By Juliette Berthier

At the end of 2018, my first paper as first author was published in a good peer-reviewed journal. As for many young researchers, this was a great event in my professional life and I celebrated this by opening a good bottle of champagne. The paper was the final result of a huge amount of work coupled with a substantial dose of uncertainty, but overcoming this challenge has given me great satisfaction and has reinforced my willingness to continue my career in research.
But in science, it happens sometimes that great discoveries are made thanks to a lucky encounter far from university offices, seminars or conferences. This is the case in this research story, which began in the tropical forest of the North Sulawesi Island in Indonesia during the summer of 2016. After a first Master’s degree in ethology and several years spent trying to find my way in academia by travelling and making many different research experiences, I had the opportunity to become involved in a very interesting research project as a volunteer research assistant in the field. Thus, I left my friends and family to spend six months in the remote rainforest of Indonesia with the aim of helping a PhD student from the University of Lincoln – Laura Martinez Inigo – with her data collection on wild crested macaques, a highly endangered primate species endemic to this small part of the world.
Around the end of my stay in this wet and luxuriant environment, while I was following my group of around 100 monkeys (who were quite lazy for once!), Laura asked me to go down to the main road of the reserve to pick up two of her friends who had come to visit for a few days. These two visitors came from France (like me) and it was so good to meet compatriots after several months far from home that we started chatting very quickly. One of these researchers – Dr Laetitia Marechal – is a former student of the Masters of Research (MRes) in Primate Biology, Behaviour and Conservation at the University of Roehampton. I didn’t know it at that time but this encounter determined the course that my life took for the next few years (and maybe for my whole career!) and was decisive in the achievement of the study that I will discuss shortly. I explained to Laetitia that I had been actively looking for a PhD bursary for more than two years, but that I was largely unsuccessful in my search. As she had experienced similar difficulties herself, and as we shared the same passion for the study of primates, she highly recommended the MRes at the University of Roehampton to me. I was only half-listening because I had other plans in mind at this point, but a few months later, after many unexpected developments and deep thoughts (ones you know are crucial for the rest of your life), I landed at London with only a small backpack, my faltering English and nowhere to live to start the MRes in Primate Biology, Behaviour and Conservation.
This course satisfied all my expectations but there quickly came the moment when I had to choose the topic of my personal research project that would count for 2/3 of my final grade. The choice was crucial but one thing was clear from the beginning: I wanted to study primate sociality. This was a good starting point but many options were still possible. Efficiently guided by my supervisor, Professor Stuart Semple, I quickly started to think that exploring the impacts of social interactions on bystanders – and more precisely interactions of social grooming, which is a key affiliative behaviour in many group-living species – could be a promising topic of research. The so-called “bystander effect” is not particularly well studied in non-human animals, and specifically in affiliative contexts. However, this phenomenon could potentially have many consequences on sociality of a huge number of social animals, mainly through the contagion of emotions and behaviours. After a proper review of the literature on the topic, I followed my instinct and the title of my research project turned out to be: Does observing grooming affect the behaviour and the emotional state of bystanders in non-human primates?At this stage, I had to find the place where I could conduct my project. This choice also determined the primate species that I ultimately observed during almost three months. My previous experience with several macaque species and a first visit to the wonderful tourist park of Trentham Monkey Forest in Staffordshire (Stoke-on-Trent) as part of the Master’s programme made the decision quite easy. The semi-free ranging Barbary macaques (Macaca sylvanus) at Trentham were chosen to be my study subjects.
After few more months dedicated to the implementation of the protocol, the acquisition of the equipment needed for my project and the writing of applications to obtain the appropriate permits and ethics approvals, I started my data collection in April 2017 in the cold, often windy, sometimes snowy, weather of the North of England. Unlike me (to my great despair), Barbary macaques are well adapted to this kind of climate as they naturally live in the Atlas and Rif Mountains of Morocco and Algeria where winters are very harsh. At this time of the year they have a thick winter coat, making them looking like fluffy teddy bears. My study required that all the adult females (the targets of my study) and preferably all the adult and sub-adult males of the group be individually identified. Thus, the first step of my data collection consisted of learning to recognise around 40 monkeys individually. Males are easier to identify than females for whom the easy way to differentiate them, at least at the beginning, is to look at their… bottoms. So I spent the first weeks of my stay observing and taking many pictures of my subjects. It was only when all the adult females had become familiar to me that I could start the data collection per se.
My method consisted of observing the behaviour of the monkeys when they witnessed a grooming interaction between two other group-mates (the testing condition) and comparing it with their behaviour recorded on another day but at around the same time while they have not been the bystander of any grooming interaction (the control condition). I mainly focused on the self-directed behaviours like scratching or self-grooming because they are good indicators of the anxiety level in many mammals, and thus reflect the emotional state of individuals. I also recorded all the socio-positive (including grooming) and aggressive behaviours expressed by my subjects as well as their spatial proximity to others.

These data were recorded opportunistically, that is to say when all the conditions (and there were a number) were suitable for my data collection. This made the task more difficult than it seems at first sight because it could become particularly frustrating when no grooming interactions occur for a long time, and monkeys spend their time feeding far from each other. Thus, at the beginning of my data collection, from April to mid-May, I walked several kilometres per day along the paths of the park, scrutinising the wood, hoping that somewhere a grooming interaction with one of my subjects as bystander would miraculously occur. Patience is probably the most important skill when conducting behavioural observation on animals. On the other hand, this unexpected situation gave me the opportunity to do some teaching by answering the questions of the tourists who came to learn about this highly endangered species. However, from mid-May to June, the weather became warmer and sunnier and the monkeys spent much more time grooming each other. Thus, I had many opportunities to record data for my testing condition. Good news! Yes, but at this time, recording the controls became an almost impossible task. This is a good illustration of the issues that researchers in the field often face. But at the end of my data collection period, I had a satisfactory amount of data to perform robust statistical analyses and to answer my research questions.
Statistical analysis is the part of the research process that could be the most annoying for people like me (for whom statistics are not much fun), but also the most exciting. It is at this stage that we know whether our intuition was good and if we made a significant discovery. After having spent so much time and energy implementing and conducting my study, I always feel a small peak of adrenaline before pressing the button that will tell whether results are statistically significant or not. In my case, after many hours spent in front of my computer screen trying to manage excel files and statistic software, I found that almost all my results were significant. Observing grooming seemed to reduce the anxiety level of bystanders, positively impact the rates of their friendly behaviours including grooming, and increase their tolerance to others’ proximity. I had good material to write not only a great Master’s thesis, but also an interesting publication that had a good chance to catch the scientific interest of many researchers not just in primatology, but also in animal behaviour in general.
In September 2017 I passed my Master’s degree with Distinction and I won the departmental prize for the best performance of the year. But this is not the end of the story because Stuart was convinced that this discovery deserved publication in a high-level journal. Considering my poor experience in this field, I let him take the reins and I learnt the publishing process at his side. Despite rejections from two high profile journals, I never felt discouraged. Our manuscript received valuable and encouraging feedback each time. Rejections are part of the publishing process and the best thing to do is to take advantage of the situation by using feedback to improve the manuscript. It is the main lesson I learnt from this experience and I sense that it will be a valuable skill for my future career. Finally, our tenacity paid off. In December 2018 my study was published in Proceedings of the Royal Society Bunder the title “Observing grooming promotes affiliation in Barbary macaques”. And, the icing on the cake, the topic was interesting enough for a more general audience and has been covered by the media in the UK as well as in France.
This is the end point of this great scientific adventure which started around two years earlier, maybe the most exiting of my professional career so far. Despite the obstacles to be overcome, I look forward for the next ones, during the PhD at the University of Kent that I am now undertaking!