Sexual Selection and Human Geographic Variation

Sexual Selection and Human Geographic Variation
Peter Frost (2008)


Abstract

Among early modern humans, a woman would face stronger competition for a mate the further away she was from the equator. Men were less available because they 1) hunted over longer distances that increased male mortality proportionately and 2) were less able to offset the resulting man shortage through polygyny. The longer the winter, the costlier it became to provision a second wife and her children, since women could not gather food in winter. Women competed the most for mates in the 'continental Arctic,' where wandering herds were the main food source. Conversely, men competed the most for mates in the Tropics, particularly after year-round agriculture emerged. This means of subsistence allowed women to become primary food producers, thereby freeing men to take more wives. Because mate competition has varied in intensity among human populations, sexual selection has correspondingly varied in intensity for certain traits, often highly visible and colorful ones. Intense female-female competition may explain an unusual convergence of color traits in northern and eastern Europeans. Intense male-male competition may explain increased masculinization of body build in highly polygynous agricultural populations of sub-Saharan Africa.


[Publications of Peter Frost: http://evoandproud.blogspot.co.at/p/my-publications.html]

European hair and eye color A case of frequency-dependent sexual selection?

European hair and eye color A case of frequency-dependent sexual selection?
Peter Frost (2006)
http://www.ceacb.ucl.ac.uk/cultureclub/files/CC2006-03-07_Frost.pdf


Abstract

Human hair and eye color is unusually diverse in northern and eastern Europe. The many alleles involved (at least seven for hair color) and their independent origin over a short span of evolutionary time indicate some kind of selection. Sexual selection is particularly indicated because it is known to favor color traits and color polymorphisms. In addition, hair and eye color is most diverse in what used to be, when first peopled by hunter-gatherers, a unique ecozone of low-latitude continental tundra. This type of environment skews the operational sex ratio (OSR) of hunter-gatherers toward a male shortage in two ways: (1) men have to hunt highly mobile and spatially concentrated herbivores over longer distances, with no alternate food sources in case of failure, the result being more deaths among young men; (2) women have fewer opportunities for food gathering and thus require more male provisioning, the result being less polygyny. These two factors combine to leave more women than men unmated at any one time. Such an OSR imbalance would have increased the pressures of sexual selection on early European women, one possible outcome being an unusual complex of color traits: hair- and eye-color diversity and, possibly, extreme skin depigmentation.

Sexual selection for indicators of intelligence

Sexual selection for indicators of intelligence
Geoffrey Miller; 2000
pages 260 (269) -> 275 (284)


Abstract

Many traits in many species have evolved through sexual selection specifically to function as ‘fitness indicators’ that reveal good genes and good health. Sexually selected fitness indicators typically show (1) higher coefficients of phenotypic and genetic variation than survival traits, (2) at least moderate genetic heritabilities and (3) positive correlations with many aspects of an animal’s general condition, including body size, body symmetry, parasite resistance, longevity and freedom from deleterious mutations. These diagnostic criteria also appear to describe human intelligence (the g factor). This paper argues that during human evolution, mate choice by both sexes focused increasingly on intelligence as a major heritable component of biological fitness. Many human-specific behaviours (such as conversation, music production, artistic ability and humour) may have evolved principally to advertise intelligence during courtship. Though these mental adaptations may be modular at the level of psychological functioning, their efficiencies may be tightly intercorrelated because they still tap into common genetic and neurophysiological variables associated with fittness itself. Although the g factor (like the superordinate factor of fitness itself) probably exists in all animal species, humans evolved an unusually high degree of interest in assessing each other’s intelligence during courtship and other social interactions and, consequently, a unique suite of highly g-loaded mental adaptations for advertising their intelligence to one another through linguistic and cultural interaction. This paper includes nine novel, testable predictions about human intelligence derived from sexual selection theory.

Who dares, wins

Who dares, wins - Heroism versus altruism in women's mate choice
Susan Kelly and R I M Dunbar; June 2001
Human Nature


Abstract

Heroism is apparently nonadaptive in Darwinian terms, so why does it exist at all? Risk-taking and heroic behavior are predominantly male tendencies, and literature and legend reflect this. This study explores the possibility that heroism persists in many human cultures owing to a female preference for risk-prone rather than risk-averse males as sexual partners, and it suggests that such a preference may be exploited as a male mating strategy. It also attempts to quantify the relative influences of altruism and bravery in the evolution of heroism. Our study found that females do prefer risk-prone brave males to risk-averse non-brave males, and that men are aware of this preference. Bravery in a male was shown to be the stronger factor influencing female choice of short-term partners, long-term partners, and male friends, with altruism playing a lesser part in their choice. Altruism was deemed important in long-term relationships and friendships, but for short-term liaisons, non-altruists were preferred to altruists. Heroism may therefore have evolved owing to a female preference for brave, risk-prone males because risk-taking acts as an honest cue for "good genes." Altruism was judged to be a less influential factor in the evolution of heroism than bravery and a demonstrated willingness to take risks.

Mutual Mate Choice: Sexual Selection Versus Sexual Conflict

Mutual Mate Choice: Sexual Selection Versus Sexual Conflict
Anne Campbell; Sep 2013
Psychological Inquiry

Parental Investment and Sexual Selection

Parental Investment and Sexual Selection
Robert L Trivers; 1972


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See also: http://www.humanbiologicaldiversity.com/

The Great Struggles of Life- Darwin and the Emergence of Evolutionary Psychology

The Great Struggles of Life - Darwin and the Emergence of Evolutionary Psychology
David M Buss; 2009
http://www.homepage.psy.utexas.edu/homepage/group/busslab/pdffiles/great%20struggles%20of%20life%20-%202009AmerPsych.pdf


Abstract

Darwin envisioned a scientific revolution for psychology. His theories of natural and sexual selection identified two classes of struggles—the struggle for existence and the struggle for mates. The emergence of evolutionary psychology and related disciplines signals the ful-fillment of Darwin’s vision. Natural selection theory guides scientists to discover adaptations for survival. Sexual selection theory illuminates the sexual struggle, highlighting mate choice and same-sex competition adaptations. Theoretical developments since publication of On the Origin of Species identify important struggles unknown to Darwin, notably, within-families conflicts and conflict between the sexes. Evolutionary psychology synthesizes modern evolutionary biology and psychology to penetrate some of life’s deep mysteries: Why do many struggles center around sex? Why is social conflict pervasive? And what are the mechanisms of mind that define human nature?

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"This article traces Darwin’s influence on evolutionary psychology and outlines the field’s development beyond Darwin’s vision."

Beauty and the beast: mechanisms of sexual selection in humans

Beauty and the beast: mechanisms of sexual selection in humans
David A Puts; 2010
http://dieoff.com/_Biology/BeautyAndTheBeast.pdf


Abstract

Literature in evolutionary psychology suggests that mate choice has been the primary mechanism of sexual selection in humans, but this conclusion conforms neither to theoretical predictions nor available evidence. Contests override other mechanisms of sexual selection; that is, when individuals can exclude their competitors by force or threat of force, mate choice, sperm competition, and other mechanisms are impossible. Mates are easier to monopolize in two dimensional mating environments, such as land, than in three-dimensional environments, such as air, water, and trees. Thus, two-dimensional mating environments may tend to favor the evolution of contests. The twodimensionality of the human mating environment, along with phylogeny, the spatial and temporal clustering of mates and competitors, and anatomical considerations, predict that contest competition should have been the primary mechanism of sexual selection in men. A functional analysis supports this prediction. Men's traits are better designed for contest competition than for other sexual selection mechanisms; size, muscularity, strength, aggression, and the manufacture and use of weapons probably helped ancestral males win contests directly, and deep voices and facial hair signal dominance more effectively than they increase attractiveness. However, male monopolization of females was imperfect, and female mate choice, sperm competition, and sexual coercion also likely shaped men's traits. In contrast, male mate choice was probably central in women's mating competition because ancestral females could not constrain the choices of larger and more aggressive males through force, and attractive women could obtain greater male investment. Neotenous female features and body fat deposition on the breasts and hips appear to have been shaped by male mate choice.

Sexual Selection on Human Faces and Voices

Sexual Selection on Human Faces and Voices
David A Puts et al., 2012
http://www.putslab.psu.edu/pdfs/Puts%20et%20al%20J%20Sex%20Res%202012-1.pdf


Abstract

Humans are highly sexually dimorphic primates, and some of the most conspicuous human sex differences occur in the face and voice. Consequently, this article utilizes research findings on human faces and voices to illustrate how human sex differences may have arisen by sexual selection (i.e., the type of natural selection favoring traits that increase mating opportunities). Evidence suggesting that sexual selection shaped women’s faces and voices is reviewed. However, sexual selection likely operated more strongly on men over human evolution. Thus, this research focuses on two types of sexual selection operating on men: female mate choice, which favors traits that attract females, and male contests, which favor traits for excluding competitors from mates by force or threat of force. This article demonstrates how masculine faces and voices advertize critical information about men’s mate value and threat potential, and reviews evidence that women’s preferences and men’s deference to masculine faces and voices reflect this information content. Data suggesting that facial and vocal masculinity influences men’s mating opportunities and reproduction are discussed, and the article concludes by highlighting directions for future research.

Individual differences in personality traits reflect structural variance in specific brain regions

Individual differences in personality traits reflect structural variance in specific brain regions
Simona Gardini et al., 2009
https://syllabus.byu.edu/uploads/gkhHMK7hTKYu.pdf


Abstract

 

Personality dimensions such as novelty seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (PER) are said to be heritable, stable across time and dependent on genetic and neurobiological factors. Recently a better understanding of the relationship between personality traits and brain structures/systems has become possible due to advances in neuroimaging techniques. This Magnetic Resonance Imaging (MRI) study investigated if individual differences in these personality traits reflected structural variance in specific brain regions. A large sample of eighty five young adult participants completed the Three-dimensional Personality Questionnaire (TPQ) and had their brain imaged with MRI. A voxel-based correlation analysis was carried out between individuals’ personality trait scores and grey matter volume values extracted from 3D brain scans. NS correlated positively with grey matter volume in frontal and posterior cingulate regions. HA showed a negative correlation with grey matter volume in orbito-frontal, occipital and parietal structures. RD was negatively correlated with grey matter volume in the caudate nucleus and in the rectal frontal gyrus. PER showed a positive correlation with grey matter volume in the precuneus, paracentral lobule and parahippocampal gyrus. These results indicate that individual differences in the main personality dimensions of NS, HA, RD and PER, may reflect structural variance in specific brain areas.

Are moral virtues attractive?

Sexual selection for moral virtues
Geoffrey F. Miller, 2007

http://hss.caltech.edu/~steve/miller.pdf



A few points of the paper:

"Research shows that many particular moral virtues are sexually attractive and relationship-stabilizing; these include: [kindness, empathy, niceness, honesty, heroism]; Most of these moral virtue preferences are stronger when seeking a serious long-term partner than a short-term lover."

"All else being equal, virtues should be favored in mate choice. They should be highly valued aspects of potential mates that individuals are motivated not just to judge passively by observation, but to probe actively..."

"One might object that intelligence is not really a moral virtue; it just happens to predict a wide range of specific moral behaviors. Yet, what is a moral virtue if not an individual differences dimension that predicts a wide range of specific moral behaviors? Moral virtues are socially attributed traits that carry predictive information about morally relevant behaviors. If kindness is a moral virtue because it predicts specific prosocial behaviors, and is valued as such, then intelligence must also be a moral virtue, along with being an academic, economic, and epistemological virtue. Another reason for accepting the quasi-moral status of intelligence is the recent convergence between virtue ethics and “virtue epistemology,” the study of cognitive and intellectual virtues (Axtell 2000; Brady and Pritchard 2003; DePaul and Zagzebski 2003). Traditional epistemology tried to evaluate the truth of particular conceptual systems through consistency and coherence criteria. By contrast, for the virtue epistemologist, true beliefs arise from acts of intellectual virtue, those typical of intelligent, rational, cognitively complex agents (Zagzebski 1996) who show impartiality, epistemic responsibility, and intellectual courage (Code 1987; Kvanvig 1992; Montmarquet 1993). For example, Aristotle named intuition, wisdom, prudence, and science as intellectual virtues. In virtue epistemology as in virtue ethics, the favored level of description is the whole individual as a cognitive/moral agent, not the isolated belief or moral act. This naturally leads to an emphasis on individual differences in epistemological virtue, differences that intelligence researchers have already succeeded in measuring with unparalleled reliability and validity for over a century ( Jensen 1998). Thus, intelligence is a sexually attractive, quasimoral trait at the intersection of virtue epistemology and virtue ethics."