There is much evidence that naturally occurring behaviors (e.g., the ingestion of food and water) and social behaviors (e.g., play, maternal behavior) can induce a reward state. This review includes definitions to distinguish between "reward" and "reinforcement," and a description of methods to assess reward and demonstrate that social interactions can indeed produce a positive affective (PA) s...

Sexual selection is a powerful evolutionary force shaping mate choice phenotypes, initiating phenotypic shifts resulting in (or reinforcing) population divergence and speciation when such shifts reduce mating probabilities among divergent populations. In the Hawaiian cricket genus Laupala, pulse rate of male calling song, a conspicuous mating signal, differs among species, potentially behaving ...

Sexual preferences in animals are often skewed toward mates with exaggerated traits. In many vertebrates, parents provide, through the learning process of "sexual imprinting," the model for the later sexual preference. How imprinting can result in sexual preferences for mates having exaggerated traits rather than resembling the parental appearance is not clear. We test the hypothesis that a by-...

Sexual isolation is a critical form of reproductive isolation in the early stages of animal speciation, yet little is known about the genetic basis of divergent mate preferences and preference cues in young species. Heliconius butterflies, well known for their diversity of wing color patterns, mate assortatively as a result of divergence in male preference for wing patterns. Here we show that t...

The evolution of novel sexual communication systems is integral to the process of speciation, as it discourages gene flow between incipient species. Physical linkage between genes underlying male-female communication (i.e. sexual signals and preferences for them) facilitates both rapid and coordinated divergence of sexual communication systems between populations and reduces recombination in th...

Whether animals ever exhibit a preference for same-sex sexual partners is a subject of debate. Japanese macaques represent excellent models for examining issues related to sexual preference in animals because females, in certain populations, routinely engage in both heterosexual and homosexual behavior over the course of their life spans. Multiple lines of evidence indicate that female homosexu...

Face perception is mediated by a distributed neural system in the human brain . The response to faces is modulated by cognitive factors such as attention, visual imagery, and emotion ; however, the effects of gender and sexual orientation are currently unknown. We used fMRI to test whether subjects would respond more to their sexually preferred faces and predicted such modulation in the reward ...

In this work, mate choice is modeled by means of the abstract concept of mutual mating propensity. This only assumes that different types of couples can have different mating success. The model is adequate for any population where mating occurs among distinct types. There is no extra assumption about particular mating scheme or preference model. The concept of mutual mating propensity permits t...

In some captive and free-ranging populations, unmanipulated female Japanese macaques (Macaca fuscata) routinely court, mount (with pelvic thrusting), compete for, and even prefer, on occasion, certain female sexual partners over certain males. The goal of this study was to determine if the cytoarchitecture of the dorsocentral portion of the anterior hypothalamic nucleus (AHdc), was male-typical...

Estrogen is associated with female sexual behaviors, particularly receptive behaviors during the reproductive cycle. Less is known about the relationship between estrogen and female preference behaviors that may precede receptivity and copulation. Separating the mechanisms underlying preference from receptivity is often confounded by the tightly coupled cycle- or estrogen-dependent expression o...