| Earlobe | |
|---|---|
| Latin | lobulus auriculae (singular), lobuli auricularum (plural) |
| Gray's | subject #229 1034 |
| System | Auditory system |
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.
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]
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.
Around the world and throughout human history, the earlobe is the most common location for a body piercing. It is common to tear the earlobe with the weight of very heavy earring, or a traumatic pull of an earring. Some cultures practice earlobe stretching, using piercing ornaments to stretch and enlarge the earlobes. Sailors used to believe that piercing one earlobe gave greater acuity in the opposite ear.
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