UNIVERSITY PARK, PA. — In recent years, biological anthropologists have initiated a deeper scientific inquiry into the evolutionary processes that have shaped the wide variety of skin pigmentation displayed by people from diverse places across the globe. However, very little attention has been given to the similarly broad varieties of human scalp hair.
In the latest episode of the Tracking Traits podcast, postdoctoral researcher Tina Lasisi relayed her aims as a scientist working on this issue, along with some of her findings and a burgeoning theory positing a possible evolutionary driver of tightly curled hair. Lasisi, who completed her doctorate in biological anthropology at Penn State in 2021 and is now working in quantitative and computational biology at the University of Southern California, began focusing on human hair variation during her undergraduate studies at the University of Cambridge, where she graduated with First Class Honors in 2014.
“What my research tries to do is to find ways to accurately and objectively measure scalp hair morphology, instead of us using these subjective terms, like curly, wavy, all of that kind of stuff,” said Lasisi. “Ultimately, one of the things that I want to do is to understand the genetics that underlie scalp hair morphology so that we can understand why it's so variable across different human populations, and so that we can understand why it evolved.”
In addition to sharing her scientific goals on the podcast, Lasisi spoke about her desire to help reverse social stigmas that have been attributed to certain hair types. She pointed out that tightly curled hair, often traditionally included in a generic “Afro” category, not only encompasses a wide range of different forms, but also may serve a very useful and practical function, from an evolutionary standpoint.
“One of the things that I found out through my Ph.D. research when I did some experiments on this,” explained Lasisi, “is that scalp hair in general is able to help protect us from solar radiation. So it reduces the amount of solar radiation that gets to your scalp, and obviously under your scalp is where your brain lives. What I also found is that when you have more tightly curled hair, it seems to be offering a higher degree of protection. So one of the things that we think is happening there is that there's a bigger distance between the top of your hair when it's curly, and your scalp. So that bigger distance probably helps in reducing even more radiation from coming down to your scalp.”
Lasisi said that, as a Black woman working in science, she is excited about the potential to give others another way of thinking about their hair, and a new perspective and appreciation for tightly curled hair's evolutionary function.
For the podcast, Penn State undergraduate student Hannah Marchok took on the role of host and interviewer. Marchok is an undergraduate student at Penn State majoring in biobehavioral health with a minor in global health and is interested in the evolution of human phenotypic variation among populations, social perceptions of race, and the history of scientific racism. For her, the podcast is a unique way to ask questions of experienced scientists who share some of her interests and help her find language to address challenging topics.
“Human variation, whether it's skin or hair, has historically often been either a sensitive subject or has been taken and misconstrued, with all of this sort of complicated history with it,” Marchock said. “So when you're approaching it now in the 21st century, how do you approach this topic in both an academic realm as well in a public realm?”
During their podcast conversation, titled “Unexplored Dimensions of Human Hair Variation,” Lasisi and Marchok also touched on Lasisi’s personal journey as a young scientist, the importance of mentorship and networking, some of the practical applications of developing a more comprehensive understanding of variable hair morphology, and Lasisi’s advice for collaborating across disciplines with colleagues who approach questions from very different perspectives.
The Tracking Traits podcast is a production of the Center for Human Evolution and Diversity, and features Penn State undergrads interviewing researchers about their work and personal passions. New episodes are released monthly, and are available on most podcast streaming services.
The Center for Human Evolution and Diversity is housed within the Department of Anthropology in Penn State’s College of Liberal Arts, with support from the Huck Institutes of the Life Sciences.