Star enjoys a moment in the sun at the Chimp Haven sanctuary in Keithville, La. Brandon Wade/AP Images for The Humane Society of the United States and Chimp Haven hide caption

itoggle caption Brandon Wade/AP Images for The Humane Society of the United States and Chimp Haven

Humans and chimpanzees — like this individual at a zoo in Australia — are animals who have evolved to forge extensive and elaborate social connections. Lisa Maree Williams/Getty Images hide caption

itoggle caption Lisa Maree Williams/Getty Images

Chimpanzee Toni celebrated his 50th birthday at the Hellabrunn Zoo in Munich on Nov. 22, 2011. Sven Hoppe/DPA/Landov hide caption

itoggle caption Sven Hoppe/DPA/Landov

Two chimps groom each other at the Save the Chimps facility in Florida. The National Institutes of Health owns about 360 chimpanzees that aren't yet retired and that are living at research facilities; new guidelines say most of its chimps should be retired. Save the Chimps hide caption

itoggle caption Save the Chimps

Rufus, 46, now lives on an island in a Florida sanctuary run by Save the Chimps. Before his rescue, Rufus lived in a facility Save the Chimps calls "the dungeon." Courtesy of Save the Chimps hide caption

itoggle caption Courtesy of Save the Chimps

Chimpanzees check out a termite mound at the Chimp Haven sanctuary in Louisiana. Chimp Haven hide caption

itoggle caption Chimp Haven

Federally funded chimps at the New Iberia Research Center in Louisiana will retire to either a lab in Texas or a chimp sanctuary in Louisiana. Courtesy of the Humane Society of the United States hide caption

itoggle caption Courtesy of the Humane Society of the United States