibrillization

Brains and blood of Alzheimer's disease (AD) patients have shown elevated mercury concentrations, but potential involvement of mercury exposure in AD pathogenesis has not been studied at the molecular level. The pathological hallmark of AD brains is deposition of amyloid plaques, consisting mainly of amyloid-β (Aβ) peptides aggregated into amyloid fibrils. Aβ peptide fibrillization is known to be modulated by metal ions such as Cu(II) and Zn(II). Here, we study in vitro the interactions between Aβ peptides and Hg(II) ions by multiple biophysical techniques. Fluorescence spectroscopy and atomic force microscopy (AFM) show that Hg(II) ions have a concentration-dependent inhibiting effect on Aβ fibrillization: at a 1:1 Aβ·Hg(II) ratio only non-fibrillar Aβ aggregates are formed. NMR spectroscopy shows that Hg(II) ions interact with the N-terminal region of Aβ(1-40) with a micromolar affinity, likely via a binding mode similar to that for Cu(II) and Zn(II) ions, i.e., mainly via the histidine residues His6, His13, and His14. Thus, together with Cu(II), Fe(II), Mn(II), Pb(IV), and Zn(II) ions, Hg(II) belongs to a family of metal ions that display residue-specific binding interactions with Aβ peptides and modulate their aggregation processes.

Landmark Typology in Applied Morphometrics Studies: What's the Point?

Landmarks are the hallmark of biological shape analysis as discrete anatomical points of correspondence. Various systems have been developed for their classification. In the most widely used system, developed by Bookstein in the 1990s, landmarks are divided into three distinct types based on their anatomical locations and biological significance. As Bookstein and others have argued that different landmark types possess different qualities, e.g., that Type 3 landmarks contain deficient information about shape variation and are less reliably measured, researchers began using landmark types as justification for selecting or avoiding particular landmarks for measurement or analysis. Here, we demonstrate considerable variation in landmark classifications among 17 studies using geometric morphometrics (GM), due to disagreement in the application of both Bookstein's landmark typology and individual landmark definitions. A review of the literature furthermore shows little correlation between landmark type and measurement reproducibility, especially when factors such as differences in measurement tools (calipers, digitizer, or computer software) and data sources (dry crania, 3D models, or 2D images) are considered. Although landmark typology is valuable when teaching biological shape analysis, we find that employing it in research design introduces confusion without providing useful information. Instead, researchers should choose landmark configurations based on their ability to test specific research hypotheses, and research papers should include justifications of landmark choices along with landmark definitions, details on landmark collection methods, and appropriate interobserver and intraobserver analyses. Hence, while the landmarks themselves are crucial for GM, we argue that their typology is of little use in applied studies. Anat Rec, 302:1144-1153, 2019. © 2018 Wiley Periodicals, Inc.

Alzheimer's disease and cigarette smoke components: effects of nicotine, PAHs, and Cd(II), Cr(III), Pb(II), Pb(IV) ions on amyloid-β peptide aggregation

Cigarette smoking is a significant risk factor for Alzheimer's disease (AD), which is associated with extracellular brain deposits of amyloid plaques containing aggregated amyloid-β (Aβ) peptides. Aβ aggregation occurs via multiple pathways that can be influenced by various compounds. Here, we used AFM imaging and NMR, fluorescence, and mass spectrometry to monitor in vitro how Aβ aggregation is affected by the cigarette-related compounds nicotine, polycyclic aromatic hydrocarbons (PAHs) with one to five aromatic rings, and the metal ions Cd(II), Cr(III), Pb(II), and Pb(IV). All PAHs and metal ions modulated the Aβ aggregation process. Cd(II), Cr(III), and Pb(II) ions displayed general electrostatic interactions with Aβ, whereas Pb(IV) ions showed specific transient binding coordination to the N-terminal Aβ segment. Thus, Pb(IV) ions are especially prone to interact with Aβ and affect its aggregation. While Pb(IV) ions affected mainly Aβ dimer and trimer formation, hydrophobic toluene mainly affected formation of larger aggregates such as tetramers. The uncharged and hydrophilic nicotine molecule showed no direct interactions with Aβ, nor did it affect Aβ aggregation. Our Aβ interaction results suggest a molecular rationale for the higher AD prevalence among smokers, and indicate that certain forms of lead in particular may constitute an environmental risk factor for AD.

Skeletal and dental effects on rats following in utero/lactational exposure to the non-dioxin-like polychlorinated biphenyl PCB 180

Polychlorinated biphenyls (PCBs) are a large class of persistent organic pollutants that are potentially harmful to human and wildlife health. Although a small number of dioxin-like (DL) PCBs are well characterized, the majority of PCBs have non-dioxin-like (NDL) modes of action and biological effects that are less understood. We conducted a dose-response study of the skeletal and dental effects of in utero/lactational exposure to 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180), a NDL PCB congener that is abundantly present in the environment and foods, including mother’s milk. In a sample of 35- and 84-day-old male and female offspring from pregnant rats exposed to different doses of PCB 180 (0, 10, 30, 100, 300, and 1000 mg/kg bw), we measured the three-dimensional (3D) coordinates of 27 landmarks on the craniofacial skeleton with a Microscribe G2X system, the buccolingual width of all molars with digital sliding calipers, and a variety of tibial parameters with peripheral quantitative computed tomography (pQCT) and a biomechanical testing apparatus. The landmark coordinates were analyzed for variation in size, shape, and fluctuating asymmetry (FA) using MorphoJ software, showing no effects on cranial size, on FA in females only (i.e., decreased asymmetry), and on shape in both sexes (i.e., decreased facial length and shift in the palatal suture). In the maxillary teeth, females in the highest dose group showed a significant decrease of 0.1 mm (p = 0.033) of the second molar only, whereas males in most dose groups showed average increases of 0.1 mm (p = 0.006–0.044) in all three molars. In the mandibular teeth, the only significant response to PCB 180 exposure was the average increase of 0.1 mm (p = 0.001–0.025) in the third molars of males only. Males also shower greater sensitivity in postcranial effects of increased tibial length and decreased cortical bone mass density, although only females showed significant effects on tibial bone area and thickness. These results demonstrate marked sex differences in effects of PCB 180, which can be attributed to differences in their underlying biological mechanisms of toxicity. Furthermore, although tooth and bone development are targets of both DL and NDL compounds, this study shows that there are marked differences in their mechanisms and effects.

OH 83: A new early modern human fossil cranium from the Ndutu beds of Olduvai Gorge, Tanzania

OBJECTIVE

Herein we introduce a newly recovered partial calvaria, OH 83, from the upper Ndutu Beds of Olduvai Gorge, Tanzania. We present the geological context of its discovery and a comparative analysis of its morphology, placing OH 83 within the context of our current understanding of the origins and evolution of Homo sapiens.

MATERIALS AND METHODS

We comparatively assessed the morphology of OH 83 using quantitative and qualitative data from penecontemporaneous fossils and the W.W. Howells modern human craniometric dataset.

RESULTS

OH 83 is geologically dated to ca. 60-32 ka. Its morphology is indicative of an early modern human, falling at the low end of the range of variation for post-orbital cranial breadth, the high end of the range for bifrontal breadth, and near average in frontal length.

DISCUSSION

There have been numerous attempts to use cranial anatomy to define the species Homo sapiens and identify it in the fossil record. These efforts have not met wide agreement by the scientific community due, in part, to the mosaic patterns of cranial variation represented by the fossils. The variable, mosaic pattern of trait expression in the crania of Middle and Late Pleistocene fossils implies that morphological modernity did not occur at once. However, OH 83 demonstrates that by ca. 60-32 ka modern humans in Africa included individuals that are at the fairly small and gracile range of modern human cranial variation.

Ancient water bottle use and polycyclic aromatic hydrocarbon (PAH) exposure among California Indians: a prehistoric health risk assessment

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are the main toxic compounds in natural bitumen, a fossil material used by modern and ancient societies around the world. The adverse health effects of PAHs on modern humans are well established, but their health impacts on past populations are unclear. It has previously been suggested that a prehistoric health decline among the native people living on the California Channel Islands may have been related to PAH exposure. Here, we assess the potential health risks of PAH exposure from the use and manufacture of bitumen-coated water bottles by ancient California Indian societies.

METHODS

We replicated prehistoric bitumen-coated water bottles with traditional materials and techniques of California Indians, based on ethnographic and archaeological evidence. In order to estimate PAH exposure related to water bottle manufacture and use, we conducted controlled experiments to measure PAH contamination 1) in air during the manufacturing process and 2) in water and olive oil stored in a completed bottle for varying periods of time. Samples were analyzed with gas chromatography/mass spectrometry (GC/MS) for concentrations of the 16 PAHs identified by the US Environmental Protection Agency (EPA) as priority pollutants.

RESULTS

Eight PAHs were detected in concentrations of 1-10 μg/m³ in air during bottle production and 50-900 ng/L in water after 2 months of storage, ranging from two-ring (naphthalene and methylnaphthalene) to four-ring (fluoranthene) molecules. All 16 PAHs analyzed were detected in olive oil after 2 days (2 to 35 μg/kg), 2 weeks (3 to 66 μg/kg), and 2 months (5 to 140 μg/kg) of storage.

CONCLUSIONS

For ancient California Indians, water stored in bitumen-coated water bottles was not a significant source of PAH exposure, but production of such bottles could have resulted in harmful airborne PAH exposure.

Characterization of Mn(II) ion binding to the amyloid-β peptide in Alzheimer's disease

Growing evidence links neurodegenerative diseases to metal exposure. Aberrant metal ion concentrations have been noted in Alzheimer's disease (AD) brains, yet the role of metals in AD pathogenesis remains unresolved. A major factor in AD pathogenesis is considered to be aggregation of and amyloid formation by amyloid-β (Aβ) peptides. Previous studies have shown that Aβ displays specific binding to Cu(II) and Zn(II) ions, and such binding has been shown to modulate Aβ aggregation. Here, we use nuclear magnetic resonance (NMR) spectroscopy to show that Mn(II) ions also bind to the N-terminal part of the Aβ(1-40) peptide, with a weak binding affinity in the milli- to micromolar range. Circular dichroism (CD) spectroscopy, solid state atomic force microscopy (AFM), fluorescence spectroscopy, and molecular modeling suggest that the weak binding of Mn(II) to Aβ may not have a large effect on the peptide's aggregation into amyloid fibrils. However, identification of an additional metal ion displaying Aβ binding reveals more complex AD metal chemistry than has been previously considered in the literature.

Cribra orbitalia as a potential indicator of childhood stress: Evidence from paleopathology, stable C, N, and O isotopes, and trace element concentrations in children from a 17th-18th century cemetery in Jēkabpils, Latvia

Cribra orbitalia (CO), or porotic hyperostosis (PH) of the orbital roof, is one of the most common pathological conditions found in archaeological subadult skeletal remains. Reaching frequencies higher than 50% in many prehistoric samples, CO has been generally attributed to a variety of factors including malnutrition (e.g., megaloblastic anemia) and parasitism. In this study, we tested the relationship between CO, trace element concentrations, and stable isotope values (δ¹³C, δ¹⁵N, δ¹⁸O) in subadult skeletons from a 17^th to 18^th century cemetery in the historic town of Jēkabpils, Latvia. A total of 28 subadults were examined, seven of which (25%) showed evidence of CO. Bioarchaeological evidence indicated high mortality for children in this cemetery: half of the burials were subadults under the age of 14, while a third were under the age of four. Life expectancy at birth was estimated to have been only 21.6 years. Trace element concentrations measured by Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) showed no relationship between presence or absence of CO and levels of manganese, zinc, strontium, barium, copper, cadmium, or lead in the bones (p>0.05). However, a significant correlation (p<0.05) was found between the presence of CO and decreased levels of iron. The correlations between CO and decreased levels of copper and lead approached significance (p=0.056 for both elements). Individuals with CO furthermore displayed significantly lower δ¹⁵N isotope values, suggesting greater consumption of lower trophic level food resources than those unaffected by CO; δ¹³C and δ¹⁸O values, in contrast, showed no significant differences. These results suggest that the prevalence of CO may be related to dietary deficiencies. In this case, low iron levels may also signify a diet low in other key vitamins (e.g., B₉ and B₁₂), which are known to cause megaloblastic anemia.

Ecce Homo: Science and Society Need Anthropological Collections

Scientific collections are crucial to understanding the biological and cultural diversity of the Earth. Anthropological collections document the human experience and the interactions between people, ecosystems, and organisms. Unfortunately, anthropological collections are often poorly known by the public and face a variety of threats to their permanent care and conservation.

Evaluating sexual dimorphism in the human mastoid process: A viewpoint on the methodology

The mastoid process is one of the most sexually dimorphic features in the human skull, and is therefore often used to identify the sex of skeletons. Numerous techniques for assessing variation in the size and shape of the mastoid process have been proposed and implemented in osteological research, but its complex form still presents difficulties for consistent and effective analysis. In this article, we compare the different techniques and variables that have been used to define, measure, and visually score sexual dimorphism in the mastoid process. We argue that the current protocols fail to capture the full morphological range of this bony projection, and suggest ways of improving and standardizing them, regarding both traditional and 3D-based approaches.

A Case of Contested Cremains Analyzed Through Metric and Chemical Comparison

Since the 1980s, cremation has become the fastest growing area of the U.S. funeral industry. At the same time, the number of litigations against funeral homes and cremation facilities has increased. Forensic anthropologists are often asked to determine whether the contents of an urn are actually cremated bone, and to address questions regarding the identity of the remains. This study uses both metric and chemical analyses for resolving a case of contested cremains. A cremains weight of 2021.8 g was predicted based on the decedent's reported stature and weight. However, the urn contents weighed 4173.5 g. The urn contents also contained material inconsistent with cremains (e.g., moist sediment, stones, ferrous metal). Analysis using XRD and SEM demonstrated that the urn contained thermally altered bone as well as inorganic material consistent with glass fiber cement. Although forensically challenging, cremains cases such as this one can be resolved using a multidisciplinary approach.

Craniofacial form is altered by chronic adult exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in Han/Wistar and Long-Evans rats with different aryl hydrocarbon receptor (AhR) structures

Mammalian bone has shown a variety of responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure in experimental and wildlife studies. Although many responses have been well characterized in the postcranial skeleton, dioxin-induced effects on the cranium are largely unknown. In this study, we investigated the effects of chronic adult exposure to TCDD on cranial size and shape in dioxin-resistant Han/Wistar (H/W) and dioxin-sensitive Long–Evans (L–E) rat strains. Three-dimensional landmark configurations for the face, vault, and base of the cranium were recorded and analyzed using geometric morphometrics (GM) and dose–response modeling. The strongest effects were shown by L–E and H/W rats with daily exposures of 100 and 1000 ng TCDD/kg bw/day, respectively, resulting in significant reductions in centroid size (CS) in all three cranial modules for both strains except for the vault in H/W rats. Consistent with previous evidence of intraspecific variation in TCDD resistance, the benchmark doses (CEDs) for cranial size reduction in L–E rats were roughly 10-fold lower than those for H/W rats. For both strains, the face showed the greatest size reduction from the highest doses of TCDD (i.e., 3.6 and 6.3% decreases in H/W and L–E rats, respectively), most likely related to dose-dependent reductions in limb bone size and body weight gain. However, intrinsic morphological differences between strains were also observed: although the control groups of H/W and L–E rats had vaults and bases of comparable size, the face was 6.4% larger in L–E rats. Thus, although H/W rats possess an altered aryl hydrocarbon receptor (AhR) that appears to mediate and provides some resistance to TCDD exposure, their smaller reductions in facial size may also relate to strain-specific patterns of cranial development and growth. Future research will be aimed at understanding how ontogenetic factors may modulate toxic effects of prenatal and lactational exposure on the mammalian skeleton.

Classification of pelvic ring fractures in skeletonized human remains

Pelvic ring fractures are associated with high rates of mortality and thus can provide key information about circumstances surrounding death. These injuries can be particularly informative in skeletonized remains, yet difficult to diagnose and interpret. This study adapted a clinical system of classifying pelvic ring fractures according to their resultant degree of pelvic stability for application to gross human skeletal remains. The modified Tile criteria were applied to the skeletal remains of 22 individuals from the Cleveland Museum of Natural History and Universidad Nacional Autónoma de México that displayed evidence of pelvic injury. Because these categories are tied directly to clinical assessments concerning the severity and treatment of injuries, this approach can aid in the identification of manner and cause of death, as well as interpretations of possible mechanisms of injury, such as those typical in car-to-pedestrian and motor vehicle accidents.

Engineered non-fluorescent Affibody molecules facilitate studies of the amyloid-beta (Aβ) peptide in monomeric form: low pH was found to reduce Aβ/Cu(II) binding affinity

Aggregation of amyloid-beta (Aβ) peptides into oligomers and amyloid plaques in the human brain is considered a causative factor in Alzheimer's disease (AD). As metal ions are over-represented in AD patient brains, and as distinct Aβ aggregation pathways in presence of Cu(II) have been demonstrated, metal binding to Aβ likely affects AD progression. Aβ aggregation is moreover pH-dependent, and AD appears to involve inflammatory conditions leading to physiological acidosis. Although metal binding specificity to Aβ varies at different pH's, metal binding affinity to Aβ has so far not been quantitatively investigated at sub-neutral pH levels. This may be explained by the difficulties involved in studying monomeric peptide properties under aggregation-promoting conditions. We have recently devised a modified Affibody molecule, Z(Aβ3)(12-58), that binds Aβ with sub-nanomolar affinity, thereby locking the peptide in monomeric form without affecting the N-terminal region where metal ions bind. Here, we introduce non-fluorescent Aβ-binding Affibody variants that keep Aβ monomeric while only slightly affecting the Aβ peptide's metal binding properties. Using fluorescence spectroscopy, we demonstrate that Cu(II)/Aβ(1-40) binding is almost two orders of magnitude weaker at pH 5.0 (apparent K(D)=51 μM) than at pH 7.3 (apparent K(D)=0.86 μM). This effect is arguably caused by protonation of the histidines involved in the metal ligandation. Our results indicate that engineered variants of Affibody molecules are useful for studying metal-binding and other properties of monomeric Aβ under various physiological conditions, which will improve our understanding of the molecular mechanisms involved in AD.

Zygomaticomaxillary suture shape analyzed with digital morphometrics: reassessing patterns of variation in American Indian and European populations

Typological classification of human zygomaticomaxillary suture (ZMS) shape is often used in forensic assessment of ancestry, following earlier studies reporting higher frequencies of "angled" sutures among American Indians and higher frequencies of "curved" sutures among Caucasians. In this paper we present a new method of digital morphometrics to quantify and compare ZMS shape in 60 American Indian and 60 European crania. Suture outlines were recorded as three-dimensional (3D) contours on digital models of adult male and female crania created with a portable 3D laser scanner. Each contour was represented by about four hundred point coordinates, which were transformed via Fourier analysis into amplitude coefficients suitable for use in linear discriminant analysis. Discriminant functions were created that accurately predicted group membership for 83% of the crania in the sample, after leave-one-out cross-validation. The results were compared with traditional typological classifications based on visual evaluation of ZMS shape, and the contour-based method was found to be more effective than the typological approach. However, the distribution of ZMS types within the two sample groups did not conform to previously reported patterns. This discrepancy indicates that ZMS shape may reflect not only genetic factors, but also environmental factors such as diet and stress. In addition, some evidence for sexual dimorphism in the zygomaticomaxillary complex was observed. Based on these findings, we recommend caution when using ZMS shape analysis in forensic ancestry determination.

Could the health decline of prehistoric California indians be related to exposure to polycyclic aromatic hydrocarbons (PAHs) from natural bitumen?

BACKGROUND

The negative health effects of polycyclic aromatic hydrocarbons (PAHs) are well established for modern human populations but have so far not been studied in prehistoric contexts. PAHs are the main component of fossil bitumen, a naturally occurring material used by past societies such as the Chumash Indians in California as an adhesive, as a waterproofing agent, and for medicinal purposes. The rich archaeological and ethnohistoric record of the coastal Chumash suggests that they were exposed to multiple uptake pathways of bituminous PAHs, including direct contact, fume inhalation, and oral uptake from contaminated water and seafood.

OBJECTIVES

We investigated the possibility that PAHs from natural bitumen compromised the health of the prehistoric Chumash Indians in California.

CONCLUSIONS

Exposure of the ancient Chumash Indians to toxic PAHs appears to have gradually increased across a period of 7,500 years because of an increased use of bitumen in the Chumash technology, together with a dietary shift toward PAH-contaminated marine food. Skeletal analysis indicates a concurrent population health decline that may be related to PAH uptake. However, establishing such a connection is virtually impossible without knowing the actual exposure levels experienced by these populations. Future methodological research may provide techniques for determining PAH levels in ancient skeletal material, which would open new avenues for research on the health of prehistoric populations and on the long-term effects of human PAH exposure.

Identification of group affinity from cross-sectional contours of the human midfacial skeleton using digital morphometrics and 3D laser scanning technology

Identifying group affinity from human crania is a long-standing problem in forensic and physical anthropology. Many craniofacial differences used in forensic skeletal identification are difficult to quantify, although certain measurements of the midfacial skeleton have shown high predictive value for group classifications. This study presents a new method for analyzing midfacial shape variation between different geographic groups. Three-dimensional laser scan models of 90 crania from three populations were used to obtain cross-sectional midfacial contours defined by three standard craniometric landmarks. Elliptic Fourier transforms of the contours were used to extract Fourier coefficients for statistical analysis. After cross-validation, discriminant functions based on the Fourier coefficients provided an average of 86% correct classifications for crania from the three groups. The high rate of accuracy of this method indicates its usefulness for identifying group affinities among human skeletal remains and demonstrates the advantages of digital 3D model-based analysis in forensic research.

Brief communication: Additional cases of maxillary canine-first premolar transposition in several prehistoric skeletal assemblages from the Santa Barbara Channel Islands of California

This article identifies and discusses seven new cases of complete maxillary canine-premolar transposition in ancient populations from the Santa Barbara Channel region of California. A high frequency of this tooth transposition has been previously documented within a single prehistoric cemetery on one of the Channel Islands. A total of 966 crania representing 30 local sites and about 7,000 years of human occupation were examined, revealing an abnormally high prevalence of this transposition trait among islanders during the Early period of southern California prehistory ( approximately 5500-600 B.C.). One of the affected crania is from a cemetery more than 7,000-years-old and constitutes the earliest case of tooth transposition in humans so far reported. The results are consistent with findings by other studies that have indicated inbreeding among the early Channel Islands groups. Together with the normal transposition rates among mainland populations, the decreasing prevalence of maxillary canine-first premolar transposition among island populations across the Holocene suggests that inbreeding on the northern Channel Islands had all but ceased by the end of the first millennium B.C., most likely as a result of increased cross-channel migration and interaction.