title: Locomotor activity influences muscle architecture and bone growth but not muscle attachment site morphology.
abstract: The ability to make behavioural inferences from skeletal remains is critical to understanding the lifestyles and activities of past human populations and extinct animals. Muscle attachment site (enthesis) morphology has long been assumed to reflect muscle strength and activity during life, but little experimental evidence exists to directly link activity patterns with muscle development and the morphology of their attachments to the skeleton. We used a mouse model to experimentally test how the level and type of activity influences forelimb muscle architecture of spinodeltoideus, acromiodeltoideus, and superficial pectoralis, bone growth rate and gross morphology of their insertion sites. Over an 11-week period, we collected data on activity levels in one control group and two experimental activity groups (running, climbing) of female wild-type mice. Our results show that both activity type and level increased bone growth rates influenced muscle architecture, including differences in potential muscular excursion (fibre length) and potential force production (physiological cross-sectional area). However, despite significant influences on muscle architecture and bone development, activity had no observable effect on enthesis morphology. These results suggest that the gross morphology of entheses is less reliable than internal bone structure for making inferences about an individual's past behaviour.
authors.affiliation: Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2114 G Street NW, Washington, DC 20052, USA; Department of Evolutionary Anthropology, Duke University, Box 90383, 103 Science Drive, Room 108, Durham, NC 27708, USA; Department of Anthropology, University of Toronto, 19 Russell Street, Toronto, ON M5S 2S2, Canada. Electronic address: karyne.rabey@duke.edu.
authors.forename: Karyne N
authors.initials: KN
authors.lastname: Rabey
authors.affiliation: Department of Anatomy, Midwestern University, 555 31st Street, Downers Grove, IL 60515, USA; Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2114 G Street NW, Washington, DC 20052, USA. Electronic address: dgreen1@midwestern.edu.
authors.forename: David J
authors.initials: DJ
authors.lastname: Green
authors.affiliation: Department of Evolutionary Anthropology, Duke University, Box 90383, 103 Science Drive, Room 108, Durham, NC 27708, USA; Department of Community and Family Medicine, DPT Program, Duke University School of Medicine, DUMC Box 104002, Durham, NC 27708, USA. Electronic address: andrea.taylor@duke.edu.
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Taylor
authors.affiliation: Department of Anthropology, University of Toronto, 19 Russell Street, Toronto, ON M5S 2S2, Canada. Electronic address: begun@chass.utoronto.ca.
authors.forename: David R
authors.initials: DR
authors.lastname: Begun
authors.affiliation: Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2114 G Street NW, Washington, DC 20052, USA; Division of Anthropology, American Museum of Natural History, New York, NY 10024, USA. Electronic address: brichmond@amnh.org.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Richmond
authors.affiliation: Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2114 G Street NW, Washington, DC 20052, USA. Electronic address: mcfarlin@gwu.edu.
authors.forename: Shannon C
authors.initials: SC
authors.lastname: McFarlin
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D005260:Female; D008124:Locomotion / Q000502:physiology*; D051379:Mice; D018482:Muscle, Skeletal / Q000502:physiology*; D010521:Periosteum / Q000502:physiology
keywords: Entheses; Exercise; Functional anatomy; Muscle fibre; Periosteal growth; Physiological cross-sectional area