The word orangutan translates from the Malay language as “person of the forest,” a fitting name for this highly intelligent great ape. The most striking feature is its coat, which is a definitive reddish-orange or russet hue. This coloration is a uniform trait across the species, setting them apart from other great apes like gorillas and chimpanzees. The shade allows for their easy identification in the dense, green canopy of their rainforest habitat.
The Defining Hue: Primary Coloration
The signature color is a deep rust or reddish-brown, often appearing like fiery orange in direct sunlight. This shade covers nearly the entire body, except for the bare face, palms, and soles of the feet. The hair itself is long, shaggy, and often appears sparse, hanging loosely from their long limbs and torso.
This dense yet flowing coat helps to protect the orangutan from both sun and rain as they spend the majority of their lives in the trees. The texture of the hair contributes to the animal’s overall appearance, giving it a somewhat unkempt yet majestic look.
Species and Age-Related Variations
The exact shade of the coat is not entirely uniform and can vary slightly across the three recognized species. Bornean orangutans (Pongo pygmaeus) generally exhibit a darker, deeper red or maroon color and possess a thicker build. In contrast, Sumatran orangutans (Pongo abelii) tend toward a lighter, paler red, sometimes presenting with a more yellowish or cinnamon tone, and typically have longer, denser fur. Tapanuli orangutans (Pongo tapanuliensis), the most recently identified species, resemble their Sumatran cousins in color but are distinguished by having hair that is notably frizzier. These subtle differences in hue reflect the genetic divergence and adaptation to their specific island environments.
Coloration also undergoes distinct changes throughout an orangutan’s life cycle, starting with their earliest years. Infants are born with a bright orange coat that is often fuzzier than adult hair, and they display light-colored skin around their eyes and mouth. As they mature past the age of three, this lighter facial skin darkens.
The coat color continues to deepen with age, progressing from bright orange to a darker maroon or chocolate shade in older individuals. Mature males, particularly those who develop prominent cheek flanges, may appear darker overall. Their faces, which are largely bare, can develop pronounced patches of dark, almost black skin, further contrasting with the deep reddish tones of their body hair.
The Biology Behind the Shade
The distinctive reddish-orange color of the orangutan’s coat is determined by the specific type of melanin pigment present in their hair follicles. Melanin is the compound responsible for all hair and skin color in mammals, existing in two primary forms. Eumelanin produces brown and black colors, while phaeomelanin is responsible for red and yellow tones. The orangutan’s striking hue results from a high concentration of phaeomelanin dominating the pigmentation process.
The hair contains a significant amount of the red and yellow-producing pigment compared to the brown-black eumelanin found in other primates. This high phaeomelanin content is a unique genetic characteristic among the great apes, which are typically dominated by eumelanin.
This coloration is hypothesized to have evolutionary significance, potentially serving as effective camouflage. The reddish tones may help them blend into the specific light conditions of the forest canopy, particularly against bark and leaves in the dim, dappled light. Other theories suggest a role in sexual selection, where the vibrant coloration may signal health and genetic fitness to potential mates.