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Directional and fluctuating asymmetry in the palmar interdigital ridge-counts
Summary
This study on German adults found directional differences in palm print ridge counts between left and right hands. Females showed greater asymmetry than males, suggesting developmental stability influences these patterns.
Area of Science:
- Anthropometry
- Human genetics
- Developmental biology
Background:
- Palmar interdigital ridge-counts are used in anthropometric studies.
- Asymmetry in bilateral traits can reflect developmental stability.
Purpose of the Study:
- To investigate directional and fluctuating asymmetry in palmar interdigital ridge-counts (c-d, b-c, a-b).
- To examine sex differences in these asymmetries.
- To explore the relationship between asymmetry and developmental stability.
Main Methods:
- Analysis of palmar interdigital ridge-counts (c-d, b-c, a-b) in a large German sample (1186 males, 1042 females).
- Statistical evaluation of directional asymmetry (DA) and fluctuating asymmetry (FA).
- Correlation and regression analyses to assess relationships between asymmetry and trait expression.
Main Results:
- The c-d and b-c ridge-counts were higher on the right side, while a-b was higher on the left.
- Females exhibited significantly larger left-sided values for all three counts compared to males.
- Fluctuating asymmetry (magnitude of L-R) was highest for c-d, followed by a-b.
- A significant quadratic relationship between FA magnitude and total ridge-count (R+L) was observed for c-d and a-b, indicating greater asymmetry in extreme phenotypes.
Conclusions:
- Palmar ridge-counts display significant directional and fluctuating asymmetries with notable sex differences.
- Extreme phenotypes in certain ridge-count areas are associated with higher fluctuating asymmetry.
- These findings support the interpretation of fluctuating asymmetry as a sensitive indicator of developmental stability.