We used to believe that emotions such as love, pain, and gratitude can only be felt by humans. But decades of research have proven that that is not true.
For example, chimpanzees—who share 98.8% of our DNA—can also experience these things as strongly as we do.
This story showing the incredible bond between humans and chimps may have happened many years ago, but it still tugs at people’s hearts to this day.

One January morning in 1974, a group of chimpanzees was set to be freed from their cold, steel cages and brought into the world outside.
These animals hadn’t seen sunlight for six years because they were used as guinea pigs for hepatitis research. Scientists have already found the vaccine, which meant certain chimps weren’t needed in the laboratory anymore.
They were to be released into a sanctuary in southern Florida to enjoy the freedom they’ve never experienced before.
While this was great news, there was one problem: they were too afraid to come out.
Linda Koebner, an animal behaviorist who was a 23-year-old graduate student at the time, was their caretaker.
“They were terrified to get out of the security of their transport cage,” she said in a segment from the 1999 documentary “The Wisdom of the Wild.”
“Whether it was afraid to step on the grass, they hadn’t been on anything but hard bars for years, or just the feel of the wind and the sun. They just huddled in the doorways and wouldn’t come out.”

But eventually, she was able to ease their fears and convinced them to step onto the grass.
“Over time we coaxed them, and Doll was right up the tree.” Koebner said. “But some of the others had never tasted any kind of freedom since they were infants riding on their mother’s back, and they had been in these little boxes for years and years.”
She then spent the next four years teaching a female named Swing, a young male named Sparky, and six-year-old Doll how to fend for themselves.
She watched over them every day and became their source of comfort whenever they needed assurance. As it was a unique experiment, nobody knew how the animals would respond to being out in the open again.
Koebner loved every minute spent with the chimps, but she had to move on eventually.

Two decades later, she had the chance to visit the chimps who have remained. In the documentary, Koebner is seen taking a boat over a small body of water to where the animals live.
As she got close to the other side, Swing comes to greet her. Uncertain if the chimps would recognize her, Koebner asked them, “Do you remember me?”
And as if to answer “yes,” Swing reaches out a hand to Koebner and shows her a huge smile. It was clear that the sweet chimp still remembered her!
Overcome with emotion, Koebner began to cry, and seeing that she looked upset, Swing promptly gave her a hug.
Suddenly, another chimp, Doll, comes over excitedly to greet her. She hugged her too, and the two chimps made noises as if they were crying themselves.
The pair clearly missed their former caretaker, who spent so much time making sure they were safe during their release many years ago.

“Chimpanzees have provided us so much in this world,” Koebner says in the documentary. “So much knowledge about ourselves, about our social lives, about our dispositions, because they are so much like us as beings.”
Incredibly, over 30 chimps have found refuge in the sanctuary in southern Florida. Inspired by their story, Koebner later founded the non-profit chimpanzee sanctuary “Chimp Haven” in Louisiana in 1995.
“These chimpanzees have taught me about resilience.” she said. “All of them have gone through such tremendous adversity, and yet they’re forgiving and they’re whole again.”
Watch their heartwarming reunion in the video below.