For further technical details on their evolutionary history, you can explore the molecular study available on BMC Evolutionary Biology . Morphological discrimination of human lice (Anoplura - PMC
: They are highly host-specific, meaning most species associate with only one type of mammal. anoplura
: Their eggs, often called "nits," are oval and whitish, cemented firmly to the host's hair. Anoplura and Humans For further technical details on their evolutionary history,
( Pediculus humanus capitis ): Resides on the scalp and is common among school children. often called "nits
( Pediculus humanus humanus ): Associated with poor hygiene and often found in the seams of clothing.