Contrary to popular belief, we aren't entirely naked. We do have hairs covering our body, and they are called the vellus hair. And we do have the same density of body hair as other apes of our size.
They recruited 29 university students through Facebook, aged between 19 and 27 years for the experiment. Each participant had one of their arms shaved. The researchers then drew a rectangle of Vaseline on both their forearms, and while the volunteers looked away, the duo placed a bed bug within the rectangles.
The results showed that fine hair helped us to avoid falling prey to parasites. The researchers further highlighted that other blood-sucking parasites prefer to bite hairless sites on bats and the featherless areas of birds.
So now you know why mosquitoes always bite you at the relatively hairless underside of wrists and ankles.
info: Dean. I, Siva-Jothy. M. T. , Biology Letters, Human fine body hair enhances ectoparasite detection. doi: 10.1098/rsbl.2011.0987