Life in a cage was all they had ever known

Animal behaviorist Linda Koebner has made the rehabilitation of wild animals — those used as research subjects, for instance — her life's mission. It all began 25 years ago when Linda was still a graduate student and was asked to participate in a pioneering project to help a small group of chimpanzees adjust to life outside a hepatitis research lab, the only existence they had known.

Chimpanzees share 98.8% of their DNA with humans, making them our closest relatives in the animal kingdom. For that reason, they have been used extensively as research subjects, from developing and testing vaccines to preparing space missions. It isn't simply their DNA that binds them to us. They also exhibit similar social bonding behaviors and experience the same feelings of joy and sadness that we do.

America's public broadcaster, PBS, filmed a documentary about their story for their Wisdom of the Wild series. Here is an excerpt which features the emotional reunion:

It's therefore all the more regrettable that, for many years, chimpanzees used as test subjects often didn't survive, and those that "retired" from research facilities usually faced the rest of their lives in cages.

Thanks to Linda's work, however, that all began to change in 1974.

Linda introduced a group of nine chimps to life outside the research lab, helping them to adjust to freedom over a period of four years. Their new home was America's first drive-through safari park: Lion Country Safari in Loxahatchee, Florida. The animals lived in their own open habitat, separated from park visitors by a moat, allowing them to enjoy the peaceful and dignified retirement they deserved.

Returning them to the wild really wasn't an option since they had either been captured at a young age or born in captivity and raised in cages. Nonetheless, adjustment to any kind of existence outside a cage was a big one. On the big day of the initial "release," Linda watched with delight as the timid animals smelled fresh grass for the first time and were able to move about freely.

She cared for any animals who were sick and spent the rest of her time healing psychological wounds. It was a massive undertaking to help them make the transition to a life of relative freedom.

But eventually, Linda had to say goodbye to the chimps she had grown so close to. The animals had learned to live as independently as possible. Even though it was very difficult for her, Linda left the chimps and went on to her next project, satisfied in the knowledge that the new colony of former research animals she had started had been a remarkable success.