Head lice are a parasite which lives on the scalp of human beings, surviving by biting the scalp and sucking tiny amounts of blood from the vessels which are directed under the skin. While recent decades have seen a drastic rise in the amount of treatment which is given to people with head lice, the problem of head lice is one which has been with humans for at least one hundred thousand years and more (the ancient ancestors of head lice are believed to have lived on the scalps of our hominid ancestors as long as one million years ago). Evolutionary studies of the mitochrondria and DNA of head lice has demonstrated that there was probably a point about one hundred thousand years ago where the population of head lice made the jump to what would become modern man and was reduced from a wide variety of subspecies to one species which all modern head lice have as their ancestor.
Studies of head lice have also demonstrated that there is evidence that our human ancestors first began to wear clothes approximately 75,000 years ago, clothes having changed the ways in which head lice could move from person to person and the patterns by which head lice were then able to spread across the world. From what may have been a single origin, head lice spread to the point that they are now a problem in all parts of the world. There are hundreds of millions of cases of head lice recorded in populations across the planet every year. Fortunately, modern treatments have made it much easier to deal with the problems of head lice infestation.
In the 1960s with the rise in international travel and transportation, the number of cases of head lice went up dramatically. In order to combat this rise in the number of head lice cases, treatments have been developed to try and kill the head lice without causing further irritation to the scalp and also to prevent head lice from returning. Standard techniques for removing lice from an infested person’s head include using a lice comb (a fine toothed comb which can catch the tiny bodies of lice) to remove living lice (there are generally a very small number of living lice on a person’s head compared to the number of eggs, however), and using some kind of chemical treatment to kill the lice as well as their eggs (also called nits). Shaving is also sometimes used as a way to remove lice, as lice lay their eggs on the shafts of hair close to the skin.
Through the use of these techniques, which have been employed in schools in many parts of the world as the official method of dealing with lice, the number of head lice cases in many countries has stabilized or decreased, although there are still millions of cases of head lice recorded every year in the United States alone. While there is a stigma associated with head lice, it remains a common condition, especially for children in school and teens.