The last surviving primate before the great apes! Gibbons are a “lesser ape” that branched off from our common ancestor with great apes. By this time, our ancestors had already lost their tails (like all apes) and were very agile in trees, using brachiation (arm-swinging) to move through the canopy. Gibbons are known for their intricate vocalizations, particularly the duets they sing to communicate with their mates and establish territory. Bipedalism in our ancestors has roots around this time, as gibbons evolved an upright posture while moving through the trees and on the ground, where they walk bipedally for short distances. Around this period, our ancestors also began to rely more on vision than smell, which many researchers believe played a significant role in the development of larger brains. This shift required more complex brain structures to process the increasingly sophisticated visual information needed for survival.

Gibbons do not exhibit the same advanced tool use or cognitive complexity seen in great apes like orangutans, which branched off a few million years later. Gibbons are not as adept at problem-solving, have weaker memory, and show fewer social skills. For example, they do not laugh—a behavior linked to emotional intelligence. Additionally, while orangutans use and even create tools, gibbons do not.