In the Evolutionary Psychology of Facial Beauty by Gillian Rhodes, a paper that’s cited
on the channel all the time, symmetry, averageness and sexual dimorphism are the three big indicators
of attractiveness. In the defining beauty / what makes a face attractive series, the
episodes put out so far talk cover just ⅓ of this attractiveness trifecta, the averageness
part. They discuss what the ideal values are by different races, genders and cephalometric
regions and while we’ll continue putting out more videos on different parts of the
face, it’s important to not neglect the other 2 important aspects to beauty.
The idea goes that symmetry indicates mate quality and strong genetic health. In her
paper Rhodes cites that the likelihood of asymmetries in human bodies occuring increase
with inbreeding, premature birth, psychosis and mental retardation[a]. Further studies[b]
from the late 20th century show that artificially making faces symmetric increases their attractiveness
although their facial features remain the same. On the other hand, asymmetry is equally
undesirable in animals. There’s many biological reasons from a loss of genetic variance to
heterozygosity but let's just say if a bird is born with asymmetrical wings, it’ll die
very quickly to natural selection. This type of example is due to fluctuating asymmetry
as it’s individual specific.
It’s important to distinguish between the two types of symmetry:
Fluctuating refers to random deviations from perfect symmetry, e.g. nemo with his deformed
flipper would die real quick if it wasn’t a disney movie.
Directional symmetry is where there is a bias towards one side, e.g. left and right handedness
with 85% being right handed. Directional symmetry can be consistent across an entire population
and so it doesn’t signal mate quality since everyone is the same and our perceptions adapt
to where it becomes unnoticeable[c] unlike fluctuating.
It’s worth noting that In Symmetry and Human Facial Attractiveness by Perrett and colleagues
it states that some degree of asymmetry may actually be desirable to make the individual
more expressive. During speech 76% make greater right handed gestures than left. Likewise
Wylie and Goodale 1988 found that spontaneous facial expressions are more asymmetric than
posed ones, but somehow found more attractive. It’s sort of like how raising one eyebrow
is seductive but raise both and you look like a surprised barn owl.
Perfect symmetry is near impossible to achieve. A small degree of bilateral asymmetry is to
be expected on every face, even our brains are asymmetric with left and right handedness.
It only becomes a problem when it’s blatantly noticeable. Research by Peck Et[d] al found
that asymmetry is greatest in the jaw, so the lower third and least in the cranium or
the upper third. Another study by Severt and Proffit[e] recorded that only 5% of asymmetry
cases were found in the upper third, 36% in the midface and 75% in the lower third. Why
is that?
One hypothesis that I’d like to throw out there, is that our dentofacial growth is somewhat
determined by our diets. This was also the conclusion of Canadian dentist, Dr Weston
Price, who compiled numerous data on how soft, Western diets lead to misaligned tooth eruption.
Could it be that the most kinetically active part of our face, the jaw, is most prone to
asymmetry because it’s dependent on so many factors for proper growth. The side you predominantly
chew your food on will have more developed masseter muscles than your weaker side, that’s
a common asymmetry. Conversely, the cranium just grows outwards, free from constant movement
or external force so it’s much less prone to asymmetry. The midface is intermediate
because it contains a lot of complex soft tissue structures like the eyes and nose so
it’s easy to imagine how the cells might mess up duplication although they’re under
a lot less physical stress unlike the jaw. But again, this is just my own personal conjecture.
In 1997 Moller and Thornhill found a weak but significant correlation regarding the
heritability of asymmetry, but it’s still a hotly disputed topic. If asymmetry is truly
heritable, then this theory I’ve proposed goes out the window and you should just pick
new parents next time.
Although the causes of asymmetry are endless, clinical scientists can break them up into
three categories:
* Malformations: a morphological (shape) related defect resulting from an abnormal development
process * Deformation: a defect caused by getting
punched in the face by sonny liston * Disruption: morphological defect caused
by a breakdown in the development process
The most common way of assessing symmetry is with a bilateral flip where you take a
face, cut it down the facial midline, typically the philtrum and compare the two sides but
if you’ve ever tried this for yourself with enough faces you’ll notice a few weaknesses
in this method. Going back to G. Rhodes, she calls out these limitations too and I paraphrase,
in taking a hemispherical flip of a face, a very slight tilt of the head or a slight
deviation from the front on view amplifies the asymmetry in the resulting chimera image.
In other words, images appear abnormally wide or narrow and this greatly affects attractiveness
results.
A better way is to blend the original face with the flipped face to offset any angle
or tilt errors in the original image which is how we now do it for every QOVES facial
report.
In the Perrett study I mentioned earlier, they use a third method where they physically
straighten asymmetries using the 1999 equivalent of the liquify tool. Figures c) and d) are
the midline flips (chimera) while b) is the new method of manually adjusting 224 facial
points for perfect symmetry.
There isn’t really much to say with bilateral symmetry. It’s either noticeable or it isn't.
Generally the most noticeable asymmetries are in the eyes as we obviously look at that
first on a face. This is seen as a deviation in the canthal tilt or the eyelid contour
where ptosis causes the upper eyelid to droop lower than the other. From what I’ve seen,
the lower eyelid doesn’t seem to be as asymmetric as the upper.
After the eyes we look to the nose because it’s also a large, salient part of the face.
In terms of bilateral asymmetry it’s usually in the nasal bridge where most people have
a crooked nose bridge that’s noticeable because the nose is dead center on the facial
midline. The nose base and nose tip aren’t as common because they’re smaller in the
case of the tip or further from the line in the case of the nose alars.
When assessing symmetry, especially for the nose and eyes it’s best to use what’s
known as transverse symmetry where horizontal reference lines are drawn to assess how well
facial features are spatially related. Ideally, on a well formed face transverse lines should
be horizontal to the occlusal plane. The occlusal plane is the imaginary plane made by your
upper and jaw coming together at rest. If for whatever reason the maxilla or mandible
is rotated or tilted this plane very clearly tilts too and is no longer parallel to the
interpupillary line. When this happens it’s called canting in dentistry and it’s clear
to see from both views how it causes a noticeable asymmetry, even if you keep your lips sealed.
This is just the tip of the iceburg but there’s numerous similar asymmetries, the majority
of which occur in the jaw and lower third. Here is an example of lateral mandibular displacement
where the lower jaw is very clearly misalligned and Chin asymmetry, where the jaw is aligned
but the chin isn’t.
For the majority of the people watching, these more serious cosmetic and dentofacial defects
likely won’t apply to you. In all of the facial reports the QOVES team has done so
far I don’t recall ever seeing any of these asymmetries we’ve just gone over.
These more serious defects create underlying biomechanical issues and so they’re corrected
early on in the interest of health.
Although we know asymmetry is undesirable for attraction, science has been unable to
properly quantify what types of asymmetries are worse. Is a crooked nose worse than a
malformed jaw? Is a case of ptosis worse for aesthetics than a maxillary cant? In 1993
Jones and Hill tried to quantify fluctuating asymmetry but produced a limited test of only
6 traits. Also it lacked repeatability so it’s virtually unusable, but it did create
a foundation to jump off of. Grammar and Thornhill in 1994 devised a method by summing the offset
of asymmetrical facial features from the facial midline.
For most people, asymmetry is actually quite easy to correct. Fillers can help produce
a more even facial contour for example Botox in the eyebrows or forehead can raise one
side to appear even. Another method is with a rhinoplasty to straighten the nasal bridge,
which is one of the more noticeable asymmetries. As for the jaw, if it’s an underlying dentofacial
alignment issue, implants aren’t going to do you much good but if it’s a case of weak
growth, then implants can go very far in correcting asymmetry, especially since they’re 3-D
printed to the client’s needs.
And with that, we bring this episode to a close. Hopefully you learned something, the
idea is to make longer 10 minute videos moving forward to explore the concepts in greater
depth and clear up confusion. If you want us to test your facial symmetry and many other
proportions, be sure to check out the QOVES facial report. All of the behind the scenes
for our content is available at Patreon and lastly follow the QOVES Studio Instagram page.
It’s being revived with fresh content and daily uploads. A lot of different testing
with Marquardt masks, other proportion masks, proportion lines and symmetry so we need your
feedback on what edits look attractive to improve our algorithm for Photoshopping faces.