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Full-Text Articles in Animal Studies
Origin And Evolution Of Large Brains In Toothed Whales, Lori Marino, Daniel W. Mcshea, Mark D. Uhen
Origin And Evolution Of Large Brains In Toothed Whales, Lori Marino, Daniel W. Mcshea, Mark D. Uhen
Veterinary Science and Medicine Collection
Toothed whales (order Cetacea: suborder Odontoceti) are highly encephalized, possessing brains that are significantly larger than expected for their body sizes. In particular, the odontocete superfamily Delphinoidea (dolphins, porpoises, belugas, and narwhals) comprises numerous species with encephalization levels second only to modern humans and greater than all other mammals. Odontocetes have also demonstrated behavioral faculties previously only ascribed to humans and, to some extent, other great apes. How did the large brains of odontocetes evolve? To begin to investigate this question, we quantified and averaged estimates of brain and body size for 36 fossil cetacean species using computed tomography and …
A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby
A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby
Jeffrey Stevens Publications
Many animal species, from arthropods to apes, share food. This paper presents a new framework that categorizes nonkin food sharing according to two axes: (1) the interval between sharing and receiving the benefits of sharing, and (2) the currency units in which benefits accrue to the sharer (especially food versus nonfood). Sharers can obtain immediate benefits from increased foraging efficiency, predation avoidance, mate provisioning, or manipulative mutualism. Reciprocity, trade, status enhancement and group augmentation can delay benefits. When benefits are delayed or when food is exchanged for nonfood benefits, maintaining sharing can become more difficult because animals face discounting and …
The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens
The Selfish Nature Of Generosity: Harassment And Food Sharing In Primates, Jeffrey R. Stevens
Jeffrey Stevens Publications
Animals may share food to gain immediate or delayed fitness benefits. Previous studies of sharing have concentrated on delayed benefits such as reciprocity, trade and punishment. This study tests an alternative model (the harassment or sharing–under–pressure hypothesis) in which a food owner immediately benefits because sharing avoids costly harassment from a beggar. I present an experiment that varies the potential ability of the beggar to harass, and of the owner to defend the food, to examine the effects of harassment on food sharing in two primate species: chimpanzees (Pan troglodytes) and squirrel monkeys (Saimiri boliviensis). For …