Scientists Locate Genes Behind Width And 'Pointiness' Of Human Nose

The human nose is affected by four genes that influence its width and "pointiness", says research from University College London (UCL). Both the nasal traits show a high level of variation among different populations.

The findings can help us improve our understanding and also our forensic technologies.

Studying more than 6,000 people with a wide range of ancestry in Latin America, scientists found that four genes---DCHS2, RUNX2, GLI3 and PAX1---are all responsible for affecting the width and pointiness of the nose.

Scientists gathered DNA samples from 6,630 participants of the CANDELA cohort from Brazil, Colombia, Chile, Mexico, and Peru. They finally narrowed the sample size to 5,958, consisting of European, Native American and African ancestry of both genders. They were analyzed for 14 facial features and their genetics.

"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."

Genetic heritage shaped by the environment over the years influences the shape and pointiness of the nose. It regulates the temperature and humidity of the air. Hence, the shape, as well as the genetics, tend to vary according to 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."

GLI3 and PAX1 are the genes that are responsible for the width, breadth of the nostrils and pointiness of the nose. DCHS2 is also strongly linked to pointiness while RUNX2 is behind the growth of the bone, as well as the width of the nose bridge.

Three genes, GLI3, DCHS2 and RUNX2, are selected by modern rather than ancient humans, and GLI3 seems to be evolving rapidly.

The findings were published in the May 19, 2016, issue of the journal Nature Communications.