Overview
- Researchers used a 2020 simian retrovirus Type II outbreak at a southern Texas primate sanctuary as a natural experiment to compare three exposed macaque groups with one unexposed group.
- In controlled trials the team offered 55 Japanese macaques a choice between food on a clean surface and food placed on real macaque feces sealed under clear epoxy to preserve visual cues while removing smell and infection risk.
- Monkeys from outbreak-exposed groups accepted the contaminated-looking food in 47 percent of trials compared with 79 percent for macaques from the unexposed group, and this pattern held whether or not individual animals had been infected.
- A separate test of 54 macaques across seven species found that animals raised as pets by humans were more likely to eat contaminated-looking food than those born and raised by macaque mothers, implicating early social learning.
- The authors interpret the results as evidence that social experience can shape a primate’s behavioral immune responses but note limits of the natural-experiment design and call for follow-up work on social transmission, persistence, and conservation implications.