With over 15 million procedures being performed in 2019 just in the United States alone, and
rhinoplastic surgery making up the majority of this, people are having more surgeries
now than ever before.
As it turns out, climate has a huge influence in how your nose is shaped, for example, the
sharp, upturned peaks of Scandanavian noses compared to the flat and wide shapes of sub
Saharan African ones.
The noses of individuals are heavily shaped by genetic influences of their ancestors',
which in turn have gone through a process of natural selection, across generations , to
best adapt to their climate.
In the tropics, where the air is warm, evolutionary changes have occurred over time affecting
the noses of their inhabitants, with noses that are more flat with nostrils open and
wide acting as a favorable genetic marker.
Quite simply put, The greater width of the nose increases the potential intake of air
needed in warmer climates, and has hence served as an evolutionary advantage for populations
living in the tropics.
If we were to place individuals with this open and wide nose evolutionary trait in colder
climates, the increased potential intake of air would serve as an evolutionary disadvantage,
allowing masses of cold air to enter and irritate the membranous lining.
A landmark research article by Zaidi et. al. speaks to the case that adaptations to climate
have caused observed differences in nose shapes among populations around the world.
The study included 2637 participants with relevant genetic ancestry data, which is an
impressively culturally diverse sample size for data collected exclusively in the United
States.
To give context to the paper, genetic scientists have been studying and measuring Noses and
extracting meaning from their results for an age now, with Thomson and Buxton publishing
an historic paper in 1923.
The paper demonstrated significant differences between 242 different crania (or skulls),
by using a mathematical ‘nasal index’, finding ethnic differences for crania composition.
For example, the skull (on the left) is an Algonquin Indian exhibiting a narrow nose
with a nasal index of 39.4.
On the other hand, on the right is a North-west Australian with a wide nose, has an index
of 55.4.
Close to a century later, in 2017, Zaidi et. al. have improved the sophistication of Thomson
and Buxton’s measuring techniques to prove variation in nose shape between West-African,
East-Asian, Northern European and Southern Asian populations by statistically modelling
3D images of participants’ faces using the 3dMD Face system.
With the ability to model noses using imaging systems, 5 nasal distances and 2 areas from
every nose were measured to quantitatively compare the shapes and sizes of noses between
populations.
The distances included the ‘Nares width’, a measurement of the distance between the
two alares of the nose as shown in the picture.
The ‘Alar base width’, similar to the Nares width, but measuring from the base of
the nose.
The ‘Nasal height’, measured from the top of the nose (known as the ‘Nasion’,
labelled ‘n’) to the bottom of the nose (the ‘Subnasale’, labelled ‘sn’).
The ‘Nasal Ridge length’, measured from the top of the nose (The nasion) to the point
of the nose (known as the ‘pronasale’, labelled ‘prn’).
And the final distance, the ‘Nasal tip protrusion’, measured from the point of the nose, the pronasale,
to the bottom of the nose, the subnasale.
Continuing, the areas from every nose that were measured were the Overall area and the
nostril area, both pictured.
What follows now is the data collated for the nose shape and size of each ethnic population.
Feel free to pause the video here to make your own inferences from the graphs provided
here, but a summarised table will detail the important findings from the dataset.
From the report, it can be seen that West Africans have the largest Nares width, Alares
base width, and the smallest nasal tip protrusion.
This correlates to a wide and flat nose.
It was also recorded that Northern Europeans have the smallest nares width and alares base
width, with the greatest nasal tip protrusion.
This actualises to a tall, point and thin nose.
East Asians were also found to have the smallest noses in terms of external surface area, and
the smallest nasal tip protrusion.
This results in a small and short nose.
To confirm what the data collected shows, West African males and Females have the largest
Nares width and alares base width and Northern European men and women have the smallest.
East Asian men and West African females have the greatest nasal height, whilst all South
Asians have the smallest.
Now, with all the data modelling complete and analysed, the researchers of this paper
set out to evidence that these differences in nose shape and size between African, Asian
and European populations was due to the evolutionary benefits unique to each of those climates.
That is, that the results of the differing nose shapes were due to differing climates,
above and beyond the effect of Genetic drift.
Genetic drift is the phenomenon in which frequencies of a certain characteristic change over generations
due to chance.
In the ladybug example, the chance event of a group of bugs being swatted has resulted
in a population decrease in blue bugs.
When it comes time for these bugs to reproduce, only a small amount will continue to hold
the blue trait.
Overtime, by chance, the overall characteristics of the population will change.
It should be noted that Genetic drift is unlikely in a large sample size.
To recognise which measurements of the nose size and shape had differences that could
not be attributed to genetic drift alone, the authors of the paper comprised a formula
and statistical procedure that assessed the variation of the data sets.
The statistical explanation behind the formula is complex, however, statistically significant
results from the data found through probability values of less than 0.05 (that is, less than
a 5% chance that we are wrong in assuming the data is meaningful) meant that there was
a difference beyond genetic drift.
In the graph pictured, Qst-Fst refers to the formula priorly mentioned, with larger resultant
values from the formula directly corresponding to smaller p-values (and hence more evidence
that there is an effect beyond genetic drift).
The red and orange violin shaped data plots, representing ‘Skin pigmentation’, ‘Nares
width’, ‘Alar base width’ and ‘Nasal tip protrusion’ are the measurements that
are found to have significant effects beyond genetic drift, evidenced by p-values less
than 0.05, as shown from the coding scheme on the side.
That is, the differences in these four factors between West African, Northern European and
South and East Asian populations are caused by differences in climates.
When we think of this logically, it makes complete sense that Skin Pigmentation, which
has not been mentioned priorly, differs for climates, as can be seen here.
It is interesting when we consider the parallel between these findings and those of skin pigmentation
in populations, stressing the influence of the climate on human physical adaptations.
We covered skin tone adaptations in our video here, so pay that a visit but before you do,
leave a like on this video in return for a 3 second blooper reel of me messing up the
recording.
[insert z1 audio]
How does this relate to you?
How the objective differences in nose shape and size between populations link to the aesthetics
and perceived attractiveness of individuals is a different can of worms.
We’re of the belief that there is no perfect nose shape but there are aggravating and mitigating
factors to attractiveness.
Unlike a jaw which can have different levels of protrusion and misalignment that decrease
or increase their attractiveness quite linearly and objectively, for instance a Scandanavian
can have more or less the same jaw shape as an Indigineous Aboriginal, with the noses
being linked to climate there is an incredibly diverse range of shapes and types to consider,
making their attraction much more subjective than other features.
However it is important to recognise deformities from simply different nose shapes.
Saddle noses caused by blunt force trauma, a deviated septum which can affect breathing,
swollen lymph nodes and a prominent dorsal hump caused by excess cartilage, weak facial
development or again trauma.
Nasal hump correction, aka the dorsal hump because it usually occurs at the dorsum of
the nose, is the most common reason for cosmetic rhinoplasty because it is an incredibly masculinizing
feature.
Native Americans harmonize best with this masculine nose shape because they have very
wide and strong faces due to their tough diet and child rearing traditions.
For instance they use cradleboards to keep infants on their backs so that their soft
skulls form aesthetically strong and wide and not narrow and dolichocephalic with a
large occipital bone like some type of alien.
For people of other ethnicities with more feminine features, it doesn’t work as well
and so correcton is often desired.
To summarise, the findings of Zaidi et.
Al's paper demonstrates that nose width, projection, and nostril size vary by geographic location,
highlighting an evolutionary adaptation of people over time to their climate.
If living in colder climates, over time, populations will have a greater proportion of people with
smaller and thinner noses to avoid sucking in too much stinging cold air, protecting
the inner lining of their nose.
On the contrary, living in warmer climates results in larger and wider noses, allowing
for more intake of air for physical activity