Post-mortem enamel surface texture alteration during taphonomic processes—do experimental approaches reflect natural phenomena?

Experimental approaches are often used to better understand the mechanisms behind and consequences of post-mortem alteration on proxies for diet reconstruction. Dental microwear texture analysis (DMTA) is such a dietary proxy, using dental wear features in extant and extinct taxa to reconstruct feeding behaviour and mechanical food properties. In fossil specimens especially, DMTA can be biased by post-mortem alteration caused by mechanical or chemical alteration of the enamel surface. Here we performed three different dental surface alteration experiments to assess the effect of common taphonomic processes by simplifying them: (1) tumbling in sediment suspension to simulate fluvial transport, (2) sandblasting to simulate mechanical erosion due to aeolian sediment transport, (3) acid etching to simulate chemical dissolution by stomach acid. For tumbling (1) we found alteration to be mainly dependent on sediment grain size fraction and that on specimens tumbled with sand fractions mainly post-mortem scratches formed on the dental surface, while specimens tumbled with a fine-gravel fraction showed post-mortem formed dales. Sandblasting (2) with loess caused only negligible alteration, however blasting with fine sand quartz particles resulted in significant destruction of enamel surfaces and formation of large post-mortem dales. Acid etching (3) using diluted hydrochloric acid solutions in concentrations similar to that of predator stomachs led to a complete etching of the whole dental surface, which did not resemble those of teeth recovered from owl pellets. The experiments resulted in post-mortem alteration comparable, but not identical to naturally occurring post-mortem alteration features. Nevertheless, this study serves as a first assessment and step towards further, more refined taphonomic experiments evaluating post-mortem alteration of dental microwear texture (DMT).

Dorset Harpoon Endblade Hafting and Early Metal Use in the North American Arctic

Composite tool hafting research has touched upon almost every era and region of human history. One aspect that has seen little attention is how those traces of hafting strategies might reflect the raw material of the endblade that an organic handle would have held. This aspect is particularly important for clarifying the scope and scale of novel raw material use in contexts that have concurrent use of different lithic, bone, and metal materials. This article analyzes harpoon heads from the Canadian Arctic in Dorset cultural contexts and identifies three different hafting techniques employed across time. For roughly one millennium, Dorset groups used a single harpoon endblade hafting technique. After AD 500, new hafting techniques were developed, corresponding with the emergence of metal use. Some of these methods are not compatible with common chipped stone materials and signal an increase in metal endblade production. However, surviving metal objects are underrepresented in museum collections because of various taphonomic processes. By recognizing the materials of the harpoon endblade and the specific constraints of some hafting techniques, it is possible to identify what these endblade materials may have been and expand the known extent and intensity of early metal use by observing the hafts alone.

The effects of dehydration and local soil on parasite recovery: A preliminary paleoparasitological evaluation on experimental coprolites

Experimental paleoparasitological approaches have been used in order to optimize the methodology previously to the application in archeological samples. In this study we evaluated the action of dehydration and local soil (Central Argentina) on the loss of parasite eggs in experimental coprolites, using two parasitological techniques: spontaneous sedimentation and sucrose-flotation. Experimental coprolites comprised fresh human feces, positive for Hymenolepis nana, Ascaris sp., and Enterobius vermicularis, submitted to controlled artificial dehydration. Experimental coprolites with soil addition were prepared by mixing archeological sediment with equal mass of fresh feces. Helminth eggs were counted and eggs per gram were estimated in each subsample. Statistical analyses were applied to compare subsamples before and after desiccation and with and without addition of soil sediment. The performance of parasitological methods statistically differed, the sucrose flotation technique being the less effective when fresh feces and experimental coprolites were analyzed. Partial deformation of eggs was observed via both techniques only in subsamples containing H. nana eggs. However, this was not seen in Ascaris sp. subsamples, possibly due to eggshell composition. We found that sample desiccation significantly decreased the number of eggs in the experimental coprolites. Mixing archeological sediment with the fecal material also resulted in significantly fewer eggs surviving, independent of desiccation. This shows that climate and soil in which archeological fecal samples are found can strongly influence the survival of parasite eggs from past populations. The small amount of parasite evidence often found in paleoparasitological analyses, including Central Argentina, could be attributed to the action of taphonomic processes rather than to the real absence of infection in these ancient populations. Importantly, the study highlights the role of local soil, confirmed for the first time by empirical data. The research provides valuable insights into the understanding of the paleoparasitological results of the region and of general paleoparasitology.

Epidemics and Wars: Comparative Archaeology and Anthropology of Ancient Greek Mass Burials

The high number of dead bodies to deal with in time of mortality crises (events marked by an unusually high number of dead in a limited amount of time) often leads to modifications in the traditional funerary practices of a society. This contribution questions the way Ancient Greeks, from the 8th till the 3rd century BC, handled such mortality crises, focusing on mass burials. In a first methodological part, we discuss the means to identify funerary sites related to mortality crises, using the methods of archaeothanatology. By confronting archaeological features (taphonomic processes, position of the remains, grave type, offerings, etc.) and bioanthropological data (number of dead, sex, age, pathologies, etc.), we will first define the main characteristics of mass burials. We will then question how to discriminate between mass burials linked to war, epidemics, massacres and famine, underlining the major importance of historical sources in this process. The second part is dedicated to the study of various cases from Athens, Paros, Chaeronea, Tanagra and Greek Sicily and their interpretation. We will argue that epidemic mass burials are the most difficult to identify, since they may present innumerable variations in terms of osteoprofiles and archaeological features. Finally, we will question our abilities, as archaeoanthropologists, to evaluate the impact of epidemics on the funerary treatment of the dead in the Ancient world.

Retrodeformation of the Steinheim Cranium: Insights into the Evolution of Neanderthals

A number of different approaches are currently available to digitally restore the symmetry of a specimen deformed by taphonomic processes. These tools include mirroring and retrodeformation to approximate the original shape of an object by symmetrisation. Retrodeformation has the potential to return a rather faithful representation of the original shape, but its power is limited by the availability of bilateral landmarks. A recent protocol proposed by Schlager and colleagues (2018) overcomes this issue by using bilateral landmarks and curves as well as semilandmarks. Here we applied this protocol to the Middle Pleistocene human cranium from Steinheim (Germany), the holotype of an abandoned species named Homo steinheimensis. The peculiar morphology of this fossil, associated with the taphonomic deformation of the entire cranium and the lack of a large portion of the right side of the face, has given rise to different hypotheses over its phylogenetic position. The reconstruction presented here sheds new light on the taphonomic origin of some features observed on this crucial specimen and results in a morphology consistent with its attribution to the Neanderthal lineage.

From Water into Sediment—Tracing Freshwater Cyanobacteria via DNA Analyses

Sedimentary ancient DNA-based studies have been used to probe centuries of climate and environmental changes and how they affected cyanobacterial assemblages in temperate lakes. Due to cyanobacteria containing potential bloom-forming and toxin-producing taxa, their approximate reconstruction from sediments is crucial, especially in lakes lacking long-term monitoring data. To extend the resolution of sediment record interpretation, we used high-throughput sequencing, amplicon sequence variant (ASV) analysis, and quantitative PCR to compare pelagic cyanobacterial composition to that in sediment traps (collected monthly) and surface sediments in Lake Tiefer See. Cyanobacterial composition, species richness, and evenness was not significantly different among the pelagic depths, sediment traps and surface sediments (p > 0.05), indicating that the cyanobacteria in the sediments reflected the cyanobacterial assemblage in the water column. However, total cyanobacterial abundances (qPCR) decreased from the metalimnion down the water column. The aggregate-forming (Aphanizomenon) and colony-forming taxa (Snowella) showed pronounced sedimentation. In contrast, Planktothrix was only very poorly represented in sediment traps (meta- and hypolimnion) and surface sediments, despite its highest relative abundance at the thermocline (10 m water depth) during periods of lake stratification (May–October). We conclude that this skewed representation in taxonomic abundances reflects taphonomic processes, which should be considered in future DNA-based paleolimnological investigations.

Taphonomy of marine vertebrates of the Pisco Formation (Miocene, Peru): Insights into the origin of an outstanding Fossil-Lagerstätte

The Miocene Pisco Formation, broadly exposed in the Ica Desert of southern Peru, is among the most outstanding Cenozoic marine Fossil-Lagerstätten worldwide. It is renowned for its exceptional preservation and abundance of vertebrate fossils, including a rich assemblage of whales and dolphins (Cetacea). Here, we integrate taphonomic data on 890 marine vertebrate fossils, gathered through 16 different localities. Our observations range from the taxonomic distribution, articulation, completeness, disposition and orientation of skeletons, to the presence of bite marks, associations with shark teeth and macro-invertebrates, bone and soft tissue preservation, and the formation of attendant carbonate concretions and sedimentary structures. We propose that the exceptional preservation characterising many Pisco vertebrates, as well as their exceptionally high abundance, cannot be ascribed to a single cause like high sedimentation rates (as proposed in the past), but rather to the interplay of several favourable factors including: (i) low levels of dissolved oxygen at the seafloor (with the intervention of seasonal anoxic events); (ii) the early onset of mineralisation processes like apatite dissolution/recrystallisation and carbonate mineral precipitation; (iii) rapid burial of carcasses in a soupy substrate and/or a novel mechanism involving scour-induced self-burial; and (iv) original biological richness. Collectively, our observations provide a comprehensive overview of the taphonomic processes that shaped one of South America’s most important fossil deposits, and suggest a model for the formation of other marine vertebrate Fossil-Lagerstätten.

Taking out the Trash: On Excavating Settlements in General, and Houses of the Battle Axe Culture in Particular

Archaeological interpretation rests partly on theory and partly on material remains, and changes in field methods can cause major changes in both areas. Longhouses were virtually unknown on mainland Sweden until the introduction of the excavator machine in the late 1970s. However, this method is biased in that the cultural practice of some periods is favoured at the expense of others. From the Battle Axe culture very few houses and artcfacts have been found, and it has bcen suggested the sitcs were not true settlements. This vicw is challenged by showing that taphonomic processes and cultural practice combine to make this period difficult to identify using the standard field method. Paradoxically, some other periods have no more remains and/or house structures than the Battle Axe period has, but they are not subjected to the same debate. Comparison with Corded Ware sites in Europe provides support for the argument that the scarcity of Battle Axe settlements is mainly due to taphonomic processes. Thc article calls for more reflective field methods on all prehistoric settlements.