Zookeepers were stumped when a female gibbon got pregnant while alone in her cage. 2 years later they say there was a tiny hole that she and a neighboring male used to copulate through.

• Momo, a white-handed gibbon, got mysteriously pregnant at a zoo in Japan in 2021.
• Momo was so protective of the baby it took years to identify the father, a zoo official told Vice.
• The species typically mates for life so the zoo is moving Momo in with Itoh, the father.

Zookeepers at a zoo in Japan were stumped when a female white-handed gibbon named Momo got pregnant in 2021, even though she had her habitat all to herself. Two years later, the zoo said it wasn't an immaculate conception after all, but the result of a small loophole, so to speak.