Video shows chimpanzees find human yawns contagious
By Geoffrey Mohan, Los Angeles Times Grown chimpanzees can't resist the power of a yawn, even if it comes from humans. That's the result of a study involving orphaned chimpanzees rescued from Africa's illegal bush meat trade. Elainie Madsen, an evolutionary psychologist from Sweden's Lund University, yawned and made other faces at the chimps at the Takugama Chimpanzee Sanctuary in Sierra Leone. She found that only the grown chimps appear to develop a contagion for yawning, just as humans do.