LINCOLN PARK — For her first 16 years, Bana, a western lowland gorilla at Lincoln Park Zoo, never got a chance to play on an experimental touch screen computer in the primate enclosure.
That all changed several weeks ago after the birth of her child, Patty, improved her standing in the zoo's gorilla troop, and Bana finally was allowed by the other females in the group to use the computer.
Bana, 17, has begun taking a puzzle challenge, which asks gorillas to tap symbols on the screen. If they tap them in a correct order, they are rewarded with a treat, such as a piece of fruit. The symbols remain the same each time, but appear in different locations on the screen.
Earlier this month, in just her second attempt ever working with two symbols, Bana correctly chose the right pattern 80 percent of the time. That had researchers at the zoo giddy.
"Even from yesterday, she went from 60 [percent] to 80. That's very good," said Frank Sladek, of the zoo's education department.
Bana, though, is not yet as advanced as Kwan, a 22-year-old silverback gorilla, who takes the test daily at about 1:30 p.m. His record, so far, is correctly identifying the order of seven symbols.
Scientists at the zoo's Regenstein Center for African Apes hope Patty doesn't wait as long to take to the interactive 42-inch screen.
Sladek said scientists hope Patty starts to work on the puzzle at a young age and one day surpasses all other gorillas at the zoo. The hope is she will be the youngest gorilla in history to work on the test.
"When you see the animals put the objects in an order, that gives us some kind of understanding of how they perceive physical and spatial location," said Steve Ross, director of the Lester E. Fisher Center for the Study and Conservation of Apes.
Lincoln Park Zoo is the only institution in the world to use the test on gorillas and has achieved significant success. Other zoos around the country use the test for chimpanzees, who are the closest living relatives to humans.
Rollie, a now 16-year-old gorilla, was one of the first at the zoo to try the puzzle and the speed at which she completed it astounded scientists. She just had a baby in November.
"The science community kind of scoffed at us, but our gorilla Rollie totally smoked the fastest chimp's time," said Tiffany Ruddle, a spokeswoman for the zoo.