Darwin's tubercle

Darwin's tubercle (or auricular tubercle) is a congenital ear condition which often presents as a thickening on the helix at the junction of the upper and middle thirds.

History

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 theorised that it was an atavistic feature.

Prevalence

The feature is present in approximately 10.4% of the Spanish adult population, 40% of Indian adults, and 58% of Swedish school children. This acuminate nodule represents the point of the mammalian ear. The trait can potentially be bilateral, meaning present on both ears, or asymmetrical, where it is only present on one ear. There is mixed evidence in regard to whether the bilateral or asymmetrical expression is related to population, or other factors. Some populations express full bilaterality, while others may express either asymmetry or bilaterality. However, bilaterality appears to be more common than asymmetry as it pertains to the expression of the trait.

Charles Darwin

Charles Robert Darwin, FRS FRGS FLS FZS (/ˈdɑːrwɪn/; 12 February 1809 – 19 April 1882) was an English naturalist and geologist, best known for his contributions to evolutionary theory. He established that all species of life have descended over time from common ancestors, and in a joint publication with Alfred Russel Wallace introduced his scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding.

Darwin published his theory of evolution with compelling evidence in his 1859 book On the Origin of Species, overcoming scientific rejection of earlier concepts of transmutation of species. By the 1870s, the scientific community and much of the general public had accepted evolution as a fact. However, many favoured competing explanations and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.