Facial symmetry

There are examples from the brain (Yakovlevian torque) and spine,[6] and inner organs (see axial twist theory), but also from various animals (see Symmetry in biology).

The aurofacial asymmetry is defined as the position of the face (mouth, nose and eyes) with respect to the mid plane of the axis through the ears.

[7] According to the theory the facial asymmetry is related to the Yakovlevian torque of the cerebrum, asymmetric heart and bowels and the spine.

Since the axial twist is located between the ear-region and the forebrain-face-region, it is predicted that the face grows from the left to the midline, as is indeed the case.

A wide variety of methods have been used to examine the claim that facial symmetry plays a role in judgments of beauty.

[18] For example, during speech, most people (76%) tend to express greater amplitude of movement on the right side of their mouth.

This is most likely caused by the uneven strengths of contralateral neural connections between the left hemisphere of the brain (linguistic localization) and the right side of the face.

Physiognomy as a practice meets the contemporary definition of pseudoscience and is regarded as such by academics because of its unsupported claims.

Statistical correlations does not inform anout possible causal dependence, so if observers judge the personality of (pictures of) symmetric faces differently than asymmetric ones, this might be due to cultural prejudice.

The five factors are:[25] Accordingly, a positive correlation was found between facial symmetry and extraversion, as judged by others from photographs,[26] as well as by the subjects themselves.

Sexual selection can only influence features that potential mates can perceive, such as smell, audition (e.g. song) and vision.

Such features might be reliable indicators of hidden fitness parameters such as a good immune system or developmental stability.

It has been argued that more symmetric faces are preferred because symmetry might be a reliable sign of such hidden fitness parameters.

Exaggerated schema of the aurofacial asymmetry as predicted by the axial twist theory . [ 7 ] : fig.1c During embryology and development, the face elements (red) are predicted to move toward the center from the left, with respect to the mid-plane between the ears.
Average aurofacial asymmetry in 200 adults. A. Red-shaded: significant asymmetry towards the left ear. B. The amount of asymmetry at the level of each arrow in panel A. Source: figure 2 of Lussanet & Osse (2012), [ 8 ] data from Blanz & Vetter (1999). [ 10 ] [ 11 ]
The gradual decrease of the aurofacial asymmetry with age until the beginning of adulthood. Source: figure 3 of Lussanet & Osse (2012), [ 8 ] data from Klingenberg et al. (2010). [ 12 ]