Changes in Cat Facial Morphology Are Related to Interaction with Humans

Citation Information

  • Authors: Hattori, M.; Saito, A.; Nagasawa, M.; Kikusui, T.; Yamamoto, S.

  • Title: Changes in Cat Facial Morphology Are Related to Interaction with Humans.

  • Journal: Animals 2022, 12, 3493.

  • DOI: https://doi.org/10.3390/ani12243493

  • Academic Editor: Leslie Irvine

  • Received: 27 October 2022

  • Accepted: 5 December 2022

  • Published: 10 December 2022

  • License: Creative Commons Attribution (CC BY) license

Simple Summary

  • Domesticated cats (Felis silvestris catus) have evolved significantly from their wild ancestors, the African wildcats (Felis silvestris lybica).

  • This study examines the changes in facial morphology—specifically nose length and eye angle—relative to human interaction.

  • Key findings include:

    • Owned domestic cats exhibit shorter noses and lower eye angles than feral and wild cats.

    • This change correlates with perceived cuteness.

    • Ferals not interacting with humans maintain facial features similar to wildcats.

Abstract

  • Aim: To clarify how interactions with humans affect cat facial morphology.

  • Study 1: Comparison of facial morphology among:

    • Ferals (mixed breed)

    • Owned domestic mixed breed cats

    • Domestic purebreds

    • African wildcats

  • Key Results: 3295 photos analyzed; significant morphological differences were observed, particularly in owned domestic cats.

  • Study 2: Correlation analysis showed no significant relation between facial morphology and years spent with owners, suggesting potential transgenerational morphological changes.

  • Study 3: Cuteness evaluations indicated that shorter noses correlate with higher cuteness ratings from humans.

Introduction

  • Human Interaction and Facial Perception: Humans judge various information from faces, including determining emotions and attractiveness.

  • Baby Schema: Defined as features (large heads, big eyes, short noses) that elicit caretaking responses from humans.

    • Effects: Faces exhibiting baby schema provoke positive emotions and a caregiving instinct in adults.

    • Relevance: Found in domestic animals, especially dogs, suggesting domestication impacts facial morphology in ways that appeal to humans.

  • Domestication Process of Cats:

    • Cats were domesticated around 10,000 years ago but maintained significant wild traits such as independence and predation behavior.

    • Previous studies yielded mixed results regarding domestication effects on brain and skull size.

  • Neotenous Characteristics: Demonstrated through changes in domestic animals' facial features (reduced brain size, differing facial structure).

  • Research Significance: Understand ongoing cat domestication and resultant morphological changes to improve human-animal relationships.

Materials and Methods

Study 1

  • Objective: To document facial morphology across cat subspecies with varying human interaction.

  • Sample Collection:

    • 50 African wildcat photos from various sources.

    • 150 feral mixed-breed cat photos (from Japanese conservation groups).

    • 661 owned domestic mixed breed photos solicited through social media.

    • 2434 photos of 60 purebred breeds collected online.

  • Morphometric Measurements (using Adobe Photoshop):

    • Nose Length: Adjusted by facial size (distance between eyes).

    • Eye Angles: Average tilt angles measured.

Study 2

  • Assessment: Effect of years living with owners on facial morphology based on data from the Feline Behavioral Assessment and Research Questionnaire (Fe-BARQ).

  • Statistical Tools: Used GLMs with Poisson distribution.

Study 3

  • Objective: To evaluate human perceptions of cuteness and morphological impacts.

  • Participant Data: 355 individuals completed an online questionnaire.

  • Experimental Design: Used altered images to assess specific features and respond to cuteness ratings.

Results

Study 1 Results

  • Measured nose lengths and eye angles among groups:

    • Nose Length Means (Adjusted):

    • African wildcats: 1.34 (SD = 0.11)

    • Feral mixed breed: 1.32 (SD = 0.17)

    • Owned domestic mixed breed: 1.23 (SD = 0.14)

    • Owned domestic purebreds: 1.14 (SD = 0.21)

    • Eye Angles Means:

    • African wildcats: 25.61 (SD = 3.06)

    • Feral mixed breed: 25.10 (SD = 3.57)

    • Owned domestic mixed breed: 25.31 (SD = 3.67)

    • Owned domestic purebreds: 22.77 (SD = 2.36)

  • Statistical Analysis:

    • Significant differences in both measurements, highlighting morphological adaptations as a result of domestic interactions.

Study 2 Results

  • Correlation between years with the owner and facial traits was revealed for eye angles (p = 0.04) but not nose length.

  • Suggests eye angle changes may be due to aging rather than directly from domestication.

Study 3 Results

  • Cuteness ratings ranked:

    • Owned domestic mixed breed: Highest (normDS = 2.28)

    • Feral mixed breed: Next (normDS = 1.69)

    • Owned domestic purebreds: Third (normDS = 1.68)

    • African wildcats: Lowest (normDS = 0.33)

Discussion

  • Implications to Maintain Neotenous Characteristics through Domestication.

  • Ownership duration's limited impact suggests morphological changes are primarily transgenerational rather than acquired.

  • Functional and aesthetic shifts in feline morphology affect human preferences reinforcing cat companion status.

  • The morphological disparity seen between feral cats and their domestic counterparts may indicate a return to wild features, termed 'feralization.'

Conclusions

  • Significant changes in cat facial morphology related to human interaction have been documented, influencing perceived cuteness which impacts human caretaking behavior—key to understanding cat domestication and its implications for future coexistence with humans.

Limitations and Future Directions

  • Need for longitudinal studies to ascertain individual changes in facial morphologies and behaviors within the same cats.

  • Future studies should clarify dietary influences on morphology and explore a broader range of morphological features beyond noses.

Here are some discussion questions related to the changes in cat facial morphology and their implications:

  1. How do you think domestication has influenced the evolution of cat behaviors and traits?

  2. In what ways does human interaction shape animal morphology beyond just cats?

  3. Considering the study's findings, what implications do you think there are for the future of cat breeding?

  4. What role does the concept of 'cuteness' play in the human-animal relationship?

  5. How might environmental factors and living conditions affect the morphological traits of domestic cats?