23 May 2006 21:08 Science & Technology Clever boy! Sheep recognise faces. They self-medicate. They're clever, dammit... By Roger Dobson Published: 21 May 2006 Sheep are not so dumb after all. New research shows that they self-medicate when they are ill. They can also identify and remember faces, both human and ovine, distinguish between happy and depressed expressions, and tell one sheep's bleating from another. Scientists have discovered that sick sheep can accurately self-medicate for stomach problems. When sheep were given food than made them unwell, they were able to select and eat the right cures for constipation and heartburn. "People learn to take aspirin for headaches and antacids for stomach aches... Is it also possible that herbivores write their own prescriptions?" ask the researchers.