There are no confirmed lice fossils so there is little evidence for where lice originated, although they were present in Ancient Egypt. There are many strains of head lice, and the strain believed to have originated in North America migrated worldwide.
Head lice are parasites that live in hair and feed on blood. They lay eggs on individual strands of hair. When the eggs hatch, the nymphs go through three growth spurts until they reach full adult size. Adult head lice must eat four or five times each day to survive.
Head lice are incapable of jumping, flying or swimming, and they only feed from humans. This means that there are a limited number of ways that lice can be transmitted. The most common way is when an uninfected person's hair comes into contact with the hair of an infected person. Lice can also be contracted by sharing hats, scarves, combs and brushes. Head lice infrequently attempt to travel by means of clothing. If they do not reach hair within a day, they starve and die.
The amount and specificity head lice must eat in combination with their slow travel speed means that they must be contiguously transferred from person to person and community to community in order for the species to survive. Head lice are able to survive because their eggs cannot be washed from the hair. Lice must be removed with over-the-counter chemicals, special combs, oils, such as tea tree or eucalyptus, or by entirely shaving the hair from the head.