BehindTheMedspeak: Darwin's Point

 

I must have been absent from anatomy class my first year of med school the day they discussed this anatomical feature, found in — believe it or not — 10% of all humans around the planet.

Better late than never.

I first learned of Darwin's point (aka Darwin's tubercle) in Melinda Beck's February 23, 2010 Wall Street Journal story about vestigial traits.

From Wikipedia: 

•••••••••••••••••••••••••••

 

Darwin's tubercle [also known as the plica semilunaris] is a congenital ear condition which often presents as a thickening on the helix, at the junction of the upper and middle thirds. The feature is present in approximately 10.4% of the population. The acuminate nodule represents the point of the mammalian ear.

This atavistic feature is so called because its description was first published by Charles Darwin in the opening pages of "The Descent of Man," as evidence of a vestigial feature indicating common ancestry among primates. However, Darwin himself named it the Woolnerian tip, after Thomas Woolner, a British sculptor who had depicted it in one of his sculptures and had first theorized that it was an atavistic feature.

The gene for Darwin's tubercle is inherited in an autosomal dominant pattern, and has incomplete penetrance, meaning that those who possess the gene will not necessarily possess the ear tubercle.

•••••••••••••••••••••••••••

 

TYWKIWDBI and RichardDawkins.net have more on the subject.