How Your Genes Shape Your Ear Lobes
Like the face, the way your ear looks is a unique feature of your body. Although ears look similar, there are small differences in shape and structure of the pinna between different people. One of the features that is less variable is the shape of the earlobe; people can only have one of two types of earlobe. The first is an attached earlobe that is small, and has no free flap that hangs down. The second type is a free earlobe, which is larger and which does hang down, clearly separated from the neck.
What is the Structure and Function of the Earlobe?
The composition of the earlobe in humans is fairly simple’ it contains connective tissue, which is made up of a mixture of fat cells and areola tissue. It has quite a good blood supply and your earlobes can be prone to turning bright red if you go from a cold day outside to a very warm room, or even if you blush with embarrassment. There is no cartilage in the earlobe – so it is soft and squishy compared to the harder, more structure parts of the upper pinna.
The function of the earlobe is something of a mystery. It doesn’t seem to do anything very much, except be a site for piercings and earrings. Losing your earlobe in an accident is rare, but it does not affect hearing or balance, its impact is really only cosmetic.
The Genetics of Earlobe ShapeOnly one gene controls the shape of the earlobe. As with all genes, you have two copies, one from your father and one from your mother. Each copy is called an allele. The allele for a free earlobe is dominant over the allele for an attached earlobe, so most people do have free earlobes. If you have parents with free earlobes and you have an attached earlobe, you can be pretty confident that both of them had one copy of the dominant allele and one copy of the recessive allele. You were the result of a one in four chance – you inherited one recessive allele from both your parents.
Although this is widely accepted, some other factors in the way that our ancestry has developed over thousands of years clearly plays some role because the proportion of attached earlobes in different racial groups varies. 67 per cent of people in Japan, for example, have an attached earlobe, with 64 per cent in China.