When a young couple went on a tour through the Bukit Lawang jungle in Indonesia, they knew they might get close to orangutans—they just didn't know how close.
Walking through the densely wooded jungle, the group was surprised when an orangutan used both hands to reach for a woman's wrist and pull her onto the ground. A young juvenile, likely the orangutan's offspring, hung onto the mother.
The woman, unsure of how to proceed, crouched on the ground gently trying to pry open the orangutan's fingers. Eventually, after being incentivized with food, the orangutan released the woman's hand and walked off with the youngster.
WATCH: CLINGY ORANGUTAN GETS TOO CLOSE FOR COMFORT
In an email with National Geographic, the couple noted that tour guides believe the orangutan may have mistaken the woman to be guide and thus carrying fruit.
The footage prompts questions of whether orangutans, which are among our closest evolutionary cousins, are typically this friendly around people.
Not quite, says orangutan behaviour expert and National Geographic grantee Cheryl Knot. Based on the orangutan's behaviour and the group's proximity to a rehabilitation centre, she believes the animal was possibly a once-captive orangutan that was rehabilitated to live in the wild.
"It's hard to interpret without knowing the orangutan, but these rehabilitants are bonded to people," Knot says. "She's making contact to hold her hand, seeking some sort of social contact."
The fact that the orangutan was close to the ground, Knot adds, also indicates a possible stint in an orangutan centre. In the wild, orangutans travel primarily in trees.
"These rehabilitated orangutans are kind of in limbo" when they return to the wild, Knot says. In centres, they often form strong bonds with people, especially if they were raised by humans from an early age.
Knot and her research team tread lightly around wild orangutans, which don't feel as comfortable around people. Wild orangutans vocalise to warn an approaching animal when they have wandered uncomfortably close. Researchers in the field also avoid more subtle forms of communication with wild orangutans, such as making eye contact.
Whether tour groups should be allowed close access to wild orangutans is a subject of debate. For instance, the Sumatran orangutans in Indonesia are classified as critically endangered by the International Union for the Conservation of Nature.
Destruction of their habitat is one of the most significant threats. Hundreds of square miles of their natural habitat has been cleared for large-scale palm oil production. Orangutans also face threats from those who seek to keep them as pets illegally.