Attached earlobe: The myth

Some civilization have earlobes that curve up between the lowest allude of the earlobe and the allude where the ear joins the head; these are known as "free" or "unattached" earlobes, as displayed in the upper left that the picture below. Other human being have earlobes the blend in v the side of the head, known as "attached" or "adherent" earlobes, as shown in the reduced right.

You are watching: One attached and one detached earlobe

Attached vs. Complimentary earlobes are regularly used come illustrate basic genetics. The myth is that earlobes have the right to be split into right into two clean categories, totally free and attached, and that a solitary gene controls the trait, with the allele for complimentary earlobes being dominant. Neither component of the myth is true.

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Earlobes ranging from unattached (upper left) to attached (lower right).
The reality

Earlobes as a character

Classroom practice on earlobe genetics say the there are two distinctive categories, free (F) and also attached (A). However, countless of the papers on earlobe genetics have mentioned that there space many civilization with intermediary earlobes (Quelprud 1934, Wiener 1937, Dutta and Ganguly 1965). El Kollali (2009) share earlobes into three types, based upon whether the attachments angle to be acute, right, or obtuse. To make the snapshot above, i searched for pictures of expert bicyclists (because lock have brief hair), discovered 12 v their ears showing, and also arranged lock from free to attached. It doesn"t look come me as if over there are simply two categories; instead, there is constant variation in the height of the attachment point (the "otobasion inferius") relative to the lowest suggest on the earlobe (the "subaurale"). My very own earlobes are exactly halfway in in between the 2 extremes; i couldn"t call you whether my earlobes have to be considered complimentary or attached.

Family studies

Carrière (1922) and also Hilden (1922) were among the very first to examine the genetics of earlobes, and they got to opposite conclusions. Carrière (1922) looked in ~ 15 families and also concluded that attached earlobes were dominant. However, every one of the offspring that A x A matings had actually attached earlobes, and also there to be no F x F matings, therefore his data are continual with either free or attached gift dominant.

Powell and Whitney (1937) looked at one family and also concluded that attached earlobes to be recessive. Wiener (1937) comment by stating that the "arbitrary classification into two sharply defined types...gives a false picture, due to the fact that all gradations in between the 2 extremes space encountered." He split earlobes into 4 arbitrary groups, native 0 (completely free) come 3 (completely attached). All feasible matings, from completely 0 x 0 come 3 x 3, developed some intermediary earlobes. Wiener (1937) concluded that earlobes were established by much more than one gene, or by a singe gene with more than 2 alleles.

Lai and also Walsh (1966) dubbed earlobes in i beg your pardon the lowest point on the earlobe to be the attachment allude "attached," and also they share all other earlobes as "free." They taped the complying with data on households in brand-new Guinea:

Parents F offspring A offspringPercent FF x F 12 2235%F x A 72 11439%A x A 37 9029%

If the myth were true, two parents with attached earlobes could not have a boy with a cost-free earlobe. There space slightly much more A offspring indigenous A x A matings, but the big numbers the F offspring native A x A matings and also A offspring indigenous F x F matings indicate that this is not a one-locus, two-allele trait.

Mohanraju and Mukherjee (1973) perform a comparable study in India and also found similar results:

Parents F offspring A offspringPercent FF x F 13 193%F x A 7 750%A x A 5 2915%

They discovered a lot stronger association between parents and also offspring, but the 5 F offspring that A x A matings room inconsistent through the myth the this is a one-locus, two-allele trait.

Conclusion

Earlobes execute not autumn into 2 categories, "free" and "attached"; over there is continuous variation in attachments point, indigenous up near the ear cartilage come well below the ear. While over there is more than likely some genetic influence ~ above earlobe attachment point, household studies show that that does no fit the basic one-locus, two-allele myth. You should not use earlobe attachments to demonstrate basic genetics.

References

Carrière, R. 1922. Über erbliche Orhformen, insbesondere das angewachsene Ohrläppchen. Zeitschrift für Induktive Abstammungs- und Vererbungslehre 28: 288-242.

Dutta, P., and also P. Ganguly. 1965. Additional observations on ear lobe attachment. Acta Genetica 15: 77-86.

El Kollali, R. 2009. Earlobe morphology: a simple classification of normal earlobes. Journal of Plastic, Reconstructive and Aesthetic surgical treatment 62: 277-280.

Hilden, K. 1922. Über die form des Ohrläppchens beim Menschen und ihre Abhängigkeit von Erblanglagen. Hereditas 3: 351-357.

Lai, L.Y.C., and R.J. Walsh. 1966. Observations on ear lobe types. Acta Genetica 16: 250-257.

Mohanraju, C., and D.P. Mukherjee. 1973. Ear lobe attachment in one Andhra town and other parts the India. Human Heredity 23: 288-297.

Mowlavi, A., D.G. Meldrum, and also B.J. Wilhelmi. 2004. Earlobe morphology delineated by 2 components: the enclosed cephalic segment and also the cost-free caudal segment. Plastic and also Reconstructive surgical procedure 113: 1075-1076.

Powell, E.F., and D.D. Whitney. 1937. Ear lobe inheritance: an unexplained three-generation photographic pedigree chart. Newspaper of Heredity 28: 184-186.

Quelprud, T. 1934. Familienforschungen über Merkmale des äusseren Ohres. Zeitschrift fü Induktive Abstammungs- und Vererbungslehre 67: 296-299.

Wiener, A.S. 1937. Complications in ear genetics. Journal of Heredity 28: 425-426.

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return to John McDonald"s homepage This web page was last revised December 8, 2011. Its address is http://betterworld2016.org/~mcdonald/mythearlobe.html. It may be cited together pp. 14-16 in: McDonald, J.H. 2011. Myths of human Genetics. Sparky home Publishing, Baltimore, Maryland.©2011 by man H. McDonald. You can probably carry out what friend want v this content; view the permissions page for details.