Researchers from University College London (UCL) have discovered the four genes that primarily affect the shape of human noses. In particular, the genes affect their width and "pointiness" - two traits that show a high level of variation between populations. The findings could help us better understand the evolution of the human face as well as improve forensic DNA technologies.
In order to pinpoint the differences in standard facial features and the genes connected to them, the team examined a population of over 6,000 people with a wide range of ancestry spanning across Latin America. The results revealed four genes: DCHS2, RUNX2, GLI3 and PAX1, all of which affect the width and pointiness of the nose.
"Few studies have looked at how normal facial features develop and those that have only looked at European populations, which show less diversity than the group we studied," said Kaustubh Adhikari of UCL and lead author of the study. "What we've found are specific genes which influence the shape and size of individual features, which hasn't been seen before."
"Finding out the role each gene plays helps us to piece together the evolutionary path from Neanderthal to modern humans," he added. "It brings us closer to understanding how genes influence the way we look, which is important for forensics applications."
Human facial features stem from genetic heritage, and part of what shaped this heritage over the years is environmental factors. The nose helps regulate the temperature and humidity of the air that we breathe, meaning that nose shape and - in turn - genetics, will vary between warmer and cooler climates.
"It has long been speculated that the shape of the nose reflects the environment in which humans evolved," said Andrés Ruiz-Linares of UCL and senior author of the study. "Identifying genes affecting nose shape provides us with new tools to examine this question, as well as the evolution of the face in other species. It may also help us understand what goes wrong in genetic disorders involving facial abnormalities."
After collecting DNA samples from 6,630 participants from the CANDELA cohort from Brazil, Colombia, Chile, Mexico and Peru, the team narrowed down the sample size to 5,958. The group included those of European, Native American and African ancestry and consisted of both men and women. The participants were analyzed for 14 different facial features and the genetics behind them.
The results revealed that the genes behind nose width and pointiness- GLI3 and PAX1- were both found to be involved in the breadth of the nostrils, DCHS2 was strongly connected to pointiness, and RUNX2 drives bone growth and guides the width of the nose bridge.
The data suggests that GLI3, DCHS2 and RUNX2 were all recently selected for in modern humans compared to ancient humans. Furthermore, GLI3 appears to be evolving at a rapid pace.
The findings were published in the May 19 issue of the journal Nature Communications.
