Final answer:
The order most closely related to primates is the primate order itself, which includes humans, with our closest relatives being within the Hominidae family that encompasses chimpanzees, gorillas, and orangutans.
Step-by-step explanation:
The order that primates are most closely related to is the primate order itself. As humans, we are part of the Hominidae family within this order, which also includes chimpanzees, gorillas, and orangutans. These species are our closest living relatives, with humans belonging to the sole species Homo sapiens. Primates exhibit diverse characteristics such as larger brains, stereoscopic vision, and an upright posture. The primate order is divided into prosimians and anthropoids. Prosimians include species like lemurs and tarsiers, while anthropoids encompass monkeys, apes, and humans.
Characteristics such as having five fingers (pentadactyl), an opposable thumb, and varied types of teeth bind us closely with other primates. The evolutionary history that we share is evident through these traits, as well as through genetic evidence indicating a high percentage of shared DNA. This shared ancestry underscores the similarities we observe, such as the nurturing behavior seen in orangutans, which is reminiscent of human parental care.