Baraka, a four-hundred-pound silverback gorilla, couldn’t take his eyesoff the twelve-year-old Calaya when she arrived at the National Zoo, inWashington, from Seattle. He already had two females in his family, but“he was very taken by Calaya from the get-go,” Becky Malinsky, the zoo’sassistant curator of primates, told me. “She was in quarantine forthirty days, but he had visual access. He wanted to look at her all day.They were smitten from the beginning.”
Within an hour of being allowed in the same room, they mated.The match was no accident.It was years in the making—the result of a complex algorithm for pairinggorillas that may be more reliable than dating Web sites for humans. It’s certainly more detailed.
The dating site for gorillas is now a key to survival of a speciesofficially considered to be critically endangered. Over the past twodecades, between sixty and seventy per cent of western lowlandgorillas have been wiped out. The Ebola epidemic is estimated tohave killed about a third of the population—tens of thousands—in the wild. Across central Africa’s Congo Basin, the greater danger is humans hunting gorillas for bushmeat and as trophies. Despiteanti-poaching laws, thousands of gorillas are killed each year, even inprotected reserves and national parks, because of limited resources forenforcement. Expanded logging and oil-palm plantations have increasinglydestroyed their natural habitats.
The initial algorithm was developed in the late nineteen-eighties—sevenyears before its human counterpart—as part of the Gorilla SpeciesSurvival Plan launched by theWashington-based Association of Zoos andAquariums.It’s been regularly refined ever since. Its calculations are based onage, experience, socialization skills, lineage, genetics, and,especially, personal chemistry.
“It’s a lot of science and a lot of personality,” Kristen Lukas, thechair of the gorilla-survival plan and the director of conservation andscience at the Cleveland Metroparks Zoo, told me. Zoologists know whenit works. “Gorillas can make guttural love vocalization that would makeyou blush,” she said.
Baraka and Calaya were a good match because he is laid-back andattentive to his troop, the name for a gorilla family. She is confident,quirky, and creative, Malinsky, the curator at the National Zoo, told me.As we watched the gorillas in the zoo’s Great Ape House, Calaya lay onher back atop a thin fire hose stretched high between tree limbs. Sheweighs over a hundred and fifty pounds, and the flattened hose was onlya few inches wide. “She’s a pro at balancing,” Malinsky said. Calayadoesn’t like to step on the ground—one of her quirks—so the zoo hasarranged milk cartons for her to sit or step on. She’s particularlyimaginative in incorporating blankets—as many as she can gather—into hernests. (Gorillas make new ones daily.) As Calaya slept on the high-wirehose, Baraka knuckle-walked with muscular agility among the exhibit’srooms every few minutes, to check on Calaya and the rest of his troop.He also kept an eye on two bachelor gorillas in an exhibit nearby.
The gorilla-matchmaking algorithm ranks potential mates on a scale fromone to six. One is the best pairing: the mates’ genes are rarer, sotheir offspring would enrich gorilla diversity. Gorillas with commongenes pull lower scores—and the survival plan may recommend that theynever breed. Females can still join a family, but they are often puton birth-control pills toprevent them from having babies, Lukas said. A human committee—pulledfrom more than fifty North American zoos—hasa “studbook” with pages of scientificdata and personality traits on each gorilla for the matchmakingdeliberations.
Baraka and Calaya got a one on the survival plan’s matchmaking scale.The other two females in Baraka’s harem, Mandara and Kibibi, are now notrecommended for breeding. Mandara has already had six babies; she is nowon birth control, which is crushed up and fed to her every morning inyogurt or a banana. (The St. Louis Zoo runs a reproductive-managementcenter oncontraception for all North American zoos.) Kibibi, third female, age nine, tends to outperform the National Zoo’s other five gorillasin cognitive research tests. But she won’t be allowed to breed withBaraka, either. They’re a poor genetic match.
Both in the wild and captivity, the majority of male gorillas do nothave families—and do not breed. Gorillas are a polygamous species. Atroop usually consists of one adult silverback—named for the thicksilver hair running from their conical heads, down their broad backs, totheir narrow torsos—with two to four females. They live with theiroffspring until the young are old enough, in their teens, to leave theirnatal group. Because of the social structure, however, two-thirds ofmale gorillas do not have mates, since more dominant males keep themaway from females.
“They never get the chance—just do the numbers,” Malinsky told me.“There are not enough females.” The males end up in bachelor groups,some with bonds as deep as a heterosexual troop. So the Gorilla SpeciesSurvival Plan also uses an algorithm to pair males whom biologists hopewill be good companions, too. “The first consideration is always what’sbest for the individual gorilla,” Lukas said.
For years, the Cleveland zoo had two males living together in a bachelordyad. Mokolo was a Type A prone to exhibit dominance daily; Bebac was achilled-out Type B who deferred to his roommate, Malinsky said. WhenBebac died lastyear, of heart disease, the zoo looked for new companions for Mokolothrough the studbook. It identified Fredrika—mature, confident, andhard to rattle—who lived at Zoo Miami, and Kebi Moya, a female who hadlong lived among large troops, at the zoo in Columbus, Ohio. InSeptember, both arrived in Cleveland to join Mokolo.
“We weren’t looking to breed. Fredrika was too old and Kebi had healthproblems,” Lukas told me. Mokolo also has heart disease. “We justwanted to give them all companionship.”
But Mokolo hadn’t been anywhere near a female for more than two decades.The two females bonded immediately. “They were cool. They didbeautifully,” Lukas recalled. But she was worried about what Mokolowould do. Males are almost twice as large as females; they have largecanines that can seriously injure.
“I’ll never forget what he looked like,” Lukas said. “Mokolo could smellthem. Suddenly, he puffed up. It was nervousness mixed with prowess—‘Ihope to impress these ladies.’ He tried to appear as big as possible,but his eyes were darting back and forth—like, ‘Oh, my God. Oh, my God.What do I do now?’ You could feel the tangible experience that Fredrikabrought to the table. She knew how to respond. If he got too close, shewould bark. For Kebi, it was her first time being with a new male. Overtime, they became more and more cohesive.” Mokolo mated with thefemales, but not for breeding.
“It was all about giving them companionship,” Lukas explained. “The guyhad been so used to his buddy.”
Do gorillas make love connections? “So many of us could tell you storiesof very special connections,” Lukas recalled. In one recent encounter,she said, Fredrika and Mokolo had sex face-to-face, which is rare amongnonhuman species. “At one point, she leaned up and put her lips to hischest, then she came down and they completed,” she said. “Was that akiss? Probably not. You’re a scientist and supposed to be observing. Butthere certainly was some tenderness.”
The instant attraction between Calaya and Baraka has stuck. After shearrived in Washington, in 2015, she was kept on birth control until lastyear, when she fully acclimated to all members of the troop. After shewas taken off the pill, she soon became pregnant. Calaya and Baraka areexpecting their first baby next month.
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