This entry was written by Kieran Baughan as part of a project done in BIAN 6133 ‘Human Reproductive Strategies’ at The Australian National University in 2019 Semester 2.
Introduction
Over the last 20 years the evolutionary driver of hunting behaviour in modern humans has been hotly debated, specifically, the reasons as to why males hunt within foraging societies. As is the case with all organisms, humans have finite resources and must optimise trade-offs between somatic effort and reproductive effort. Hunting behaviour in modern humans can be viewed as investing in reproductive effort, however, whether this act is a demonstration of mating or parenting effort is far less clear. The original proposal, which was the general consensus up until the turn of the millennia, states that men hunt to supply resources and nutritional needs to their mate and offspring, otherwise known as family provisioning. Yet, a new view has arisen stating that males may not necessarily hunt for family provisioning of even for subsistence, but to display honest signals of quality, perhaps as a form of male-male competition or mate choice, with the best hunter earning social status and higher reproductive success. This essay focusses on reviewing the main sources of literature which support the two arguments and shed light on the major hypothesis on this hot topic of human behaviour.
Main Text
Family Provisioning
Human behavioural ecologists hypothesise the role of male hunting forms a sexual division of labour, with females and males foraging for different types of food which would be brought back and shared amongst themselves, their offspring and kin (Marlowe, 2007). It’s said that in hunter-gatherer societies, females gather supplementary plant-based foods like berries and nuts whilst men bring meat back to camp which forms the bulk of the nutritional requirements, in doing so creating a pair bonded, nuclear family (Marlowe, 2007). Two assumptions regarding this hypothesis exists; first, that men should make foraging decisions based on providing the highest nutritional or calorific returns and second, these returns should be distributed to the female and their offspring (Wood & Marlowe, 2014).
Whilst this hypothesis was coined in the 1980’s, Gurven et al (2009) spearheaded a heated exchange of reviews in favour of family provisioning over the challenging “showing off” hypothesis. In a fiery review of Hawkes (1991) paper, Gurven et al (2009) laid out some empirical evidence, mainly disputing conclusions met by Hawkes (1991), yet stated that the overall calorific yield provided by large game was far superior to that of alternative strategies like small game hunting or gathering. In the Hadza for example, large game hunting provided up to four times the calories which small game would have provided (Gurven et al, 2009) thus males in this society appear to choose a strategy which provides the greatest nutritional return. Additionally, Gurven et al (2009) also shows some evidence of preferential food sharing, where the males share their kill with their kin before dispersing it amongst the community (a fundamental flaw in the family provisioning hypothesis).
Marlowe (2007), also a strong advocate for the family provisioning hypothesis, tested the sex specific specialisations across modern foragers and whether the degree of sexual division of foraging labour varies cross-culturally. If the family provisioning hypothesis accurately explains men’s hunting behaviour, we should expect that males foraging goals should vary depending on environmental conditions and food availability as they choose the most productive strategy. Marlowe (2007) discovered that men do tend to vary their foraging strategy based on habitat variation and when net primary production is high men will conduct considerably more gathering. Alternatively, when NPP is low men do more hunting, which is understandable, if there is low production of plant foods, one would expect men to choose a higher calorific option. This study therefore supports the family provisioning hypothesis.
A more recent paper conducted by Wood & Marlowe (2014) continued on with the Gurven et al (2009) argument of the showing off hypothesis, this time demonstrating that Hadza men allocate a considerable amount of hunting time also gathering honey, nuts and fruit in addition to small and large game. The authors also address the collective action problem, which states a hunter’s family doesn’t receive benefits from the kill as it is distributed amongst the group, instead that the net gain from big game hunting and additional gathering maximises flow of calories throughout the nuclear family (Wood & Marlowe, 2014). It’s important to note that the research from which Wood & Marlowe (2014) stake their claims are from one society, the Hadza, hardly enough evidence to dismiss a valid counter hypothesis. In addition, the authors seem to overlook the previous paper which states foraging societies appear to prioritise plant-based foods when available, which doesn’t explain why some societies choose to be hunting specialists in such favourable habitats and why most foraging societies engage in big game hunting.
The Showing Off Hypothesis
Hawkes (1991) first coined the “showing off hypothesis” after her work with the Ache, a foraging society from Eastern Paraguay, where she proposed some unique and controversial ideas about the intentions of male hunters. The author proposes two alternative investment strategies when males accumulate more food than they can consume, either they can invest in present or future offspring (family provisioning) or make this extra resource publicly available, gaining the attention of potential future mates and social status (Hawkes, 1991) (show-off). Hawkes (1991) believes the latter strategy not only benefits the hunter, whom has greater access to females and higher social status, but to their current mate who’s offspring would be carrying the same successful trait and to neighbours who gain more resources (Hawkes, 1991). This hypothesis, although readily dismissed by some, would explain why hunters happily relinquish the majority of their kill to others and why they would invest much time in big game hunting to begin with, especially considering gathering often returns equally quality resources.
In later studies, Hawkes et al (2014) defend they hypothesis from their doubters and conduct a comparison study between data on the Hadza from Wood & Marlowe (2014) and their own data from the same society. Hawkes et al (2014) concluded that due to a hunter and his family only getting approximately 10% of the kill and the majority of meat the family consumes is from others, the family provisioning hypothesis doesn’t explain this relationship. Furthermore, if a hunter was to truly maximise payoff for his nuclear family, he should focus on small game hunting (Hawkes, 2014). Whilst the Hadza do show some support for the family provisioning hypothesis as men bring larger quantities of meat to their family than to others, data from both studies seem to also support an alternative hypothesis.
Hawkes (1991) and Hawkes et al (2014) aren’t alone in their critical observations of men’s foraging goals. Smith & Bird (2000) suggested turtle hunting among the Meriam of Torres Strait, Australia could be explained by the costly signalling theory (CST). Although the CST differs in some respects to the signalling hypothesis and the authors are clear to separate the two, behaviours of the men in Meriam still participate in hunting for the opportunity to show off their quality rather than nutritional requirements. Hunters also share food within the community yet often don’t decide to whom the food is distributed, so how can he be sure of reciprocity? Smith & Bird (2000) state that turtle hunting expresses underling signals of quality such as strength, skill and leadership and hunters reap benefits from this form of costly signalling.
Food sharing amongst non-human primates
When studying any aspect of human behaviour from an evolutionary perspective it’s important to also consider our findings in context with our closest relatives. Amongst other primates, food sharing and division of labour is very rare, yet foraging decisions are often made based on patchiness of food availability in both space and time (Jaeggi & Gurven, 2013). Food sharing in primates tends to evolve in species that forage in difficult ecological niches, for example adults may share with their offspring if the juvenile would struggle to survive otherwise (Jaeggi & Gurven, 2013). Food sharing between adults is most common in chimpanzees, as male reproductive success is limited by female availability, they can gain access to mates by sharing food (Jaeggi & Gurven, 2013). Furthermore, food sharing is uncommon in monogamous primates and may only occur if the male is certain he is raising his own offspring (Jaeggi & Gurven, 2013).
Conclusion
Whether the evolutionary driver of male hunting is family provisioning or showing off will probably always be a heated discussion, perhaps due to authors trying to preserve the old view of a human nuclear family. But current evidence seems to suggest a combination of these hypothesis were responsible for the evolution of hunting in a distant past. One ponders the idea that ancestral humans favoured plant-based foods for subsistence but due to seasonality small game hunting was adopted during the low NPP months, a trait which may have been favoured by run-away selection leading to big game hunting as a signalling strategy of good quality.
References
Gurven, M., & Hill, K (2009). Why do men hunt? A reevaluation of “man the hunter” and the sexual division of labor. Current Anthropology, 50(1), 51-74.
Hawkes, K. (1991). Showing off: tests of an hypothesis about men's foraging goals. Ethology and sociobiology, 12(1), 29-54.
Hawkes, K., O’Connell, J. F., & Jones, N. G. B. (2014). More lessons from the Hadza about men’s work. Human Nature, 25(4), 596-619.
Jaeggi, A. V., & Gurven, M. (2013). Natural cooperators: food sharing in humans and other primates. Evolutionary Anthropology: Issues, News, and Reviews, 22(4), 186-195.
Marlowe, F. W. (2007). Hunting and gathering: the human sexual division of foraging labor. Cross-cultural research, 41(2), 170-195.
Smith, E. A., & Bird, R. L. B. (2000). Turtle hunting and tombstone opening: Public generosity as costly signaling. Evolution and Human Behavior, 21(4), 245-261.
Wood, B. M., & Marlowe, F. W. (2014). Toward a reality-based understanding of Hadza men’s work. Human Nature, 25(4), 620-630.
