Evolution of Vulnerability (eBook)

Implications for Sex Differences in Health and Development

David C. Geary (Autor)

eBook Download: PDF | EPUB

2015 | 1. Auflage
444 Seiten
Elsevier Science (Verlag)
978-0-12-801747-0 (ISBN)

Infos

Biologists have known for decades that many traits involved in competition for mates or other resources and that influence mate choice are exaggerated, and their expression is influenced by the individuals' ability to tolerate a variety of environmental and social stressors. Evolution of Vulnerability applies this concept of heightened sensitivity to humans for a host of physical, social, psychological, cognitive, and brain traits. By reframing the issue entirely, renowned evolutionary psychologist David C. Geary demonstrates this principle can be used to identify children, adolescents, or populations at risk for poor long-term outcomes and identify specific traits in each sex and at different points in development that are most easily disrupted by exposure to stressors. Evolution of Vulnerability begins by reviewing the expansive literature on traits predicted to show sex-specific sensitivity to environmental and social stressors, and details the implications for better assessing and understanding the consequences of exposure to these stressors. Next, the book reviews sexual selection-mate competition and choice-and the mechanisms involved in the evolution of condition dependent traits and the stressors that can undermine their development and expression, such as poor early nutrition and health, parasites, social stress, and exposure to man-made toxins. Then it reviews condition dependent traits (physical, behavioral, cognitive, and brain) in birds, fish, insects, and mammals to demonstrate the ubiquity of these traits in nature. The focus then turns to humans and covers sex-specific vulnerabilities in children and adults for physical traits, social behavior, psychological wellbeing, and brain and cognitive traits. The sensitivity of these traits is related to exposure to parasites, poor nutrition, social maltreatment, environmental toxins, chemotherapy, and Alzheimer's disease, among others. The book concludes with an implications chapter that outlines how to better assess vulnerabilities in children and adults and how to more fully understand how, why, and when in development some types of environmental and social stressors are particularly harmful to humans. - Describes evolved sex differences, providing predictions on the traits that will show sex-specific vulnerabilities - Presents an extensive review of condition-dependent traits in non-human species, greatly expanding existing reviews published in scientific journals, and more critically, extending these to humans - Applies condition-dependent traits to humans to identify children, adolescents, or populations at risk for poor long-term outcomes

David C. Geary is a cognitive developmental and evolutionary psychologist at the University of Missouri. He has wide ranging interests but his primary areas of research and scholarly work are children's mathematical cognition and learning and Darwin's sexual selection as largely but not solely related to human sex differences. Professor Geary directed a 10-year longitudinal study of children's mathematical development from kindergarten to ninth grade, with a focus on identifying the core deficits underlying learning disabilities and persistent low achievement in mathematics. The study was funded by the National Institutes of Health (US), including through a MERIT award to professor Geary. One result has been the identification of the school-entry number knowledge that predicts economically-relevant mathematical competencies in adolescence. As a follow-up, professor Geary is directing a second longitudinal study, funded by the National Science Foundation (US), to identify the preschool quantitative competencies that predict this school-entry number knowledge. Professor Geary has also published conceptual and theoretical articles on individual differences in children's mathematical learning, as well as a book published by the American Psychological Association, Children's mathematical development (1994); recently translated into Korean. Professor Geary has also contributed to applied and policy related work on this topic, serving, for instance, on the President's National Mathematics Advisory Panel, and chairing it's learning processes task group. Professor Geary's interests in evolution are reflected in two of his other books published by the American Psychological Association, The origin of mind: Evolution of brain, cognition, and general intelligence (2005), and Male, female: The evolution of human sex differences (1998, 2010 second edition). The corresponding empirical work ranges from the study of changes in brain volume during hominid evolution to human mate choices to hormonal responses to simulated (video game) competition. Professor Geary's current interests in this area follow from several of his collaborative studies on the effects of prenatal toxin exposure on sex differences in cognition and behavior in mice. Specifically, traits related to Darwin's sexual selection are often exaggerated relative to other traits. These would include, for example, the bright plumage of the males of many species of bird that in turn is a good indicator of their behavioral and genetic health. These traits are particularly sensitive to environmental disruption, even in healthy individuals. Professor Geary's in progress book, The evolution of vulnerability, is focused on these traits in humans and how they can be used to identify at-risk populations and individuals.

Inhalt

Front Cover 1
Evolution of Vulnerability: Implications for Sex Differences in Health and Development 4
Copyright 5
Contents 6
Preface 10
Chapter 1: Vulnerability 12
The Value Added by an Evolutionary Perspective 14
Nonhuman Vulnerabilities 15
Human Vulnerabilities 18
Conclusion 20
Chapter 2: Sexual Selection and the Evolution of Vulnerability 22
Sexual Selection 23
Compete for or Choose Among Mates? 24
Rate of Reproduction 25
Operational Sex Ratio 26
Male-Male Competition 27
Physical Competition 28
Behavioral Competition 30
Brain and Cognitive Competition 32
Female Choice 35
Female-Female Competition and Male Choice 37
Reversed Sex Roles 37
Female-Female Competition and Social Selection 38
Male Choice 40
Expression of Condition-Dependent Traits 41
Genetic Variance and Inbreeding Depression 42
Parasites and Immunocompetence 44
Nutritional and Social Stressors 46
Toxins 48
Conclusion 49
Chapter 3: Condition-Dependent Traits in Birds and Fish 52
Birds 53
Organization of Reviews 54
Physical Traits 77
Color 77
Types of Color Signals 77
Conditional Dependent Signals 80
Takeaway Message 83
Size 84
Takeaway Message 86
Behavioral Traits 87
Takeaway Message 88
Brain and Cognitive Traits 89
Takeaway Message 91
Fish 91
Physical Traits 100
Color 100
Size 101
Behavioral Traits 102
Conclusion 102
Chapter 4: Condition-Dependent Traits in Arthropods and Mammals 106
Arthropods 107
Physical Traits 107
Color 108
Size 108
Behavioral Traits 123
Mammals 128
Physical Traits 128
Color 128
Size 134
Behavioral Traits 136
Scent 136
Behavior 140
Brain and Cognitive Traits 153
Conclusion 161
Chapter 5: Sexual Selection and Human Vulnerability 164
Vulnerability in Boys and Men 166
Physical Traits 170
Behavioral Traits 173
Brain and Cognitive Traits 177
Folk Psychology 178
Folk Physics 179
Brain 179
Vulnerability in Girls and Women 183
Physical Traits 183
Behavioral Traits 184
Brain and Cognitive Traits 187
Decoding Nonverbal Behavior and Facial Expressions 187
Language 188
Theory of Mind and Person Schema 189
Brain 190
Conclusion 192
Chapter 6: Human Vulnerability for Physical and Behavioral Traits 194
Physical Vulnerabilities 195
Skeletal Development 195
Height 196
Pelvic Development 209
Muscle Mass and Fat Reserves 214
Physical Fitness and Activity 215
Facial Features and Skin Attractiveness 217
Scent and Health 219
Behavioral Vulnerabilities 220
Children’s Play 221
Social Behavior 232
Social Signals 234
Risk Taking and Emotional Composure 235
Conclusion 239
Chapter 7: Human Vulnerability for Brain and Cognitive Traits 242
Cognitive Vulnerabilities 243
Folk Psychology 243
Theory of Mind and Emotion Recognition 243
Language 257
Folk Physics 263
Natural Stressors 271
Toxins 272
Testosterone and Antiandrogen Therapy 274
Brain vulnerabilities 276
Threat Detection and Emotion Regulation 276
Amygdala, Hippocampus, and Trauma 277
Men’s Condition-Dependent Hippocampus 288
Conclusion 291
Chapter 8: Implications for Human Health and Development 294
Defining and Assessing Well-being and Vulnerability 295
Assessing Vulnerability in Preschool Children 297
Assessing Vulnerability in School-Age Children and Adolescents 298
Assessing Vulnerability in Adults 300
Defining Stressors 300
Are All Natural Stressors Equal? 301
Toxins 303
Conclusion 305
References 306
Species Index for Tables 374
Author Index 380
Subject Index 414
Color Plate 424

Textauszug

Chapter 1

Vulnerability

Abstract

Evolution of vulnerability begins by reviewing the expansive literature on traits predicted to show sex-specific sensitivity to environmental and social stressors. It also details the implications for better assessing and understanding the consequences of exposure to these stressors. Next, the book reviews sexual selection – mate competition and choice – and the mechanisms involved in the evolution of condition-dependent traits and the stressors that can undermine their development and expression. These include poor early nutrition and health, parasites, social stress, and exposure to man-made toxins. Next, it reviews condition-dependent traits (physical, behavioral, cognitive, and brain) in birds, fish, insects, and mammals to demonstrate the ubiquity of these traits in nature. The focus then turns to humans and covers sex-specific vulnerabilities in children and adults regarding physical traits, social behavior, psychological wellbeing, and brain and cognitive traits. The sensitivity of these traits is related to the exposure to parasites, poor nutrition, social maltreatment, environmental toxins, chemotherapy, and Alzheimer’s disease, among others. The book concludes with a chapter on implications that outlines how to better assess vulnerabilities in children and adults, and how to more fully understand how, why, and when in development certain types of environmental and social stressors are particularly harmful to humans.

Keywords

Vulnerability

Sex differences

Evolution

Sexual selection

Social selection

Behavior

Brain

Cognition

Development

Children

Adults

Birds

Fish

Insects

Mammals

Toxins

Parasites

Social stressors

Malnutrition

Health

Disease

Wellbeing

Chapter Outline

The Value Added by an Evolutionary Perspective   3

Nonhuman Vulnerabilities   4

Human Vulnerabilities   7

Conclusion   9

The question of whether one sex or the other is more vulnerable to stressors is an intriguing and important one. Historically, the question has focused on the issue of male vulnerability (e.g., Greulich, 1951; Stini, 1969; Stinson, 1985). Even Darwin (1871) noted the excess of premature male mortality in many species, including the higher mortality of boys than girls during infancy. It is indeed the case that boys are more likely to die in infancy than girls, even with the dramatic declines in overall mortality over the past two centuries (Martin, 1949; Read, Troendle, & Klebanoff, 1997), and surviving boys are overrepresented among children with mild to serious medical or physical conditions (Jacobziner, Rich, Bleiberg, & Merchant, 1963). It is also the case that young men die at higher rates than young women – often as a direct result of male-on-male aggression (Wilson & Daly, 1985) or due to status seeking “showing off” (e.g., reckless driving; Evans, 2006) – and that men have a shorter life span than women (Allman, Rosin, Kumar, & Hasenstaub, 1998). These are certainly important vulnerabilities and can be placed in the context of the evolution of life histories (e.g., environmental influences on the timing of reproductive competition), some of which are discussed in Nesse and Williams’s (1996) introduction to evolutionary medicine (see also Belsky, Steinberg, & Draper, 1991; Ellis, 2004; Figueredo et al., 2006).

However, they are not my focus. Rather, I am interested in the more nuanced questions of why some traits – specific physical features, behaviors, or cognitive competencies – are more easily disrupted by exposure to stressors than others, and why these trait-specific vulnerabilities can differ between the sexes and across species. For instance, why does poor nutrition during adolescence affect the height and physical fitness of boys more than girls (Prista, Maia, Damasceno, & Beunen, 2003), but the early stage of Alzheimer’s disease affects the language competencies of women more than men (Henderson, Watt, & Galen Buckwalter, 1996)? In broader perspective, why does prenatal exposure to toxins compromise the spatial-navigation abilities of male deer mice (Peromyscus maniculatus), but leave unaffected the spatial abilities of same-species females or males of their cousin species, the California mouse (Peromyscus californicus; Jašarević et al., 2011; Williams et al., 2013). Vulnerability from a life history perspective, in contrast, is focused on how exposure to stressors influences the timing (not disruption) of reproductive traits, such as age of menarche, or modifies how sexual relationships are formed and maintained (Del Giudice, 2009; Ellis & Del Giudice, 2014). Again, these are important issues, but beyond the scope of what I wish to accomplish in this book.

My goal is to outline and provide evidence for a simple conceptual model – traits that have been elaborated through sexual or social selection are especially vulnerable to disruption by exposure to environmental and social stressors – that allows us to understand the vulnerabilities of adolescent boys, women with Alzheimer’s disease, and male deer mice, among many others, and places all of them in a unifying evolutionary context. The model enables the identification of sex- and species-specific traits whose development and expression are vulnerable to disruption by disease, poor nutrition, social stressors, and exposure to man-made toxins (e.g., environmental toxins and chemotherapy).

The concept that pulls cross-species vulnerabilities together is found with Darwin’s (1871) sexual selection – competition for mates and mate choices – and West-Eberhard’s (1983) social selection – competition for reproductively relevant resources (e.g., high-quality food) other than mates. The key is that these social dynamics result in the evolutionary exaggeration of traits that facilitate competition or that make one attractive to mates. These traits are either signaled directly (e.g., through physical size) or indirectly (e.g., through plumage coloration that is correlated with diet quality) and can be physical, behavioral, or involve brain and cognition, as will be illustrated in subsequent chapters. Whatever the trait, they are effective signals because they convey information about the individual’s level of exposure to stressors and the ability to cope with them.

Identifying these traits and the conditions that can disrupt their expression is complicated, however, because a trait that signals competitive ability, for instance, in one sex or species may or may not signal competitive ability in the other sex or in other, even closely related species (Andersson, 1994). For either sex or any species, the identification of vulnerable traits requires an understanding of the evolutionary history of the species, in particular the traits that facilitate competition for mates and other resources and that influence mate choices. I provide the background needed to understand competition and choice and the sensitivity of the associated traits to environmental and social stressors in Chapter 2 and illustrate the ubiquity and diversity of these traits in Chapters 3 and 4.

I then apply these same principles to humans and detail the traits that I predict will be more vulnerable to stressors in boys and men, and the traits that I predict will be more vulnerable in girls and women. The existing literature on human sex differences does not allow for an evaluation of all of these predictions, but I provide proof of concept illustrations of sex differences in physical and behavioral vulnerabilities in Chapter 6 and in brain and cognitive vulnerabilities in Chapter 7. Implications for understanding and studying the nuances of human vulnerabilities are discussed in Chapter 8. I outline some of the key points of subsequent chapters in the second section below. In the first, I provide a few thoughts on why an evolutionary perspective on human vulnerabilities is important.

The Value Added by an Evolutionary Perspective

There are many things in the world that can be harmful to people, including premature birth, pre- and postnatal exposure to toxins, poor nutrition, infestation with parasites, poverty, and childhood maltreatment, among others. Indeed, these risks are well recognized and in many cases extensively studied (e.g., Hotez et al., 2008; Kim & Cicchetti, 2003), but they have not been framed in terms of sex differences in risk. The key to fully understanding the consequences of exposure to these potential hazards is to understand the traits that are most likely to be affected by them, and when in development these traits are most likely to be disrupted. Without this knowledge, we may assess traits that are not strongly affected by risk exposure, miss those that are affected, or assess the right traits but at...

Produkt-Details

• Erscheint lt. Verlag: 28.7.2015
• Sprache: englisch
• Themenwelt: Geisteswissenschaften ► Psychologie ► Allgemeine Psychologie
• Themenwelt: Geisteswissenschaften ► Psychologie ► Biopsychologie / Neurowissenschaften
• Themenwelt: Geisteswissenschaften ► Psychologie ► Entwicklungspsychologie
• Themenwelt: Geisteswissenschaften ► Psychologie ► Sexualität / Partnerschaft
• Themenwelt: Geisteswissenschaften ► Psychologie ► Verhaltenstherapie
• Themenwelt: Naturwissenschaften ► Biologie ► Humanbiologie
• Themenwelt: Naturwissenschaften ► Biologie ► Zoologie
• Themenwelt: Sozialwissenschaften ► Soziologie ► Mikrosoziologie
• ISBN-10: 0-12-801747-3 / 0128017473
• ISBN-13: 978-0-12-801747-0 / 9780128017470