Kirki's colobus: They died in zoos until their strange secret was revealed (9 photos)

Kirk's colobus is a medium-sized monkey (10-12 kilograms) native to the forests of Zanzibar, an island archipelago off the east coast of Africa. The monkey was described as early as the mid-19th century, and scientific expeditions documented its lifestyle in considerable detail. Therefore, in the mid-20th century, several zoos decided to add colobus monkeys to their collections.





Hello, I'm here to see you...



I'd rather just sit on the roof and watch the sun rise, instead of playing these human games...

But all their attempts ended in disaster. Absolutely all of the colobus monkeys eventually died from digestive problems, despite receiving a standard primate diet of fruit, greens, and a little meat. Naturally, such a mysterious and massive death couldn't help but attract the attention of scientists.





If you're a herbivore, why do you have such fangs?

They turned their attention to Kirk's colobus monkeys with renewed interest and realized that their knowledge of the monkeys' diet was, to put it mildly, incomplete.



People, your strange diet has already turned my hair gray...

Yes, colobus monkeys do eat fruits and greens, but with two important nuances. To survive in competition with other monkeys, they have greatly distorted their tastes, so they eat green fruits and poisonous leaves that not even every caterpillar can eat.



And I value withered leaves more than fresh bananas!

And to digest all this filth, they transformed their stomachs into a complex four-chambered organ, more reminiscent of a cow's. They also acquired several extremely beneficial symbiotic bacteria and an advanced liver that effectively breaks down phytotoxins.



Yes, they eat bark too. The only primates who do.

But in exchange, colobus monkeys lost something important: the ability to digest sugars. It didn't disappear completely, of course, but it diminished so much that they can only digest tiny amounts of sugar obtained from breaking down leaves and green fruits. And that's precisely why colobus monkeys died en masse in zoos: they were fed juicy, sweet fruits, which are worse than poison for them.



"Slightly toxic, tough leaves are the ideal diet for any primate," Kirk's colobus tells us.

However, their relationship with poisons is also complex. Despite their excellent resistance to toxins, colobus monkeys don't hesitate to eat dirt, nibble on ashes from a fire, or even bite into coal. The benefits of this pastime are obvious: charcoal (or even soil) acts as an adsorbent, trapping toxins in the gastrointestinal tract and preventing them from entering the bloodstream. Activated charcoal works on the same principle.



Bon appétit, coal eaters!

And we suspect that monkeys acquired this habit from humans. It's impossible to prove this directly, of course, but we have indirect evidence. For example, monkeys living near human habitation regularly raid stoves and fires, and the primate population density near coal outcrops is several times higher than the average for their habitat. But they're clearly not suited to such close quarters: in these areas, intraspecific aggression is higher and the birth rate is lower.



If there's no coal or ash nearby, no problem—they can always be replaced with clay.

And even despite this knowledge, you won't find a colobus monkey in a zoo today—their dietary needs are too specific, and it's too difficult to meet them. Therefore, these animals still live exclusively in the wild, where they know what they need to eat and in what order!