Week 16: Greensboro Science Center Reflections

The primates I saw at the Greensboro Science Center were javan gibbons, lemurs (ring tailed lemurs, red ruffed lemurs, and mongoose lemurs), and black howler monkeys.

The gibbon enclosure was a decent size, especially considering it only holds one adult male, one adult female, and one infant gibbon and because the gibbons are small primates. However, it is difficult to discern whether or not the space is sufficient for them, because during the time I saw them they were mostly sedentary. Therefore, I am not sure how much they move around in the enclosure during their more active times. I personally did feel pleased by the size of the space, though. The gibbons in the group were all the same species – it was composed of two mates and their infant. I did not witness any strange behavior that indicates stress from captivity. It was extremely interesting to watch one of the adult gibbons walking bipedally on the ground to take some grass to eat. The gibbon had to walk with its arms held out for balance, which is a behavior I would not have expected, but upon seeing it I realized the necessity of it. Besides this, the gibbons did not move much from the logs they were sitting on, except for the infant who was mostly playing but itself.

Below: the two adult gibbons on branches and the infant with its blanket on the ground (picture taken by me)


Below: the infant gibbon with its blanket (picture taken by me)


For a while, the infant was on the ground with a small piece of blanket-type fabric, and it seemed to be amusing itself by pulling the blanket over itself and rolling around. Later, the gibbons had moved to ledges on the rock structure by their indoor enclosure. Here, the infant was swinging from ropes hanging from the ceiling and the adults were still not really playing with it.

The lemur enclosure was definitely too small for the number of lemurs in it. I think there were about 10 lemurs in the enclosure, and it was at least half the size of the gibbon enclosure (if not more). The lemurs were very active while I was watching them, and they definitely did not seem to have enough space. I think the enclosure should be at least double the size. The lemur exhibit had three species, which are a common grouping. They were playing on different tree branches, small hanging hammock-type swings, ledges on a rock formation, and a tube hanging from the ceiling. They were also climbing the netting of the enclosure.

Below: a lemur on one of the swings (picture taken by me)


No abnormal behavior was evident, but the lemurs were mostly very active (besides the mongoose lemurs, who stayed on the ledge of the rock formation and did not movie). They were jumping between different swings and branches and sitting in the hanging tube. Something unique was that there was a ring tailed lemur that was missing an arm. This could have been a deformation, or otherwise an injury sustained in captivity. Dr. Rodrigues explained that sometimes limbs have to be amputated after primates stick them through holes in the fencing of enclosures and cannot get them back out. Despite its disability, the lemur was just as active as the others and was doing the same things.

Lastly, the howler monkey exhibit was perhaps the most exciting to watch. The enclosure was slightly larger than the lemur enclosure, but not by much, and there were about 5 howler monkeys in it (of only one species).

Below: a howler monkey on one of the logs (picture taken by me)


Once again, it would have been much better to have a larger enclosure. The howler monkeys were very active, which helped illustrate why the exhibit needs to be expanded. They were using all of the space, and it did not seem to be enough. Something unique about the howler monkeys’ behavior was their high level of activity. We all expressed our surprise that the howler monkeys were the most active of the three primates we saw! Howler monkeys are expected to be a more sedentary species. Another interesting behavior was seen when, at a couple points in time, howler monkeys were traveling across the enclosure on the ground, which is something howler monkeys usually do not do. They were amusing themselves in a habitat similar to the lemurs’ – it had various tree branches and some swings, and the monkeys were also climbing a fair amount on the netting of the enclosure.

I found the exhibits dismaying, because they did not seem to have enough information about the primates. I think that more literature is good for several reasons; it helps the adults at the zoo understand more about the animals so they can explain to the children what is going on with more knowledge and less assumptions and misconceptions. Just in my short time watching the primates, I overheard some very incorrect statements that parents were making to their children about what the primates were doing. Also, more information would have been great about the origins of the gibbons and the threats that they face. If the value of zoos is promoting education and conservation of these primates, then more of an effort needs to be put into that element. It bothers me especially because that is probably the simplest part of the entire exhibit; it is not extremely difficult to find information about primates – I’m sure the majority of students in our Primate Behavior & Biology class could come up with better signage at these exhibits.


Week 15: Fossey Archives (Conservation)

The document I chose was a letter from Dian Fossey to Richard Wragham, of the Department of Anthropology at Harvard University (sent from the Karisoke Research Center in Ruhengeri, Rwanda, Central Africa, and dated November 12, 1976). She begins by describing what is going on around the campsite and details for his future visit. Then, the letter takes a surprising turn as she criticizes him for talking to people at the Primate Congress in Cambridge about gorilla conservation problems. Fossey proclaims that what he did is not a true conservation effort, and tells him to “try presenting the following gambit the next time you talk gorilla conservation”. She then proceeds to explain how just that day, five park guards had brought a Twa poacher to her who she knew to be involved in a large number of gorilla and elephant killings outside of her study area. She declares “I knew his name well and had longed for his skin for a very long time”, which is a rather alarming statement. Then, Fossey explains how she and the others at her site stripped the man, laid him “spread-eagled” on the ground in front of her cabin, and “lashed the holy blue sweat out of him” with nettle branches and leaves, aiming at the more sensitive areas of his body. Fossey specifies that she asked for nettles to be used on the man because of his bad poaching history. She says they then conducted a “black-magic routine” composed of mace, ether (a recreational drug that impairs the body), needles, and sleeping pills. According to Fossey, “That is called ‘conservation’ – not talk”. Apparently, to Fossey, physical action such as this is all that she feels classifies as a true conservation effort. Then she concludes by saying the man is set to be in jail for a year, and that she has been successful in the last month with working with the lawyers in the country. And, she ensures Richard Wragham, “Everything I do, by the way, is legal”.

This letter was appalling to me when I read it. In fact, I re-read it just to make sure that I had understood everything properly. Fossey’s ultimate goals might have been fine, but her actions were despicable. In my opinion, in order to be on the “right” or “good” side of a conflict, people have to hold themselves above the actions of the people they are fighting against. For example, if someone wanted to protest a company’s use of palm oil that requires burning areas of the rainforest, setting that company’s headquarters on fire would be extremely counterproductive. Nobody is going to feel sympathy towards someone who stoops just as low as what they are fighting against. I have to say that Dian Fossey comes across as truly insane in this letter. Considering the way her life ended, I think it becomes very easy to conclude that Dian Fossey did not conduct her conservation efforts correctly.

There are several ways we can promote conservation today that are much better and more ethical that what Dian Fossey did. One way is to provide economic and food support to the locals of those areas so they do not need to hunt the animals for meat and/or money. Also, it would be beneficial to offer education to the local communities about the primates in the area where they live so they understand why these are creatures that need to be saved (e.g. their high levels of cognition, their approaching extinction). Fossey’s biggest issue, in my opinion, was that she seemed to view the locals as her enemy and with that perspective ultimately made them  more opposed to her than they might have already been. Meanwhile, I have read some really great stories in Primate Ethnographies about primatologists who managed to establish strong and even close relationships with the locals, which cultured a certain amount of respect between them. Thanks to these narratives, I know it can be done. It just requires a great amount of patience on the part of the primatologists and an acceptance that sometimes even their maximum effort will not get through to the locals, but that they cannot escalate the situation even if that occurs.

Below is a picture of students from a school in Africa participating in a conservation education program that the Columbus Zoo helps fund along with the Dian Fossey Gorilla Fund International and the Karisoke Research Center.

Gorilla conservation

Photo © Columbus Zoo and Aquarium, 2012

Source for Document: Dian Fossey Archives, Folder: MS 596 Box 13, DF BIO, 1976 July – Dec

Week 14: Polyspecific Associations

In Primate Behavior and Ecology, Strier describes many different groups of species that form polyspecific associations. Some do it for predator protection, while others, like moustached tamarins and saddleback tamarins, do it for foraging benefits. They have been observed forming permanent polyspecific associations in Manu National Park, as well as other areas of Peru and Amazonia.

Below is a picture of a saddleback tamarin:

Saddleback 1

In Primate Ethnographies, tamarins are described as extremely tame primates. They do not generally mind human presences, and are in fact generally curious about them. This is an important feature of tamarins to consider, because it seems to be a contributing factor to their willingness to form polyspecific associations across species. A large part of why that association works is probably due to tamarins’ docile demeanor. This is perhaps also evident in the fact that tamarins do not only form these cooperative groups with other tamarin species; Primate Ethnographies describes how saddleback tamarins also join together with marmosets in the wild.

Below is a picture of a moustached tamarin:

Moustached 1

The polyspecific association that occurs between saddleback tamarins and moustached tamarins is a daily event – they form permanent unions. Single groups of each species will join together, sharing a territory and mutually defending it. During the day, the two species forage together. This is a functional set-up, because the saddleback tamarins and moustached tamarins do not occupy the same niche. Their locomotor styles vary, as saddleback tamarins mostly forage in the understory (less than 4 meters above ground) of the forest while moustached tamarins find their food in the area of the lower and middle canopy (4 to 15 meters off the ground). The insects that they eat also differ; the results from a 12-month study in northeastern Peru revealed that saddleback tamarins and moustached tamarins that affiliated with each other only ate three of the same insect species.

Below is a picture of two saddleback tamarins:

Saddleback 2

The saddleback tamarins can benefit greatly from foraging with the moustached tamarins, because when moustached tamarins lose insects, they are generally then caught and eaten by the saddleback tamarins below. A specific study mentioned from the Brazilian Amazonia showed that approximately 40% of the insects that saddleback tamarins ate came down from the foraging moustached tamarins above. Both species also benefit from their polyspecific association because it allows for further protection of their range.

Below is a picture of a moustached tamarin:

Moustached 2

Another primate has been shown to form polyspecific associations with these tamarins, although this relationship is seasonal and non permanent. Occurring mostly during the rainy season in Bolivia, when fruit grows abundantly, Goeldi’s monkeys have been observed affiliating with tamarins. This is a foraging strategy for the Goeldi’s monkeys, as they will follow tamarins in the forest to be lead to sources of fruit.

Below is a picture of a Goeldi’s monkey infant with an adult:

Goeldi 1

However, when the dry season begins, Goeldi’s monkeys diets’ change and subsequently differ from that of tamarins. Therefore, when the rainy season ends, Goeldi’s monkeys are rarely found associating with tamarins.

Below is a picture of a Goeldi’s monkey infant:

Goeldi 2


The polyspecific associations that these species form are really interesting, because it reveals that collaboration occurs in the wild. These primates are able to perceive how to use each other for mutual benefit. Also, as evidenced by the Goeldi’s monkeys, these primates are able to understand when it is useful to form affiliations and when it is better not to.

Week 13: How Do We Assess Cognition?

In the movie Ape Genius, ape cognition is studied in a variety of ways; in fact, the film illustrates the vast options of methods which can be used to evaluate ape cognition and how these different studies can lead to various revelations. One method that was shown was observing apes in the wild and looking for activities such as tool use to reveal cognitive abilities. Through wild observational studies like this, researchers were able to discover that chimpanzees use tools for hunting – the chimpanzees sharpen sticks to create spears, and then jab the spears into tree hollows to stab bush babies. Chimpanzees were also observed utilizing sticks to catch termites; some chimpanzees had more sophisticated methods than others (such as digging up a termite hill and then shoving the stick into the hole to catch termites). Tool use is a very significant discovery in the wild; it mean that these chimpanzees developed this behavior on their own, without an influence of humans. Obviously, if the same studies were done in captivity, it would be very difficult to know how much of the chimpanzee tool use was innate versed learned and imitated. Therefore, there are huge benefits of studying primates in the wild.

This leads to another way to research cognition: there were some studies in the film where researchers would try to teach primates various things. One example was when a researcher trained a chimpanzee, Ai, to match a number with a number of dots (so that the chimpanzee could learn what the numbers represented). Then, once the chimpanzee learned numbers 1-9, the researcher displayed the numbers helter-skelter on a screen and Ai learned how to touch the numbers in ascending order. Taking the study a step further, after Ai touched the number 1, white boxes would cover all of the numbers. Ai was still able to touch them in ascending order based off his memory. Another research study in captivity was with the bonobo Kanzi, who was taught to understand approximately 3,000 English words. Kanzi can be directed to do something (like as shown in the video, to put keys in the refrigerator), and he can understand what is being asked and do it. These studies exhibit some of the huge benefits of studying primates in captivity – it allows researchers to actually try to teach behaviors to the primates. While this does not reveal what sort of behavior the primates would naturally do in the wild, it does show the cognitive capabilities that these primates have; abilities that are not evident just by watching them interact in the wild.

From these different studies, it becomes clear that research in the wild that is only observational is beneficial for showing the natural development of behaviors in these animals. However, in order to understand the true level of cognition that these primates have, captive studies are necessary, and teaching certain activities to the primates can reveal their limits of understanding. While these revelations are interesting, there is a question about the value of these findings. I have to say that it is not clear to me why it is important to know the cognitive abilities of non-human primates, or at least important enough that it requires putting these animals in captivity. It is good to learn about animals, but the costs of these studies are questionable as to the overall worth.

Below I have inserted the link for a clip showing the reporter Lisa Ling interacting with Kanzi, the bonobo I mentioned before who was taught to understand English words and to use symbols to communicate. I think that this cognitive study was well-designed because he was taught language, as the researcher Sue states in this video, just like she taught language to her son. This allows for a better comparison of bonobo cognition and the cognition of a young human. Also, because bonobos do not learn English in the wild, this is the only way to really see how much bonobos can learn and understand. Because Kanzi never reached the level of communication where he could simply have a conversation with someone (e.g. talking about the weather), this study was also successful with showing the limits of bonobo cognition. While these are very smart animals, they are still in no way close to human’s level of cognition and communication. This is a good revelation for anyone who believes the idea that chimpanzees and/or bonobos are going to conquer the world one day (i.e. Planet of the Apes).

Kanzi the bonobo on Oprah


Week 12: Second Article Review

For my second article review, I chose to once again focus on a journal article that discusses one of my favorite primates – the bonobo. This is also an article that I will be utilizing for my final research paper for this class. The article I selected, “Issues in Bonobo (Pan paniscus) Sexual Behavior”, was written by Ben G. Blount of the University of Georgia, and was published in the journal American Anthropologist in 1990. It examines the sexual behavior of bonobos, comparing and contrasting their interactions with those of human ancestors and chimpanzees. The bonobos’ preference to copulate in a face-to-face position is evaluated by considering various observational studies of bonobos, and the unique female sexual anatomy and physiology is also explored. In addition, the relationship between sexual interactions and feeding is investigated.

The findings of one of the studies revealed an important factor that connects feeding with sexual encounters between bonobos. Sexual activity increased when higher prized food was obtained by a bonobo; essentially, the bonobo with the prized food grows anxious when approached by others, so the approaching individuals initiate sexual encounters with that bonobo. In the study, this was found to reduce the stress levels of the bonobo possessing high quality food; therefore, sexual activity among bonobos can be connected with the purpose of easing tensions, rather than directly relating it to feeding itself.

Other research that was mentioned focused on the occurrence of sex in the ventral-ventral position (which is when the two individuals face each other). This position was found to be the most common for a variety of different groups. For example, the females that were observed most commonly had sex in this position, as well as the males. In addition, sex between males and females, males and males, and females and females, all most commonly involved the ventral-ventral position as well.

The article also revealed some very interesting information about how much the female anatomy of bonobos varies from that of chimpanzees, and why those changes have impacted bonobo sexual behavior. For example, the clitoris of bonobo females is “relocated anteriorally” and is therefore “more exposed and more elevated” than in a chimpanzee (Blount, 1990). This relocation of the clitoris causes ventral-ventral copulation to provide “maximal stimulation”, leading bonobo females to prefer that position (Blount, 1990). Additionally, during their menstrual cycle, bonobos exhibit sexual swelling for “approximately 75%” of that time, while chimpanzees only show swelling for “50% or less” of their cycle (Blount, 1990). This increased amount of time spent with sexual swellings subsequently increases the amount of time that bonobos are participating in sex, however it is also noted that bonobo sexual behavior is not restricted to this timeframe.

The article did an excellent job at exploring many different areas of reasoning for how modern bonobos and chimpanzees vary, mentioning physical features as well as results from observational studies. The research was extremely thorough and there were not any topics that seemed to be forgotten when comparing the two species. The author also did a great job at continually offering chimpanzees as a source of comparison so that the uniqueness of some of the features of bonobos could be appreciated. Also, the author successfully included explanations about how each of the characteristics mentioned affect bonobo behavior, and why certain behaviors exist.

Something that could have improved this article would have been the inclusion of more text to explain the various terms that were mentioned. Many of the vocabulary that was used in the article was highly scientific, and while it was the proper terminology, it would have been helpful to offer more of a background because they are not especially common terms . For example, it would have been beneficial if the author had included more of an explanation about the female sexual anatomy and physiology. The information was presented in an overly straightforward manner, with specific anatomical features being mentioned without any introduction or background given.

Overall, “Issues in Bonobo (Pan paniscus) Sexual Behavior” was an excellent journal article that comprehensively explored the topic of bonobo sexual behavior: what the behaviors are and why they seem to occur. This article is a significant contribution to bonobo research, because it covers a large amount of information about these great apes but manages to keep the information concise and to the point. Various research studies were also utilized as sources of information, which keeps the article from becoming too one-sided or from not representing a large enough sample to be correct about its points. The author also made sure to include text at the end of his article stating that, while bonobos and humans might appear to be more similar than chimpanzees and humans, none of the information he mentioned is enough of a basis to conclude that bonobos and humans are actually more genetically related. This was an important inclusion, because it ensures that nobody gains any false impressions from his findings and jumps to conclusions that we have not yet proven. This article will undoubtedly be a huge aid for my final paper on bonobo sexuality.



Blount B. 1990. Issues in Bonobo (Pan Paniscus) Sexual Behavior. Am Anthropol 92:702-714.

Week 11: Proposed Paper Topic

As I have been seriously contemplating what I will write about in my final paper for Primate Behavior and Biology, I continually find myself going back to the same topic that has sparked my interest many times before while studying primates – bonobo sexuality. The research on bonobo sexual behavior is fascinating and important, because it reveals so much more about the non-conceptive side of sex. In humans, the occurrence of sex for purposes besides reproduction is common and widespread, and has even lead to the huge development of industries that provide methods of protection from pregnancy (condoms are a multi-billion dollar global industry).

Below: bonobos genital-genital rubbing

Bonobo genital rubbing

Therefore, when I first heard about the sexual behavior of bonobos, my interest was immediately caught. In one of the articles I was reading for preliminary research, the author remarked that there are people who claim that this type of sexual behavior is “unnatural” in humans, just like many say that women being in charge is “unnatural” (thanks to bonobos for also throwing that idea away). I think that the general knowledge that most people still have about those topics is very incorrect, so learning more about this fascinating and relatable behavior is really valuable. Not enough people know about the many different ways that animals live in the wild, or how complex their lives can be. My friends laugh at how passionately I explain the true diversity of primate behavior, and there is no denying that I tend to become extremely engrossed in the topic.

I am planning on writing my paper in the form of a literature review. I want to discuss the sexuality of bonobos and its effect on their social behavior, using chimpanzees (their closest relative) as a source of comparison. The focus of my writing will be specifically on their sexual behavior, however I think that it is important to also consider its impact, which is why I will be discussing sociality as well. I already know a fair amount about the sexual behavior of bonobos, from previous reading/blog posts for this class as well as from the Intro to Biological Anthropology class I took last semester. However, I have never done any in-depth research about it, so my knowledge is more general. I look forward to understanding more about these amazing primates!

Below: a bonobo exhibiting sexual swelling

Bonobo sexual swelling

I hope to learn more about the different findings from studies on bonobos; for example, I read an article about how a study revealed that bonobo sexuality seems to be an innate behavior and not learned. I would be really interested in looking further into the question of how much of their interactions are from what they have been taught and seen, or instinctual. It would also be beneficial to research theories for why bonobos and chimpanzees have such different sexual behaviors. I am already aware that chimpanzees face more challenges than bonobos for finding food, which has caused a major impact on their behavior and lifestyle. However, I am still not sure what the hypothesis is for why that difference in life challenges would lead to sex functioning as it does in bonobo society. I am not sure how much of that question has been answered or even can be, but I definitely want to explore it further.

From the preliminary research that I have done so far, I have found several sources that I think will be useful for my paper:

De Waal F, Lanting F. 1997. Bonobo: The Forgotten Ape. London: University of California Press.

Manson J, Perry S, Parish A. 1997. Nonconceptive Sexual Behavior in Bonobos and Capuchins. Int J Primatol 18:767-786.

Woods V, Hare B. 2011. Bonobo but not chimpanzee infants use socio-sexual contact with peers. Primates 52:111-116.


Week 10: Zoo Impressions

Seeing the gorillas in person what similar to what I expected, because I have seen so many videos and pictures that this point, and I had also been to the zoo when I was younger. What did surprise me, though, was that while they were doing everything I would pretty much expect, it felt like I was seeing them with a fresh pair of eyes. It was my first time seeing non-human primates in person since I gained so much more knowledge about them in anthropology classes, so I really felt like I understood them better. When some people came up to the glass and were making so-called gorilla noises like “hoo hoo hah hah”, I realized how ignorant most people are about these incredible animals. Gorillas are not dumb – in fact, in some areas they are smarter than humans – but most of the other zoo-goers didn’t seem to realize this. I finally was able to recognize how little I had appreciated non-human primates before taking an anthropology class, which was a really rewarding realization.

I really enjoyed observing the gorillas, because I am probably most fascinated by the apes. Viewing the primates that are closest to humans is a truly engrossing experience. They are so majestic, and so similar to humans, yet also incredibly different. I am definitely happy, therefore, that we were able to also observe the chimpanzees for a period of time in the morning. I will say that I am more partial to gorillas than chimpanzees, though, because frankly chimpanzees scare me. Even though I was behind the glass, I was glad to spend the majority of my time looking at animals that would be less likely to eat my face off if I came in contact with them! The gorillas were also very exciting to watch because there were two youngsters in the enclosure that were absolutely adorable. Watching them play with each other and with the adults was a truly amazing sight; I would say the cutest time was when the babies cuddled with their mothers for an afternoon nap.

I wouldn’t say that seeing the primates in their enclosures affected my perspective on captivity as much as learning about primates has. By this, I mean that I have always had an issue with zoos and have personally protested the way animals are captured and held for humans to view them like they are simply a form of entertainment. I feel very strongly that keeping animals for this purpose is very unethical; allowing humans the opportunity to observe animals is much less significant than allowing animals live as unharmed and unbothered by humans as possible. I feel like we’ve done enough already to their habitats, we don’t need to completely remove them from the wild for our pleasure purposes. Even with these views, I would say that learning more and more about how intelligent and incredible primates are, the unjustness of their placement in zoos has become even more defined for me. They are such beautiful creatures, and they can understand a lot of what is going on around them, so keeping them captive just feels very wrong. Additionally, reading Gorillas in the Mist shed more light for me on the horrendous effects of capturing a wild animal for a zoo. In order to take a baby gorilla, every other member of the gorilla group generally ended up dying. That is surely not an okay price for the gorillas to pay for human amusement. Therefore, I can say with even more fervor that I strongly protest the holding of animals in zoos.

Below is a picture I took at the zoo of my favorite sight – a gorilla baby!


Week 9: Spring Break!

Week 8: Fossey Archives – Behavior

The document I chose is “Results of 1976 Census Work on Mt. Mikeno and Adjacent Areas, Zaire”, which outlines different parts of the observation process. The gorillas being observed were put into 9 different groups (totaling 93 animals), and many were differentiated by noseprints taken by field workers. (Noseprints are sketches of the nostril’s shapes and linear indentations that are seen above the nostrils; these are recorded with the help of binoculars and Fossey had a total of 20 recorded at this time.) The decision to form the groups as they did were based on their size, composition, and the consistency of the group’s ranging pattern. Noseprints could not be utilized with every gorilla that was studied, which meant that Fossey had to sometimes rely only on observations (and no solid evidence) that the same gorilla was being studied. For example, in the Group A that she observed, she believed that a dominant silverback present in 1976 was the same as one from 1973 but for a reason that is unstated could not use noseprints to prove this suspicion. The age of infants also had to be approximated based on their size and visual observations.

From this document, it is clear that Fossey was very careful to ensure that the population sizes of each individual gorilla group as well as the total number of gorillas being observed was carefully recorded. Additionally, the following information was recorded specific to each research camp: hours in field, hours of contact, number of contacts, number of workers, noseprints obtained, days spent, and dates. The hours in the field are counted not by the number of people but by the exact time (e.g. if two people travel together in the field for an hour, the total hours in the field is only one hour and not two). Also, contact with a gorilla is defined as the time during which a gorilla group or individual were within visual observation of the field workers. The numbers that are given for hours in field and hours of contact are both shown as being extremely precise; they are recorded into the second decimal place. It is clear from this that Fossey and her fellow field workers were extremely serious about making all elements of their observations as accurate as possible and that they paid great attention to detail.

Also, with the specific groups being observed (Groups A-I), Fossey made note of every immigration that took place (that she knew of), and also made sure to record where each group’s range was and if it overlapped with that of another group. She used this information to make predictions about immigration patterns. She also made note of ages found by studying gorilla dung. Fossey additionally includes what groups she believes are the same in 1976 as they were in 1973, how many births/deaths occurred in that time period, and how the adult/sub-adult ratios and adult male/female ratios have changed. Fossey also makes sure to state that group (Group F) was specifically difficult to study because of the precipitous area of Mt. Mikeno that they lived on. From this, it becomes evident that researchers can be limited at times with their observational capabilities solely based on the difficult environment that animals might be living in. Additionally, with many of the notes for different groups, Fossey remarks that there is not a large amount of data because the researches had spent a relatively short time observing those groups. Reasons for this could be varied, but it seems that maybe Fossey did not have the resources to gain better observations of these many different groups or that the observational process simply needed improvement.

Fossey also took extensive notes on Group H for how the range of that group changed greatly since 1973, and how it seemed to be the cause of humans. She said that the new range was now surrounded by human cultivation, and also that the group seemed to have sustained some great losses due to human encroachment. This offers a perspective into the difficulties that researchers like Fossey must face when conducting their observations, as other humans interference gets in the way of their research and negatively affects the populations they are studying. There is also a section that shows all recorded signs of human encroachment, especially indications of poachers. Fossey says that she and her workers were breaking the traps that poachers and even guards had set out to catch animals – they destroyed 215 traps in a period of five days. She records difficulties with the guards trying to convince her and her researches to stay out of certain areas (that were heavily laid with traps) by claiming that no gorillas resided in those areas. Fossey also recorded the presence of other animals, which she used largely to show the impact of the poachers and to indicate the trend of poacher activity – she recorded a 94% reduction of elephant and buffalo sightings, and a 56% reduction of the monkey population between 1973 and 1976. She does note that there might be a lack of accuracy in the 1976 recordings that could interfere with these statistics, but that even taking that into account the huge impact of poachers is obvious.

Following her report of 1976, she included the census report from 1973 for direct comparison, and at the very end were the various drawings of noseprints accumulated through the field studies (the pictures were divided based on group and also included the year that each noseprint was taken and some form of identification of the animal it was taken from).

Dian Fossey

Photo © Dian Fossey Gorilla Fund International

Source: Dian Fossey Archives, Folder: MS 596 Box 13, DF BIO, 1976 July – Dec

Document: Results of 1976 Census Work on Mt. Mikeno and Adjacent Areas, Zaire

Week 7: Food and Social Organization

Food is incredibly important when considering the social organization of primates, because food is essential to living: depending on the temporal availability and spacial distribution of resources, which affects the ease of getting those resources, different social organizations will be favored. Essentially, food = survival, so primates need to function in groups that will favor and benefit their ability to get food.

Below: a spider monkey eating

Anthro Spider Monkey Eating

With a more specific group, this becomes increasingly necessary – pregnant females and lactating mothers must not only receive the regular amount of calories to support themselves, but an additional portion of nutrients in order to support their children. The most calorically taxing time for a mother is when she is lactating, so having access to food at that time is necessary for the survival of both mother and child. This is why some species are seen having a concentrated number of births at a certain time of the year – it is generally correlated with the seasonality of food. Additionally, when a female has a diet that provides her a healthy amount of nutrition, her general reproductive success is improved. Therefore, females have an even stronger needs to ensure that their structure of their society offers them maximum feeding benefits.

In the article “Fission-Fusion Social Organization in Ateles and Pan“, Symington draws on the behavioral similarities and genetic differences of spider monkeys and chimpanzees as an example of how species who are distantly related can function with very similar social organizations.

Below: a spider monkey

Anthro Spider Monkey

Below: chimpanzees

Anthro Chimpanzee

As Symington points out, these two species are in fact “as distantly related as is possible within the nonhuman anthropoid primates”, making their similarities even more striking. Specifically, both of these primates live in fission-fusion societies. Individuals travel in “subgroups”, and the members of these groups can change extremely often. This is a unique feature to the spider monkeys and chimpanzees – other primates, such as hamadryas and gelada baboons, also function in fission-fusion societies, but their parties are comparatively rigid in their structure. The members of these subgroups do, however, come from a structured larger group (sort of like a community).

This similarity in lifestyle is a result of the comparable ecological pressures that these primates face. When the ecological environment is similar, that means that the availability of food resources is similar. The power that food availability can have on a species is evident when considering the differences between chimpanzees and bonobos.

Below: bonobos

Anthro Bonobo

The hypothesis for why bonobos are a much more cohesive and peaceful society than chimpanzees is that bonobos did not face the competition for food resources that their closest relative, chimps, did. While chimpanzees were struggling with gorillas to compete with, bonobos were existing in, comparatively, a much better lifestyle. Keeping this example in mind, it becomes evident why ecology and its effect on food resources ultimately changes the social structure so much.

Strier also discusses spider monkeys and chimpanzees, and describes how they are unique in their adherence to a high quality diet, whereas most other primates fluctuate the types of food they most eat based on what is available in that season. This is why females in spider monkey and chimpanzee social groups do not establish strong positions or relationships – they are more successful on their own than competing with others. It is therefore always important to consider primates on more than one level, meaning that people can never rely solely on the genetic closeness of primates or a similarity in  behavior to compare two species. Primates are much more complex than that, and there are a large amount of factors that need to be discussed in order to understand what the life of a primate species is like.

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