The Next Decade of Sexual Science: Synergy From Advances in Related Sciences

Journal of Sex Research, May, 2001 by Janet Shibley Hyde

I believe that, like any other science, sexual science will advance the most in the next decade if we learn from our neighbors, that is, if we pay attention to advances in related disciplines. I present here some snapshots of interesting research outside sexual science that I hope will inspire researchers to pursue these ideas and connect them with their own work.

Primatology: Monogamous Primates

If one listens to the sociobiologists and evolutionary psychologists, one definitely gets the impression that humans are an adulterous, promiscuous lot and that we are this way because of an evolutionary heritage of promiscuity in all other species (e.g., Birkhead, 2000; Fisher, 1992). These tales make for luscious, lusty reading, but they typically overlook exceptions to the patterns they claim. What follows is one of those exceptions.

Snowdon (2001) studies cotton-top tamarins, small monkeys that are native to the forests of South America. This species is interesting because they are socially monogamous--that is, an adult male and female form a lifelong pair bond. They are upset when separated from the partner and engage in an explosion of sexual activity when reunited with the partner. They spend much time in close proximity to their partner and grooming the partner. Most sexual behavior is nonconceptive--that is, it occurs at a time when the female is not ovulating. Mating with someone other than the partner is rare. Males participate fully in the care of infants and show an elevation in their levels of prolactin during their mate's gestation (Ziegler & Snowdon, 2000).

I provide the example of the cotton-top tamarins not because I want to convince you that humans are inherently monogamous, but rather to stimulate critical thinking about overgeneralizations found in evolutionary theorizing, and to stress the need for more, and more careful, research on the sexual behavior of other species, particularly before we make sweeping generalizations to "human nature." In addition, we should note that primate research is one area where researchers can make direct observations of sexual behavior, something that has proven to be difficult if not impossible in human sex research. Primatology, therefore, is a great discipline for interdisciplinary synergy with sexual science.

Behavioral Neuroscience: Impact of Behavior and Experience on Biology

A traditional model throughout the behavioral sciences has been that biology influences or even determines behavior. Some scientists, of course, are critical of this model and instead prefer the model that environment influences behavior. My focus is not on either of those models, but rather on a new one emerging from behavioral neuroscience in the last few years, and that is that behavior and experience influence biology, specifically neuroanatomy. This phenomenon is termed neural plasticity.

Marler and her colleagues study social behavior in two species of mice (Peromyscus), the monogamous California mouse and the polygamous white-footed mouse native to Wisconsin. In the monogamous California mouse, males engage in care of their young and are more aggressive toward intruders than are white-footed male mice (Bester-Meredith, Young, & Marler, 1999).

Bester-Meredith and Marler (2001) did a cross-fostering experiment with these two species. Half of the California mouse pups were raised by California mouse parents, and half were raised by white-footed mouse parents. White-footed pups were similarly fostered. Male California mice raised by white-footed parents were significantly less aggressive than California mice raised by California parents. Arginine vasopressin (AVP) is a neurotransmitter. It has been found, over several species, that AVP is associated with both aggressive behavior and parental behavior. Under normal rearing conditions, California mice, the more aggressive species, show more AVP-releasing neurons in the bed nucleus of the stria terminalis than white-footed mice do (Bester-Meredith et al., 1999). And, to complete this picture to perfection, the California mice raised by white-footed parents had significantly fewer AVP-releasing neurons in the bed nucleus of the stria terminalis than California mice raised by California parents. Essentially, then, the early parental-rearing environment influenced the biology--the very neurons--of the California mice. Social interactions influence biology.

It is also worth noting that AVP is the neurotransmitter associated with testosterone. In this research, however, testosterone levels were not altered by cross fostering (Bester-Meredith & Marler, 2001).

This phenomenon--that social experience modifies biology--has been replicated with other species and with other social interactions as the influences on biology (e.g., dominance in golden hamsters, Delville, Melloni, & Ferris, 1998; for a review of data with humans, see Cacioppo, Berntson, Sheridan, & McClintock, 2000; for a more general introduction to the history and promise of behavioral neuroscience, see Kandel & Squire, 2000).