Spider Monkey

Spider monkeys (Genus Ateles) live in rainforests throughout South America. They have long arms, 25% longer than their legs, and prehensile tails that function as fifth limbs for swinging/climbing. Their arms are so long that they don’t actually know what to do with them when on the forest floor. The absence of thumbs in this species, resulting in a four-fingered hand, helps with brachiation. If rainforests disappear in 1,000 years due to deforestation, Spider monkeys would need more terrestrial/semi-terrestrial adaptations. Their arms would become shorter and their bodies would adjust for walking. Social group size, currently reaching up to 100, may decrease to reduce predation risk in more open habitats. As climates grow hotter and drier, lighter fur could help reflect heat and larger noses would aid in cooling and moisture regulation. Dietary patterns would likely change from predominantly fruit to more opportunistic feeding.