Track Changes version of revised ms from Why men trophy hunt

The killing of Cecil the lion (Panthera leo) ignited enduring and increasingly global discussion about trophy hunting (Nicholls 2015 Nature (doi:10.1038/nature.2015.18101)). Yet, policy debate about its benefits and costs (e.g. (Di Minin et al. 2016 Trends Ecol. Evol. 31, 99–102. (doi:10.1016/j.tree.2015.12.006); Ripple et al. 2016 Trends Ecol. Evol. 31, 495–496. (doi:10.1016/j.tree.2016.03.011)) focuses only on the hunted species and biodiversity, not the unique behaviour of hunters. Some contemporary recreational hunters from the developed world behave curiously, commonly targeting ‘trophies’: individuals within populations with large body or ornament size, as well as rare and/or inedible species, like carnivores (Darimont et al. 2015 Science 349, 858–860. (doi:10.1126/science.aac4249)). Although contemporary hunters have been classified according to implied motivation (i.e. for meat, recreation, trophy, or population control; (Festa-Bianchet 2003 Animal Behavior and Wildlife Conservation (eds M Festa-Bianchet, M Apollonio), pp. 191–207); (Mysterud 2011 J. Appl. Ecol. 48, 827–834. (doi:10.1111/j.1365-2664.2011.02006.x))) as well the ‘multiple satisfactions’ they seek while hunting (affiliation, appreciation, achievement; (Hendee 1974 Wildl. Soc. Bull. 2, 104–113)), an evolutionary explanation of the motivation underlying trophy hunting has never been pursued. Too costly (difficult, dangerous) a behaviour to be common among other vertebrate predators, we postulate that trophy hunting is in fact motivated by the costs hunters accept. We build on empirical and theoretical contributions from evolutionary anthropology to hypothesize that signalling these costs to others is key to understanding, and perhaps influencing, this otherwise perplexing activity.