Stressors and Aggression in Non-Human Primates

Introduction:

Resource stress has plagued human and non-human primates since our origins in Africa (White, and Barbara, 2000). The aggressive behavior associated with the loss of resources has been the catalyst to conflict throughout human history. War and conflict are human behaviors that have been with us since our early ancestors made footprints along paths in the Great Rift Valley of Ethiopia. Conflict in the case of human behavior often results when the stress of unsafe conditions or a lack of resources for survival are not available (White and Barbara, 2000). Observing our non-human counterparts may provide a looking glass by which to understand aggressive human behaviors in the face of adversity. The similarities between human and non-human aggressive behaviors remain focused on that of the Pan Troglodyte (Chimpanzee) (Stanford, 1998). The examination of perceived ecological stressors and the adaptive responses of both human and non-human primate may provide a better understanding of how a lack of resources results in conflict or aggressive behavior.

One of the final frontiers in comparing human and non-human behavior is using the information to aid in understanding human responses and social behaviors. Using the chimpanzee behavior as a guide regarding the effects of stress under resource scarcity; may present a window to the origins of aggression and human conflict. The underlying causes of aggression both human and non-human stem from a combination of both environmental and biological adaptations to handling stress (Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood, 2016). Performing this research project will present valuable information as to when resource stressors provide an aggressive response. The most important aspect is to discover at what level resource scarcity activates aggression. The secondary part of the research hinges on the nature of conflicts. Addressing conflict resolution of humans/non-humans may also present connections between a more adaptive and less aggressive response.

Literary Review:

The earliest form of aggression such as squabbles among local groups over a resource is among the most common in early hominids (White, and Barbara, 2000). Human aggression is a very primal state that may hinge on the aspects of fear and both real and perceived ecological stressors (White and Barbara, 2000). Stanford (1998) indicates that simply accessing behaviors without considering the underlying causes of behaviors is an injustice to our hominid cousins. Focusing on perceived stressors and not just behaviors may change many held assumptions about both chimpanzees and humans. Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood (2016) explain that distinct areas of the brain and brain chemistry may aid in both human and non-human primate’s response to restricted resources.

Wilson, Boesch, Fruth, Furuichi, Gilby, Hashimoto, and Wrangham, (2014) focus on ecology as the main reason for aggressive behaviors in chimpanzees. The chimpanzee on the average record about 1.7 killings per year depending upon location. The information suggests other factors at play regarding resource availability. Wilson, Boesch, Fruth, Furuichi, Gilby, Hashimoto, and Wrangham, (2014) also indicated that a location modified by humans to make resources more plentiful to the chimpanzees resulted in fewer killings within any of those areas that were modified.

Wrangham & Glowacki (2012) explain that violent chimpanzee behavior evolved and was a direct reflection of the environment in which the chimpanzee group resided. Issues of resource stress increased violence. The violence was also very apparent in the action of killing rival leaders and establishment of patrols to protect resources. The contribution of such information gives validity to the argument that there are several factors influencing behavior. The behavior is a response to stressors created when a resource is lacking. The actions of primates in captivity should be much less than those in the wild if specific behaviors are indeed the result of resource stress. Biological issues may contribute to aggressive behavior but are not a complete picture of the underlying cause.

Maxwell and Reuveny (2000) describe the future of human kind as riddled with conflict due to resource stress. Maxwell and Reuveny (2000) indicate by 2050 that the population of the world may be approaching nine billion people. Finite resources and an ever-growing population lead one to believe conflicts especially in developing countries could become more prevalent. Maxwell and Reuveny (2000) explain that other factors of conflicts must be addressed to gain a full scope of the ramifications regarding a severe conflict. The categories addressed are diverting labor in the result of a conflict, death rate increase, and resource growth/ replenishment (Maxwell and Reuveny, 2000). The implications of a conflict in which labor must be diverted away from resource gathering only exacerbates the situation. In the case of the chimpanzee with a small troop or a small human village such a decision could be catastrophic (Maxwell and Reuveny, 2000). The act of moving labor into war and away from gathering or agriculture in a smaller population may result in the extinction. The combination of these actions with an increased death rate from violence can cripple a society (Maxwell and Reuveny, 2000). Though humans can use technology as a means to avoid conflict, our excessive consumption may drive us as a species ever closer to conflicts. Oddly in both the case of human and chimpanzee behavior our efforts to gain resources via militant actions only result in more conflict.

Research Question: What are the underlying environmental and biological factors that lead to increased aggression and behavioral changes in chimpanzees?

Studies of primates tend to focus on simple causes and aspects which at times limit our views concerning aggressive responses (Stanford, 1998). The chimpanzees in captivity have a distinct advantage from those living in the wild. While in the wild, troops may at times be under great stress due to resource limitations (Stanford, 1998). The case of captive primates is much different as the basics of Maslow’s theory is strictly adhered too to prevent violent outbursts. The need to understand aggression in primates under stress may have far reaching effects in finding effective means of conflict resolution under less than adequate resource availability (Guest, 2014). The recognition of aggressive behavior and underlying causes may find their connection to a simple yet effective adaptation (Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood, 2016). The brain of the chimpanzee has evolved over eons, and adaptive skills for survival have become more and more prevalent (Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood, 2016). Modest evolutionary changes may be the difference between problem solving under stress versus aggressive outburst and even militant behaviors (Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood, 2016). The human and non-human responses to resource stress are similar as some become frustrated and aggressive while others problem solves without the aggression. The far-reaching effects of this study could be in identifying how the brain of hominins matures under stress and extremely difficult circumstances.

Methodology:

The basic framework starts by analyzing human and non-human behaviors. The second step is the reaction of all parties to a lack of resources and then the responses associated. Biological data included along with information regarding similarities in behaviors. Lastly, the combination of data from survey’s, interviews, and behavioral analysis will all be combined to determine a conclusion and path of future study.

The current research project will focus on participant observations mostly from an etic point of view. Interviews of primatologists and spectators during their daily events will provide much of the data regarding behavioral obsevations. The observational technique will make up the main part of the study while collecting data with ethograms. Surveys are also an important data collection technique that will present valuable information regarding the perception of zoo keepers and habitat workers regarding aggressive primate behavior. The ethograms are very important due to the information yielded toward behaviors preceding aggressive behaviors.

Statement of Ethics:

The letter of informed consent is given to all parties as to the purpose and need for the study. All surveys will have their identities completely protected by a letter number coding system. All files, folders, written, video footage, and audio recordings are kept under the complete control of the researcher. At no time will the information be granted to a second party without the written permission of all parties involved. During the surveillance of non-human primates, consideration as not to interfere with their daily activities. While being viewed at no time will the individuals be manipulated or coerced in any way. No harm will come to any participants as a result of this study either human or non-human primate.

Information on the selected group and subculture

The group investigated is two part in nature and one in fact aids in the understanding of the other. The first group observed are the non-human primates. The group consists of Chimpanzees five females ranging between seven and forty-nine years of age. There are also three males in the troop ranging from six to thirty-three years in age. The males in question including the six-year old male are highly protective of all female counterparts. The males on several occasions exhibited protective behaviors when the misinterpreted the action of a construction worker in an adjacent habitat as hostile. The male chimps persuaded the females to remain near the door that leads to an inner enclosure. The conflict resolved after the three male chimps performed a perimeter patrol of the enclosure. The behavior seemed to produce genuine stress as the chimps mistook the construction worker behavior as possibly hostile. The observation also suggests the males may have found the workers as rivals and after resources. The determination was evident based on the alpha male Mwami’s actions of checking feeding locations, water source, and blankets after returning seeming to assure that no one had removed an item as it was left.

Specific feeding behaviors were especially interested as Ruben the six-year-old male has established a bartering system by which to establish social acceptance. Ruben during feeding would collect parsnips during feeding and hide them in the corner. There were times when Ruben when Mwami scolded Ruben for his behavior, but the violence was minimal. Ruben would then trade the parsnips for grooming and favor with Mwami. The interesting reasoning of Ruben suggests the development of material culture in which a specific item gains a form of social currency. The exchanges in Rubens case are useful as given the size of the troop and his age Ruben with one day become the leader of the troop in question.

The females of the troop also displayed specific behaviors that one may consider material culture and class separation. The female apes have a selection of blankets available at any given time during the day. However, not all blankets have the same pattern nor color. Kirsty a seventeen-year-old female would fight endlessly over a pink/red flannel pattern blanket, and once she had the blank, the other would gather around suggesting the blanket held some social currency. The other females at times eve attempted to exchange food or grooming for the blanket. The blanket carrier would also lead female chimps around the enclosure to tube foraging areas and water. Once the female chimp loses the blanet so was the subjective class level of the individual. The chimpanzee troop consider the blanket a resource and protect it as such. Males also seemed to bond closure with the female holding the blanket. The females seemed attached to the local resources like food, water, and blanket were kept close at all times.The surveyed individuals will be classified with a number and letter structure to conceal identity.

Primatologist which we will refer to as A1 has several years as not only a Primatologist but also an Anthropologist. Dr. Pedersen has a Ph.D. in Primatology which was very valuable in identifying specific behaviors associated with captive primates. Dr. Pedersen provided information as to the interactions of males and females and how resources may are viewed in a captive location. Dr. Pedersen explained that wild and captive chimps might become very territorial in regards to an interpretation of resource loss. Dr. Pedersen also indicated that chimpanzees in captivity understand and remember those who normally visit a location and may becoming agitated especially in a lab setting if someone appears unsupervised by those individuals to which they are familiar (J. Pedersen, personal communication, January 10, 2018).

The other informants were those surveyed that interacted with primates. Those surveyed ranged in ages from nineteen thru 25 years of age. The group consisted of three females and two males. The interesting part of those surveyed would suggest that education level and expectations of interaction were intertwined (C1, C2, C3). Those with higher education levels seemed to behavior more docile while interacting with the chimps (C1, C2, C3). Those surveyed with lower education levels seemed to have a different expectation as they would pound on the glass and make faces (C4, C5). C5 in several instances attempted to display aggression near the observation glass which initiated a response from Mwami as a challenge. No Human females were observed behaving aggressively toward the chimps, and they also had higher education levels than the human males. The most interesting observation would be how the chimps interacted with children. The smaller the child, the more interested the chimps became.

Setting /Location:

The setting can best be described a step into the world of non-human primates. The path leading up to the enclosure has two very special statues of past residents. One of the primate statues is that of a silverback gorilla and the other of a very old chimpanzee. The eerie part of the path comes as one must pass the enclosure of the orangutan, affectionately referred to as the sentinel. The orangutan sits inside a hill top enclosure that overlooks all who enter the chimpanzee area. The chimpanzee enclosure consists of several jungle gym items, foraging tubes, and a mock termite hill with honey ports. Water is readily available through a small waterfall near the entrance to the indoor enclosure. The measurements are roughly three hundred feet in length and approx. Four hundred feet across. Surrounded by a mote and fenced wall to prevent escape attempts. The viewing glass for spectators backs up to a rocky half circle to give the effect of being immersed in the life of the chimpanzee.

Carried out observation research of the Chimpanzees at the Oklahoma City Zoo. Observations were carried out at 9 am, 1:25 pm (feeding), and 4:30 pm to gather information about specific behavior during certain parts of the day. Interviews with the primatologist were conducted over the phone and via email. Conducted surveys in the zoo spectator viewing area, all individuals were given informed consent letters as required.

January 10, 2018 - Interview with primatologist (Dr. Janni Pedersen)

January 15, 2018 - Observations of Chimpanzee population from 8am-3pm

January 20, 2018 - Observations of Chimpanzee population 8am-4pm

February 8, 2018 - Observations of Chimpanzee population 12 pm – 3 pm

Feburary 10, 2018- Observations of Chimpanzee population 12 pm – 5 pm

Feburary 12, 2018- Observations of Chimpanzee population 12 pm – 5 pm

February 18, 2018 – collected surveys observed interaction with spectators (C1-C5)

Research methods

The data gathered via ethnographic questioning, surveys, ethograms, video, and audio yielded a large amount of data and a deeper understanding of aggressive behavior in non-human primates. The ethograms were conducted on each primate at least twice the ethogram gauged responses to ecological and social behaviors. Specific times of the day were used in conjunction with the ethograms to find specific responses that repeated at a given the time of day. Feeding time and snack time were used most often as energy and agitation displayed more readily. Lastly, carried out surveys of the public spectators and also visual observations. The observations rendered interesting information especially along three lines male, female, and children that interacted (which will be elaborated on in the data analysis section). Surveys were also conducted to understand better how those interacting with the apes understood their behavior. The importance was whether the public could identify anxious or aggressive behaviors.

Data analysis

Dr. Pedersen (primatologist) provided deep information regarding Chimpanzee behavior and how threats are perceived. The explanation of aggression during the interview described two specific areas in which aggression would become significant. Social and food sources bring about the most aggressive responses. Dr. Pedersen presented of a female chimpanzee that had difficulty integrating socially and in turn, intentionally caused conflicts among a troop. While observing the troop, on several occasions a younger chimp found a way to play/tease an older female chimp (Cindy) to the point of violent agitation. The response from the rest of the troop seemed to be against Cindy. Viewing such an agitation several times the young chimp seemed to try and cause trouble for the older female. Food was a great point of agitation for the entire troop. The displays by Ruben of hiding particular food items and using them as currency is an incredible adaptation. Violence always quickly followed the point of feeding as Mwami intended to each first and would behavior with outburst until the hierarchy was understood. An outburst over controlled situations brings to mind the thought of territorial behaviors in the wild when food or water is stressed. The situation under little control in the wild would become exasorbated as no one would help in the of shortage (Wilson, Boesch, Fruth, Furuichi, Gilby, Hashimoto, and Wrangham 2014).

During the interview the importance of sound reduction with enclosures and the importance of lowering stress and anxiety. Although stress and anxiety seemed very little between spectators and the troop, there was a form of increased agitation when the crowd size became too large. The group size of spectators put the chimps at a numbers disadvantage and as such the troop banded together for grooming if the crowd size was over about fifteen spectators. Dr. Pedersen also indicated that chimpanzees view standing over them as a form of aggression and may respond accordingly. During research, if Mwami was near the glass and a large man was near the glass a perceived threat put him in a position to respond. Larger men six feet tall or above would agitate Mwami, but no outburst was noted. However, during feeding time if on lookers of similar size were near the glass Mwami did respond violently toward the glass. There seemed to be a misunderstanding by Mwami that larger men may have threatened available resources at this particular point. There seemed to be no other items causing the agitation and the response.

Per Dr. Pedersen, the Chimpanzees, especially in captivity, show little differences in aggression from season to season. Chimpanzees in the OKC Zoo have heated housing areas to which they can enter and exit as needed. Seasons in such a case are no longer issues as most behaviors as stated in Maslow's hierarchy of needs are being met (Guest, 2014). The visible increase in aggressive behavior or change to a more aggressive response comes during puberty. Those entering puberty begin to find their social position and hormones also come into play. The number of perspective mates can also cause issues. The case of a small number of given pairs or one particular sex if short supply could result in aggressive behaviors. The blankets given to the chimps and the class status seem to come into play as the Kirsty for example held Mwami’s attention when she possessed the pink/red checkered blanket. Without the blanket, Mwami tended to respond very little to grooming requests or any other advances.

The most interesting find by ethogram was that of Mwami. During an afternoon feeding January 20, 2018, the weather was particularly chilly, and winds were increasing. During this feeding Mwami became very hostile and began fighting with other chimps to assure he would eat first. One could theorize that due to the environment of the particular day that Mwami became agitated and perceived the difficult conditions as a threat and interpreted the feeding as a chance to secure hierarchy and survival. Hierarchy seems to be key in this case as once established everyone seemed to fall in line except Ruben who was using modified currency in the form of parsnips.

Surveys conducted during the observations of human spectators lead to some interesting information and differences between males and females. Female spectators seemed to be more in tune with the actions of the chimpanzee than their male counterparts. The interpretation of facial expressions of the chimpanzee was also interpreted easily by females surveyed. The females, however, were unable to identify militant behavior such as patrolling the perimeter of the enclosure. Chimpanzees tend to play a bit rougher than their human counterparts, and such actions could often become misinterpreted as violence by the female onlookers. The males surveyed found the play to be normal. Fewer individuals tended to act more aggressively toward the chimpanzees, and educated individuals tended to more docile when attempting to interact.

Interpretation

Spending some days with the chimpanzee troop one particular item became very apparent. Chimpanzees in captivity do notice and are fully aware of the situation in which they live in captivity. The chimpanzees were very docile in most cases unless a perceived resource threat or physical threat ether by crowd size or unknown noise came to the forefront. Wilson, Boesch, Fruth, Furuichi, Gilby, Hashimoto, and Wrangham (2014) explains that in the case of chimpanzees that the aggression used may be an adaptive response to specific stressors. When first contemplating the project the belief that chimpanzees lacked proper reasoning skills was my misconception (Stimpson, Barger, Taglialatela, Gendron-Fitzpatrick, Hof, Hopkins, and Sherwood, 2016). The chimpanzee fully understands their captivity, and as such only resort to violence when the troop perceives a threat against the only home they have available. Material culture is a large portion and an adaptation that has increased while in captivity. The blankets and the special diet items do indeed hold both class status and currency among the troop. Material culture once developed not only supplies a system of economic structure but also seems to increase volatility among a society. The future of mankind may hinge on the fact that when resources become stressed that the most important aspect is to adapt, work together, and find a solution. Maxwell and Reuveny (2000) indicate that in developing countries the loss of a resource can spiral a country into chaos if plans are not in place to work together and settle conflicts.

Chimpanzees are in fact susceptible to resource stress in captivity, although, the resources that are stressed are by interpretation of the troop. The decision as to what is declared a resource once made by the troop will then be protected the as if it is the only item left on earth. Warnica (2017) explains that currently is South Africa that humans are about to experience the direst of resource losses. The city of Cape Town will run out of water on or near May 13, 2018. The issue is affected by both climate change and corruption within the government. The entire planet will bear witness to the results of millions going without a necessary resource. The future is uncertain in Cape Town and difficult days are ahead, to find a brighter future we must learn from the mistakes of the past evolve from the primal responses and find solutions.

The aggression seen by chimpanzees in the wild and captivity is merely a symptom of underlying causes. The stressors mainly ecological and sometimes social have a definite effect on the chimpanzee social and behavior. The brain chemistry and biological differences between chimpanzee and bonobo are striking. The bonobo having denser serotonergic axon may indeed have a biological advantage when access a problem requiring adapaptability. One must not overlook the adaptability of the chimpanzee patrols, and kill of rivals which may have been an evolutionary adaptation that allowed them to thrive under difficult conditions. The militant reaction is very similar to the reaction of humans trying to conserve resources. Aggressive behavior in times of lacking resources may be the driving force behind the human conflict in several parts of the world. The decision humans must address as the more evolved of the species is to decide the road of egalitarian compromise or the all-out destruction of only the most adaptive and lethal survive. In the end, humans must focus on finding a way to lessen the traits from the aggressive tendencies of the chimpanzee and problem solve our way to a better tomorrow.

References

Guest, H. S. (2014). Maslow's Hierarchy of Needs—The sixth level. The Psychologist, 27(12),

982-983.

Maxwell, J., & Reuveny, R. (2000). Resource Scarcity and Conflict in Developing Countries.

Journal of Peace Research, 37(3), 301-322. Retrieved from http://www.jstor.org.proxy-library.ashford.edu/stable/425347

Rossman, G. B., & Rallis, S. F. (2017). An introduction to qualitative research: Learning in the Field (4th ed.). Retrieved from https://content.ashford.edu

Stanford, C. (1998). The Social Behavior of Chimpanzees and Bonobos: Empirical Evidence and Shifting Assumptions. Current Anthropology, 39(4), 399-420. doi:10.1086/204757

Stimpson, C. D., Barger, N., Taglialatela, J. P., Gendron-Fitzpatrick, A., Hof, P. R., Hopkins, W.

D., & Sherwood, C. C. (2016). Differential serotonergic innervation of the amygdala in bonobos and chimpanzees.

Social Cognitive and Affective Neuroscience, 11(3), 413-422.doi:10.1093/scan/nsv128

Warnica, M. (2017). In South Africa, Cape Town faces a water shortage. CBC Radio,

White, R. E., & Barbara, D. P. (2000). On Maslow, monkeys, and evolution. Academy of

Management. The Academy of Management Review, 25(4), 697. Retrieved from https://search.proquest.com/docview/210949418?accountid=32521

Wilson, M. L., Boesch, C., Fruth, B., Furuichi, T., Gilby, I. C., Hashimoto, C., & ... Wrangham, R. W. (2014). Lethal aggression in Pan is better explained by adaptive strategies than

Human impacts. Nature, 513(7518), 414-417. doi:10.1038/nature13727

Wrangham, R., & Glowacki, L. (2012). Intergroup Aggression in Chimpanzees and War in

Nomadic Hunter-Gatherers. Human Nature, 23(1), 5-29. doi:10.1007/s12110-012-9132-