Sit. Roll over. Fetch. Do dogs really know what people are saying?
A study published this week in the journal Science suggests dogs can understand both the words that humans speak and the way they are intoned.
That would mean the basic brain chemistry needed to process language may be much older than the human species, and is likely present in other animals.
A team of researchers from Eotvos Lorand University in Hungary trained dogs to lie still in a functional MRI brain scanner. They then looked at the parts of the dogs' brains that lit up when they heard various words in different intonations.
The dogs heard some words of praise, and words that were meaningless, in both praising and neutral tones of voice.
The left hemisphere of the dogs' brains lit up when they heard meaningful words or phrases, such as "Well done," regardless of the tone of voice the researchers used. It did not light up when they heard words that had no meaning to them. The left hemisphere of the brain also plays a dominant role in how humans process language.
The dogs' neural "reward center," which is connected to feelings of happiness and pleasure, similarly lit up when the dogs heard praising words. And the right hemisphere of the brain showed activity when they heard words in a positive tone of voice, even if they were meaningless.
An accompanying news release referred to the results as a "first step to understanding how dogs interpret human speech," saying more research is likely needed to confirm and expand upon the findings. The researchers also note in their study that dogs could have developed the ability to understand language as humans were domesticating them, but that possibility is "unlikely."
The study concludes by saying that what makes words uniquely human is not the ability to understand them, "but the invention of using them."