Highly read on http://royalsocietypublishing.org in December

Hirsute individuals are better able to sense blood-sucking bed bugs crawling on their skin than are their less hairy counterparts.

Isabelle Dean and Michael Siva-Jothy at the University of Sheffield, UK, tested the ability of 29 volunteers to detect the presence of bed bugs (Cimex lectularius) on a shaved and an unshaved arm. The volunteers detected the insects more frequently with their unshaved arm than their shaved one, and unshaved arms with a greater density of hair were more sensitive to the insects. Hairier skin also upped the time bed bugs took to find a feeding location.

Humans may have evolved less body hair to make parasites easier to see and remove, but the authors suggest that fine body hair has been maintained to enhance their detection.

Biol. Lett. http://dx.doi.org/10.1098/rsbl.2011.0987 (2011)