Valentina Truppa, Marco Gamba, Roberta Togliatto, Marta Caselli, Anna Zanoli, Elisabetta Palagi, Ivan Norscia
{"title":"Manual preference, performance, and dexterity for bimanual grass-feeding behavior in wild geladas (Theropithecus gelada)","authors":"Valentina Truppa, Marco Gamba, Roberta Togliatto, Marta Caselli, Anna Zanoli, Elisabetta Palagi, Ivan Norscia","doi":"10.1002/ajp.23602","DOIUrl":null,"url":null,"abstract":"<p>We assessed whether wild geladas, highly specialized terrestrial grass eaters, are lateralized for bimanual grass-plucking behavior. According to the literature, we expected that complex motor movements in grass feeding would favor the emergence of a population-level hand bias in these primates. In addition, we described geladas' manual behavior based on systematic observations of several individuals. Our study group included 28 individuals belonging to a population of free-ranging geladas frequenting the Kundi plateau, Ethiopia. We filmed monkeys while feeding on grass, and hand preference and performance were coded. Geladas performed more plucking movements per second with their left hand (LH) compared to the right one and preferred their LH both to start and finish collection bouts. Also, the rhythmic movements of each hand had a significant tendency toward isochrony. Finally, geladas used forceful pad-to-pad precision grips, in-hand movements, and compound grips to pluck and collect grass blades, considered the most advanced manual skills in primate species. The LH's leading role suggests an advantage of the right hemisphere in regulating geladas' bimanual grass-feeding behavior. The tactile input from the hands and/or rhythmic hand movements might contribute to explaining this pattern of laterality. Our findings highlighted the importance of adopting multiple laterality measures to investigate manual laterality. Moreover, the need to speed up the execution time of manual foraging might be a further important factor in studying the evolution of manual laterality and dexterity in primates.</p>","PeriodicalId":7662,"journal":{"name":"American Journal of Primatology","volume":"86 5","pages":""},"PeriodicalIF":2.0000,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"American Journal of Primatology","FirstCategoryId":"99","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/ajp.23602","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ZOOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
We assessed whether wild geladas, highly specialized terrestrial grass eaters, are lateralized for bimanual grass-plucking behavior. According to the literature, we expected that complex motor movements in grass feeding would favor the emergence of a population-level hand bias in these primates. In addition, we described geladas' manual behavior based on systematic observations of several individuals. Our study group included 28 individuals belonging to a population of free-ranging geladas frequenting the Kundi plateau, Ethiopia. We filmed monkeys while feeding on grass, and hand preference and performance were coded. Geladas performed more plucking movements per second with their left hand (LH) compared to the right one and preferred their LH both to start and finish collection bouts. Also, the rhythmic movements of each hand had a significant tendency toward isochrony. Finally, geladas used forceful pad-to-pad precision grips, in-hand movements, and compound grips to pluck and collect grass blades, considered the most advanced manual skills in primate species. The LH's leading role suggests an advantage of the right hemisphere in regulating geladas' bimanual grass-feeding behavior. The tactile input from the hands and/or rhythmic hand movements might contribute to explaining this pattern of laterality. Our findings highlighted the importance of adopting multiple laterality measures to investigate manual laterality. Moreover, the need to speed up the execution time of manual foraging might be a further important factor in studying the evolution of manual laterality and dexterity in primates.
期刊介绍:
The objective of the American Journal of Primatology is to provide a forum for the exchange of ideas and findings among primatologists and to convey our increasing understanding of this order of animals to specialists and interested readers alike.
Primatology is an unusual science in that its practitioners work in a wide variety of departments and institutions, live in countries throughout the world, and carry out a vast range of research procedures. Whether we are anthropologists, psychologists, biologists, or medical researchers, whether we live in Japan, Kenya, Brazil, or the United States, whether we conduct naturalistic observations in the field or experiments in the lab, we are united in our goal of better understanding primates. Our studies of nonhuman primates are of interest to scientists in many other disciplines ranging from entomology to sociology.