Animal attraction: some similarities in human and non-human animal mate-choice

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Animal attraction some similarities in human
and non-human animal mate-choice

• Anthony Little

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Symmetry in Animals
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Preferences for Symmetry
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Non-Human Species Preferences for Symmetry

• Scorpion fly females prefer males with
  symmetrical bodies
• All animals prefer symmetry in their mates. The
  male Japanese scorpion flies with the most
  symmetrical wings gets the most mates."

Thornhill, 1992
Gil Grissom, CSI, Season 2
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Non-Human Species Preferences for Symmetry

• Female barn swallows prefer males with
  symmetrical tail feathers
• Female zebra finches prefer symmetrical males

Møller, 1994, Anim Behav
Swaddle Cuthill, 1994, Nature
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Symmetry

• Most features are supposed to be symmetrical
• Deviation from symmetry reflects imperfect
  development
• Symmetry a measure of quality

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Measuring Symmetry
Attractiveness ratings of women correlate with
measured symmetry
Grammer Thornhill, 1994, JCP Penton-Voak et
al., 2001, PRSB
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Symmetry Manipulation
The lower images are made using the left/right
average of the 224 feature points (only 4 are
Marked here)
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Original
Symmetric
Symmetry is found attractive
Perrett et al., 1999, EHB
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Symmetry is More Associated with Attractiveness
in Opposite-Sex Faces
Little et al., 2008, Behavioural Ecology
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The Hadza of Tanzania

• Live in small bands
• Hunt with bows and arrows
• Gather roots, tubers and wild fruits
• Conditions representative of human evolution?

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Hadza Face Preferences
Symmetry
symmetric
original
5 pairs
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Hadza Face Preferences
Symmetry
original
symmetric
5 pairs
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Little, Apicella, Marlowe (2007) Proc Royal Soc
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Macaque Preferences
Symmetry
Preferred by females
asym
sym

• Gaze longer at symmetrical face

Waitt Little (2006) IJP
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Relationships between Sexual Dimorphism and
Symmetry
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Measuring Symmetry Sexual dimorphism
Penton-Voak, et al. 2001, Proc Royal Soc
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Hadza, Europeans, Macaques

• Measured symmetry and masculinity in
• 70 Hadza, 177 European, 123 Macaques
• Males

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Hadza, Europeans, Macaques

• Correlation between S and M in all
• Suggests common origin to development
• Good-genes? Good environment?

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Conclusions

• We can examine the importance of certain traits
  across species
• Many animals prefer symmetric mates
• Facial asymmetry appears linked to other
  important traits in primates

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Conclusions

• There are some broad similarities between humans
  and other animals
• Understanding how other animals choose their
  mates can help us understand behaviour in humans
• ...and vice versa