Sex differences in facial asymmetry indices among Hausa ethnic group of Nigeria

Lawan Hassan Adamu, Samuel Adeniyi Ojo, Barnabas Danborno, Samuel Sunday Adebisi, Magaji Garba Taura

Annals of Bioanthropology 2016 4(2):105-110

Background: Evaluation of facial symmetry in a given population may help in understanding the level of environmental stress exposed by the population. Within the same population, males and females may respond differently to environmental stressors, which can be manifested as deviation from perfect symmetry. Objectives: The study seeks to investigate the sex differences in three asymmetry indices and to also determine the side dominance and type of asymmetry in facial features among Hausas of Kano state, Nigeria. Materials and Methods: A cross-sectional study carried out on Hausas of Kano state. A total of 283 individuals comprising 147 males and 136 females of age range 18–25 years were selected using simple random sampling technique. Photometric methods were used to capture the face. Three indices, signed asymmetry (SA), absolute asymmetry (AA), and composite asymmetry (CA), were used to assess asymmetry in facial dimensions. Independent sample t-test was used to test for sex differences in the variables, and one sample t-test was used to determine fluctuating asymmetry. Results: The result showed that females tend to have statistically significant mean value only in orbital width. For zygon to gnathion facial distance, the statistically significant higher mean was observed in males. For the three indices asymmetry, no significant sexual dimorphism in SA index was observed. However, males tend to have leftward SA in orbital width and zygon to gnathion distance. In AA and CA, a significant sexual dimorphism was noticed only in zygon to gnathion distance. Females had higher mean value in AA than the males; however, CA tended to be higher in male population. The facial variables exhibited fluctuating type of asymmetry. Conclusion: There are sex differences in AA and CA indices. Left warded type of SA was exhibited in male of Hausa origin. The facial asymmetry in Hausa ethnic group of Kano is more of fluctuating type of asymmetry.

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