Zookeepers finally crack the mysterious case of an isolated gibbon's pregnancy

It’s a classic “who’s the dad?” drama—except this time, it’s happening at a zoo. When Momo the gibbon gave birth two years ago at the Kujukushima Zoo & Botanical Garden, zookeepers were stunned. Momo lived alone in her enclosure, separated by not one, but two barriers from the other gibbons. Yet, somehow, she became pregnant. After two years of detective work, the mystery has finally been solved: the father is Itoh, a 34-year-old agile gibbon. Move over, Maury Povich—this is gibbon gold.

Momo’s pregnancy baffled zoo staff from the start. How could she have conceived when she was kept apart from the other gibbons? To complicate matters, Momo was fiercely protective of her baby, making it nearly impossible for zookeepers to collect DNA samples. After years of careful attempts, the team was finally able to gather DNA from Momo’s son. They analyzed it against four potential fathers living nearby, and the results were undeniable: Itoh was the dad.

Turns out, love—or at least biology—finds a way, even in the most improbable of circumstances.

The mystery of how the gibbons at Kujukushima Zoo & Botanical Garden managed to mate had zookeepers stumped until DNA testing revealed the truth. According to a report by CNN, it appears that the two primates had connected through a small, nine-millimeter perforated board that separates the male, Itoh, and the female, Momo when they rotate out of the exhibition area in the morning and afternoon. Mating is a process that gibbons take seriously. They are incredibly picky when it comes to choosing a partner, selecting based on appearance, social behavior and vocalizations. Itoh must have gone through quite a process to attract Momo's attention, which is why the staff was so shocked to learn what had happened.

Now that the full family picture has come into view, the zoo is slowly working on having Itoh join Momo and her son. It will take some time for them to get used to each other, but hopefully, they can soon live together as one family.

To ensure that there are no more surprise pregnancies, the staff has replaced the perforated board with a partition that has no openings. They are also monitoring the gibbons more closely and providing enriching activities to keep them entertained. While it is unfortunate that Momo and Itoh will no longer be able to mate, the staff is happy that the mystery of Momo's pregnancy has been solved and that the two will soon be reunited.

Editor's note: This article was originally published on February 22, 2023. It has since been updated.