1. Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Graham Kerr Building, Glasgow G12 8QQ, UK
2. Department of Anthropology, University of Washington, 314 Denny Hall, Box 353100 Seattle, WA 98195-3100, USA
3. Départemente de Médecine, Institut de recherche en immunologie et en cancérologie, Université de Montréal, 2950 chemin de Polytechnique, Montréal, Québec, Canada H3T 1J4
4. Institute of Evolutionary Biology, University of Edinburgh, Ashworth Labs, The King's Buildings, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK