Of the five species in the Xindi Council, the Primates are regarded as the most intellectually advanced and the less physically resilient. Their technological skills have earned them fame among the other species, which assigned the Primates to supervise the construction of their massive weapon that they planned to use against Earth.
The Primates themselves are generally honest, but arrogant over their intellectual superiority. They were the first species to take in consideration Captain Archer's claims that the Xindi were being manipulated by the Sphere Builders; a transdimentional race which had heavily assisted the Xindi following the destruction of their former homeworld. At the end, the Primates were the main driving force that lead their government to change sides in the conflict and it is hinted that a few centuries in the future, all Xindi will become members of the United Federation of Planets.