Ann Arbor Times

The immune performance of wild capuchin monkeys in Costa Rica is affected by rising temperatures, according to a study conducted by the University of Michigan. The research highlights that younger monkeys are particularly susceptible to heat.

Jordan Lucore, a doctoral student in anthropology at U-M, led the study which found that two weeks of warmer temperatures—around 86 degrees Fahrenheit—resulted in decreased generalized immune system performance in these primates. This part of the immune system responds immediately when the body detects a threat.

Lucore commented on the findings: “We think this has implications for understanding the effects of climate change because we’re seeing this unlikely relationship between the immune system and temperature in this particular study species, and we’re seeing it at much lower temperatures than expected,” adding that “Eighty six degrees Fahrenheit is not that hot.”

Published in Science Advances, these results were unexpected as endothermic animals like mammals are generally believed to maintain their body temperature despite environmental changes. The study focused on white-faced capuchins within Costa Rica's Taboga forest reserve, part of the Capuchinos de Taboga Research Project initiated in 2017. This project explores various aspects such as cognition and behavior of these primates and is co-directed by Jacinta Beehner and Thore Bergman from U-M, along with Marcela Benítez from Emory University.

“Capuchins are thought of as generalist species because they live in a lot of different places with different climates and diverse ecologies. They’re successful generalists,” Lucore said. “That was another concerning thing about the results: I can’t believe we’re seeing this in capuchins. They are quite resilient.”

Typically invasive methods are used to study immune systems through blood serum biomarkers; however, Lucore utilized neopterin levels measured non-invasively through urine samples collected using a "clean catch" method.

The research indicated that young monkeys showed more significant declines in immune performance due to high temperatures compared to other age groups. Lucore noted: “We discovered that young individuals’ immune systems may be particularly affected by temperature compared to the rest of the age groups.” This is crucial since young animals rely heavily on their generalized immune system while their adaptive immunity develops over time.

Long-term health impacts remain uncertain, requiring further studies across multiple generations to determine if reduced immune function leads to poorer health or reproductive outcomes among wild animals. While direct human applications may be limited, insights into how climate change affects wildlife physiology could be valuable.

“Climate change is happening. It’s going to have effects on anyone living on Earth in ways that you may not expect, and especially on these fundamental systems that we need to survive,” Lucore stated.

Key contributions came from field team members Amy White, Lorena Sinclair, Vasco Alexandre Martins, Sarah Kovalaskas, Juan Carlos Ordoñez; analysis support was provided by Andrew Marshall from U-M’s departments of anthropology and ecology & evolutionary biology.