In 2011, 72 male lab beagles stepped into the sunshine for the first time.
Now we're tearing up over retired lab chimps doing the same.
This January, a National Institute of Health report recommended the retirement of 401 of the government's 451 lap chimps.
Some have already arrived — and were introduced to the wide open sky for the first time.
Watch their moving reactions to the great outdoors below.
According to the Chimp Haven blog, "Once the chimpanzees are retired to Chimp Haven, our employees do everything possible to ensure their health and happiness throughout the rest of their lives. Chimpanzees are incorporated into larger social groups which allow them to choose who to interact with. They are also provided access to a variety of outdoor areas including forested habitats, play yards, courtyards and jungle gyms. Every chimpanzee has the choice to spend their time outside or inside. It is also wonderful to see chimpanzees experience grass for the first time and even climb trees!"