While both belong to the Primate family, monkeys and apes are distinctly different from one another. Millions of years ago, familial ancestors to both groups were identical, but evolution led to divisions within the family. They are both physically and evolutionarily separate, with clear distinctions apparent between them.
Primates are divided into two groups, prosimians and anthropoids. The prosimian group includes lemurs and tarsiers, and is considered the more primitive group. Anthropoids are further divided into three groups: monkeys, apes, and hominids, including humans.
The monkey subgroup contains over 200 different species of monkey, including baboons, tamarins, macaques, and capuchins. It is also divided into geographical groups, with Old World monkeys inhabiting Africa and Asia, and New World monkeys living throughout Central and South America. Apes are also divided, but along terms of size. Gorillas, chimpanzees, bonobos, and orangutans are called “greater apes” because of their large body size, while gibbons and siamangs are often referred to as “lesser apes.”
While both monkeys and apes share certain physical features, such as forward-facing eyes and flexible limbs, there are several physical differences between the two groups. No ape species possesses a tail, while monkeys do. Monkeys are much more used to life in trees than apes, and use their tail as a fifth limb. Additionally, monkeys are not capable of using their arms to swing between branches, as apes can. Having a tail makes monkeys ideally suited for life in the treetops, while apes seem to have evolved to live comfortably on the ground or in trees.
With the exception of the gibbon, apes are considerably larger than monkeys. They have broad backs and arms that are longer than their legs. Most monkeys feature chests that a longer than they are broad, and have an arm-length equal to or shorter than their legs.
The greatest differences between these primates are believed to lie in intelligence levels. Monkeys are far more similar to the primitive prosimians in brain capacity and capabilities. Apes are closer to their human counterparts, able to learn forms of sign language, use tools, and display problem solving skills. It is believed that apes, particularly chimpanzees, gorillas, and orangutans, are much more similar to humans than they are to monkeys. Some ape species carry a 98% genetic match with humans, while monkeys are considerably less similar.
Monkeys and apes are clearly different, despite common terminology often using the words as interchangeable. One thing both share in common, however, is a high level of endangerment and extinction threats. These animals have survived for millions of years and through considerable threats to their environments. People who would like to help protect them should contact a reputable conservation agency and ask about their efforts to prevent harm from being done to our closest animal cousins.