Human noses are shaped by just four genes that determine if the organ is large, small, pointy, rounded, or snubbed. This study could have a profound impact on genetics and forensics.
Noses are differentiated to a significant degree between various populations of people. This is especially true of the pointiness and width of the organ. These adaptations are believed to be driven by environmental conditions where people built their homes. The narrow noses of Europeans, for instance, may have been an adaptation to the cold, dry conditions on that continent.
University College London (UCL) researchers examined nearly 6,000 people across Latin America who are considered to have a wide range of ancestries. Half the subjects were of mixed European heritage, while 45 percent were Native Americans, and one in 20 descended from Africans. Researchers examined 14 separate facial features, comparing physical features to individual genetic records.
Investigators found four genes responsible for shaping the nose - GLI3, PAX1, RUNX2, and DCHS2. The gene RUNX2 controls the width of nose bridges, DCHS2 directs pointiness of the nose, while the other two genetic snippets determine the breadth of nostrils. They also identified a fifth gene, known as EDAR, which directs the chin's protrusion.
This research could allow the development of new techniques to reconstruct the facial features of crime victims by examining their DNA. The discovery could also lead to a new understanding of how the human nose evolved over time.
"Finding out the role each gene plays helps us to piece together the evolutionary path from Neanderthal to modern humans. It brings us closer to understanding how genes influence the way we look, which is important for forensics applications," Kaustubh Adhikari, the first author and a cell and developmental biology researcher from UCL, said.
Each of the genes examined in this study appears to be undergoing modern evolution, changing during the reign of our modern species. It is possible the great diversity of human faces may have developed as a means of facilitating recognition of individuals.
Past studies on facial structures have only examined European populations, which present a far more narrow genetic background than seen in this new study.
Analysis of the genes and how they help to shape the human face was profiled in the journal Nature Communications.
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