Male Super-hairiness

[Paul Crowl]

This is an interesting condition -- from an evolutionary point
of view. Clearly, if environmental conditions were favourable
for the selection of this gene (or type of gene), humans could
rapidly become as hairy as chimps. OR, to put it another way,
-- it is clear that there has been strong selective pressure
(in recent evolutionary times) to stay naked.

http://www.channel4.com/health/microsites/E/embarrassing_illn-
esses/programme6_6.html

See first item: gigantic hairy mole

Or Beckers Nevus

What is it? A skin condition where men have a large one-sided
brown patch, sometimes over half the upper back or chest, or
on the shoulder.

After puberty it often becomes darker and quite hairy, a
feature also called hypertrichosis. Occasionally acne may
develop in the nevus. It's caused by an overgrowth of the
epidermis (upper layers of the skin), pigment cells
(melanocytes) and hair follicles.

Why do some people get it? Nobody really knows, although it's
relatively common and often hereditary, linking it to a gene
defect which hasn't been properly identified yet. It may be
triggered by circulating androgens (male hormones such as
testosterone), which is why it appears in males at puberty.