The rainforest is only one of the many habitats that baboons inhabit. The only animal that occupies more ecological niches than baboons is humans, and baboons aren't far behind. If something wipes humanity off the globe, these intelligent and clever animals could well take our place as the dominant primate.
All five true baboons belong to the genus Papio, but the Big Four of baboon species are the yellow, olive, chacma and Guinea, known collectively as savanna baboons. All of these can, and do, live in any area, and on any available edibles, on the African continent, including tropical rainforest. The fifth, the hamadryas, has taken itself more or less out of the group by limiting its territory to the rocky deserts of the Middle East, with no accessible rainforests, but they can, and do, interbreed with all the others wherever their territories converge, so they're still part of the baboon gene pool.
Several other species are commonly referred to as baboons, but they're really not. The gelada monkey (Theropithecus gelada) of no-rainforest Ethiopia is a genus that diverged from the baboon line several thousand years ago. The mandrill (Mandrillus sphinx) and the drill (Mandrillus leucophaeus) are closely related to the baboon but have been separated into their own genus; they live exclusively in tropical rainforests. The "baboons" of the rainforests of Belize in South America are actually black howler monkeys (Alouatta pigra) -- "baboon" is just what they're called in the local language.
Baboons react to a new environment the way Clint Eastwood and the U.S. marines do: "You adapt. You overcome. You improvise." Shirley Strum's Pumphouse Gang, a troop of olive baboons, did exactly that when they had to be moved far away from their home range in order to save their lives from humans. Individual baboons, curious adolescent males, went exploring and brought back information and communicated it to the troop when they rejoined it at night. This showed that baboons, like humans, practice group thinking (not GroupThink or hive mind, which are the exact opposite). Even though baboons evolved as creatures of the open savanna, with this attitude a tropical rainforest is exploitable territory for them.
Home, Sweet Home
Baboons require two basic things to survive: a water supply and a high place to sleep safe from predators. Other than that, they can make do. The tropical rainforest supplies both and is also rich in food, so they moved in. Some, like the Guinea baboons, liked it so much that they stayed, but the others left Eden and moved on to explore and colonize the Great Unknown, just like human pioneers. The only thing that keeps them off the polar icecaps is that they haven't quite figured out how to do what humans have done: wear clothes.
- African Wildlife Foundation: Baboon
- Animal Diversity Web: Papio (Baboons)
- IMDb: Heartbreak Ridge (1986)
- New York Times: Chronicles of the Pumphouse Gang
- Animal Planet: Ask the Baboon Experts
- Science 2.0:The Genius of the Beast; Who’s Smarter: Chimps, Baboons or Bacteria? The Power Of Group IQ ( Part I ); Howard Bloom
- The New York Times Sunday Review: The Rise of the New Groupthink
- National Geographic: Swarm Theory
- Anup Shah/Digital Vision/Getty Images