Cosmos, Jacqui Hayes, Oct. 17, 2006
Do you look like your father when you’re angry? Probably more than you’d imagined. Facial expressions may be inherited, Israeli researchers say.
According to scientists, every person has a set of facial expressions that is unique to them, a signature of their identity that remains stable over time. Stable patterns of facial expressions arise before a baby is six months old, but until now, scientists were unsure whether these patterns were learned or innate.
“We were interested to examine whether there is a unique family facial expression signature,” said lead author Gili Peleg from the University of Hafa in Israel. “We [correctly] assumed that we would find similarities between the facial expressions of relatives.”
The study, which is published today in the U.S. journal, Proceedings of the National Academy of Sciences, involved 21 participants who had been blind from birth, each with either one or two relatives who had normal vision. According to the researchers, blind individuals have no way of learning the facial expressions of their relatives by mimicry. The common perception that blind people touch other’s faces to sense their expressions was revealed to be, in fact, very impolite behaviour.
Forty-three different facial movements were recorded, including movements such as: biting the lower lip on the left-hand side; moving the lips while pressed together, as though chewing; rolling the upper lip inside the mouth; sticking out the tongue slightly while touching both lips; and pulling down the corners of the mouth while pushing the chin forward.
“These findings indicate the existence of a hereditary basis for facial expressions,” Peleg explained.
When each emotional state was analysed separately, the computer correctly allocated the blind individual to his or her family most often for the negative emotion anger, at 75 per cent.
To induce a state of anger, the researchers asked each person to relate a past experience which caused them to feel angry. The individuals were encouraged to use as much detail as possible in order to relive the experience. This was also how sadness and joy were induced.
This study paves the way for discovery of the genes that influence facial expressions. According to the researchers, “Genes may control muscles’ and bones’ structure, innervation and even perception.” Further research will explore the evolutionary significance of these heritable facial expressions.