Why do mammals hop? Understanding the ecology, biomechanics and evolution of bipedal hopping

McGowan, Craig P.; Collins, Clint E.

doi:10.1242/jeb.161661

Cited by 34 publications

(33 citation statements)

References 117 publications

(197 reference statements)

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“…Bipedal hopping is a highly specialized mode of terrestrial locomotion that has arisen independently in six lineages of mammals (McGowan and Collins, 2018). It has been hypothesized that bipedal hopping evolved as an adaptation for erratic behavior (e.g.…”

Section: Introductionmentioning

confidence: 99%

Jumping mechanics of desert kangaroo rats

Schwaner

Lin

McGowan

2018

Journal of Experimental Biology

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Kangaroo rats are small bipedal desert rodents that use erratic vertical jumps to escape predator strikes. In this study we examined how individual hind limb joints of desert kangaroo rats (Dipodomys deserti) power vertical jumps across a range of heights. We hypothesized that increases in net work would be equally divided across hind limb joints with increases in jump height. To test this hypothesis, we used an inverse dynamics analysis to quantify the mechanical output from the hind limb joints of kangaroo rats jumping vertically over a wide range of heights. The kangaroo rats in this study reached maximal jump heights up to ∼9-times hip height. Net joint work increased significantly with jump height at the hip, knee and ankle, and decreased significantly at the metatarsal-phalangeal joint. The increase in net work generated by each joint was not proportional across joints but was dominated by the ankle, which ranged from contributing 56% of the work done on the center of mass at low jumps to 70% during the highest jumps. Therefore, the results of this study did not support our hypothesis. However, using an anatomical model, we estimated that a substantial proportion of the work delivered at the ankle (48%) was transferred from proximal muscles via the biarticular ankle extensors.

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Section: Introductionmentioning

confidence: 99%

Jumping mechanics of desert kangaroo rats

Schwaner

Lin

McGowan

2018

Journal of Experimental Biology

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“…It may seem counterintuitive that the paired contacts of right and left hind limbs should indicate an asymmetrical gait, however, this deviates from the symmetry criterion that right and left contacts be one-half stride cycle out of phase. Bipedal hopping is found convergently in several groups of rodents, including springhares, kangaroo rats, and jerboasand the only large bipedal hoppers are the wallabies and kangaroos, with male red kangaroos equaling human body mass (reviewed by McGowan and Collins, 2018). Bipedal skipping, a gait occasionally used by children and sometimes in reducedgravity conditions, is the only asymmetrical gait used by humans (Minetti, 1998(Minetti, , 2001aAckermann and van den Bogert, 2012).…”

Section: Bipedal Gaitsmentioning

confidence: 99%

Linking Gait Dynamics to Mechanical Cost of Legged Locomotion

Lee

Harris

2018

Front. Robot. AI

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For millenia, legged locomotion has been of central importance to humans for hunting, agriculture, transportation, sport, and warfare. Today, the same principal considerations of locomotor performance and economy apply to legged systems designed to serve, assist, or be worn by humans in urban and natural environments. Energy comes at a premium not only for animals, wherein suitably fast and economical gaits are selected through organic evolution, but also for legged robots that must carry sufficient energy in their batteries. Although a robot's energy is spent at many levels, from control systems to actuators, we suggest that the mechanical cost of transport is an integral energy expenditure for any legged system-and measuring this cost permits the most direct comparison between gaits of legged animals and robots. Although legged robots have matched or even improved upon total cost of transport of animals, this is typically achieved by choosing extremely slow speeds or by using regenerative mechanisms. Legged robots have not yet reached the low mechanical cost of transport achieved at speeds used by bipedal and quadrupedal animals. Here we consider approaches used to analyze gaits and discuss a framework, termed mechanical cost analysis, that can be used to evaluate the economy of legged systems. This method uses a point mass perspective to evaluate the entire stride as well as to identify individual events that accrue mechanical cost. The analysis of gait began at the turn of the last century with spatiotemporal analysis facilitated by the advent of cine film. These advances gave rise to the "gait diagram," which plots duty factors and phase separations between footfalls. This approach was supplanted in the following decades by methods using force platforms to determine forces and motions of the center of mass (CoM)-and analytical models that characterize gait according to fluctuations in potential and kinetic energy. Mechanical cost analysis draws from these approaches and provides a unified framework that interprets the spatiotemporal sequencing of leg contacts within the context of CoM dynamics to determine mechanical cost in every instance of the stride. Diverse gaits can be evaluated and compared in biological and engineered systems using mechanical cost analysis.

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“…Penguins use either a walking or a 'waddling' gait when moving on land (Griffin & Kram, 2000). Quadrupedal mammals can perform a variety of gaits, such as walking, trotting, running, racking, cantering, hopping, galloping, bounding and stotting (Caro, 1986;McGowan & Collins, 2018). Insects and spiders also show extensive variation in their locomotor patterns (Ting et al, 1994;Spagna & Peattie, 2012;Weihmann, 2013;Wilshin et al, 2018), although their gaits have not been as thoroughly described.…”

Section: Introductionmentioning

confidence: 99%

Variation in movement: multiple locomotor gaits in Neotropical harvestmen

Escalante

Badger

Elias

2019

Biological Journal of the Linnean Society

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In order to move successfully in variable conditions, many animals have evolved the ability to switch between several patterns of locomotion or gaits. Here, we describe and differentiate between putative locomotor gaits in the harvestman, an arachnid that uses a hexapod-like alternate tripod gait. We recorded Neotropical harvestmen of the genus Prionostemma moving across a flat surface using high-speed video. We reconstructed three-dimensional trajectories and associated kinematics and found four different locomotor gaits: running, stotting, bobbing and walking. Gaits differed in their performance and postural kinematics, body trajectory, gait diagrams and/or kinetic and potential energy exchange. Our approach points out the importance of using multiple kinematic features to differentiate gaits. The use of a specific gait was not predicted by leg length, body area or sex. We propose testable hypotheses regarding the function of each gait and the factors that drive the evolution of different gaits. Ultimately, the diversity of locomotory gaits can allow animals to respond to different environmental challenges and contexts.

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Why do mammals hop? Understanding the ecology, biomechanics and evolution of bipedal hopping

Cited by 34 publications

References 117 publications

Jumping mechanics of desert kangaroo rats

Jumping mechanics of desert kangaroo rats

Linking Gait Dynamics to Mechanical Cost of Legged Locomotion

Variation in movement: multiple locomotor gaits in Neotropical harvestmen

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