Human sex recognition: a developmental voice-based model of brain circuits.

Abstract

Pheromonal, neuroimaging, and comparative evidence converge on a limbic-hypothalamic axis-including the amygdala, bed nucleus of the stria terminalis (BNST), and hypothalamus-that organizes sex-related behaviors. In many mammals, this system is driven by chemosensory input via the vomeronasal organ (VNO) and accessory olfactory bulb (AOB). In humans, however, the functional role of the VNO is uncertain, and no consistent sex pheromone has been identified. The Human Sex Recognition (HSR) model proposes a sensory substitution at the level of input: auditory signals, conveyed through the medial geniculate nucleus (MGN), provide the primary entry point into this conserved system. Within this framework, human voice signals are proposed to serve as a functional analog to pheromonal cues in other mammals. Developmentally, auditory cues, available prenatally and throughout childhood, provide an early scaffold for the acquisition of visual and other sex-related cues through cortical learning. These multimodal representations converge on limbic-hypothalamic circuits, which are reorganized at puberty to support the participation of sex recognition in sex-related behavior. By specifying the primary sensory channel interfacing with a conserved neural architecture, the HSR model offers a biologically grounded alternative to pheromone-based accounts and generates testable predictions regarding the neural and developmental basis of human sex recognition.