The hidden chemicals affecting primates’ hormones
In many of the world’s rainforests, human activities threaten the survival of our closest living relatives: primates. Some of these activities, such as deforestation and hunting, are well documented and heavily criticised, while others, such as the output of chemical pollution, remain largely hidden. At Indiana University Bloomington in the US, Dr Michael D. Wasserman, head of the Primate Environmental Endocrinology Lab (PEEL), is investigating how chemicals in the environment, including pollutants such as pesticides and flame retardants, impact the survival of primates.
Talk like a primatologist
Cortisol — a steroid hormone, produced in greater quantities in response to stress or danger, that increases blood sugar levels, boosts metabolism and suppresses other body systems, such as the immune system, to direct energy towards immediate survival
Endocrine system — a network of glands that acts as a communication system using hormones to gear the cells and tissues of the body towards collective goals including growth and development, reproduction, survival and metabolism
Endocrinology — the study of the endocrine system in humans or other animals
Flame retardant — a chemical, often applied to consumer goods, that reduces the risk of fire
Forest fragmentation — the fracturing of large areas of continuous forest into smaller patches separated by farmland, roads and other anthropogenic (human-created) features
Hormones — chemical messengers, released by glands of the endocrine system, that are sent to cells, tissues and organs via the bloodstream to regulate biological processes and behaviours
Phytoestrogen — a compound that occurs naturally in some plants and resembles the hormone oestrogen
Primates — the order of mammals including apes (humans are a type of ape), monkeys, lemurs, bushbabies, lorises and tarsiers
From wide-eyed bushbabies and ring-tailed lemurs to giant silverback gorillas and our closest living relatives – chimpanzees and bonobos – primates are a diverse and charismatic group of mammals. As primates ourselves, we humans have always had a soft spot for our furry, forest-dwelling cousins. However, despite our affections and shared ancestry, many of our fellow primates are under threat from the far-reaching impacts of human activity.
“Primates are facing an extinction crisis driven by increasing human population and resource consumption,” says Dr Michael D. Wasserman from Indiana University Bloomington. “Specific threats include climate change, invasive species, infectious diseases, habitat loss, forest fragmentation, hunting and pollution.” Untangling and responding to this complex web of threats is no easy task, and requires a multi-faceted approach.
“Conservation efforts attempt to mitigate these threats through education, policy, management and research,” says Michael. However, mitigation can be difficult when the threats are hard to spot and their impacts are less dramatic than the crashing of felled trees or the smoking remains left in the wake of a forest fire. For example, chemical pollutants in the environment may not directly kill primates, but they can severely hamper their long-term survival and reproductive capabilities. Michael and his team at the Primate Environmental Endocrinology Lab (PEEL) are studying how both naturally-occurring and anthropogenic chemicals affect the endocrine systems of primates in tropical forests.
The endocrine system
The body’s endocrine system is driven by hormones, chemical messengers that influence how different parts of the body function. “The endocrine system is one of the main ways that cells, tissues and organs communicate with each other within an animal’s body,” says Michael. “It plays major roles in growth, development, reproduction and survival.” For instance, the hormone cortisol is released in response to a perceived threat (like a predator) to increase blood glucose levels, thus providing energy to immediately deal with the threat. Other hormones play a role in longer-term processes. Oestrogen, for example, develops and regulates the reproductive system.
When the signal of these hormones is disrupted, it can mean bad news for bodily functions. “Endocrine disruption can affect growth and development trajectories, lower reproductive success or even reduce survival,” says Michael. Especially when primate populations are small, reduced fertility or premature death of even a few individuals can present severe dangers for the survival of the species.
Natural and polluting chemicals
The endocrine system can be influenced by the environment, both through naturally-occurring substances and those introduced by humans. Previously, Michael has studied a group of chemicals called phytoestrogens, which occur naturally in some plants and closely resemble oestrogen hormones. “Phytoestrogens can bind to oestrogen receptors inside primate cells, affecting their physiology and behaviour,” explains Michael. Yasmin Lord, a PhD student working at PEEL, is aiming to build off Michael’s research by examining phytoestrogens in the diet of the mantled howler monkey in Costa Rica.
The team at PEEL are also investigating the impacts of artificial chemicals, in particular those found in pesticides and flame retardants. “Because these chemicals are applied to crops or consumer goods worldwide, they frequently find their way into natural ecosystems,” says Michael. “Some of these chemicals can be harmful to primates through direct toxic effects or through more subtle endocrine disruption.”
Research in the field
Investigating the effects of endocrine disruptors on primates involves going out into the forests where these primates live to collect samples and data. “We follow groups of primates, keeping a record of what they eat and collecting samples of the plants in their diet to analyse for phytoestrogens,” explains Michael. “We also collect faecal samples, which we analyse for levels of pollutants and hormones to assess the effects of ingested chemicals on the endocrine system.” These analyses are conducted by scientists back in the lab, such as Dr Marta Venier, an environmental chemist, also at Indiana University Bloomington.
This work takes Michael and the PEEL team to tropical forest field sites in places like Kibale National Park in Uganda and La Selva Research Station in Costa Rica, both places that are well known for their primate populations. As well as assessing endocrine disruptors, the researchers at PEEL study how other aspects of human activity affect these animals. “We also study the effects of research, tourism, agricultural practices and environmental policies on primate diversity, abundance and physiology,” says Michael. “In particular, we assess their stress levels by measuring levels of cortisol in faecal samples.”
Understanding how all of these human activities, from chemical pollution to eco-tourism and environmental policy, impact primates is vital to the conservation efforts that aim to protect these animals.
From research to conservation
PEEL’s findings provide valuable information that helps inform efforts to conserve primate species as effectively as possible. “Our goal is to provide insight into overlooked factors influencing primate conservation, ecology and evolution,” says Michael. “It’s surprising how little research has focused on the effects of pollution on wild primates.”
PEEL is now expanding its work to new areas in India, led by PhD students Diganta Mandal and Elizabeth Coggeshall, and in Madagascar, led by Maire O’Malley, another of Michael’s PhD students. “We are also expanding our examination of the potential effects of chemical exposure beyond hormones, to areas such as the gut microbiome and biological ageing, through new collaborations,” says Michael.
Dr Michael D. Wasserman
Associate Professor, Department of Anthropology
Director, Human Biology Program
Principal Investigator, Primate Environmental Endocrinology Lab (PEEL)
Indiana University Bloomington, USA
Fields of research: Primatology, conservation biology, environmental endocrinology
Research project: Studying how chemicals in the environment affect the endocrine systems of wild primates
Funders: US National Science Foundation (NSF), Indiana University
About primatology
Primatology involves studying the relationships between primates and their environment, and ways to ensure that these relationships are not negatively impacted by human activities. Michael explains more about this area:
“Conducting fieldwork in the tropics is highly rewarding. It provides opportunities to experience new species and landscapes, explore intriguing scientific questions, and build relationships with a diverse range of cultures, communities and individuals. It’s a constant exploration of new ideas and experiences. However, such endeavours take a lot of energy, and it can be challenging to balance international research with family life.
“Collaboration is essential to research in primatology. This includes collaborating with international scientists with different areas of expertise, as well as communities that share their local ecological knowledge and allow you to visit their forests, homes and farms. Many members of our team are from communities neighbouring the forests where we work, including our project manager in Uganda, Richard Mutegeki.
“Science is often incorrectly perceived as dry and reductionist; however, there is a lot of creativity in science. Coming up with interesting, novel questions drives productive science. Being an effective scientist requires a combination of many different skills: organisation, management, logic, communication and creativity. That’s what makes it such an exciting career!
“Although there are many threats to biodiversity today, I see reasons to be hopeful. We know what we need to do to tackle climate change and other environmental threats. With young people being so concerned about these issues and dedicated to careers focused on solving them, we will soon turn the corner on both the biodiversity and climate crises.”
Reference
https://doi.org/10.33424/FUTURUM534
Maire stands above the Onive River in Tsinjoarivo, Madagascar, with rice fields and forest patches dispersed throughout the landscape.
© Kaia Wasserman.
Pathway from school to primatology
At school and college, useful subjects include biology, chemistry, mathematics and geography. If available, psychology, environmental science and social science can also be useful. At university level, Michael suggests studying biology, anthropology or environmental science.
Michael recommends seeking out independent research opportunities at school or university, and participating in a study abroad programme. Work in primatology usually involves international travel to field sites, so it’s important to learn whether you enjoy this style of work.
To learn more about primatology, Michael recommends reading Karen Strier’s Primate Behavioural Ecology, Noel Rowe’s The Pictorial Guide to the Living Primates and Ian Redmond’s The Primate Family Tree. He also notes the Planet Earth documentary series and other BBC Earth series as visually stunning introductions to primate behaviour.
Explore careers in primatology
Michael suggests visiting Primate Info Net, hosted by the Wisconsin National Primate Research Center, to find relevant resources, media and opportunities.
Indiana University Bloomington offers the NSF Research Experience for Undergraduates, enabling undergraduates to work on individual research projects in animal behaviour over the summer.
Michael notes the International Primatological Society and the American Society of Primatologists as two important organisations that hold a wide array of resources surrounding education, networking and opportunities in primatology.
Salaries within primatology vary widely, depending on sector and expertise. According to Salary.com, the average ecologist salary in the US is around $71k.
Meet Michael
From an early age I wanted to be a biologist. Early snorkelling experiences inspired me to be a marine biologist, but after studying tropical forest ecology and conservation in Costa Rica during my undergraduate programme, my interests moved towards primates and terrestrial landscapes.
My undergraduate degree was at the University of Florida. The study abroad course in Monteverde, Costa Rica, really started my career. When I returned to Florida the next semester, I immediately got involved with the Chapman Fish and Monkey research lab, which worked on primate and fish ecology and conservation in Uganda. They funded my first trip to Uganda in 2003, and I’ve been working there ever since – over 20 years now!
The first time visiting a new place is always special. Your eyes are wide open to new species, landscapes and questions. My first trip to Uganda, to study how forest fragmentation influenced food availability, parasite load, faecal cortisol and red colobus monkey abundance, remains my most memorable.
For this career, it’s important to be dedicated, hard-working, persistent and adaptable. It’s also worthwhile to be a good listener and respect everyone you interact and work with. Everyone has something to teach you. I have had many role models at various stages along my career path, both professional and personal. They have taught me important lessons about science, academic careers and life in general.
To unwind from work, my favourite thing to do is spend time with my family. This includes playing basketball and football (soccer in the US), gardening, trying new foods and travelling.
Michael’s top tip
While it’s important to be practical when choosing a career, it’s just as important to find something you are passionate about. The career you pick will determine much of your life, so pick something you love.
Meet Marta
Dr Marta Venier runs the environmental chemistry lab that analyses PEEL samples.
In my lab, we analyse contaminants in the air, faeces and plant samples collected during PEEL research trips. We employ state-of-the-art technology and equipment, including gas and liquid chromatography coupled with mass spectrometry to identify contaminants.
Dr Wasserman and I met in a serendipitous way, and we immediately realised that we had common research interests and that our expertise and experiences were complementary. Working together allows us to be exposed to each other’s research fields and keep our minds open.
Being persistent (like the chemicals that I measure!) has helped me in my career, especially during my graduate studies. My passion for environmental chemistry was instilled by Professor Ron Hites, who was also a great academic role model. His door was always open for students and no question was ever perceived as dull or not smart.
New chemicals are constantly being introduced into the market to satisfy industry and consumer needs. This means analytical and environmental chemists are always busy. By tracking the presence of chemicals in the environment and common products, I hope that my work provides useful information both for regulators, when they need to enact new laws, and for consumers, who can make informed choices when shopping.
Marta’s top tips
1. The best path forward is one that allows you to follow your passion. When you’re armed with passion, the energy will allow you to overcome the difficulties and problems you will inevitably encounter.
2. Environmental chemistry is an applied discipline where you can apply your knowledge for solving problems and make a real impact anywhere in the world.
Meet Richard
Richard Mutegeki is the project manager for the PEEL project at Kibale National Park, Uganda.
My role involves a lot of planning, co-ordinating and budgeting. I must also ensure that our project operates within the local rules and regulations and maintain good relationships with the local authorities.
Working with wildlife and people has been a goal for me since childhood, so this role is a dream come true. Working in this position has helped me build a rich network of individuals in the field of environmental conservation. These people have continuously encouraged my professional development and helped me raise funds for my further education and training.
We need to do everything we can to save the remaining primate species. I hope to train as many people as I can, imparting my knowledge of conservation and further broadening the project’s network of collaborators.
Richard’s top tip
Choose a path that will allow you to influence decisions that may help solve or mitigate global problems like climate change, biodiversity loss and pollution.
Meet Elizabeth
Elizabeth M.C. Coggeshall is a PhD candidate studying the mother-infant relationships of Himalayan langur monkeys at Kedarnath Wildlife Sanctuary, India.
My research involves exploring how mother langurs buffer stress for their babies in stressful environments. My days consist of following the langurs and collecting behavioural and faecal samples to investigate their responses to stress. We wake up at dawn and follow the troop through forests and agricultural fields until they reach their sleeping site in the evening.
My biggest challenges come from living in and adapting to a new country and culture. As a woman working and travelling independently, this can be difficult. The most important characteristic to build is perseverance. The more you learn, the more you realise how little you know and that your success is only defined by you, no matter what others say.
I hope to help preserve populations of primates that are on the front lines of anthropogenically driven environmental change. This means studying and conserving the often-forgotten populations outside of protected spaces.
Elizabeth’s top tips
1. Don’t compare yourself to others. Take your time and follow your own path.
2. You don’t have to go to college to be successful. If you’re not sure of a set path, consider community college, trade schools, etc.
3. Don’t just go through the process of memorisation and regurgitation; challenge your mind and be prepared to learn more than you thought was possible.
Meet Diganta
Diganta Mandal is a PhD student studying population distributions of Himalayan langur monkeys and the effects of endocrine disruptors at Kedarnath Wildlife Sanctuary, India.
Working in Himalayan weather can be extremely challenging, and conducting research in high-altitude areas with limited resources and connectivity is difficult. However, these challenges come with their advantages, as they connect me to nature and bring me closer to the people around me. The local communities hold more knowledge about the Himalayas than any other source of knowledge, and learning about their experiences, daily lives and languages pushes me to explore more.
During my time in India, I have directed a short film about the coexistence of the Himalayan langurs and the people of the Himalayas. I have also helped to train local people about our scientific work and made people aware of the importance of conservation, especially young children.
While studies of our closest relatives, primates, reveal the history of humankind and its evolution, they also reflect the future. I believe in a holistic approach towards conservation, as the intricate relationships between all species, including humans, are delicate, and once broken, could fall like dominoes. This simple concept is the motivation behind my work.
Diganta’s top tips
1. Perseverance is the key to success, and success has many forms.
2. Choose a path that connects your interests with your abilities.
3. Finding fun in the work you do makes it more enjoyable.
Meet Yasmin
Yasmin Lord is a PhD student studying reproductive success and phytoestrogen consumption among mantled howler monkey groups in Costa Rica.
Conducting research in the rainforest can be both challenging and rewarding. The heat and the active wildlife can be overwhelming, but the peaceful green canopy, beautiful views and extraordinary relationships you build with the community and fellow researchers are unforgettable.
Being a Black woman studying bioanthropology is not always easy. I have had to be resilient, but my relationships with the professors and friends that believe in me, such as Dr Andrea Wiley, Dr Wasserman and Elizabeth Coggeshall, have helped massively. Talking to the people who believe in you and sharing your experiences with them can help immensely.
Feeling and seeing the mental and physical damage of being a coloured woman in STEM made me want to do more. I began mentoring young Black women in STEM fields to help them find their voice and assist them in being the best in what they want to do. Meeting, mentoring and motivating these young women has helped me find my own voice and allowed me to recognise my own strength.
My great grandmother is my greatest motivator. When I was a child, we would go to the zoo together, and the primates were always my favourite. Before her passing, I had the opportunity to go to Costa Rica with Dr Wasserman and study primates in the rainforest. I was terrified, but she encouraged me saying, “What an extraordinary adventure – don’t be afraid of your own greatness. How do you know if you don’t try?” So, I went – and that trip changed me.
Yasmin’s top tips
1. Make sure you chose something that you want to do; not your parents or teachers.
2. No one knows you better than you know yourself. You can do it, so long as you apply yourself and keep trying.
3. Keep those that support you close and listen to what they have to say. Sometimes you need someone on the outside to remind you who you are on the inside.
Meet Maire
Maire O’Malley is a PhD student studying the behaviour and diets of lemurs in Tsinjoarivo, Madagascar.
My fieldwork consists of daily lemur observations where I record their every behaviour for an extended period of time and collect samples of the plants they eat. Once fieldwork is completed, the lab work begins back in the US, which consists of analysing the nutritional content of each plant consumed by the lemurs.
One challenging aspect of fieldwork is the isolation from family and friends back home. However, it’s an honour to be surrounded by a supportive local community and to collaborate with them to facilitate conservation management plans to protect lemurs.
Before graduate school, I had a few internships at zoos around the US which solidified my interest in primatology research and gave me insight into how influential research can be for the protection of animals. Conserving and studying primates is beneficial to you and me, to global biodiversity, and to environmental health.
Maire’s top tips
1. Try new things and be open to different possibilities. You never know where you might end up!
2. In academia and primatology, you often get rejected, so the ability to not give up is really valuable.
Do you have a question for Michael or his team?
Write it in the comments box below and they will get back to you. (Remember, researchers are very busy people, so you may have to wait a few days.)
Learn more about forest ecosystems in Costa Rica:
www.futurumcareers.com/how-do-hurricanes-impact-forest-ecosystems
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