Hereditary family signature of facial expression

Universality in facial expression and perception Expressed in isolated populations. “Eyebrow-flash” in Himba Universality in facial perception Humans and Apes Blind from birth and sighted persons Young & old

Individual facial expression “signature” A genetic basis of inter-individual anatomical variation in facial muscles Individual differences are stable over time neonates Born blind Particular facial movements Intensities, (Duchenne and non-Duchenne smiles) Timing Frequencies Variability Perception

Is there a unique family facial expression “signature”?

Darwin (1872) “The inheritance of most of our expressive actions explains the fact that those born blind display them, as I hear from the Rev. R.H.Blair, equally well with those gifted with eyesight” Participants: 24 born blind and 30 sighted individuals, belong to 21 families. Emotional states: Think-concentrate, sadness, anger, disgust, joy and surprise were induced in an individual interview of 55 minutes. Analyses based on 18.5 hours of video Documenting by using index of 43 facial movements Facial expressions of Blind from birth and their close relatives

In-Out family test-Method What is the frequency of occurrence of a facial movement of a congenitally blind person within his family relative to the frequency of its occurrence outside of his family? The “In family” value is based on congenitally blind subjects that show a particular facial movement and is defined as the proportion of their family members (excluding the congenitally blind members) that show this particular facial movement. The “Out family” value is based on congenitally blind subjects that do not show this particular facial movement, whilst their family members do. The “Out family” value is defined as the proportion of family members of these congenitally blind subjects that shows the particular facial movement.

Results of the In-Out family test In family Out family

Results of the In-Out family test In family Out family

Summary of the “In-Out family test” In the entire interview and in think- concentrate, sadness, and anger, the frequency of occurrence of a facial movement of a congenitally blind individual in his family is significantly higher than that outside his family.

Three families each including two born blind brothers These results are based on data collected during the entire interview and show that even in families with two born blind brothers the frequency of occurrence of a facial movement of a congenitally blind individual within his family is significantly higher than that outside his family. N=6

The classification test Comparing the gestalt of facial movements of born blind to those of their relatives The number of all possible partitions is: A successful classification =the blind from birth subject was classified to the group including his family

Results of the classification test 80% correct classification over the entire interview, 75% in anger, 69% in surprise, 66% in disgust, 60% in joy, 59% in sadness, and 54% in think-concentrate

Conclusions The correlation between the repertoires of born-blind subjects to those of their sighted relatives indicates a family facial expression “signature”. It is shown that the motor patterns underlying facial expressions, have a strong heritable basis, and that visual input is not required.

Thanks Prof. Eviatar Nevo * Prof. Gadi Katzir ** Dr. Ofer Peleg * Ms. Michal Kamara *** Prof. Hagit Hel-Or *** Prof. Danny Keren *** Dr. Leonid Brodsky * The Caesarea Rothschild Foundation *** * Institute of Evolution, University of Haifa ** The Biology Department, Oranim, University of Haifa *** The Computer Science Department, The University of Haifa