It has recently been suggested that stiff-legged bipedality, as is currently seen in both humans and orangutans, evolved as an adaptation to access and move about safely and efficiently on thin, compliant branches and lianas (Thorpe et al, 2007a). It might allow them to maintain a safer grip, while they could use the energy stored in the branch to “bounce” along with a slow running-like gait, like a person on a trampoline. However, whether movement of this type is possible depends on the stiffness and effective mass of the branches, and hence their resonant frequency. All of these will fall towards the tip of the branch. The mechanical properties of the branches and trunks of trees will also affect the ways in which other primates and smaller arboreal mammals access and move about in them. The aim of this project is to understand how tree flexibility limits and modifies locomotion of arboreal mammals. To achieve this, the student will film orangutans moving on horizontal branches of trees to determine their kinematics, the movement of their centre of gravity and the movements of the branch. The dynamic mechanical properties of the branches will also be determined using the films and by carrying out bending tests on the branches. The dynamic mechanical properties of the branches and trunks of a range of tropical and temperate trees will also be measured to enable us to predict how they will affect the locomotion of other arboreal animals such as squirrels and other primates. This NERC-funded studentship is part of a wider project led by Dr Thorpe at Birmingham University on the evolution of stiff-legged bipedality. The student will be expected to work extensively in the field in Sumatra and the UK. The studentship is open to UK/EU students (subject to eligibility) with a relevant degree in Life Sciences or Physical Sciences (first or upper second class honours).Thorpe, S.K.S. Holder, R.L. and Crompton, R.H. 2007a Origin of human bipedalism as an adaptation for locomotion on flexible branches Science 316, 1328-1331 Thorpe, S.K.S., Crompton, R.H., Alexander, R..McN. 2007b Orangutans utilise compliant branches to lower the energetic cost of locomotion Biology Letters 3, 253-256
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