While perhaps not a pleasant thought, lice have long been a part of human history. Studying the coevolution relationship between humans and lice has shed much light on human story. Dr. David Reed, the Curator of Mammals and Associate Director of Research and Collections at the University of Florida Museum, has been studying the coevolution of humans and lice, an area of research that has developed only within the last 20 years. Reed’s groundbreaking research has the potential to fill in some big gaps in humans’ rather sketchy fossil record and provides important data that might have applications in medicine and biology. Two questions that this research has already begun to ask are when did we become less hairy and when did we start wearing clothes.
Figure 5.31 shows three types of lice associated with humans: the head louse (Pediculus humanus capitis), the body louse (Pediculus humanus corporis), and the crab louse or pubic louse (Pthirus pubis). Body lice infest clothing and lay their eggs on fibers in the fabric. Head and pubic lice infest hair, laying their eggs at the base of hair fibers. The human head and body lice (genus Pediculus) share a common ancestor with chimpanzee lice, while crab lice (genus Pthirus) share a common ancestor with gorilla lice. By tracking louse variations, scientists have been able to determine when the head louse and pubic louse diverged, enabling estimates as to when we lost our extra hair and when we started to wear clothes. It is interesting to note that the divergence of the genus Pediculus (head and body lice) correlates with the divergence of the human lineage from chimpanzees about six million years ago. Research on lice also provides further support for the Out of Africa model of human migration. Reed has observed that the genome of African lice shows a higher degree of genetic diversity than that of lice found elsewhere in the world, supporting the hypothesis that both humans and lice existed in Africa first.
Many hypotheses about what may have triggered the loss of hair in humans point to thermoregulation, the need to control body temperature in extreme conditions. Living in the heat of the savanna, humans needed a cooling mechanism to enable them to be better hunters. Other evidence of adaptation to the heat includes the appearance of sweat glands, which are more numerous in humans than in other primates. Another theory about the cause of the loss of hair among humans suggests that it was an adaptation to control parasites on the body. Did people immediately throw on clothes after losing all of that extra body hair? Reed’s research suggests that the wearing of clothes was not something that happened quickly. Humans lost body hair about a million years ago and didn’t start wearing clothes until around 170,000 to 190,000 years ago. That’s about 830,000 years living in their birthday suits! When humans began to wear clothes, the body louse adapted structures that enabled them to attach to clothes instead of hair.
Profiles in Anthropology
Molly Selba
Personal History: From the time Molly was young, she knew she wanted to be an anthropologist.
She took an archaeology class at the local community college when she was a high school student and went to field school over the summer. In college, she completed a double major in archaeology and anthropology, with a minor in Museums and Society. She later gained experience working with different museum collections and held internships at the Baltimore City Medical Examiner’s Office and the Smithsonian Museum of Natural History. After completing her undergraduate degrees, she knew that she wanted to pursue anthropology as a full-time career and began working towards her master’s and doctorate in biological anthropology.
Area of Anthropology: For Molly the most interesting thing about biological anthropology is the information that bones can tell us. Initially she was interested in what the history of disease could tell us about the lives of people in the past, but as she worked with biological anthropologists, her focus shifted to understanding how evolution can impact the shape of different bones.
She received her undergraduate degree from Johns Hopkins University in Baltimore, Maryland, and her Master’s degree from the University of Florida, where she is currently a PhD candidate. Her research interests include comparative anatomy, cranial morphology, and anatomical sciences education. She is most interested in how cranial morphology varies within and between species and how it is impacted by factors such as evolution and selective breeding practices. Her earlier research focused on the differences in cranial morphology in dogs created by artificial selection for facial reduction. Her dissertation research currently focuses on a comparative study of facial reduction across bats, primates, and dogs.
Accomplishments in the Field: For Molly her most important accomplishment in the field of anthropology has been in education and outreach. Throughout her time in graduate school, she was involved in school visits, working with teachers to facilitate the inclusion of human evolution into existing science curricula. She has specifically focused on helping educators find teaching materials that are culturally inclusive and responsive. She has led multiple professional development workshops for teachers on the same topic and has visited over two dozen classrooms and interacted with over 1,200 students in the last four years. Making science accessible to K-12 educators is an extremely important part of being a researcher, and she believes everyone in academia should strive to be effective science communicators.
“Studying biological anthropology helps us better understand our origin story as a species. It helps us recognize why our anatomy is the way that it is, how morphological changes over time can take place, and why we have such a diversity of life on earth. Just being able to recognize and identify our anatomy is only half the challenge—more important is our understanding why various traits are adaptive, how structure relates to function, or why leftover anatomical traits still persist in our body to this day.”
The content of this course has been taken from the free Anthropology textbook by Openstax