Dietmar Crailsheim - Academia.edu (original) (raw)
Papers by Dietmar Crailsheim
Emerging infectious diseases, Jun 1, 2024
The Journal of Experimental Biology, Aug 31, 2023
Ecologies, May 13, 2024
Interactions on the Welfare of Captive Chimpanzee Groups (Pan troglodytes).
Ecologies
Wild chimpanzees live in large and complex social communities, but their complexity is determined... more Wild chimpanzees live in large and complex social communities, but their complexity is determined by the number of potential social partners as well as the frequent changes in group composition due to fission–fusion dynamics. Alternatively, captive housed chimpanzee groups are usually much smaller and less complex. However, studies have shown that groups can be housed in adjacent habitats, potentially increasing the number of social partners, i.e., granting additional relationship opportunities and enhanced social complexity. While most social network studies analyze social groups as closed systems, this study assessed the impact of social interactions between two neighboring groups of chimpanzees, based on two social network indices (Vertex strength centrality and Deviation from edge weight disparity). Furthermore, Linear Mixed Models (LMMs) were employed to assess whether gender, age, and intra-/intergroup directionality influenced these indices. We recorded occurrences of social ...
Animals
Wild chimpanzees (Pan troglodytes) live in flexible fission–fusion societies with frequent change... more Wild chimpanzees (Pan troglodytes) live in flexible fission–fusion societies with frequent changes in both group size and composition. These changes depend mostly on resource availability and individual social preferences yet in captivity are determined by housing organizations. During a period of seven years, we observed a group of sanctuary chimpanzees, focusing on how they adapted to changes in the group composition over time. Using linear mixed models (LMMs), factors such as group size, sex ratio, seasonality, and the individuals’ sex and origin (wild caught vs. captive born) were considered in order to evaluate the impact on the chimpanzees’ activity levels, the occurrence of undesired behaviors (abnormal and self-directed behaviors) and the social grooming networks. Our results indicate that the activity levels and the occurrence of undesired behaviors were impacted by changes in group composition and the individuals’ biographic background. The colder season was marked by high...
Scientific Reports
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low- to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees’ biograp...
Scientific reports, Jan 4, 2018
A correction to this article has been published and is linked from the HTML and PDF versions of t... more A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Scientific reports, Jan 9, 2017
The genus Pan is the closest related to humans (Homo sapiens) and it includes two species: Pan tr... more The genus Pan is the closest related to humans (Homo sapiens) and it includes two species: Pan troglodytes (chimpanzees) and Pan paniscus (bonobos). Different characteristics, some of biomedical aspect, separate them from us. For instance, some common human medical conditions are rare in chimpanzees (menopause, Alzheimer disease) although it is unclear to which extent longevity plays an active role in these differences. However, both humans and chimpanzees present similar pathologies, thus, understanding traits in chimpanzees can help unravel the molecular basis of human conditions. Here, we sequenced the genome of Nico, a central chimpanzee diagnosed with a particular biomedical condition, the Chiari malformation. We performed a variant calling analysis comparing his genome to 25 whole genomes from healthy individuals (bonobos and chimpanzees), and after predicting the effects of the genetic variants, we looked for genes within the OMIM database. We found a novel, private, predicte...
Animals
The question of ‘if and how captive primates are affected by visitors’ has gained increasing atte... more The question of ‘if and how captive primates are affected by visitors’ has gained increasing attention over the last decades. Although the majority reported undesirable effects on behavior and wellbeing, many studies reported contradicting results. Most of these studies were conducted at zoos, typically with little or no control over visitors’ actions. Yet little is known about the impact under very controlled visitor conditions. In order to fill this gap, we conducted this study at a primate sanctuary which allows public access only via a guided visit under strict supervision. We observed 14 chimpanzees, recording their behavior during, after and in the absence of guided visits over a 10-month period. Furthermore, we categorized the visitors regarding group size and composition to see if certain group types would produce a stronger impact on the chimpanzees’ behavior. As expected, we found visitors at the sanctuary to produce only a neutral impact on the chimpanzees’ behavior, dete...
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low-to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees' biographical background on the social interaction types and found affiliative behaviour as well as allogrooming to be affected by adverse early life experiences. We conclude that this multiplex approach provides a more realistic framework giving detailed insight into the sociability of these chimpanzees and can function as a tool to support captive care management decisions.
Animals
Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions f... more Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions from early infancy onwards. The preferred option for ending their existence as pet or circus chimpanzees is their rescue and transfer to a primate sanctuary that will provide them with optimal living and social conditions, so that they can thrive. In this case study, we had the rare opportunity to compare the activity budgets of three chimpanzees from their time as pets in 2004 to their time living at the MONA sanctuary in 2020, after almost a decade in the centre. We found their behaviour patterns changed in accordance with the sanctuaries’ rehabilitation objectives. Resting periods increased considerably while vigilance simultaneously declined sharply. Moreover, the chimpanzees’ social competence increased as allogrooming became the predominant social behaviour, and agonistic interactions diminished even though they were living within a larger social group at the sanctuary. All three ch...
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low-to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees' biographical background on the social interaction types and found affiliative behaviour as well as allogrooming to be affected by adverse early life experiences. We conclude that this multiplex approach provides a more realistic framework giving detailed insight into the sociability of these chimpanzees and can function as a tool to support captive care management decisions. Network approaches based on social behaviours of nonhuman animals facilitated the successful evaluation of how sociality is shaped by evolutionary and ecological conditions and reflected in behavioural processes, such as social learning 1 and cooperation 2 , and also in the spread of diseases 3,4. Furthermore, it enabled researchers to investigate, simulate and predict patterns of hierarchies 5 , information transmission efficiency 6 , group cohesion and stability 7,8. Traditionally social networks were analysed by aggregating information and/or investigating only one type (e.g. a certain behaviour or distance) of connection between individuals. While this approach might seem narrow, it did allow the explanation of trends and patterns, which had been misinterpreted or underrated previously 9. However, as research on social networks advanced over time and databases became bigger and more varied, the necessity arose to get insights in social networks that are even more realistic. Considering the multidimensional nature of the network components in space and time 10,11 , it became obvious that in order to fully grasp social structures and dynamics, it was essential to construct multiple social networks based on a variety of edges (i.e. connections between nodes) between the same set of nodes (i.e. individuals) 12. A great many studies on a variety of species, ranging from insects to nonhuman primates demonstrated the complexity of social structures in the animal kingdom 13,14. Particularly for nonhuman primates, who are living in complex social societies, using a variety of strategies and behaviours to interact and connect with each other 15 , it seems a promising approach to implement a more realistic framework in order to explore their social structures. Especially during the last two decades, algorithms and computational technologies have been developed, providing the means to analyse and visualize complex multilayer relationships 16. Hence, the use of these multilayer networks is now also recommended 17 and it has already been used in the studies of primate behaviour 18,19. While it is recommendable to create a multilayer network based on several edges, the question of how many edges should be taken into account remains. Keeping in mind that an increase of data collected comes with a certain price, the right equilibrium between information gain, efficiency and redundancy has to be found 20,21 .
Journal of Veterinary Behavior
PLOS ONE, 2020
The long-term effects of early life adversities on social capacities have been documented in huma... more The long-term effects of early life adversities on social capacities have been documented in humans and wild-caught former laboratory chimpanzees (Pan troglodytes). However, former pet and entertainment chimpanzees have received little attention to date. This study aimed to investigate the long-term effects of early life experience on 18 former pet and entertainment chimpanzees, based on social grooming data collected at a primate rescue centre over a 12-year period. Moreover, we also focused on the possible short-term effects that alterations to group composition might have on grooming patterns. For this purpose, we compared stable and unstable periods (i.e. where alterations to group composition occurred). We used two individual social network measures to analyse the grooming activity and the distribution of grooming among group mates for each individual. We could show that wild-caught chimpanzees were significantly more selective regarding their grooming partners and spent less time grooming when compared to their captive born companions. We also found that individuals who were predominantly housed without conspecifics during infancy spent less time grooming compared to those who were predominantly housed with conspecifics during infancy. Furthermore , we found that alterations to the group composition had short-term effects on the distribution of social grooming from a more equal distribution during periods with a stable group composition towards a more unequal and selective distribution during unstable periods. Thus, we conclude that the social grooming networks of former pet and entertainment chimpanzees are shaped not only by long-term effects such as early life experience, but also by short-term effects such as alterations to group composition. Remarkably, we found not only captive born chimpanzees but also wild-caught individuals to adjust their grooming to socially challenging situations by modifying their grooming distribution in a similar way.
Plos One, 2020
The long-term effects of early life adversities on social capacities have been documented in huma... more The long-term effects of early life adversities on social capacities have been documented in humans and wild-caught former laboratory chimpanzees (Pan troglodytes). However, former pet and entertainment chimpanzees have received little attention to date. This study aimed to investigate the long-term effects of early life experience on 18 former pet and entertainment chimpanzees, based on social grooming data collected at a primate rescue centre over a 12-year period. Moreover, we also focused on the possible short-term effects that alterations to group composition might have on grooming patterns. For this purpose, we compared stable and unstable periods (i.e. where alterations to group composition occurred). We used two individual social network measures to analyse the grooming activity and the distribution of grooming among group mates for each individual. We could show that wild-caught chimpanzees were significantly more selective regarding their grooming partners and spent less time grooming when compared to their captive born companions. We also found that individuals who were predominantly housed without conspecifics during infancy spent less time grooming compared to those who were predominantly housed with conspecifics during infancy. Furthermore , we found that alterations to the group composition had short-term effects on the distribution of social grooming from a more equal distribution during periods with a stable group composition towards a more unequal and selective distribution during unstable periods. Thus, we conclude that the social grooming networks of former pet and entertainment chimpanzees are shaped not only by long-term effects such as early life experience, but also by short-term effects such as alterations to group composition. Remarkably, we found not only captive born chimpanzees but also wild-caught individuals to adjust their grooming to socially challenging situations by modifying their grooming distribution in a similar way.
Emerging infectious diseases, Jun 1, 2024
The Journal of Experimental Biology, Aug 31, 2023
Ecologies, May 13, 2024
Interactions on the Welfare of Captive Chimpanzee Groups (Pan troglodytes).
Ecologies
Wild chimpanzees live in large and complex social communities, but their complexity is determined... more Wild chimpanzees live in large and complex social communities, but their complexity is determined by the number of potential social partners as well as the frequent changes in group composition due to fission–fusion dynamics. Alternatively, captive housed chimpanzee groups are usually much smaller and less complex. However, studies have shown that groups can be housed in adjacent habitats, potentially increasing the number of social partners, i.e., granting additional relationship opportunities and enhanced social complexity. While most social network studies analyze social groups as closed systems, this study assessed the impact of social interactions between two neighboring groups of chimpanzees, based on two social network indices (Vertex strength centrality and Deviation from edge weight disparity). Furthermore, Linear Mixed Models (LMMs) were employed to assess whether gender, age, and intra-/intergroup directionality influenced these indices. We recorded occurrences of social ...
Animals
Wild chimpanzees (Pan troglodytes) live in flexible fission–fusion societies with frequent change... more Wild chimpanzees (Pan troglodytes) live in flexible fission–fusion societies with frequent changes in both group size and composition. These changes depend mostly on resource availability and individual social preferences yet in captivity are determined by housing organizations. During a period of seven years, we observed a group of sanctuary chimpanzees, focusing on how they adapted to changes in the group composition over time. Using linear mixed models (LMMs), factors such as group size, sex ratio, seasonality, and the individuals’ sex and origin (wild caught vs. captive born) were considered in order to evaluate the impact on the chimpanzees’ activity levels, the occurrence of undesired behaviors (abnormal and self-directed behaviors) and the social grooming networks. Our results indicate that the activity levels and the occurrence of undesired behaviors were impacted by changes in group composition and the individuals’ biographic background. The colder season was marked by high...
Scientific Reports
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low- to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees’ biograp...
Scientific reports, Jan 4, 2018
A correction to this article has been published and is linked from the HTML and PDF versions of t... more A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Scientific reports, Jan 9, 2017
The genus Pan is the closest related to humans (Homo sapiens) and it includes two species: Pan tr... more The genus Pan is the closest related to humans (Homo sapiens) and it includes two species: Pan troglodytes (chimpanzees) and Pan paniscus (bonobos). Different characteristics, some of biomedical aspect, separate them from us. For instance, some common human medical conditions are rare in chimpanzees (menopause, Alzheimer disease) although it is unclear to which extent longevity plays an active role in these differences. However, both humans and chimpanzees present similar pathologies, thus, understanding traits in chimpanzees can help unravel the molecular basis of human conditions. Here, we sequenced the genome of Nico, a central chimpanzee diagnosed with a particular biomedical condition, the Chiari malformation. We performed a variant calling analysis comparing his genome to 25 whole genomes from healthy individuals (bonobos and chimpanzees), and after predicting the effects of the genetic variants, we looked for genes within the OMIM database. We found a novel, private, predicte...
Animals
The question of ‘if and how captive primates are affected by visitors’ has gained increasing atte... more The question of ‘if and how captive primates are affected by visitors’ has gained increasing attention over the last decades. Although the majority reported undesirable effects on behavior and wellbeing, many studies reported contradicting results. Most of these studies were conducted at zoos, typically with little or no control over visitors’ actions. Yet little is known about the impact under very controlled visitor conditions. In order to fill this gap, we conducted this study at a primate sanctuary which allows public access only via a guided visit under strict supervision. We observed 14 chimpanzees, recording their behavior during, after and in the absence of guided visits over a 10-month period. Furthermore, we categorized the visitors regarding group size and composition to see if certain group types would produce a stronger impact on the chimpanzees’ behavior. As expected, we found visitors at the sanctuary to produce only a neutral impact on the chimpanzees’ behavior, dete...
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low-to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees' biographical background on the social interaction types and found affiliative behaviour as well as allogrooming to be affected by adverse early life experiences. We conclude that this multiplex approach provides a more realistic framework giving detailed insight into the sociability of these chimpanzees and can function as a tool to support captive care management decisions.
Animals
Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions f... more Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions from early infancy onwards. The preferred option for ending their existence as pet or circus chimpanzees is their rescue and transfer to a primate sanctuary that will provide them with optimal living and social conditions, so that they can thrive. In this case study, we had the rare opportunity to compare the activity budgets of three chimpanzees from their time as pets in 2004 to their time living at the MONA sanctuary in 2020, after almost a decade in the centre. We found their behaviour patterns changed in accordance with the sanctuaries’ rehabilitation objectives. Resting periods increased considerably while vigilance simultaneously declined sharply. Moreover, the chimpanzees’ social competence increased as allogrooming became the predominant social behaviour, and agonistic interactions diminished even though they were living within a larger social group at the sanctuary. All three ch...
Advances in the field of social network analysis facilitate the creation of multiplex networks wh... more Advances in the field of social network analysis facilitate the creation of multiplex networks where several interaction types can be analysed simultaneously. In order to test the potential benefits of this approach, we investigated the sociability of atypically raised chimpanzees by constructing and analysing 4-layered multiplex networks of two groups of former pet and entertainment chimpanzees (Pan troglodytes). These networks are based on four social interaction types (stationary vicinity, affiliative behaviour, allogrooming, passive close proximity) representing low-to high-level interaction types in terms of sociability. Using the tools provided by the MuxViz software, we could assess and compare the similarity and information gain of each these social interaction types. We found some social interaction types to be more similar than other ones. However, each social interaction type imparted different information. We also tested for a possible impact of the chimpanzees' biographical background on the social interaction types and found affiliative behaviour as well as allogrooming to be affected by adverse early life experiences. We conclude that this multiplex approach provides a more realistic framework giving detailed insight into the sociability of these chimpanzees and can function as a tool to support captive care management decisions. Network approaches based on social behaviours of nonhuman animals facilitated the successful evaluation of how sociality is shaped by evolutionary and ecological conditions and reflected in behavioural processes, such as social learning 1 and cooperation 2 , and also in the spread of diseases 3,4. Furthermore, it enabled researchers to investigate, simulate and predict patterns of hierarchies 5 , information transmission efficiency 6 , group cohesion and stability 7,8. Traditionally social networks were analysed by aggregating information and/or investigating only one type (e.g. a certain behaviour or distance) of connection between individuals. While this approach might seem narrow, it did allow the explanation of trends and patterns, which had been misinterpreted or underrated previously 9. However, as research on social networks advanced over time and databases became bigger and more varied, the necessity arose to get insights in social networks that are even more realistic. Considering the multidimensional nature of the network components in space and time 10,11 , it became obvious that in order to fully grasp social structures and dynamics, it was essential to construct multiple social networks based on a variety of edges (i.e. connections between nodes) between the same set of nodes (i.e. individuals) 12. A great many studies on a variety of species, ranging from insects to nonhuman primates demonstrated the complexity of social structures in the animal kingdom 13,14. Particularly for nonhuman primates, who are living in complex social societies, using a variety of strategies and behaviours to interact and connect with each other 15 , it seems a promising approach to implement a more realistic framework in order to explore their social structures. Especially during the last two decades, algorithms and computational technologies have been developed, providing the means to analyse and visualize complex multilayer relationships 16. Hence, the use of these multilayer networks is now also recommended 17 and it has already been used in the studies of primate behaviour 18,19. While it is recommendable to create a multilayer network based on several edges, the question of how many edges should be taken into account remains. Keeping in mind that an increase of data collected comes with a certain price, the right equilibrium between information gain, efficiency and redundancy has to be found 20,21 .
Journal of Veterinary Behavior
PLOS ONE, 2020
The long-term effects of early life adversities on social capacities have been documented in huma... more The long-term effects of early life adversities on social capacities have been documented in humans and wild-caught former laboratory chimpanzees (Pan troglodytes). However, former pet and entertainment chimpanzees have received little attention to date. This study aimed to investigate the long-term effects of early life experience on 18 former pet and entertainment chimpanzees, based on social grooming data collected at a primate rescue centre over a 12-year period. Moreover, we also focused on the possible short-term effects that alterations to group composition might have on grooming patterns. For this purpose, we compared stable and unstable periods (i.e. where alterations to group composition occurred). We used two individual social network measures to analyse the grooming activity and the distribution of grooming among group mates for each individual. We could show that wild-caught chimpanzees were significantly more selective regarding their grooming partners and spent less time grooming when compared to their captive born companions. We also found that individuals who were predominantly housed without conspecifics during infancy spent less time grooming compared to those who were predominantly housed with conspecifics during infancy. Furthermore , we found that alterations to the group composition had short-term effects on the distribution of social grooming from a more equal distribution during periods with a stable group composition towards a more unequal and selective distribution during unstable periods. Thus, we conclude that the social grooming networks of former pet and entertainment chimpanzees are shaped not only by long-term effects such as early life experience, but also by short-term effects such as alterations to group composition. Remarkably, we found not only captive born chimpanzees but also wild-caught individuals to adjust their grooming to socially challenging situations by modifying their grooming distribution in a similar way.
Plos One, 2020
The long-term effects of early life adversities on social capacities have been documented in huma... more The long-term effects of early life adversities on social capacities have been documented in humans and wild-caught former laboratory chimpanzees (Pan troglodytes). However, former pet and entertainment chimpanzees have received little attention to date. This study aimed to investigate the long-term effects of early life experience on 18 former pet and entertainment chimpanzees, based on social grooming data collected at a primate rescue centre over a 12-year period. Moreover, we also focused on the possible short-term effects that alterations to group composition might have on grooming patterns. For this purpose, we compared stable and unstable periods (i.e. where alterations to group composition occurred). We used two individual social network measures to analyse the grooming activity and the distribution of grooming among group mates for each individual. We could show that wild-caught chimpanzees were significantly more selective regarding their grooming partners and spent less time grooming when compared to their captive born companions. We also found that individuals who were predominantly housed without conspecifics during infancy spent less time grooming compared to those who were predominantly housed with conspecifics during infancy. Furthermore , we found that alterations to the group composition had short-term effects on the distribution of social grooming from a more equal distribution during periods with a stable group composition towards a more unequal and selective distribution during unstable periods. Thus, we conclude that the social grooming networks of former pet and entertainment chimpanzees are shaped not only by long-term effects such as early life experience, but also by short-term effects such as alterations to group composition. Remarkably, we found not only captive born chimpanzees but also wild-caught individuals to adjust their grooming to socially challenging situations by modifying their grooming distribution in a similar way.