Loading...
25 results
Search Results
Now showing 1 - 10 of 25
- Using remote sensing and machine learning to reconstruct paleoenvironmental features in the Koobi Fora FormationPublication . Dorans, Elizabeth R.; Coelho, Joao D'Oliveira; Anemone, Robert L.; Bobe, Rene; Carvalho, Susana; Forrest, Frances; Braun, David R.Advances in Geographic Information Systems and Remote Sensing technologies have the potential to revolutionize archaeological and paleontological fieldwork. Machine learning models have been effective in identifying conditions ideal for preservation, exposure, and discovery of fossils in a range of geographic contexts. Researchers working in the Koobi Fora Formation of northern Kenya have long inquired about the geographic patterning of extinct fauna and their respective paleoenvironments. This project is the first attempt to use machine learning techniques to capture paleoecological patterns utilizing topographical and spectral variables that may be predictive of the input of aquatic components in the paleoenvironments of the Koobi Fora Formation.
- Death among primates: a critical review of non-human primate interactions towards their dead and dyingPublication . Goncalves, Andre; Carvalho, SusanaFor the past two centuries, non-human primates have been reported to inspect, protect, retrieve, carry or drag the dead bodies of their conspecifics and, for nearly the same amount of time, sparse scientific attention has been paid to such behaviours. Given that there exists a considerable gap in the fossil and archaeological record concerning how early hominins might have interacted with their dead, extant primates may provide valuable insight into how and in which contexts thanatological behaviours would have occurred. First, we outline a comprehensive history of comparative thanatology in non-human primates, from the earliest accounts to the present, uncovering the interpretations of previous researchers and their contributions to the field of primate thanatology. Many of the typical behavioural patterns towards the dead seen in the past are consistent with those observed today. Second, we review recent evidence of thanatological responses and organise it into distinct terminologies: direct interactions (physical contact with the corpse) and secondary interactions (guarding the corpse, vigils and visitations). Third, we provide a critical evaluation regarding the form and function of the behavioural and emotional aspects of these responses towards infants and adults, also comparing them with non-conspecifics. We suggest that thanatological interactions: promote a faster re-categorisation from living to dead, decrease costly vigilant/caregiving behaviours, are crucial to the management of grieving responses, update position in the group's hierarchy, and accelerate the formation of new social bonds. Fourth, we propose an integrated model of Life-Death Awareness, whereupon neural circuitry dedicated towards detecting life, i.e. the agency system (animate agency, intentional agency, mentalistic agency) works with a corresponding system that interacts with it on a decision-making level (animate/inanimate distinction, living/dead discrimination, death awareness). Theoretically, both systems are governed by specific cognitive mechanisms (perceptual categories, associative concepts and high-order reasoning, respectively). Fifth, we present an evolutionary timeline from rudimentary thanatological responses likely occurring in earlier non-human primates during the Eocene to the more elaborate mortuary practices attributed to genus Homo throughout the Pleistocene. Finally, we discuss the importance of detailed reports on primate thanatology and propose several empirical avenues to shed further light on this topic. This review expands and builds upon previous attempts to evaluate the body of knowledge on this subject, providing an integrative perspective and bringing together different fields of research to detail the evolutionary, sensory/cognitive, developmental and historical/archaeological aspects of primate thanatology. Considering all these findings and given their cognitive abilities, we argue that non-human primates are capable of an implicit awareness of death.
- How much older than the oldowan? Tool use and manufacture in the last common ancestor of Pan and HomoPublication . Carvalho, Susana; Rolian, Campbell
- Could it be culture? An inter-troop comparison of baboon behaviour in Gorongosa National Park, MozambiquePublication . Muschinski, Jana; Lewis-Bevan, Lynn; Biro, Dora; Carvalho, SusanaBaboons in Gorongosa National Park have been observed to strip bark off Acacia robusta trees, chew the fibres underneath the bark, and spit out wadges. These actions leave identifiable marks on trees. Work conducted during 2018 indicates regional variation exists within the park1. Some trees exhibit stripping on the trunk, likely by elephants, in addition to (or instead of) on upper branches. We resurveyed all sites for bark stripping in 2019 and tested several ecological hypotheses following the method of exclusion2, 3.
- Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-spongesPublication . Hockings, Kimberley J.; Bryson-Morrison, Nicola; Carvalho, Susana; Fujisawa, Michiko; Humle, Tatyana; McGrew, William C.; Nakamura, Miho; Ohashi, Gaku; Yamanashi, Yumi; Yamakoshi, Gen; Matsuzawa, TetsuroAfrican apes and humans share a genetic mutation that enables them to effectively metabolize ethanol. However, voluntary ethanol consumption in this evolutionary radiation is documented only inmodern humans. Here, we report evidence of the long-term and recurrent ingestion of ethanol from the raffia palm (Raphia hookeri, Arecaceae) by wild chimpanzees (Pan troglodytes verus) at Bossou in Guinea, West Africa, from 1995 to 2012. Chimpanzees at Bossou ingest this alcoholic beverage, often in large quantities, despite an average presence of ethanol of 3.1% alcohol by volume (ABV) and up to 6.9% ABV. Local people tap raffia palms and the sap collects in plastic containers, and chimpanzees use elementary technology-a leafy tool-to obtain this fermenting sap. These data show that ethanol does not act as a deterrent to feeding in this community of wild apes, supporting the idea that the last common ancestor of living African apes and modern humans was not averse to ingesting foods containing ethanol.
- Using nonhuman culture in conservation requires careful and concerted actionPublication . Carvalho, Susana; Wessling, Erin G.; Abwe, Ekwoge E.; Almeida-Warren, Katarina; Arandjelovic, Mimi; Boesch, Christophe; Danquah, Emmanuel; Diallo, Mamadou Saliou; Hobaiter, Catherine; Hockings, Kimberley; Humle, Tatyana; Ikemeh, Rachel Ashegbofe; Kalan, Ammie K.; Luncz, Lydia; Ohashi, Gaku; Pascual‐Garrido, Alejandra; Piel, Alex; Samuni, Liran; Soiret, Serge; Sanz, Crickette; Koops, KathelijneDiscussions of how animal culture can aid the conservation crisis are burgeoning. As scientists and conservationists working to protect endangered species, we call for reflection on how the culture concept may be applied in practice. Here, we discuss both the potential benefits and potential shortcomings of applying the animal culture concept, and propose a set of achievable milestones that will help guide and ensure its effective integration existing conservation frameworks, such as Adaptive Management cycles or Open Standards.
- Unsupervised learning of satellite images enhances discovery of late Miocene fossil sites in the Urema Rift, Gorongosa, MozambiquePublication . d’Oliveira Coelho, João; Anemone, Robert L.; Carvalho, SusanaPaleoanthropological research focus still devotes most resources to areas generally known to be fossil rich instead of a strategy that first maps and identifies possible fossil sites in a given region. This leads to the paradoxical task of planning paleontological campaigns without knowing the true extent and likely potential of each fossil site and, hence, how to optimize the investment of time and resources. Yet to answer key questions in hominin evolution, paleoanthropologists must engage in fieldwork that targets substantial temporal and geographical gaps in the fossil record. How can the risk of potentially unsuccessful surveys be minimized, while maximizing the potential for successful surveys?
- Chimpanzee face recognition from videos in the wild using deep learningPublication . Schofield, Daniel; Nagrani, Arsha; Zisserman, Andrew; Hayashi, Misato; Matsuzawa, Tetsuro; Biro, Dora; Carvalho, SusanaVideo recording is now ubiquitous in the study of animal behavior, but its analysis on a large scale is prohibited by the time and resources needed to manually process large volumes of data. We present a deep convolutional neural network (CNN) approach that provides a fully automated pipeline for face detection, tracking, and recognition of wild chimpanzees from long-term video records. In a 14-year dataset yielding 10 million face images from 23 individuals over 50 hours of footage, we obtained an overall accuracy of 92.5% for identity recognition and 96.2% for sex recognition. Using the identified faces, we generated co-occurrence matrices to trace changes in the social network structure of an aging population. The tools we developed enable easy processing and annotation of video datasets, including those from other species. Such automated analysis unveils the future potential of large-scale longitudinal video archives to address fundamental questions in behavior and conservation.
- Automated face recognition using deep neural networks produces robust primate social networks and sociality measuresPublication . Schofield, Daniel P.; Albery, Gregory F.; Firth, Josh A.; Mielke, Alexander; Hayashi, Misato; Matsuzawa, Tetsuro; Biro, Dora; Carvalho, SusanaLongitudinal video archives of behaviour are crucial for examining how sociality shifts over the lifespan in wild animals. New approaches adopting computer vision technology hold serious potential to capture interactions and associations between individuals in video at large scale; however, such approaches need a priori validation, as methods of sampling and defining edges for social networks can substantially impact results.Here, we apply a deep learning face recognition model to generate association networks of wild chimpanzees using 17 years of a video archive from Bossou, Guinea. Using 7 million detections from 100 h of video footage, we examined how varying the size of fixed temporal windows (i.e. aggregation rates) for defining edges impact individual-level gregariousness scores.The highest and lowest aggregation rates produced divergent values, indicating that different rates of aggregation capture different association patterns. To avoid any potential bias from false positives and negatives from automated detection, an intermediate aggregation rate should be used to reduce error across multiple variables. Individual-level network-derived traits were highly repeatable, indicating strong inter-individual variation in association patterns across years and highlighting the reliability of the method to capture consistent individual-level patterns of sociality over time. We found no reliable effects of age and sex on social behaviour and despite a significant drop in population size over the study period, individual estimates of gregariousness remained stable over time.We believe that our automated framework will be of broad utility to ethology and conservation, enabling the investigation of animal social behaviour from video footage at large scale, low cost and high reproducibility. We explore the implications of our findings for understanding variation in sociality patterns in wild ape populations. Furthermore, we examine the trade-offs involved in using face recognition technology to generate social networks and sociality measures. Finally, we outline the steps for the broader deployment of this technology for analysis of large-scale datasets in ecology and evolution.
- Risk perception and terrestriality in primates: a quasi‐experiment through habituation of chacma baboons (Papio ursinus) in Gorongosa National Park, MozambiquePublication . Hammond, Philippa; Lewis‐Bevan, Lynn; Biro, Dora; Carvalho, SusanaObjectives Habituation is a common pre-requisite for studying noncaptive primates. Details and quantitative reporting on this process are often overlooked but are useful for measuring human impact on animal behavior, especially when comparing studies across time or sites. During habituation, perceived risk of a stimulus-human observers-is assumed to decline with repeated exposure to that stimulus. We use habituation as a quasi-experiment to study the landscape of fear, exploring relationships between actual risk, perceived risk, mediating environmental variables, and behavioral correlates. Materials and Methods We recorded vocalizations and observer-directed vigilance as indicators of perceived risk during habituation of two troops of chacma baboons (Papio ursinus) in Gorongosa National Park, Mozambique. Here, we model changes in these variables as a function of habituation time, troop, time of day, and habitat features. We also model the relationship between each of the anti-predator behaviors and ground-use, exploring whether they predict greater terrestriality in the baboons. Results In both troops, vocalization rates and observer-directed vigilance declined with cumulative exposure to observers, but were heightened later in the day and in denser habitat types. We found that terrestrial activity was negatively related to levels of both vocalizations and observer-directed vigilance. Discussion This study provides a quantitative assessment of the impact of human observation on primate behavior and highlights environmental variables that influence anti-predator behaviors, perhaps indicating heightened perception of risk. The relationship between perceived risk and terrestriality is significant for understanding the evolution of this rare trait in primates.
- «
- 1 (current)
- 2
- 3
- »