Why men trophy hunt

1. Introduction

The killing of Cecil the lion (Panthera leo) ignited enduring and increasingly global discussion about trophy hunting [1]. Yet, policy debate about its benefits and costs (e.g. [2,3]) 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 [4]. Although contemporary hunters have been classified according to implied motivation (i.e. for meat, recreation, trophy or population control, [5,6]) as well the ‘multiple satisfactions’ they seek while hunting (affiliation, appreciation, achievement; [7], an evolutionary explanation of the motivation underlying trophy hunting (and big-game fishing) 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.

2. Man the show off?

Subsistence hunting among traditional ‘hunter–gatherers’, which also targets larger-bodied prey, provides a starting point for understanding trophy hunters from the developed world. Owing to disagreement over the relative importance of potential benefits men receive from hunting, however, evolutionary explanations as to why subsistence hunters target large prey attract competing theories and significant controversy. Some assert that energetic and nutritional returns to hunters and individuals they provision best explain why men accept the costs of big-game hunting (e.g. [8,9]). Others invoke the pressure to share large prey as an explanation for wide distribution of meat (e.g. [10]). But why target prey that will be mostly consumed by others? An alternative hypothesis, consistent with data across hunter–gatherer systems, starts by noting that men generally target species that are not only large-bodied but also—and, importantly—impose high cost (i.e. high failure risk; [11,12]). The hypothesis considers the carcass not only as food but also a signal of the costs associated with the hunter’s accomplishment.

The Meriam peoples of Australia provide a flagship illustration of this association. There, men, women and children collect green turtles (Chelonia mydas) when they come ashore to lay eggs. In contrast, only men hunt them at sea. Pursuing turtles in boats, hunters accept significant economic and personal cost, including a dive into dangerous waters [13], despite the fact that most of what they acquire will be consumed by other community members [14,15].

Such seemingly irrational behaviour is resolved by costly signalling theory [16] from which the hypothesis draws. The theory considers the social status and prestige that accrue to successful hunters. The Maasai peoples of eastern Africa themselves describe lion killing as a manhood ritual that awards prestige to the hunter who first spears the animal [17]. Why is status awarded? Simply put, killing large, dangerous, and/or rare prey is difficult with high failure risks that impose costs on the hunter. Accordingly, successful hunts signal underlying qualities to rivals and potential allies. This holds true for successful Meriam turtle hunters, who gain social recognition, get married earlier to higher-quality mates, and have more surviving children [14]. For such behaviour to be maintained, even the attempted hunt must signal that the hunter can sustain the handicap of high-cost, low-consumption activity, providing honest evidence of underlying phenotypic quality [14,15,16].

We propose that an assessment of contemporary trophy hunting behaviour offers fresh additional evidence for a costly signalling model to explain any big-game hunting. First, inedible species, like carnivores commonly targeted by trophy hunters, make nutritional and sharing hypotheses implausible. Second, evidence for show-off behaviour appears clear. Trophy hunters commonly pose for photographs with their prey, with the heads, hides and ornamentation prepared for display [18]. Interestingly, similar costly display occurs in other taxa. For example, chimpanzees (Pan troglodytes) likewise pay a cost in time and effort spent hunting without commensurate food consumption gains; interpretations of related display behaviour support a social status model (reviewed in [19]). Similarly, some seabirds like the pigeon guillemot (Cepphus columba) show off ‘display fish’, sometimes for hours. Often discarding them, the behaviour is likewise thought to be social, related to site-ownership display [20]. Third, whereas some might argue that caloric returns for edible trophy hunted species are high and associated costs of failure low (owing to advanced killing technology and foods easily purchased by participants), the behaviour still imposes costs that guarantee the honesty of the signal; while rarely costly in terms of danger or difficulty, hunts for endangered species can be extraordinarily expensive. Moreover, even the everyday hunter who targets larger individuals within populations pays the opportunity costs of forgoing income-generating activities as well as sustenance lost by passing up smaller, abundant prey. We note that the signal can honestly reflect a hunter’s socio-economic standing (and qualities that underlie it) but not necessarily any remarkable physical abilities ([21]; figure 1), given the efficient technology contemporary trophy hunters employ [4].

• Received November 22, 2016.
• Accepted March 8, 2017.