Darwin, sexual selection, and the brain

Abstract

One hundred fifty years ago Darwin published The Descent of Man, and Selection in Relation to Sex, in which he presented his theory of sexual selection with its emphasis on sexual beauty. However, it was not until 50 y ago that there was a renewed interest in Darwin’s theory in general, and specifically the potency of mate choice. Darwin suggested that in many cases female preferences for elaborately ornamented males derived from a female’s taste for the beautiful, the notion that females were attracted to sexual beauty for its own sake. Initially, female mate choice attracted the interest of behavioral ecologists focusing on the fitness advantages accrued through mate choice. Subsequent studies focused on sensory ecology and signal design, often showing how sensory end organs influenced the types of traits females found attractive. Eventually, investigations of neural circuits, neurogenetics, and neurochemistry uncovered a more complete scaffolding underlying sexual attraction. More recently, research inspired by human studies in psychophysics, behavioral economics, and neuroaesthetics have provided some notion of its higher-order mechanisms. In this paper, I review progress in our understanding of Darwin’s conjecture of “a taste for the beautiful” by considering research from these diverse fields that have conspired to provide unparalleled insight into the chooser’s mate choices.

The contribution of mate-choice, couple convergence and confounding to assortative mating

“…Our results point to AM being stronger among females compared to males which is consistent with the notion first put forth by Darwin, that females are, in general, choosers, while males are courters 31 . Furthermore, our results suggest that fitness and anthropometric measures are important initially (at the time of mate-choice), but their correlation decreases with time, i.e.…”

Song Preference in Female and Juvenile Songbirds: Proximate and Ultimate Questions

“…Questions about the evolution of female song preference is of great scientific significance for neurobiologists who study the mechanisms underlying song preference. Explanations for the evolution of mating preference are mostly based on direct or indirect benefit to individuals as a result of their mate choices, or sensory or perceptual biases that affect the receivers in general contexts ( Jennions and Petrie, 1997 ; Kokko et al, 2003 ; Ryan, 2021 ). Both these are general and well-established theoretical frameworks, but in case of birdsong research, particularly the former one has been the target of intensive discussion and empirical examination.…”

Cognition and Its Shaping Effect on Sexual Conflict: Integrating Biology and Psychology

“…However, as it has been increasingly pointed out by researchers of fields like that of evolutionary biology, physiological and genetic responses cannot be fully understood in the absence of the social environment and the cognitive processes that are constantly regulating animals’ activity (sensu organic selection by Baldwin, 1896 (see e.g., West-Eberhard, 2003 ; Diogo, 2017 ; for general reviews). Within the particular domain of mating, the modulating role of cognition has become increasingly acknowledged (e.g., Bateson and Healy, 2005 ; Prum, 2017 ; Ryan, 2021 ). Animals need to be able to identify sexual partners as such, to distinguish between receptive and non-receptive conspecifics, to identify their own sexual arousal, to assess the quality of a potential mate and to pursue him or her to achieve successful mating (e.g., Pfaus et al, 2001 ).…”

“…Moreover, this evaluation needs to be orchestrated with the constant monitoring of the ever-changing environmental conditions of the given time and space in which mating is about to take place. In other words, mating is importantly affected by cognitive processes that include motivation, perception, learning, memory and decision-making (see Pfaus et al, 2001 for a review on how learning shapes mating in rats) and thus, they cannot be overlooked if we aim to understand it fully (see Bateson and Healy, 2005 ; Ryan, 2021 for a more general review). Likewise, as we have previously pointed out ( Alvarez and Koene, 2018 ), we think that the current available data on sexual conflict cannot lead to a comprehensive understanding of this topic since it leaves out an important aspect of an animal’s life, i.e., its ontogeny, that, as will be further argued, can crucially shape the mating response and, therefore, the outcome of the sexual conflict (i.e., the costs) that is faced at each mating encounter.…”

“…Although mate choice has been defined as a cognitive process that starts off with the perception and assessment of a conspecific (e.g., Bateson and Healy, 2005 ; Ryan et al, 2009 ; Dougherty, 2020 ; Ryan, 2021 ), as pointed out previously, it often seems to be understood as driven by an output from a nervous system that receives a specific amount of stimulation that triggers a sexually receptive response (i.e., a physiological response more than a cognitive one; e.g., Bakker, 1999 ; Iwasa and Pomiankowski, 1999 ; Andersson and Simmons, 2006 ; Kopp et al, 2018 ). It is true that, within any given species, sensory organs are responsive to specific ranges of stimulation and, as such, it is natural to observe predispositions for particular stimuli that are common to the majority of the individuals of the opposite sex (e.g., natural preference for red bellies in female guppies, Kodric-Brown, 1993 ; see also Ryan, 2021 for a review). However, this does not imply that perceptual preferences are purely innate nor fixed (e.g., see Weary et al, 1993 ).…”