Throughout human evolution, there has been a distinctive variation in facial features. These traits have been examined by anthropologists to find the origins of diversification due to adaptation to the environment.
Although there is evidence that heritage plays a major role in the development of physical features, there is not enough understanding on a molecular level regarding the characterization of the human face.
Through a rigorous study, scientists have determined that there are four major genes that have a direct influence on the shape of the nose as a person is formed, which is a significant advance as only two other studies have been carried out that placed a heavy emphasis on studying facial features due to genetic background.
Studying facial features
The DNA of over 5,958 individuals was examined with the objective of determining which ones shared genes that corresponded to whether the nose was wide, narrow, pointy if it had a deep valley or large nostrils. The team used the same methodology used for a previous study that identified the genes that act upon outer ear morphology.
The genes that act upon the shape of the nose were identified as PAX1, RUNX2, GLI3, and DCHS2.
The research team from the University of London examined people from Latin America due to their ethnic diversity in order to study the origin of the shape of facial features. The face of 6,275 participants was surveyed, hailing from Peru, Brazil, Chile, Colombia and Mexico. Their ancestry included European, African and Native American, which allowed the research team to have a broad array of genetic background to establish the probable links.
3D imaging was applied to closely review the facial features by measuring the exact proportions of each characteristic and to establish a statistic connection to the suspected genes. Nose dimensions, lip thickness, cheekbone protrusion, forehead profile and brow protrusion were among the examined facial features and each one was linked to one or more potential genes that dictated its formation.
The study stems from the fact that very little research has taken place on the topic, and the ones that have been performed took into account European individuals mostly. Researchers managed to find the four aforementioned genes, plus another known as EDAR, which influences chin protrusion.
PAX1, RUNX2, GLI3, and DCHS2 are among the genes that regulate how cartilaginous tissue grows on the body and how the bone mass that makes up facial features takes one shape or another. PAX1 and GLI3 were the ones that got more closely related to the nostrils while DCHS2 controlled the prominence of the nose. RUNX2 determines how the nasal bones are formed and the overall width of the bridge.
Knowing how facial features are developed allows the scientific community to have a greater insight towards evolutionary factors and how they have been able to shape the human phenotype for thousands of years. The human nose is responsible for regulating temperature and humidity, allowing us to breathe in different kinds of weather.
What scientist know is that facial features come from genetics. The genes of the father and the mother combine through Mendel’s laws and divert into a specific set of physical features, something known as a phenotype. The human phenotype dictates whether the person will have blue eyes, brown hair, separated earlobes, a prominent nose and so on.
But when it comes to the features that were analyzed in the study, it isn’t enough to just analyze the persons’ phenotype through typical biological procedures. Since before the study, scientists have known that ethnicity plays a major role in the shape and proportion of the nose. Digital imaging can also be used as a typically inaccurate method of predicting how the nose will develop throughout a persons’ life; the same explanation goes for plastic surgery, as people might want to know how their nose will look like after exiting the operation room.
“It brings us closer to understanding how genes influence the way we look, which is important for forensics applications,” said Dr. Kaustubh Adhikari, lead author of the study, referring to the importance of analyzing genetic heritage to understand how humans evolve.
Bottom line
Weather conditions play a major role in how an organism develops over time. People in hotter countries tend to have a darker skin color and darker overall facial features while people in colder countries are pale and their bodies are usually built to withstand dry climates. The nose plays in important role in our relation with the environment.
It is a matter of time until scientists are able to discern which are the genes that shape our body as a whole. People often refer to the term “designer babies” when talking about genetically designed humans so they display previously-selected morphology of their physical features. There has been an important amount of controversy regarding experimentation on in-vitro humans, where researchers are asking to extend the 14-day limit of human embryo testing.
Human experimentation is still a delicate matter, as it is the borderline between morals and scientific progress. Many argue that human experimentation will allow scientists to understand genetic and heritable diseases, but at the cost of using potential human lives as disposable specimens.
Source: Nature