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Biology subjects

Cucchi, T.

Publications and source records attributed to Cucchi, T..

6 recordsLinked to original sources

Bioarchaeological evidence for commensal brown rats (Rattus norvegicus) in early Neolithic China

Due to its commensal relationship with humans, facilitating its dispersal from its natural range in East Asia, the brown rat (Rattus norvegicus) is now one of the most cosmopolitan and invasive mammals. Brown rats are also vectors of human pathogens and the most commonly used mammalian model (after mice) for biomedical research. Despite their major role in biodiversity loss and medicine, our understanding of a likely origin for their commensal relationship with humans in China still relies on modern population genetics, without a reliable timeframe of localisation. In this research, we have tried to fill this gap using direct information from the archaeological remains of rats collected by Chinese colleagues in several archaeological sites dated between 9000 and 3500 BP. Thanks to high-resolution morphometrics and direct 14C dating, we have identified the occurrence of the brown rat (Rattus norvegicus) within the domestic area deposits of the early Neolithic site of Jiahu by 7500 cal BP, suggesting a tentative link between rice agriculture and an early commensal behaviour of this species.

zoology↗

Brain size reduction in dogs was already established at least by the Late Neolithic of western Europe, 5,000 years ago

The timing and causes of brain size reduction in domestic dogs remain uncertain. Using endocasts volume as a proxy for brain size, this study provides a first insight into long-term brain size evolution in the wolf-dog lineage. We compared endocranial volumes of 185 modern and 22 prehistoric wolves and dogs ranging from Western Europe to Australia, and spanning the Pleniglacial (35 Ky BP) to the Late Neolithic (5 Ky BP). Our results reveal that Pleistocene so called "protodogs" show no brain size reduction compared to coeval Pleistocene wolves. Instead, we observed a slightly larger relative endocranial volume in the 35,000-year-old protodog from Goyet, which could suggest increased behavioural flexibility in the presence of humans. This hypothesis needs to be tested further. In contrast, Late Neolithic dogs show a drastic 46% brain size reduction with an endocranial volumes comparable to modern small terrier and toy breeds. The anxious and wary temperaments of these Late Neolithic dogs, induced by the brain tissue reorganization associated with such a size reduction, could have served an alerting purpose, among the many other potential roles dogs could have played within this Late Neolithic socio-ecosystems.

zoology↗

Genomic and morphometric evidence for Austronesian-mediated pig translocation in the Pacific

Human mediated translocation of non-native pig species (genus Sus) to the islands of Wallacea and Oceania has significantly altered local ecosystems. To investigate the timing and trajectory of these introductions, we conducted both genomic analyses of 576 pig nuclear genomes and a geometric morphometric analysis of 714 modern and ancient dental remains. Our analyses demonstrate that feral and domestic pigs in Wallacea and Oceania possess diverse ancestries resulting from the introduction of multiple, sequential pig populations followed by gene flow. Despite the variability in their genomic ancestry these pigs all possess a distinct tooth morphology, and a genetic link to the Chinese domestic pig populations that accompanied the dispersal of Austronesian language speakers [~]4,000-3,000 years ago via Taiwan and the Philippines.

evolutionary biology↗

Can growth in captivity alter the calcaneal microanatomy of a wild ungulate?

AO_SCPLOWBSTRACTC_SCPLOWReduced mobility associated with captivity induces changes in biomechanical stress on the skeleton of domesticated animals. Due to bone plasticity, bones morphology and internal structure can respond to these new biomechanical stresses over individuals lifetime. In a context where documenting early process of animal domestication is challenging, this study will test the hypothesis that change in mobility patterns during a wild ungulates life will alter the internal structure of its limb bones and provide a proof of concept for the application of this knowledge in Zooarchaeology. Using the calcaneus as a phenotypic marker through qualitative and quantitative 3D microanatomical analyses, we relied on a comparative study across wild boars (Sus scrofa) populations from controlled experimental conditions with different mobility patterns (natural habitat, large pen, and stall) and archaeological specimens collected from middle and late Mesolithic as surrogate for the norm of reaction in European wild boar phenotype before the spread of agriculture and domestic pigs. Results provide evidence for compressive and tensile forces as the main elements affecting the variation in the cortical thickness along the calcaneus. Furthermore, changes in the internal structure of the calcaneus between mobility patterns are observed but their intensity is not directly associated with the degree of mobility restriction and only weakly impacted by the size or weight of the individuals. Despite having greater bone volume, the calcaneus of the Mesolithic wild boars displays a very similar microanatomy compared to the present-day hunted or captive wild boars. These results suggest that calcaneal microanatomy is more affected by population differences than by locomotor variation. For all these reasons, this preliminary study doesnt support the use of microanatomy of the calcaneus as an indicator of change in locomotor behaviour induced by captivity in the archaeological record.

developmental biology↗

Palaeogenomic analysis of black rat (Rattus rattus) reveals multiple European introductions associated with human economic history

The distribution of the black rat (Rattus rattus) has been heavily influenced by its association with humans. The dispersal history of this non-native commensal rodent across Europe, however, remains poorly understood, and different introductions may have occurred during the Roman and medieval periods. Here, in order to reconstruct the population history of European black rats, we generated a de novo genome assembly of the black rat, 67 ancient black rat mitogenomes and 36 ancient nuclear genomes from sites spanning the 1st-17th centuries CE in Europe and North Africa. Analyses of mitochondrial DNA confirm that black rats were introduced into the Mediterranean and Europe from Southwest Asia. Genomic analyses of the ancient rats reveal a population turnover in temperate Europe between the 6th and 10th centuries CE, coincident with an archaeologically attested decline in the black rat population. The near disappearance and re-emergence of black rats in Europe may have been the result of the breakdown of the Roman Empire, the First Plague Pandemic, and/or post-Roman climatic cooling.

evolutionary biology↗

Deep learning for species identification of modern and fossil rodent molars

Reliable identification of species is a key step to assess biodiversity. In fossil and archaeological contexts, genetic identifications remain often difficult or even impossible and morphological criteria are the only window on past biodiversity. Methods of numerical taxonomy based on geometric morphometric provide reliable identifications at the specific and even intraspecific levels, but they remain relatively time consuming and require expertise on the group under study. Here, we explore an alternative based on computer vision and machine learning. The identification of three rodent species based on pictures of their molar tooth row constituted the case study. We focused on the first upper molar in order to transfer the model elaborated on modern, genetically identified specimens to isolated fossil teeth. A pipeline based on deep neural network automatically cropped the first molar from the pictures, and returned a prediction regarding species identification. The deep-learning approach performed equally good as geometric morphometrics and, provided an extensive reference dataset including fossil teeth, it was able to successfully identify teeth from an archaeological deposit that was not included in the training dataset. This is a proof-of-concept that such methods could allow fast and reliable identification of extensive amounts of fossil remains, often left unstudied in archaeological deposits for lack of time and expertise. Deep-learning methods may thus allow new insights on the biodiversity dynamics across the last 10.000 years, including the role of humans in extinction or recent evolution.

zoology↗