Darwinian Tubercle Of Pinna

Clinical Features

Ayers (1899) reported a 3-month-old black fetus with 'pithecoid' ears, involving the presence of a Darwinian point on the outer helix that was more prominent on the left than the right. In addition, the author described a trough extending from the external edge of the helical border forward, downward, and inward across the antihelical depression into the depths of the fossa angularis, and stated that there had been only the 'faintest indication' of this groove in embryonic ears he had previously examined. Ayers (1899) also noted that he had observed in children the presence of a 'tuft of relatively long hairs upon the Darwinian point' that seemed to disappear later, as he had not seen it on any adult ear; he proposed the term 'Darwinian tuft,' and suggested that it represented a remnant of the apical hair tuft commonly developed in mammals and often reaching a significant size, as in the lynx.

Noting that the 'tuberculum darwinii' was the most frequently studied characteristic of the ear, Quelprud (1935) examined the ears of 116 pairs of identical twins, 127 fraternal twins, 718 unrelated individuals from rural Germany, 559 Berlin students, and 147 schoolgirls, classifying cases by the degree of size or projection, from very pronounced to absence of the trait. Differences were observed to depend on age and sex: in males the tubercle generally increased in size with increasing age, whereas in females the reverse was the case. Variations were also found between the right and left ear, with the tubercle being more developed on the right, and when unilateral, the right side predominated. The author stated that the twin studies clearly revealed the hereditary nature of the trait.

Winchester (1958) reported a 6-generation family segregating a 'rather conspicuous point or tubercle' on the infolded edge of the outer portion of the ear, the so-called 'Darwin's ear point,' as an autosomal dominant with incomplete penetrance. The trait showed variable expressivity, being unilateral in some affected individuals and bilateral in others.

Hoyme (1993) discussed minor anomalies, including the Darwinian point or tubercle of the pinna, and stated that the significance of minor anomalies lies in the fact that they may be external indicators of occult major anomalies and/or part of a pattern that defines a multiple malformation syndrome.

Hunter and Yotsuyanagi (2005) reviewed the embryologic development and morphology of the external ear and suggested that the Darwinian tubercle might lie in the ultimate position of the fifth (hyoid) hillock (as shown in the figures of Streeter, 1922) and represent a simple exuberance of that hillock during embryogenesis, and that the small nick or notch that is sometimes seen in the same area, the so-called 'Darwinian notch,' might represent a relative growth failure. They noted that to date there was no clinical significance or specific syndromic association attached to the Darwinian tubercle.