Jim's fiance was always so sweet and bipedal. Then one day he found her scurrying along on all fours, as if nothing was even wrong.
Change in Diet:One of the earliest symptoms is a change in diet. If someone close to you is at risk for becoming a marmoset, you may notice them eating a lot of frogs, lizards, flowers, fruit and tree sap. If you suspect that someone you know might be a marmoset, surprise them with flowers. Do they put it in water right away? Or do they start nibbling?
Appearance: Take a good look at your suspected marmoset friend. The changes are subtle, but unmistakeable if you know what you're looking for. Has the person in question lost weight recently? Is this person approximately the size of a rat and less than a pound? Is (s)he furry, with black eyes and a snout-like nose? Marmosets are also often very stinky creatures. Have you noticed a signature stench? If these symptoms sound familiar, marmosism is a definite possibility.
She didn't want to be rude, but his penchant for playing with his feces wasn't helping any.
Behaviour: Marmosets are mostly arboreal, meaning they keep to the trees, and they don't talk much, using a series of shrieks and howls instead. You may not notice this right away however, as modern day society is enough to make anyone want to take a last stand atop the highest tree, and shriek their protest against the insanity and torment of today's world. You bastards! You'll never break me! I'm sorry, I just needed to rant.
Unshaven rebels.
That's how it always starts, they start hanging with a furrier crowd, and before you know it, they're missing class, their eyes are bloodshot, and the only thing that matters is their next hit. Desperate for the sugar high, tearing away tree bark to get at the sweet sap within. Don't you know you're destroying your family?!
It's true. Even marmosets can live a full and happy life. Except for dental hygiene. There's nothing to be done for that.