When we arrived at the monkey forest today, we were greeted with the most exciting news:
A baby Barbary macaque! We spent a bit of time watching the others follow mom and her new baby around before we headed off to start the long day of data collection.
I hope to write more on why babies are so important in Barbary macaques soon (edit: I have now done so here), but for now, I just have time for this quick note. Check back soon for more on Barbary socioecology!
Today, I successfully collected data on my fortieth subject, which means I am halfway done with my data collection for my current project! I am happy to report that everything is going well so far. Additionally, I have been getting better at figuring out who my subjects are without the help of the staff.
Over the next few weeks, in addition to data collection for my own project, I also hope to focus more on getting photos of some of the babies and juveniles born since the lab’s last trip. The appearance and facial freckle pattern of the adults does not drastically change from year to year. However, in their first four years of life, the babies change drastically! Here is an example of the same monkey, three years apart:
As we hope to continue returning to the Trentham Monkey Forest, maintaining an accurate ‘Monkey Facebook’ can help our team during future data collection trips. In any case, I am looking forward to the next half of my trip and the remainder of my data collection! Thanks again for following along.
Today, we took the day off in celebration of Francesca’s birthday (and also because we had worked several 8-12hr workdays in a row and all needed a nice break).
While the day was full of all the typical birthday things (e.g. presents, candles, and ice cream cake), we also decided to check out a nearby national park known as the Peak District National Park.
We completed a trail to a geological formation known as ‘The Roaches’, The ridge looks over Leek, England. We learned the name refers not to the insect, but to the French word for rocks (les roches). Though a short hike (only 505m), the top provided a beautiful lookout over Leek and the surrounding farms.
We had a great afternoon taking in the countryside, but we are all looking forward to getting back to data collection tomorrow!
Many times, I’ve been asked by family and friends what exactly it is that I do when I am working with the monkeys. Generally, I respond that I show the monkeys something and then see how they respond. While this is technically true, it is not very specific.
While my research falls into a lot of different categories (developmental psychology, comparative cognition, social cognition, etc.), put simply, I am really interested in what monkeys know about what others know or can see. This ability is called ‘theory of mind’, and it refers to the way that we are able to think about other people’s perceptions, emotional states, beliefs, knowledge (or ignorance), desires, and perspectives [1]. Humans do this every day, all the time. We can think about what other people are thinking when we are talking with them and when we are talking about them, when we are thinking about them, looking at them, etc. If you are chatting with someone and then suddenly they begin to frown, you might infer that something you said made them sad. Similarly, if you are talking with someone and suddenly their gaze shifts to something behind you, you will likely turn around (an aside: this latter ability is called ‘gaze following’ and is so cool that I hope to cover it separately at some point, more on gaze following later..)
Anyways, after decades of work by my adviser and some of her past students, we generally believe that rhesus monkeys, while able to do visual [2] and auditory [3] perspective taking, are not doing ‘theory of mind’ the same way that humans are (the details of this are complicated, but if you are interested, see [4]). Put simply, it does not seem like rhesus macaques can represent events that differ from the current state of the world. A quick example might make this more clear.
Imagine that you are sitting in a room with two of your family members — your mom and sibling. Your mom is cleaning, and your sibling is reading a book, but then gets up to grab something from the other room and leaves the book on the coffee table. While they are gone, you mom accidentally puts the book back on the shelf. When your sibling comes back, where do you think they would look for the book?
For us, this should be easy to figure out: your sibling left the book on the coffee table, so they should look for the book on the table because they didn’t know that your mom moved the book to the shelf since they were out of the room. Even a more simplified version of this task is not so simple for a monkey. In an experiment from 2011, they failed to form expectations about where the person should look for the hidden object [5].
However, as aforementioned, rhesus macaques do seem capable of using another person’s visual perspective. Further, they can use this visual perspective to form an expectation about where the person should search for an object [5]. Because recent studies in different species of macaques show differences in their social cognition [6], I am interested in whether Barbary macaques will form expectations about how a person should act (like rhesus macaques), or will show a different pattern of behavior.
To do this, I sit about a meter away from the Barbary macaques (see the first picture above) and show them a series of actions on a stage. A second person sits directly behind me and films a close-up video of the monkey’s face.
Later, we remove all of the information relevant to the study, and have someone who is blind to the study hypothesis watch all the videos back and code when they think the monkey is looking at the experimental setup. Finally, we compare average looking in the different experimental conditions to see whether or not Barbary macaques generally expect people to act consistently with their visual perspectives.
I will keep you updated with the results with the study as soon as I know, but this can sometimes take months! Let me know in the comments (or contact me directly) if you have any other questions or want to know more about anything I wrote about here. Thanks for following along so far and I hope to update you again soon.
[1] Frith, C., & Frith, U. (2005). Theory of mind. Current Biology, 15(17), R644-R645.
[2] Flombaum, J. I., & Santos, L. R. (2005). Rhesus monkeys attribute perceptions to others. Current Biology, 15(5), 447-452.
[3] Santos, L. R., Nissen, A. G., & Ferrugia, J. A. (2006). Rhesus monkeys, Macaca mulatta, know what others can and cannot hear. Animal Behaviour, 71(5), 1175-1181.
[4] Martin, A., & Santos, L. R. (2016). What cognitive representations support primate theory of mind?. Trends in Cognitive Sciences, 20(5), 375-382.
[5] Marticorena, D. C., Ruiz, A. M., Mukerji, C., Goddu, A., & Santos, L. R. (2011). Monkeys represent others’ knowledge but not their beliefs. Developmental Science, 14(6), 1406-1416.
[6] Rosati, A. G., & Santos, L. R. (2017). Tolerant Barbary macaques maintain juvenile levels of social attention in old age, but despotic rhesus macaques do not. Animal Behaviour, 130, 199-207.
Today, I finished my first week collecting data at the Trentham Monkey Forest. I am hoping to make another post later about the town we are living in (Kingsley, Stoke-on-Trent, England), on the monkey park (Trentham Monkey Forest) that we are working in, and the species that we are working with (Barbary macaque), but for now, a quick recap on the last week!
We arrived at the park first thing on Monday (7 May 2018) morning to meet with the director of the park. He was super friendly and helpful. We went over the rules of the park, met with some of the staff, and then finally headed through the front gate to meet the monkeys first hand!
As I mentioned in an earlier post, Trentham Monkey Forest is home to 140 Barbary macaques. Unlike some of the other field sites that I have worked at in the past, these monkeys do not have easily visible tattoo IDs. This means that we have to learn all of the monkeys by sight — no easy task!
How do we tell all the monkeys apart? There are a few tricks that help us distinguish one monkey from another.
First, Barbary macaques live in large social groups, and they typically stay in these groups for their entire lives. Because the monkeys at Trentham Monkey Forest are allowed to live freely like they would in the wild, they too live in two large social groups. For us, the first step is generally to figure out what social group we are working in, so that we can narrow down the list of possible monkeys.
Next, we identify the sex of the monkey. Though the monkeys only exhibit very subtle sex differences after they go through sexual maturity (around 5/6 years old for females and 7/8 years old for males). I was really terrible at this when I first arrived, but got better over the week. Males are generally larger than females, have a larger build, and more pronounced canine teeth [1].
(A quick aside: It is pretty rare that we get a glimpse of the teeth as the monkeys only show them when they yawn. Monkeys will yawn when they are trying to warn another individual to stay away [2], so we have luckily not had any of those directed at us.)
Last but not least, adult female Barbary macaques have sex skin swellings which show individual differences: the swellings manifest as large, cushion-looking pads of skin on their butt [3]. They can be pink or deep blue/purple (or some combination of the two colors), and have different patterns and scars. While these help us distinguishing female versus male adults, they are not as pronounced in young Barbary macaques.
Once we know the group and the sex of the individual, we start to flip through our monkey ‘Facebook’. Every day we carry around tablets that have a folder of close-up monkey faces (like the images I shared above), and compare the monkeys sitting in front of us to the monkey face images that we have where we verified the individual identity with a staff member or the professor that we are working with. The monkeys have different patterns of freckles, moles, and scars on their faces, different nose and general face shapes, and different face and surround hair coloration patterns. To my surprise, with some practice, we have become pretty good at distinguishing one monkey from another. Each day is a little easier than the last!
Alright, well it is time for me to get back to working on the monkey Facebook. Check in again next week for more on the Barbary macaque and where I am living for the summer. Thanks for following along so far.
[1] Paul, A., Kuester, J., Timme, A., & Arnemann, J. (1993). The association between rank, mating effort, and reproductive success in male Barbary macaques (Macaca sylvanus). Primates, 34(4), 491-502.
[2] Deputte, B. L. (1994). Ethological study of yawning in primates. I. Quantitative analysis and study of causation in two species of Old World monkeys (Cercocebus albigena and Macaca fascicularis). Ethology, 98(3‐4), 221-245.
[3] Nunn, C. L. (1999). The evolution of exaggerated sexual swellings in primates and the graded-signal hypothesis. Animal Behaviour, 58(2), 229-246.
Today marks the beginning of what will be a 13-week summer of monkeys. My itinerary over the coming months includes a long trip to the United Kingdom, followed by some time in my favorite place in the entire world, and wraps up with a week in San Antonio, Texas. Let me explain.
Later this evening, I will debark on a flight to Heathrow International Airport, followed by a short train ride to Trentham, U.K. There, I will be conducting social cognitive research at the Trentham Monkey Forest, home to 140 Barbary macaques (Macaca sylvanus). Native to the Algerian Mountains, Barbary macaques are unique for a few reasons. First, they are the only macaque species known to reside outside of Asia. Similar to the other macaques, they are highly skilled at adapting to just about anywhere and can survive in a range of ecosystems including forests, grasslands, and of course, the mountainous regions of Algeria & Morocco. In addition, Barbary macaques engage in alloparenting, or cooperative care of the offspring by nondirect relatives [1]. Father macaques also help in caring for their own offspring. This is highly unusual among primates, and especially among macaques. Finally, the Barbary macaques are believed to be more tolerant than the species I typically study [2], the rhesus macaque (more on them below!). As such, the Barbary macaques provide a really neat study species for us to look at in comparison to other more despotic species to see how sociality influences cognition.
Following my extended stay in the United Kingdom, I will head to Punta Santiago, Puerto Rico. Punta Santiago, Puerto Rico is a small fishing village on the east coast of Puerto Rico. Of the last four years, I’ve lived in Punta Santiago collectively for about a year and a half and have come to deeply love the community there. Needless to say, I am really looking forward to going back.
Right off the coast is a small island called Cayo Santiago, and home to the Cayo Santiago Biological Field Station. There are over 1,200 rhesus macaques (Macaca mulatta) on the island, diverse in age, sex, and social status, giving us the unique opportunity to study social cognition in a free-living primate under naturalistic conditions. As aforementioned, rhesus macaques are despotic — they exhibit a strict linear dominance hierarchy where there is an alpha male and then a number of males that each rank a little bit lower than the last. Compared to many of the other macaques, and especially the Barbary macaques, they are aggressive and exhibit relatively low rates of reconciliatory behaviors [3]. Rhesus macaques are well studied — to date, we know a lot about their social cognition thanks to the work of the Comparative Cognition Lab at Yale and a number of other labs around the world that travel to Puerto Rico to study these monkeys [4]. More on the field site, Punta Santiago, my research, and Puerto Rico more generally later, but you will have to follow along for those updates!
My final destination for the summer is San Antonio, Texas, where I will be attending the 41st Meeting of the American Society for Primatologists. I’ve never been to Texas before, so I’m pretty excited to visit and I’m hoping I’ll have at least a little time to explore. If you have any recommendations for a day trip or dinner, please let me know!
Alright, well, I have a bit of writing to get to, but I hope that this provides some insight into my crazy life, and some relief to my friends and family who keep asking me to explain where I will be all summer. I’ll try to update this blog regularly with some details about my travel and information about my research. Stay tuned for more photos!
[1] Small, M. F. (1990). Alloparental behaviour in Barbary macaques, Macaca sylvanus. Animal Behaviour, 39(2), 297-306.
[2] Thierry, B. (2007). Unity in diversity: lessons from macaque societies. Evolutionary Anthropology: Issues, News, and Reviews, 16(6), 224-238.
[3] Waal, F., & Ren, R. (1988). Comparison of the reconciliation behavior of stumptail and rhesus macaques. Ethology, 78(2), 129-142.
[4] Drayton, L. A., & Santos, L. R. (2016). A decade of theory of mind research on Cayo Santiago: insights into rhesus macaque social cognition. American journal of primatology, 78(1), 106-116.
‘Dispatches from the Field’ is my blog that features a number of different types of posts including:
For more information about me and my own research, you can visit my website (alyssaarre.com), my google scholar page (here), or my twitter (here).
Please feel free to contact me if you want to share your research or field site, a cool citizen science or volunteer opportunity, or a feature on you and your work. My email is alyssa.arre (at) yale.edu
— Alyssa