Earlobes Information
The human earlobe is composed of tough areolar and adipose (fatty) connective tissues, lacking the firmness and elasticity of the rest of the pinna. Since the earlobe does not contain cartilage it has a large blood supply and may help to warm the ears and maintain balance. However earlobes are not generally considered to have any major biological function.[1] The earlobe contains many nerve endings, and for some people is an erogenous zone.
Size and shape
Earlobes average about 2 cm long, and elongate slightly with age.[2] Whether the earlobe is free or attached is a classic example of a simple genetic dominance relationship; freely hanging earlobes are the dominant allele and attached earlobes are recessive. Therefore, a person whose genes contain one allele for free earlobes and one for attached lobes will display the freely hanging lobe trait. It is a common misconception that this implies a precise 3-to-1 ratio between free and attached lobes in the human population. Such a ratio would require that the allele frequency for free lobes were precisely 50%, which there is no reason to assume. The frequency of attached earlobes among Japanese subjects is 67.1%, and among Chinese subjects, it is 64.3%.[3]
| A free earlobe | An attached earlobe, with piercing and tattoo |
Earlobes are normally smooth, but occasionally exhibit creases. Creased earlobes are associated with genetic disorders, including Beckwith-Wiedemann syndrome. Earlobe creases are also associated with an increased risk of heart attack and coronary heart disease; however, since earlobes become more creased with age, and older people are more likely to experience heart disease than younger people, age may account for the findings linking heart attack to earlobe creases.[4] However, this correlation proved to be untrue in persons of Asian descent (Chinese and Japanese) and Native American Indians. See Frank's Sign.
Earlobe piercing
Tutankhamen displaying a stretched earlobe piercing.Around the world and throughout human history, the earlobe is the most common location for a body piercing.
References
- ^ Popelka, Gerald (August 31 1999). "Re:Why do we have earlobes, what are they for, since when?". MadSci Network. http://www.madsci.org/posts/archives/aug99/934627537.Ev.r.html.
- ^ Azaria R, Adler N, Silfen R, Regev D, Hauben DJ (June 2003). . Plast. Reconstr. Surg. 111 (7): 2398–402; discussion 2403–4. doi:10.1097/01.PRS.0000060995.99380.DE. PMID 12794488. .
- ^ Lai LY, Walsh RJ (1966). "Observations on ear lobe types". Acta Genet Stat Med 16 (3): 250–7. PMID 5953713.
- ^ MedlinePlus Encyclopedia Earlobe Creases
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Sat, 04 Dec 2010 04:53:36 GMT
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