SEXUAL SELECTION AND VOCALIZATION IN HUMANS AND NONHUMAN ANTHROPOID ...

142 Pages·2014·2.15 MB·English

The Pennsylvania State University
The Graduate School
College of the Liberal Arts

SEXUAL SELECTION AND VOCALIZATION IN
HUMANS AND NONHUMAN ANTHROPOID PRIMATES

A Dissertation in
Anthropology
by
Alexander Kirkland Hill

© 2014 Alexander Kirkland Hill

Submitted in Partial Fulfillment
of the Requirements
for the Degree of

Doctor of Philosophy

May 2014
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The dissertation of Alexander Kirkland Hill was reviewed and approved* by the following:

David A. Puts
Associate Professor of Anthropology
Dissertation Advisor
Chair of Committee

Nina G. Jablonski
Distinguished Professor of Anthropology

Mark D. Shriver
Professor of Anthropology

Daniel J. Weiss
Associate Professor of Psychology and Linguistics

Drew Rendall
Professor of Psychology, University of Lethbridge, Canada
Special Member

George R. Milner
Professor and Head of Anthropology

*Signatures are on file in the Graduate School.
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ABSTRACT
This dissertation consists of three studies focusing on sexual selection and vocalizations.
The first study explores the influence of sexual selection on vocalizations in nonhuman
anthropoids. Recordings of 1451 vocalizations from 40 species were measured for vocal
fundamental frequency (F ), the acoustic correlate of pitch. Data on mating system, habitat, and
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male and female body size were collected for these species. Controlling for body size sexual
dimorphism, we found that males had relatively lower F compared to females in polygynous
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species than in monogamous species, indicating that sexual selection favors lower F among
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anthropoids.
The second study focuses on men’s vocal, facial, and body masculinity in order to
evaluate the relative influence of individual traits on mating success and the mechanisms, form,
and direction of these sexual selective pressures. We ascertained men's dominance and
attractiveness from male and female acquaintances. On a large American university campus, 63
men from two social fraternities provided anthropometric measurements, facial photographs,
voice recordings, and reported mating success (number of sexual partners). These men assessed
each other's dominance, and 72 women from two socially affiliated sororities assessed the men's
attractiveness. We measured facial masculinity from inter-landmark distances and vocal
masculinity from acoustic parameters. We additionally obtained facial and vocal attractiveness
and dominance ratings from unfamiliar observers. Results indicate that dominance and the traits
associated with it predict men's mating success, but attractiveness and the traits associated with it
do not.
The final study concerns relationships between the human voice and fluctuating
asymmetry (FA), a putative biomarker for genetic quality. We explored these relationships in
three samples representing both US university participants (Study 1: n=91 males; Study 2: n=151
males and 233 females) and Tanzanian hunter-gatherer participants (Study 3: n=51 males and 64
females). Voice recordings were collected and rated for attractiveness, and measures of FA were
computed from two- and three-dimensional facial images, as well as finger lengths. Only among
Study 2 females did we observe the previously-documented negative relationship between vocal
attractiveness and FA as measured from two-dimensional facial imagery. No relationship was
found between vocal attractiveness and three-dimensional FA.
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TABLE OF CONTENTS

List of Tables .............................................................................................................................. vii
List of Figures ............................................................................................................................ viii
Preface.......................................................................................................................................... ix

CHAPTER ONE: FOUNDATIONS OF THE RESEARCH ........................................................ 1
1.0 Introduction ................................................................................................................. 2
2.0 Acoustics ..................................................................................................................... 3
3.0 Sexual selection and vocal fundamental frequency across anthropoid primates ........ 4
4.0 Quantifying the strength and form of sexual selection on men’s traits ...................... 7
5.0 The silence of symmetry? Revisiting relationships between attractiveness and
fluctuating asymmetry ................................................................................................ 8
6.0 Summary ................................................................................................................... 10
Bibliography ................................................................................................................... 11
CHAPTER TWO: SEXUAL SELECTION AND VOCAL FUNDAMENTAL
FREQUENCY ACROSS ANTHROPOID PRIMATES ................................................ 18
1.0 Introduction ............................................................................................................... 19
2.0 Methods..................................................................................................................... 21
2.1 Data collection .............................................................................................. 21
2.2 Acoustic measurement ................................................................................. 26
2.3 Additional data .............................................................................................. 27
2.4 Statistical approach ....................................................................................... 27
3.0 Results ....................................................................................................................... 32
3.1 Habitat and sexual dimorphism in F ............................................................ 32
0
3.2 Mating system and sexual dimorphism in F ................................................ 32
0
3.3 Fundamental frequency and body size .......................................................... 32
4.0 Discussion ................................................................................................................. 36
5.0 Limitations ................................................................................................................ 38
6.0 Acknowledgements ................................................................................................... 39
7.0 Collaborators to receive co-authorship upon publication of this chapter ................. 39
Bibliography ................................................................................................................... 40
Appendix A: Researchers and institutions providing nonhuman primate
vocalizations, and the species provided by each ................................................. 44
Appendix B: Sources for body weight data per species ................................................. 46
CHAPTER THREE: QUANTIFYING THE STRENGTH AND FORM OF SEXUAL
SELECTION ON MEN’S TRAITS................................................................................ 55
1.0 Introduction ............................................................................................................... 56
2.0 Methods..................................................................................................................... 58
2.1 Participants .................................................................................................... 58
2.2 Participant procedures ................................................................................... 58
2.3 Independent male and female rater procedures ............................................ 59
2.4 Data treatment ............................................................................................... 60
2.5 Statistical analysis ......................................................................................... 61
3.0 Results ....................................................................................................................... 62
3.1 Female choice ............................................................................................... 62
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3.2 Male contests ................................................................................................ 64
3.3 Female choice vs. contests ............................................................................ 66
3.4 Mating success .............................................................................................. 66
3.5 Additional analyses ....................................................................................... 68
3.5.1 Subjective ratings of faces and voices ........................................... 68
3.5.2 Sociosexuality ................................................................................ 69
4.0 Discussion ................................................................................................................. 69
5.0 Acknowledgements ................................................................................................... 73
6.0 Collaborators who received co-authorship upon publication of this chapter ........... 73
Bibliography ................................................................................................................... 74
Appendix A: Descriptive statistics for male participants ............................................... 80
Appendix B: The vector of standardized linear selection gradients (β) and the
matrix of standardized quadratic and correlational selection gradients (γ)
for the four male traits (with facial and vocal attractiveness replacing
facial and vocal masculinity) operating through female choice, male
contests and mating success ................................................................................ 81
Appendix C: The M matrix of eigenvectors from the canonical analysis of γ in
Appendix B for female choice and mating success ............................................ 82
Appendix D: The vector of standardized linear selection gradients (β) and the
matrix of standardized quadratic and correlational selection gradients (γ)
for the four male traits (with facial and vocal dominance replacing facial
and vocal masculinity) operating through female choice, male contests
and mating success .............................................................................................. 83
Appendix E: The M matrix of eigenvectors from the canonical analysis of γ in
Appendix D for male contests and mating success ............................................. 84
Appendix F: The vector of standardized linear selection gradients (β) and the
matrix of standardized quadratic and correlational selection gradients (γ)
for five male traits operating through mating success ........................................ 84
Appendix G: The M matrix of eigenvectors from the canonical analysis of γ in
Appendix F for mating success ........................................................................... 85
Appendix H: The vector of standardized linear selection gradients (β) and the
matrix of standardized quadratic and correlational selection gradients (γ)
for the influence of men’s attractiveness, dominance and sociosexuality
on mating success ............................................................................................... 85
Appendix I: The M matrix of eigenvectors from the canonical analysis of γ in
Appendix H ......................................................................................................... 85
CHAPTER FOUR: THE SILENCE OF SYMMETRY? REVISITING RELATIONSHIPS
BETWEEN ATTRACTIVENESS AND FLUCTUATING ASYMMETRY ................ 86
1.0 Introduction ............................................................................................................... 87
2.0 Study 1 ...................................................................................................................... 90
2.1 Participants .................................................................................................... 90
2.2 Three-dimensional facial data ....................................................................... 90
2.3 Two-dimensional facial and finger length data ............................................ 91
2.4 Voice recordings ........................................................................................... 92
3.0 Study 2 ...................................................................................................................... 93
3.1 Participants .................................................................................................... 93
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3.2 Procedures ..................................................................................................... 93
4.0 Study 3 ...................................................................................................................... 94
4.1 Participants .................................................................................................... 94
4.2 Procedures ..................................................................................................... 94
4.2.1 Anthropometry and fluctuating asymmetry ................................... 94
4.2.2 Voice .............................................................................................. 95
5.0 Results ....................................................................................................................... 95
5.1 Study 1 .......................................................................................................... 96
5.1.1 Vocal attractiveness and masculinity ............................................. 96
5.1.2 Facial attractiveness and masculinity............................................. 96
5.2 Study 2 .......................................................................................................... 97
5.2.1 Vocal attractiveness and masculinity ............................................. 97
5.2.2 Facial attractiveness and masculinity........................................... 100
5.3 Study 3 ........................................................................................................ 101
6.0 Discussion ............................................................................................................... 102
6.1 Fluctuating asymmetry................................................................................ 102
6.2 Masculinity ................................................................................................. 106
7.0 Limitations .............................................................................................................. 106
8.0 Conclusions and future directions ........................................................................... 107
9.0 Acknowledgements ................................................................................................. 107
10.0 Collaborators to receive co-authorship upon publication of this chapter ............. 107
Bibliography ................................................................................................................. 108
Appendix A: Zero-order Pearson correlations for measures of attractiveness,
masculinity, and vocal parameters among Study 1 males ................................ 116
Appendix B: Zero-order Pearson correlations for measures of attractiveness
and masculinity among Study 2 males.............................................................. 116
Appendix C: Zero-order Pearson correlations for measures of attractiveness
and masculinity among Study 2 females .......................................................... 116
Appendix D: Zero-order Pearson correlations for measures of fluctuating
asymmetry among Study 1 males ..................................................................... 117
Appendix E: Zero-order Pearson correlations for measures of fluctuating
asymmetry among Study 2 males ..................................................................... 117
Appendix F: Zero-order Pearson correlations for measures of fluctuating
asymmetry among Study 2 females .................................................................. 117
Appendix G: Zero-order Pearson correlations for measures of fluctuating
asymmetry among Study 3 males ..................................................................... 117
Appendix H: Zero-order Pearson correlations for measures of fluctuating
asymmetry among Study 3 females .................................................................. 118
Appendix I: Descriptive statistics of variables for Study 1 males ................................ 118
Appendix J: Descriptive statistics of variables for Study 2 males ................................ 118
Appendix K: Descriptive statistics of variables for Study 2 females ........................... 119
Appendix L: Descriptive statistics of variables for Study 3 males ............................... 119
Appendix M: Descriptive statistics of variables for Study 3 females ........................... 119
CHAPTER FIVE: FINAL REMARKS ON THE RESEARCH ............................................... 120
Bibliography ................................................................................................................. 128
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LIST OF TABLES

Table 1. Number of vocalizations by sex for each primate species ............................................ 23
Table 2. Mean F , F IQR, and body weight by sex, as well as habitat, social system,
0 0
and mating system for each species ................................................................................ 29
Table 3. The vector of standardized linear selection gradients (β) and the matrix of
standardized quadratic and correlational selection gradients (γ) for the four
male traits operating through female choice, male contests and mating success ........... 64
Table 4. The M matrix of eigenvectors from the canonical analysis of γ in Table 3
for female choice, male contests and mating success ..................................................... 65
Table 5. The vector of standardized linear selection gradients (β) and the matrix of
standardized quadratic and correlational selection gradients (γ) for the
influence of men’s attractiveness and dominance on mating success ............................ 68
Table 6. The M matrix of eigenvectors from the canonical analysis of γ in Table 5 .................. 68
Table 7. Zero-order Pearson correlations for measures of FA and attractiveness
among Study 1 males ...................................................................................................... 96
Table 8. Zero-order Pearson correlations for measures of FA, masculinity, and vocal
parameters among Study 1 males ................................................................................... 96
Table 9. Zero-order Pearson correlations for measures of FA and vocal attractiveness
and FA and facial attractiveness among Study 2 females ............................................... 98
Table 10. Zero-order Pearson correlations for measures of FA and vocal and facial
attractiveness among Study 2 males ............................................................................... 99
Table 11. Zero-order Pearson correlations for measures of FA and masculinity among
Study 2 males ................................................................................................................ 101
Table 12. Zero-order Pearson correlations for measures of FA and masculinity among
Study 2 females ............................................................................................................. 101
Table 13. Zero-order Pearson correlations for measures of FA, vocal attractiveness,
and vocal parameters among Study 3 males ................................................................. 102
Table 14. Zero-order Pearson correlations for measures of FA, vocal attractiveness,
and vocal parameters among Study 3 females .............................................................. 102
Table 15. Relationships between FA and vocal and facial attractiveness and
masculinity/femininity across samples ....................................................................... 103
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LIST OF FIGURES

Figure 1. Possible relationships among fundamental frequency, dominance,
attractiveness, mating success, and reproductive success ................................................. 6
Figure 2. Causal model used in the present work ....................................................................... 22
Figure 3. Edit window in the acoustics software program Praat ................................................ 28
Figure 4. Phylogenetic tree with sexual dimorphism in F in extant anthropoids,
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and inferred sexual dimorphism in F in the last common ancestors of
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these species .................................................................................................................... 33
Figure 5. Relationship between male F /female F and mating system adjusted for
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sexual size dimorphism, but without controlling for phylogeny .................................... 34
Figure 6. Relationship between male F /female F and mating system when
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controlling for sexual size dimorphism and phylogeny .................................................. 35
Figure 7. Linear (β) and quadratic (γ) relationships between men’s traits, success
under female choice and male contests, and mating success .......................................... 63
Figure 8. Correlational selection on eigenvectors m and m under female
1 4
choice, male contests, and mating success................................................................... 67
Figure 9. Relationship between facial attractiveness and facial FA among Study 1 males ........ 97
Figure 10. Relationship between vocal attractiveness and facial FA among Study 2 females ... 98
Figure 11. Relationship between vocal attractiveness and total FA among Study 2 females .... 99
Figure 12. Relationship between facial attractiveness and total FA among Study 2 females .. 100
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PREFACE
I was the chief researcher involved in the studies reported in this dissertation and my
contributions thus comprised a larger percentage of the work than did those of any of my
collaborators. These contributions included (1) managing the execution of all three projects, (2)
submitting Internal Review Board requests, (3) developing protocols for data collection, (4)
collecting the data (with the exception of data used in the second and third studies described in
Chapter Four, which were collected previously by my adviser and one of my collaborators), (5)
training and scheduling Puts lab research assistants and overseeing their work, (6)
troubleshooting problems, (7) facilitating and participating in statistical analyses, (8) writing and
editing the manuscript contained herein, and (9) successfully defending the research on
November 22nd, 2013 before the members of my dissertation committee.
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To my parents and the members of the Puts Lab, 2008-2014