Answer:
Evolution and different environments.
Explanation:
Primates are intelligent in their own ways, such as motor control, the use of hands and feet simultaneously, control of both hands for different things at the same time.
Dolphins for example, however, they lack the limbs that primates do, so they don't need motor control as much as primates. They evolved to be very social animals, and that allows them to excel in groups while maintaining a pattern seeking brain much like primates, without the motor control capabilities.
