Apes, a group of primates, exhibit a remarkable diversity in size, particularly in body weight, across different species. Understanding these weight differences provides insight into their biology and adaptations.
How Much Do Different Apes Weigh?
The great apes include gorillas, orangutans, chimpanzees, and bonobos. Gorillas are the largest of all primates. Male gorillas can weigh between 136 to 227 kg (300 to 500 lbs), while females typically range from 68 to 113 kg (150 to 250 lbs). Eastern gorillas are larger than western species; adult male eastern gorillas can weigh up to 220 kg (484 lbs) and females up to 97.7 kg (215 lbs).
Orangutans also display significant sexual dimorphism. Adult male orangutans average around 75 kg (165 lbs), but can reach up to 136 kg (300 lbs), particularly dominant males with cheek pads. Females are smaller, usually weighing 37-54 kg (82-120 lbs).
Chimpanzees are more robust than bonobos. Male chimpanzees weigh between 40 to 70 kg (88 to 154 lbs), and females weigh between 27 to 50 kg (60 to 110 lbs). Bonobos, more slender, males weigh between 34 to 60 kg (75 to 132 lbs), with an average of 45 kg (99 lbs), and females average 26 to 36 kg (57 to 80 lbs). This makes bonobos the smallest of the great apes.
What Makes Ape Weights Vary?
Several factors contribute to the varied weights observed among ape species and even within a single species. Sex is a primary determinant, as males are consistently larger and heavier than females across all great ape species, a phenomenon known as sexual dimorphism. This difference is particularly pronounced in gorillas and orangutans.
Age also plays a role in an ape’s weight. Infants are born small; for example, newborn gorillas weigh about 1.8 to 2.3 kg (4 to 5 lbs). Their weight increases as they mature, reaching peak size in adulthood.
Diet and habitat influence an ape’s weight. Apes in the wild consume varying diets; for instance, gorillas eat fibrous vegetation, while chimpanzees rely on fruit. The availability and nutritional content of food directly affect their ability to gain and maintain weight.
Beyond these factors, individual variation exists among apes of the same species, sex, and age. Like humans, genetic predispositions and health can lead to natural weight differences. Consistent access to high-quality nutrition can also cause captive apes to weigh more than their wild counterparts.