A Lousy Sense of Smell
Scientists have mapped the genome of the body louse (Pediculus humanus humanus) and found that it has a lousy sense of smell.
The louse contains 108 million DNA base pairs (bp) whereas their human host genome has three billion bp.The blood of their human host is the exclusive diet of the louse so they did not evolve to have a sense of smell. The louse is responsible for the spread of diseases like typhus and trench fever.
Scientists are itching to learn more about the genome of the louse as it may help to prevent epidemic outbreaks of these diseases among people who live in insanitary conditions.Analysis of DNA reveals that the body louse evolved from head lice when humans started wearing clothes some 190.000 years ago.The evolutionary process of louse will undoubtedly have entomologists scratching their heads for quite some time.