The Peacock Fallacy: Art as a Veblenian Signal

The fact that world-over people seem inexplicably motivated to allocate time and effort to apparently useless cultural practices, like the arts, has led several evolutionary scholars to suggest that these might be costly Zahavian signals correlated with genetic fitness, such as the infamous peacock’s tail. In this paper, I review the fundamental arguments of the hypothesis that art evolved and serves as a costly Zahavian signal. First, I look into the hypothesis that humans exert mate choice for indirect benefits and argue that the data supports mate choice for direct benefits instead. Second, I argue that art practice may well be a costly signal, however not necessarily related to good genes. Third, I suggest that Thorstein Veblen’s original concept of conspicuous signals as social tools to obtain and convey prestige provides a better account than the Zahavian model for the evolution and function of art in society. As a Veblenian signal, art could still have many of the effects suggested for visual art as a Zahavian signal, except not for the indirect benefits of optimal offspring, but for the direct benefits of acquiring and conveying social status.

Women’s Perception of Attractiveness of Men’s Faces Inversely Correlates with Men’s Serum Testosterone During the Fertility Phase of the Menstrual Cycle

The attractiveness of the human face may signal the genetic suitability of a mate. The ‘ovulatory shift hypothesis’ postulates that women in the fertile phase of the menstrual cycle prefer faces of masculine men that signal ‘good genes’, whereas in the non-fertile phase they prefer good parental providers. We studied relationships between serum total testosterone and face attractiveness of 77 healthy men (20-29 years, mean±SD 22.44±1.79) as rated by 19 healthy women (20-27 years, mean±SD 22.84±1.96) on day 13 of their menstrual cycle. Using advanced Bayesian multilevel modeling we showed that the attractiveness of faces is negatively associated with the concentration of serum testosterone in the men, even taking into account the concentration of serum estrogen in the raters. The average face composited from images of 39 faces rated above pool median attractiveness rate, was slightly narrower than the average face composited from 38 less attractive faces. Our results challenge the ‘ovulatory shift hypothesis’ as faces of males with higher circulating testosterone were rated as less attractive than faces of males with lower testosterone by women on the fertile phase of the cycle.

Inferring Preferred Mating Strategies Through Body Fat and Sex-Typical Body Features

Identifying reproductive opportunities and intrasexual rivals has necessitated the evolution of sensitivity to features diagnostic of mate value. In determining the presence of good genes through physical features, individuals may additionally infer targets’ short- and long-term mating motives. This study tested how individuals perceive men and women’s mating intentions through physical features conducive to reproductive goals. Participants evaluated preferred mating strategies of male and female targets varying in size of sex-typical features (i.e., muscles or breasts) and adiposity. Greater adiposity connoted long-term mating interest. Large muscles and breasts connoted short-term mating interests. We frame results from an affordance management framework with respect to inferences regarding parental investment and intrasexual competition.

The evidence for good genes ovulatory shifts in Arslan et al. (2018) is mixed and uncertain

In Arslan et al. (2018), we reported ovulatory increases in extra-pair sexual desire, in-pair sexual desire, and self-perceived desirability, as well as several moderator analyses related to the good genes ovulatory shift hypothesis, which predicts attenuated ovulatory increases in extra-pair desire for women with attractive partners. Gangestad and Dinh (2021) identified errors in how we aggregated two out of four main moderator variables. We are grateful that their scrutiny uncovered these errors. After corrections, our moderation results are more mixed than we previously reported and depend on the moderator specification. However, we disagree that the evidence for moderation is robust and compelling, as Gangestad and Dinh (2021) claim. Our data are consistent with some previously reported effect sizes, but also with negligible moderator effects. We also show that what Gangestad and Dinh (2021) call an "a priori [...] more comprehensive and valid composite" is poorly justifiable on a priori grounds, and follow-up analyses they report are not robust to a composite specification that we consider at least as reasonable. Psychologists have to become acquainted with techniques such as cross-validation or training and test sets to manage the risks of data-dependent analyses. In doing so, we might learn that we need new data more often than we intuit and should remain uncertain far more often.

Genetics of Life and Death

Longevity seems to run in families, and very old people are sometimes said to have “good” genes. There might be something to that. If there is a key to immortality, molecular geneticists may be able to find it. They recently began to explore the genes and other factors that cause us to age and eventually die and are finding intriguing hints of ways that death can be deferred, such as through caloric restriction, epigenetic techniques, and manipulation of telomeres and stem cells. Inherent in such studies is the concept that many of the diseases associated with aging, such as heart disease, diabetes, cancer, and neurodegenerative disease—the things that kill most people—may be symptoms of the disease of aging.

Inferences of Parental Abilities Through Facial and Bodily Features

This chapter explains that within the corpus of research showing the extent to which cues to physical attractiveness connote individuals’ specific value as a mate, findings have begun to recognize how these cues specifically apply to inferring parental abilities. Namely, this research suggests some physical features that were likely selected due to their connotations of heritable fitness may dually implicate a person as an especially effective parent. Such work additionally demonstrates the instances in which features not selected for their connotation of what we typically consider heritable fitness (i.e., adiposity) become desirable while providing additional evidence for the trade-offs in selecting short- and long-term mates. This selection of adiposity further clarified what is actually meant when researchers discuss selecting for good genes. That is, individuals could be inferring parental abilities through adiposity, thus leading individuals to select mates with higher levels for a long-term context given that connotation.

Adaptation to a bacterial pathogen in Drosophila melanogaster is not aided by sexual selection

Theory predicts that sexual selection should aid adaptation to novel environments, but empirical support for this idea is limited. Pathogens are a major driver of host evolution and, unlike abiotic selection pressures, undergo epidemiological and co-evolutionary cycles with the host involving adaptation and counteradaptation. Because of this, populations harbor ample genetic variation underlying immunity and the opportunity for sexual selection based on condition-dependent “good genes” is expected to be large. In this study, we evolved populations of Drosophila melanogaster in a 2-way factorial design manipulating sexual selection and pathogen presence, using a gram-negative insect pathogen Pseudomonas entomophila, for 14 generations. We then examined how the presence of sexual selection and the pathogen, as well as any potential interaction, affected the evolution of pathogen resistance. We found increased resistance to P. entomophila in populations that evolved under pathogen pressure, driven primarily by increased female survival after infection despite selection for resistance acting only on males over the course of experimental evolution. This result suggests that the genetic basis of resistance is in part shared between the sexes. We did not find any evidence of sexual selection aiding adaptation to pathogen, however, a finding contrary to the predictions of “good genes” theory. Our results therefore provide no support for a role for sexual selection in the evolution of immunity in this experimental system.

Faces of men with high serum testosterone are less attractive for women during the fertility phase of the menstrual cycle

The attractiveness of the human face plays an essential role in mating as it may signal the genetic suitability of a mate. The controversial 'ovulatory shift hypothesis' postulates that women in the fertile phase of the menstrual cycle would prefer faces of masculine men with high testosterone that signals 'good genes', whereas in the non-fertile phase they prefer traits signaling the willingness to provide parental care. To examine relationships between men's testosterone and women's preferences for men's faces on day 13 of the menstrual cycle, 19 young women rated the attractiveness of images of the natural faces of 77 young men. Using advanced Bayesian multilevel modeling we showed that the attractiveness of men's faces is significantly lower in men with a high concentration of serum total testosterone, even taking into account the concentration of serum estrogen in the raters. The average men's face composited from images of 39 faces rated above pool median attractiveness rate, was slightly narrower than the average face composited from 38 less attractive faces. Our results challenge the 'ovulatory shift hypothesis' as faces of males with high circulating testosterone were rated as less attractive than faces of males with lower testosterone by women on the fertile phase of the cycle.

Direct and indirect effects of male genital elaboration in female seed beetles

Our understanding of coevolution between male genitalia and female traits remains incomplete. This is perhaps especially true for genital traits that cause internal injuries in females, such as the spiny genitalia of seed beetles where males with relatively long spines enjoy a high relative fertilization success. We report on a new set of experiments, based on extant selection lines, aimed at assessing the effects of long male spines on females in Callosobruchus maculatus . We first draw on an earlier study using microscale laser surgery, and demonstrate that genital spines have a direct negative (sexually antagonistic) effect on female fecundity. We then ask whether artificial selection for long versus short spines resulted in direct or indirect effects on female lifetime offspring production. Reference females mating with males from long-spine lines had higher offspring production, presumably due to an elevated allocation in males to those ejaculate components that are beneficial to females. Remarkably, selection for long male genital spines also resulted in an evolutionary increase in female offspring production as a correlated response. Our findings thus suggest that female traits that affect their response to male spines are both under direct selection to minimize harm but are also under indirect selection (a good genes effect), consistent with the evolution of mating and fertilization biases being affected by several simultaneous processes.