The distribution of Earlobe attachment and Cerumen type among Niger Deltans
Introduction: The objective of the study was to determine the distribution of two morpho-genetic traits namely cerumen type and earlobe attachment among Niger Deltans.
Methods: This observational research embraced descriptive cross-sectional survey method and involved the use of data form, direct observation and interviews. Cluster sampling was employed in this study which involved 2304 subjects. Cerumen types (dry and wet) were determined by visual examination. The two fold classification of earlobe attachment types by Powell and Whitney were followed in the study.
Results: The Niger Deltans displayed a higher frequency of attached ear lobes (58.98%) and a low frequency of free ear lobes (40.97%). The gender difference was not significant (P > 0.05). The wet cerumen was seen to be more frequent. The wet cerumen was seen to be more frequent in the females. The gender difference in the distribution of cerumen type was not significant (P > 0.05).
Conclusion: The distribution of earlobe attachment and cerumen type in the Niger Delta region has been documented. The Niger Deltans possess a higher frequency of attached ear lobes. The wet cerumen was more frequent in the females.
Keywords: Distribution, Earlobe, Attachment, Cerumen, Niger Deltans
Earlobe attachment refers to the way the bottom of the ear is connected to the head. “Free” dominant genes cause the ear to be lobed and the attachment to the head is genetically in an upward direction. The
recessive “attachment” gene results in an upward earlobe and a more horizontal attachment to the head (Lai and Walsh, 1966).
Figure 1: Photograph of attached earlobe
Two genetically determined types of cerumen (earwax) exist: the wet type, which is dominant, and the dry type, which is recessive. The wet type of earwax has a higher concentration of lipid and pigment granules (50% lipid) in the substance than the dry type (30% lipid) (Guest et al.,
Figure 2: Photograph of free earlobe
2004). Dry earwax is frequent in East Asians, whereas wet earwax is common in other populations (Yoshiura et al., 2006). Earwax type has been used by anthropologists to track human migratory patterns in some parts of the world (Bass and Jackson, 1977).
A study was done on the pattern of morphogenetic traits combination amongst the population of Ekpoma in Nigeria (Nwaopara et al., 2009). A remarkable research was done on morphogenetic traits combination pattern amongst the population of Ekpoma, Nigeria: focus on tongue rolling, ear lobe attachment, blood groups and genotypes (Nwaopara et al., 2008). A study considered the o c c u r r e n c e s o f t h e f r e q u e n c y d i s t r i b u t i o n o f morphological, genetical and behavioural traits among the people of Indian region (Bhasin et al., in 1992). The study area is the Niger Delta region in Nigeria. The Niger Delta is the southernmost region of Nigeria. Although it occupies ninety percent of the Nigerian coastline, it is specifically between the Mahin River estuary in the west and the Cross River estuary in the east. The region has been producing oil since 1956 (Enemugwem, 2010).
Literature search reveals dearth of data on the distribution of cerumen type and earlobe attachment in the Niger Delta Region in Nigeria. The objective of the study was to determine the distribution of morpho-genetic traits namely cerumen type and earlobe attachment among Niger Deltans. This study provides a comprehensive data for use in anthropology and forensic medicine.
MATERIALS AND METHODS
The study which is an observational research embraced the descriptive cross-sectional survey method and involved the use of data form, direct observation and interviews. Cluster sampling was employed in this study and the research involved 2304 subjects. The research subjects met the following criteria: Parents and grandparents must be from Niger Delta and subjects had no history of craniofacial trauma or disorder.
Cerumen types (dry and wet) were determined by visual examination. Any cerumen which was grey and flaky was regarded as dry. The wet type was the class for honey-brown to dark-brown and moist cerumen. The two fold classification of earlobe attachment types of Powell and Whitney (1937) were followed in the study. People with earlobes that curve up between the lowest point of the earlobe and the point where the ear joins the head were regarded as having free or unattached earlobes. Others with earlobes that blend in with the side of the head were noted as having attached earlobes. Ethical clearance was sought from the Research and Ethics Committee in the Faculty of Basic Medical Science of the Delta State University prior to the commencement of this research. All subjects were verbally informed about the aim of the study and they agreed to participate.
Data collection was done between the first day and the last day of the months of March and July respectively in the year 2013. Statistical analyses were performed using SPSS version 18. Results were arranged according to gender to ascertain the occurrence of sexual dimorphism. The chi-square test was useful in this regard. The morpho-genetic traits were compared between the genders. Values at P<0.05 were termed significant.
The results revealed that 1147 (49.79%) males and 1157 (50.21%) females participated in the present study.
Table 1: The distribution of earlobe attachment among Niger Deltans.
The Niger Deltans possess a higher frequency of attached ear lobes (58.98%) and a low frequency of free ear lobes (40.97%). The gender difference was not significant (P > 0.05).
Table 2: The distribution of cerumen type among Niger Deltans
Table 2 shows that the wet cerumen was seen to be more frequent. The wet cerumen was seen to be more frequent in the females. The gender difference was not significant (P > 0.05).
The frequency of dry cerumen was shown to be low (37.5%) in the sampled Niger Deltan population. This study did not agree with the high frequencies of dry type cerumen found in Eskimos of the Nome and Bethel areas of Alaska (Bass and Jackson, 1977). The frequencies of dry cerumen were also shown to be high in Mongoloid populations and low among Europoids. Intermediate frequencies were found among peoples of subequatorial Africa. Findings from some studies have exposed the potential for using cerumen type as a marker in population and anthropological studies (Ibraimov, 1991).
The present study did not concur with the findings of Yoshiura et al. (2006) who documented that dry earwax is seen in up to 95% of East Asians, but in no more than 3% of people of European and African origin. Yoshiura et al. (2006) also stated that populations in Southern Asia, the Pacific Islands, Central Asia, Asia Minor, and Native North Americans and those of Asian ancestry, fall in the middle with dry earwax incidence ranging from 30 to 50 percent. Petrakis et al. (1967) determined the occurrence of sticky and dry cerumen in 483 Indians from various tribes of the United States and saw elevated frequencies of the dry cerumen in Indians of pure ancestry. Among the Niger Deltans, dry cerumen was seen to have almost equal occurrences in males and females. This did not concur with
Singh and Sengupta who in 2004 did research on the Assamese Sikhs in India. They saw that dry cerumen was highly frequent in the males (61.54%), while the wet type predominated in females (55.77%). The present study concurred with that of Singh and Sengupta ( 2004) with reference to the non-significant gender difference (P > 0.05) seen in the cerumen type.
The present analysis of data on ear lobe attachment revealed an incidence of attached ear lobe of 58.98%. The frequency of attached ear lobes seen did not concur with Nwaopara et al., (2008) who reported 31.61% for attached earlobe and 63.39% for free earlobe. The present study did not concur with Kalia and Gupta (1978) who observed higher incidence of free ear lobes (73.84%). The present study did not concur to that where the frequency of free ear lobes was found to be in the range of 56% to 74% in five endogamous groups of Haryana by Yadav et al., (2000). The present analysis of data on ear lobe attachment differed from that by Singh and Sengupta in 2004 who researched on the Indians and saw that the frequency of free earlobe (83.65%) is higher than attached earlobe (16.35%). They observed that in females, frequency of free earlobe show relatively higher incidence (90.38%) than in the males (76.92%). The sex variation as revealed from their chi-square test was significant (0.01 >P) (Singh and Sengupta, 2004). This study did not concur with theirs as the males in this study had frequency of free earlobe which showed relatively higher incidence (21.66%) than that of the females (19.31%).
The distribution of earlobe attachment and cerumen type in the Niger Delta region has been documented. The Niger Deltans possess a higher frequency of attached ear lobes. The wet cerumen was more frequent in the females.
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