Bull and donkey studied for social bonding in Ethiopia

Biologists from the Università di Pisa observed a bull and a donkey stud and engaged in sexual behavior as part of a social bond in Ethiopia.

The researchers spent two weeks monitoring the animals, whom they named Achilles and Patroklos after figures from Homer’s Iliad. During this period, the bull mounted the donkey 51 times. The donkey did not show any signs of distress or defensive reactions during these encounters.

The team noted that the animals also engaged in other intimate behaviors, including licking, rubbing, and cuddling. The researchers stated that the animals had access to other potential mates of both sexes, meaning the behavior was not caused by a lack of other options. While the bull showed aggression toward other males, the donkey remained passive during its interactions with the bull. Elisabetta Palagi and her team suggest that sexual behavior can serve social functions beyond reproduction.

The researchers believe the interactions between the two animals may help maintain their social connection. The study aims to help scientists understand the evolutionary origins of cross-species homosexuality. The two animals were separated in March 2026 due to a lack of grass, but the team hopes to reunite them to see if they resume their previous behaviors.