Primates represent a diverse order of mammals, encompassing species from small lemurs to large apes. Understanding their precise classification can sometimes be complex. This article aims to clarify why gibbons are considered apes and how they fit into the broader primate family.
Gibbons: Definitely Apes
Gibbons are apes, not monkeys. They belong to the family Hylobatidae, which includes around 20 species, such as the lar gibbon and the siamang. Often referred to as “lesser apes,” gibbons are distinguished from “great apes” (chimpanzees, gorillas, orangutans, and humans) primarily by their smaller size and anatomical differences. Despite their smaller stature, their shared evolutionary history and defining characteristics firmly establish them as members of the ape superfamily.
Key Characteristics of Apes
Apes, including gibbons, share several defining characteristics that distinguish them from monkeys. Apes do not possess tails, unlike most monkeys. They generally have a larger brain size relative to their body size and exhibit more complex cognitive abilities. Their skeletal structure features broader chests and shoulder joints designed for a wide range of motion. This anatomy supports their characteristic locomotion methods, which include brachiation (swinging through trees) and a more upright posture, allowing for bipedal movement on the ground.
Unique Traits of Gibbons
Gibbons possess distinct traits that make them unique even among apes, though these characteristics still align with their ape classification. They are renowned for their exceptional brachiating ability, moving with remarkable speed and agility through the forest canopy by swinging their long arms. They can cover distances up to 15 meters in a single swing and reach speeds of up to 55 kilometers per hour. Gibbons are smaller than great apes, with the largest species, the siamang, weighing up to 14 kilograms, while the smallest great ape, the bonobo, weighs significantly more.
Gibbons typically live in small, monogamous family groups consisting of a mated pair and their offspring. They are also known for their loud, complex vocalizations, often referred to as “songs.” These elaborate duets, frequently performed by both males and females, serve important functions like marking territorial boundaries and reinforcing pair bonds.
Gibbons’ Place in the Primate Family
Within the broader primate family, gibbons are members of the superfamily Hominoidea, which includes all apes. This superfamily is divided into two main families: Hylobatidae (gibbons, or lesser apes) and Hominidae (great apes: orangutans, gorillas, chimpanzees, bonobos, and humans). Gibbons diverged from the lineage leading to great apes approximately 16.8 million years ago.
Their classification as lesser apes highlights their smaller body size and certain behavioral differences compared to the larger great apes. Genetic and morphological evidence consistently places gibbons firmly within the ape group, separate from monkeys.