Apes are some of humanity’s closest living relatives. Found across Africa and Southeast Asia, their complex behaviors and familial bonds offer a window into sophisticated animal societies. Understanding what defines an ape is the first step in appreciating their place in the natural world.
What Distinguishes Apes from Monkeys?
One of the most straightforward ways to distinguish an ape from a monkey is the absence of a tail. Apes do not have tails, a feature that evolved due to a mutation in the TBXT gene. In contrast, most monkeys possess tails, which they use for balance as they navigate through trees.
Body size and skeletal structure also set apes apart. Apes are larger and heavier than most monkeys, with broad chests and highly flexible shoulder joints. This anatomy is adapted for brachiation, a form of locomotion where they swing from branch to branch, which gives them a more upright posture. Most monkeys, in contrast, run along the tops of branches rather than swinging below them.
The way apes move on the ground also differs. Many great apes, such as gorillas and chimpanzees, practice knuckle-walking by supporting their weight on their knuckles. Lesser apes, like gibbons, are highly arboreal but can walk bipedally when on the ground.
Beyond physical traits, apes possess a larger brain-to-body size ratio than monkeys. This increased brain size is linked to complex problem-solving skills, tool use, and sophisticated social behaviors. These cognitive functions are considered more advanced than those of monkeys.
The Two Families of Apes
The superfamily Hominoidea, which includes all apes, is divided into two families: lesser apes and great apes. The lesser apes (family Hylobatidae) include gibbons and siamangs, all native to Asia. These primates are characterized by their smaller body size compared to great apes and their long arms, adapted for an arboreal lifestyle.
Gibbons are masters of brachiation, using their ball-and-socket wrist joints to swing through the forest canopy. They live in smaller social groups than great apes and are known for their loud calls. The largest lesser ape, the siamang, can weigh up to 14 kg (31 lbs), and their diet consists mainly of fruit, leaves, and insects.
The second family, Hominidae, consists of the great apes: orangutans, gorillas, chimpanzees, bonobos, and humans. These species are found in Africa and Southeast Asia and are distinguished by their larger size. For instance, the smallest great ape, the bonobo, weighs between 34 to 60 kg (75 to 132 lbs).
Orangutans are the largest tree-dwelling animals, while gorillas are the largest of all primates and are primarily terrestrial. Chimpanzees and bonobos are the most closely related to humans, sharing a significant portion of our DNA.
Cognitive Abilities and Social Structures
The cognitive abilities of apes are evident in their widespread use of tools. Chimpanzees, for example, use sticks to “fish” for termites, stones to crack nuts, and leaves as sponges to soak up water. This behavior is not instinctual but is learned by observing other members of their group, demonstrating cultural transmission.
Communication among apes is complex, involving vocalizations, facial expressions, and body language to convey information. Beyond their natural communication, some apes in research settings have learned human sign language, highlighting their capacity for symbolic communication.
Apes are adept problem-solvers, capable of understanding cause and effect and devising solutions to challenges. In experimental settings, they have shown the ability to solve puzzles to obtain a reward.
The social lives of apes are intricate. They live in social hierarchies where relationships, alliances, and family bonds shape their daily interactions. Individuals can form coalitions to challenge the social order, and family units, particularly the bond between a mother and her offspring, can last a lifetime.
Conservation Status and Threats
The survival of most ape species is under threat. According to the International Union for Conservation of Nature (IUCN), most great ape species are classified as Endangered or Critically Endangered. This status means they face a high risk of extinction in the wild.
The primary driver of their decline is habitat loss. Forests in Africa and Asia are cleared for agriculture, logging, and human settlement, shrinking the territory available for apes. This deforestation fragments ape populations, which isolates them and reduces their genetic diversity, making them more vulnerable to other threats.
Poaching for the bushmeat trade poses another danger. Apes are hunted for their meat, and infants are often captured for the illegal pet trade after their mothers are killed. This practice has greatly reduced populations of gorillas, chimpanzees, and orangutans.
Finally, apes are susceptible to human diseases. Due to our close genetic relationship, pathogens that cause illnesses like Ebola, measles, and respiratory infections in humans can be transmitted to ape populations. As human settlements expand closer to ape habitats, the risk of disease transmission increases.