# Interspecies Sexual Behavior Observed in Ethiopian Bull and Donkey Researchers document a consistent, selective social bond between two different animal species. - **Source:** [Popular Science](https://www.popsci.com) - **Published:** 2026-11-02 - **Topic:** [Business](https://brifing.si/c/business) - **Original article:** - **On Brifing:** https://brifing.si/s/070fd32e-2b7d-4339-a814-180c1a8d1a08 ## Documenting Interspecies Sexual Interactions A study published in Current Biology details the unique relationship between a bull named Achille and a male donkey named Patroclo. Observed on an Ethiopian plateau, this pair engaged in repeated sexual interactions despite having access to potential partners of their own species and opposite sexes within the same pasture environment. ## Consistent Social Bonding Patterns Researchers from Università di Pisa noted that these interactions were not isolated incidents but part of a selective social bond. The animals exhibited various affiliative behaviors, including licking, rubbing, and nuzzling, which suggests that the sexual mounting was integrated into a broader, consistent social relationship between the two distinct individuals. ## Observation of Mounting Frequency Between March 6 and March 19, the research team recorded 51 instances of mounting behavior between the bull and the donkey. Patroclo, the donkey, actively participated by presenting his hindquarters to the bull and nipping at him, showing no defensive reactions or attempts to avoid the bull's persistent sexual advances. ## Absence of Alternative Mating Constraints The study emphasizes that these behaviors occurred in an environment where both animals had ample access to other potential mates. When Achille attempted to mount another male donkey, that individual displayed clear avoidance and aggression, highlighting that the specific bond between Achille and Patroclo was highly selective and mutually accepted. ## Evolutionary Biology Research Context Elisabetta Palagi and her team at UNIPI argue that this case challenges traditional views on animal sexual behavior. By moving beyond simple reproductive explanations, the findings suggest that sexual interactions in nonhuman species can function as complex social traits, potentially serving purposes related to tension reduction or long-term relationship maintenance. ## Comparative Behavioral Analysis Previous research on nonhuman primates has shown that same-sex mounting can act as a mechanism for conflict resolution and bond strengthening. The researchers are now investigating whether similar evolutionary benefits apply to this interspecies pair, aiming to understand how behavioral flexibility allows animals to navigate their complex social environments. ## Implications for Future Studies This case serves as a starting point for broader inquiries into how social relationships shape sexual behavior across different species. Future research will need to determine the specific functions of these interactions, such as whether they provide tangible benefits to the individuals involved or simply facilitate group cohesion within the pasture. ## Redefining Social Trait Complexity The observation of Achille and Patroclo underscores that sexual behavior in animals is often more nuanced than strictly reproductive biology suggests. By documenting this unusual union, the study invites scientists to reconsider the role of sexual interactions in maintaining social structures and the adaptability of animals in diverse environments. ## Sources covering this story - https://www.popsci.com/environment/bull-male-donkey-same-sex-relationship/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._