Widow's peak

A widow's peak is a V-shaped point in the hairline in the center of the forehead. Hair growth on the forehead is suppressed in a bilateral pair of periorbital fields. Without a widow's peak, these fields join in the middle of the forehead so as to give a hairline that runs straight across. A widow's peak results when the point of intersection on the forehead of the upper perimeters of these fields is lower than usual.

A widow's peak is a distinct point in the hairline in the center of the forehead; it is a dominant inherited trait. There are varying degrees of the peak. People who do not have a widow's peak have a hairline that runs straight across.

The term stems from the belief that hair growing to a point on the forehead – suggestive of the peak of a widow's hood – is an omen of early widowhood. The use of peak in relation to hair dates from 1833. The expression widow's peak dates from 1849. The use of peak may refer to the beak or bill of a headdress, particularly the distinctive hood with a pointed piece in front – a biquoquet – which widows wore as a hood of mourning dating from 1530. Another explanation for the origin of the phrase suggests that it may be related to the mourning caps worn as early as the 16th century. A mourning cap or 'Mary Stuart Cap' is a cap which features a very distinctive triangular fold of cloth in the middle of the forehead, creating an artificial widow's peak. The use of peak referring to a point in the cloth covering the forehead dates to at least 1509 when it appears in Alexander Barclay’s The Shyp of Folys:

And ye Jentyl wymen whome this lewde vice doth blynde Lased on the backe: your peakes set a loft.

Ely Guv Hintonith and M. Michael Cohen hypothesized the widow's peak hairline to be an anomaly that results from a lower-than-usual point of intersection of the bilateral periorbital fields of hair-growth suppression on the forehead. This can occur because the periorbital fields of hair-growth suppression are smaller than usual, or because they are more widely spaced. Wide spacing also explains the association between ocular hypertelorism – that is, the eyes being abnormally far apart – and widow's peak; this was suggested by findings in an unusual case of ocular hypertelorism in which surrounding scalp-hair growth was suppressed by an ectopic (displaced) eye. Widow's peaks are a symptom of Donnai-Barrow syndrome, a rare genetic disorder caused by mutations in the LRP2 gene. Other genetic syndromes occasionally associated with widow's peaks include Waardenburg syndrome and Aarskog syndrome.

...
Wikipedia