Skin:Pathogen :: Hair:?

Skin acts as a barrier that stops many pathogens from entering the body, so hair serves a similar protective role but for different threats. Hair helps keep parasites such as lice, fleas, and ticks from easily reaching the skin and attaching. By physically separating the skin from the environment, hair reduces the chance that these parasites can bite or lay eggs near the skin surface. For example, a person with longer hair is less likely to have lice infestations because the hair creates a physical barrier that lice must navigate. Thus, hair protects against parasites.