DOGS MAY have hitherto unknown mental abilities, according to scientific research published last week. The latest study suggests that dogs can count and that their barks are more complex than previously thought.
Many apes and monkeys are able to count. But Robert Young, an animal behaviour expert at the Pontifical Catholic University of Minas Gerais in Belo Horizonte, Brazil, suspected that dogs did, too.
Prof Young and his student Rebecca West of the University of Lincoln, borrowed a technique that has been used to show that five-month-old babies can count, according to a report in the latest issue of New Scientist.
Toy dolls are placed in front of a baby and then a screen is raised to hide them. The infant then watches as some dolls are added or taken away before the screen is lowered to reveal the final result.
If the experimenter has added or taken away a doll, the baby looks at the dolls for longer, presumably because the number of dolls contradicts the baby's expectations.
In tests on eleven dogs, they stared at bowls containing treats for much longer when the sums did not add up, says a report in Animal Cognition.
In New Scientist, Dr Sophia Yin, of the University of California, Davis, reports that dogs isolated from their owners tend to use high-pitched, single barks.
When the doorbell rings, barks are lower and harsher, often fusing into a long "superbark".
But barks during play are high-pitched and uneven, often coming in clusters.