A zookeeper at the Cincinnati Zoo recently spotted two bonobos playing in a way that human parents might recognize.

Zeke, a seven-year-old male, was seen playing "airplane" with a two-year-old bonobo named Bo (short for Bolingo).

Their keeper, Jeremy Phan, recorded a video that shows Bo balancing on Zeke's upright foot. At times, Zeke bobs his leg, bouncing Bo up and down. Zeke also reaches up and pats Bo on the back repeatedly.

"Zeke started tickling him," says Phan. You can't hear it on the video, but Phan says Bo was laughing. Their laughs are lower-pitched and breathier than that of humans. In some frames, Bo can be seen smiling with his lips pulled up and his gums exposed.

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