Did your mother ever tell you to stop making a funny face because it might "freeze" that way? Well, in a way, she was right. New research suggests that facial expressions may be "frozen" by your genes.
Comparing the expressions of blind people to other family members, researchers discovered there's probably a genetic component to facial expressions and that human faces may be programmed from the start to look, and act, the same as those of their parents and siblings.
"There is evidence for a hereditary basis for facial expressions," said the study's lead author, Gili Peleg, a doctoral candidate at the University of Haifa in Israel. "This study paves the way for discovering genes that influence facial expressions, understanding their evolutionary significance, and elucidating repair mechanisms for syndromes characterised by lack of facial expression, such as autism," the researcher said.
"This is an interesting study that raises yet another question about those qualities that we have thought of as having a purely emotional basis," commented Dr Charles Goodstein, a psychoanalyst and professor of psychiatry at New York University Medical Centre. "Many more qualities may be based on physiology and genetics than we've realised."
He said that having families share similar facial expressions might perform some evolutionary function. "If you have the genetically linked capacity to emulate the facial expressions of your parents, in terms of evolution, you'd probably be the most likely to survive," he said. "There's evolutionary value to having similar facial expressions; you may be more likely to gain the care, love and attention of your parents."
Peleg, under the supervision of professors Eviatar Nevo and Gadi Katzir at the International Graduate Centre of Evolution at the University of Haifa, compared the facial expressions of 21 people who were blind from birth to the expressions of 30 of their relatives. The facial expressions of congenitally blind people could not have been influenced by their environment, the researchers pointed out, since they remain visually unaware of their relatives' faces.
Each study volunteer was interviewed individually and all experienced sadness, anger and joy at some point during the interview. Facial expressions were photographed and indexed. In most cases, families did exhibit a unique family facial expression "signature," according to the researchers. In fact, in about 80 percent of cases, family members could be accurately linked to individual participants, based on their range of facial expressions.
"We found that the frequency of a facial movement of a congenitally blind subject in his family is significantly higher than that outside his family," said Peleg.
"There will always be debate about what traits are nature vs. nurture," said Goodstein. "This study eliminates an important consideration, however: What could have been envisioned by the child."
Environment could still play a role in the development of facial expressions, even in blind children, he added. Goodstein theorised that when a child first smiles, a parent might recognise the expression and be pleased by it. "What if the parent rewards the baby's smile and pats the baby? That smile is more likely to become a habitual smile," noted Goodstein.
"Facial expressions may be hardwired at birth, but they may not," he added. Results of the study were published in this week's online issue of the Proceedings of the National Academy of Sciences.
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