Bodily Oddities

Attached and free earlobes

Also called: Earlobe attachment · Adherent earlobe

Some earlobes hang free and others join the head directly. Textbooks taught this as one gene, but a 2017 study found at least 49 genetic regions involved, and the two shapes blend into each other.

Ears Skin and hair Variation Structural
Debunked myth Genetic Try it

How common

Both shapes are common Common · 10–50% The share of attached lobes varies widely by population and by where the judge draws the line.

Do you have this?

These are answers from visitors, not a study.

How it works

The earlobe is the soft flap at the bottom of the ear. It has no cartilage, only skin, fat, and blood vessels1. In a free lobe the flap hangs below the point where the ear meets the head. In an attached lobe the bottom of the ear joins the head directly, with no hanging part.

School biology classes long used this as the textbook example of a trait controlled by one gene, with free lobes dominant and attached lobes recessive2. That story is wrong. When people are lined up, lobes do not sort into two neat groups. They form a range, from clearly free through in-between shapes to clearly attached2. Family studies show that two parents with attached lobes can have children with free lobes, which a one-gene recessive trait would not allow2.

In 2017 a study of several thousand people scanned the whole genome for links to lobe shape and found at least 49 regions of DNA involved1. The trait is polygenic, meaning many genes each add a small effect1.

Try it

  1. Look at one ear in a mirror, side on.
  2. Find the lowest point where the ear meets the cheek.
  3. If the lobe hangs below that point and you can lift it away from the head, it is free.
  4. If the lobe curves straight into the cheek with no hanging flap, it is attached.
  5. Check the other ear, then check family members. Expect a mix and some in-between cases.

History and culture

Earlobes, tongue rolling, and hitchhiker’s thumb are the three classic classroom traits, and all three have been shown to be more complex than taught2. The lobe stays in textbooks because it is easy to see and harmless to discuss.

Sources and further material

  1. Encyclopedia Earlobe Shaffer et al., 2017, for the genome-wide study.
  2. Article Myths of Human Genetics: Attached earlobes John H. McDonald, University of Delaware Reviews the family studies and shows that lobe shape is continuous.
Ears Variation

Darwin's tubercle

A small bump on the folded rim of the ear, which Darwin thought was the leftover tip of a pointed ancestral ear. Between 10% and 58% of people have one, depending on the population.

10–58% of people
Bones Variation

Hitchhiker's thumb

A thumb whose top joint bends back past 50 degrees, once taught as a simple recessive gene. Thumb angle is really a smooth range, and the genetics are not that simple.

24–36% of people
Mouth Trick

Tongue rolling

Between 65% and 84% of people can curl the sides of the tongue up into a tube. For decades it was taught as a simple one-gene trait. It is not.

65–84% of people
Ears Variation

Preauricular pit

A tiny hole in the skin just in front of the ear, present from birth, that leads to a short blind tunnel. It is harmless unless it gets infected.

0.1–10% of people