The frontal sinuses, located between and above the eyebrows, are shaped as uniquely as a fingerprint. Since 1925, they have been used by forensic anthropologists to identify human remains when dental or other medical records were missing.
Boston University School of Medicine (BUSM) researchers found that frontal sinus development was more influenced by sexual dimorphism than by parentage, and that it was the interaction between these two factors that produced the most significant variation.
“People usually tend to be interested in themselves, their origins and their bodies. This study examines a fascinating structure as unique to humans as a fingerprint and begins to shed light on why this feature is so unique to each individual,” said corresponding author Sean Talman, Ph.D., assistant professor of anatomy and neurobiology. Former graduate student Austin Shamlou, M.S., now a research technician at Massachusetts General Hospital, co-authored the study.
Researchers analyzed computed tomography (CT) scans of more than 300 people who were identified as male or female at birth. Individuals were also classified by ancestral origin: African, Asian, European, or Hispanic. Using Photoshop, the authors created a contour of the frontal sinus layer by layer and took measurements of maximum height, width and depth. These frontal sinus contours were divided into three groups and compared with variables. The study concluded that neither gender nor ethnicity significantly affected sinus shape when considered individually, but there was significant variation in maximum height and maximum depth when the two factors were considered together.
“It is interesting that the interactive effects of sexual dimorphism and adaptive population history affect frontal sinus size,” said Tallman, who added that a clear picture has yet to be found.
Tallman said further research is needed to address why the frontal sinus forms unique structures for each individual. He cautioned that in the US, sine variation does not occur along the ancestral line, suggesting that there was significant overlap in ancestral climates or that climate adaptations no longer influenced variation in the US
These findings appear online in the journal Biology.