The pygmy marmoset, natively found in the western Amazon Basin in South America, is the smallest primate and monkey in the world, weighing just more than 3.5 ounces (about 100 grams). It has a short lifespan (for monkeys) of 12 years. These monkeys are known to fall out of trees, and this factor is what leads to their often interrupted lifespan. A Goeldi’s marmoset has an even shorter life expectancy at 10 years, while a Philippine tarsier can live as little as 2 years and as long as 12.