It is one of dermatology’s tedious and fun facts that, in contradistinction to say scabies or head lice, you treat body lice by treating not the patient (directly) but the clothing. The pharmacological agent is a washing machine. But the excerpt quoted below tells you something wonderful about science: you get things out that you never expected. Spontaneous generation — not in the real world — but in the world of ideas. Well, almost.
Scientific efforts to shed light on the prehistory of clothes have received an unexpected boost from another line of research, the study of clothing lice, or body lice. These blood-sucking insects make their home mainly on clothes and they evolved from head lice when people began to use clothes on a regular basis. Research teams in Germany and the United States analysed the genomes of head and clothing lice to estimate when the clothing parasites split from the head ones. One advantage of the lice research is that the results are independent from other sources of evidence about the origin of clothes, such as archaeology and palaeoclimatology. The German team, led by Mark Stoneking at the Max Planck Institute for Evolutionary Anthropology, came up with a date of 70,000 years ago, revised to 100,000 years ago, early in the last ice age. The US team led by David Reed at the University of Florida reported a similar date of around 80,000 years ago, and maybe as early as 170,000 years ago during the previous ice age. These findings from the lice research suggest that our habit of wearing clothes was established quite late in hominin evolution.