User:Katherinegaffney/sandbox/My sandbox: Hunting Hypothesis

The Hunting Hypothesis
Related Topics: The Gathering Hypothesis, Brain size

This article attempts to outline the evidence found by evolutionary psychologists to support the Hunting Hypothesis. David Buss, a prominent psychologist in the field, outlines the points of evidence discussed. Any papers cited are merely expansions on a piece of evidence he presented in his text book Evolutionary Psychology: The New Science of the Mind.

In paleoanthropology and evolutionary psychology, the Hunting Hypothesis attributes the impetus for evolution of the modern human to the shift from foraging to hunting by ancestral hominoid species. As a result of hunting, humans developed tools to skin, separate, and slice meat. It is argued that hunting and the subsequent tool development also led to the enlargement of the human brain, and language skills vital to collaboration on collective hunts.

As societal evidence Buss cites that modern tribal societies use hunting as their primary means of acquiring food. The Aka Pygmies in the Central African Republic spend 56% of their quest for nourishment hunting, 27% gathering, and 17% processing food. Additionally, the !Kung in Botswana retain 40% of their calories from hunting and this percentage varies from 20% to 90% depending on the season. For physical evidence Buss first looks to the guts of humans and apes.The human gut is dominantly comprised of the small intestines, which are responsible for the rapid breakdown of proteins and absorption of nutrients. The ape’s gut is primarily colon, which indicates a vegetarian diet. This structural difference supports the hunting hypothesis in being an evolutionary branching point between modern humans and modern primates. Buss also cites human teeth in that fossilized human teeth have a thin enamel coating with very little heavy wear and tear that would result from a plant diet. The absence of thick enamel also indicates that historically humans have maintained a meat-heavy diet. Further, Buss looks to Vitanmins A and B12, which the body is unable to produce, but are found in meat. The absence of these vitamins in the human body also implies a human dependence upon meat to obtain such vitamins. Finally, Buss notes that the bones of animals human ancestors killed found at Olduvai Gorge have cut marks at strategic points on the bones that indicate tool usage and provide evidence for ancestral butchers.

Sexual division of labor (evolutionary perspective)
According to the hunting hypothesis women are preoccupied with pregnancy and dependent children and so do not hunt because it is dangerous and less profitable. Gisjbert Stoet highlights the fact that men are more competent in throwing skills, focused attention, and spatial abilities, however, he debunks the idea that women gather for they have better spatial abilities for in his research he is found that men are in fact better at visual search and gathering (Experiments 1 and 2). Stoet offers the explanation that sexual division of labor was not the result of the connection between memory and gathering, but a result of men’s superior hunting abilities so women turned to gathering to fill the occupational gap. Another possible explanation for women gathering is their inherent prioritization of rearing offspring, which is difficult to uphold if women were hunting.

Parental Investment
Buss purports that the hunting hypothesis explains the high level of human male parental investment in offspring as compared to primates. Meat is an economical and condensed food resource in that it can be brought home to feed the young, however it is not efficient to carry low-calorie food across great distances. Thus, the act of hunting and the required transportation of the kill in order to feed offspring is a reasonable explanation for human male provisioning.

Male Coalitions
Buss suggests that the Hunting hypothesis also explains the advent of strong male coalitions. Although chimpanzees form male-male coalitions, they tend to be temporary opportunistic. Contrastingly large game hunters require consistent and coordinated cooperation to succeed in large game hunting. Thus male coalitions were the result of working together to succeed in providing meat for the hunters themselves and their families. Kristen Hawkes suggests further that obtaining resources intended for community consumption increases a male’s fitness by appealing to the male’s society and thus being in the good favor of both males and females. The male relationship would improve hunting success and create alliances for future conflict and the female relationship would improve direct reproductive success. Buss proposes alternate explanations of emergence of the strong male coalitions. He suggests that male coalitions may have been the result of group-on-group aggression, defense, and in-group political alliances. This explanation does not support the relationship between male coalitions and hunting.

Hawkes proposes that hunters pursue large game and divide the kill across the group. Hunters compete to divvy up the kill to signal courage, power, generosity, prosocial intent, and dedication. By engaging in these activities hunters receive reproductive benefits and respect These reproductive benefits lead to greater reproductive success in more skilled hunters. Evidence of these hunting goals that do not only benefit the families of the hunters are in the Ache and Hadza men. Hawkes notes that their hunting techniques are less efficient than alternative methods and are energetically costly, but the men place more importance on displaying their bravery, power, and prosocial intent than on hunting efficiency. This method is different as compared to other societies where hunters retain the control of their kills and signal their intent of sharing. This alternate method aligns with the coalition support hypothesis, in efforts to create and preserve political associations.

Reciprocal Altruism
The meat from successful large game hunts are more than what a single hunter can consume. Further, hunting success varies by week. One week a hunter may succeed in hunting large game and the next may return with no meat. In this situation Buss suggests that there are low costs to giving away meat that cannot be eaten by the individual hunter on his own and large benefits from the expectation of the returned favor in a week where his hunting is not successful. Hawkes calls this sharing “tolerated theft” and purports that the benefits of reciprocal altruism stem from the result that families will experience “lower daily variation and higher daily average” in their resources.

Provisioning may actually be a form of sexual competition between males for females. Hawkes suggests that male provisioning is a particularly human behavior, which forges the nuclear family. The structure of familial provisioning determines a form of resource distribution. However, Hawkes does acknowledge inconsistencies across societies and contexts such as the fluctuating time courses dedicated to hunting and gathering, which are not directly correlated with return rates, the fact that nutrition value is often chosen over caloric count, and the fact that meat is a more widely spread resource than other resources.

The Show-Off Hypothesis
The show-off hypothesis is the concept that more successful men have better mate options. The idea relates back to the fact that meat, the result of hunting expeditions, is a distinct resource in that it comes in large quantities that more often than not the hunter’s own family is not able to consume in a timely manner so that the meat doesn’t go sour. Also the success of hunting is unpredictable whereas berries and fruits, unless there is a drought or a bad bush, are fairly consistent in seasonality. Kristen Hawkes argues that women favor neighbors opting for men who provide the advantageous, yet infrequent meat feasts. These women may profit from alliance and the resulting feasts, especially in times of shortage. Hawkes suggests that it would be beneficial for women to reward men who employ the “show-off strategy” by supporting them in a dispute, caring for their offspring, or providing sexual favors. The benefits women may gain from their alignment lie in favored treatment of the offspring spawned by the show-off from neighbors. Buss echoes and cites Hawke’s thoughts on the show-off’s benefits in sexual access, increased likelihood of having children, and the favorable treatment his children would receive from the other members of the society. Hawkes also suggests that show-offs are more likely to live in large groups and thus be less susceptible to predators. Show-offs gain more benefits from just sharing with their family (classical fitness) in the potential favorable treatment from the community and reciprocal altruism from other members of the community.

Hawkes uses the Ache people of Paraguay as evidence for the Show-off hypothesis. Food acquired by men was more widely distributed across the community and inconsistent resources that came in large quantities when acquired were also more widely shared.

While this is represented in the Ache according to Hawkes, Buss notes that this trend is contradicted in the Hadza who evenly distribute the meat across all members of their population and whose hunters have very little control over the distribution. In the Hadza the show-off hypothesis does not have to do with the resources that result from hunting, but from the prestige and risk that is involved in big game hunting. There are possible circuitous benefits such as protection and defense.

Applications of the Show-off Hypothesis:
Why hunters forge male coalitions, even though the hunter’s personal return rate is lower and hunters eat less of their own kill than other family and community members.