This study investigates the functional connectivity of the precuneus in both humans and macaque monkeys, revealing three distinct subdivisions: anterior sensorimotor, central cognitive/associative, and posterior visual. These subdivisions correspond to different functional roles, with the anterior precuneus connected to sensorimotor regions, the central precuneus linked to cognitive areas, and the posterior precuneus associated with visual processing. These findings align with anatomical studies in monkeys, suggesting that resting-state functional connectivity (RSFC) reflects underlying anatomy. The precuneus is not a homogeneous region but rather functionally heterogeneous, and its subdivisions may be important for understanding its role in various cognitive tasks and clinical conditions. The consistency between functional connectivity patterns in monkeys and humans supports RSFC as a viable tool for cross-species comparisons of functional neuroanatomy. The study also highlights the importance of considering the precuneus as a heterogeneous region in neuroimaging studies. The results suggest that future research should consider the heterogeneity of the precuneus when studying its functional roles. The study also discusses the relevance of these findings to the default-mode network, noting that the precuneus is not a component of this network, but rather a separate region with distinct functional connectivity patterns. The study concludes that the precuneus and other areas within the parieto-occipital cortex comprise a series of related but discrete regions that participate in distinct functional networks. This differentiation is especially important considering the rise of interest in the default-mode network. The study also emphasizes the need for further research to understand how the complexity of the precuneus and its interactions in several large-scale networks relate to high-level processing in both humans and nonhuman primates.This study investigates the functional connectivity of the precuneus in both humans and macaque monkeys, revealing three distinct subdivisions: anterior sensorimotor, central cognitive/associative, and posterior visual. These subdivisions correspond to different functional roles, with the anterior precuneus connected to sensorimotor regions, the central precuneus linked to cognitive areas, and the posterior precuneus associated with visual processing. These findings align with anatomical studies in monkeys, suggesting that resting-state functional connectivity (RSFC) reflects underlying anatomy. The precuneus is not a homogeneous region but rather functionally heterogeneous, and its subdivisions may be important for understanding its role in various cognitive tasks and clinical conditions. The consistency between functional connectivity patterns in monkeys and humans supports RSFC as a viable tool for cross-species comparisons of functional neuroanatomy. The study also highlights the importance of considering the precuneus as a heterogeneous region in neuroimaging studies. The results suggest that future research should consider the heterogeneity of the precuneus when studying its functional roles. The study also discusses the relevance of these findings to the default-mode network, noting that the precuneus is not a component of this network, but rather a separate region with distinct functional connectivity patterns. The study concludes that the precuneus and other areas within the parieto-occipital cortex comprise a series of related but discrete regions that participate in distinct functional networks. This differentiation is especially important considering the rise of interest in the default-mode network. The study also emphasizes the need for further research to understand how the complexity of the precuneus and its interactions in several large-scale networks relate to high-level processing in both humans and nonhuman primates.