A very smart collie dog named Rico has stunned German researchers by learning words with the apparent flair of a young child, Science magazine reports.
Rico. Is he smarter than the average dog?
Rico understands more than 200 words and can work out the meaning of new ones, by a process of elimination.
What is more, Rico can often remember new words after a whole month - even though he has only heard them once before, the scientists claim.
However, some experts are sceptical Rico tells us anything new about language.
From the study of a German family's Border collie, researchers at the Max Planck Institute for Evolutionary Anthropology say that some aspects of speech comprehension evolved earlier than, and separate from, human speech.
Tests with Rico show that he can learn the names of unfamiliar toys after just one exposure to the new word-toy combination.
Julia Fischer and colleagues set up experiments in which a new toy was placed amongst seven familiar toys.
When Rico was asked to fetch the new item, using a name it had never heard before, he correctly retrieved it in seven out of 10 attempts.
The researchers say that he appreciates, as do young children, that new words tend to belong to objects that do not already have names.
"Apparently he was able to link the novel word to the novel item based on exclusion learning, either because he knew that the familiar items already had names or because they were not novel," say the researchers.
A month later, having been denied access to the new toys, Rico could often still remember the new names.
"What blew us away was that after a single exposure he was able to remember four weeks later, in half of the cases," co-author Julia Fischer told BBC News Online. "If he hadn't remembered, we wouldn't have been surprised. So when he came out of the room with the correct toy we were all stunned."
Rico's performance, say scientists, is comparable to a three-year-old child.
Katrina Kelner, Science's deputy editor for life sciences, said: "Such fast, one-trail learning in dogs is remarkable."
"This ability suggests that the brain structures that support this kind of learning are not unique to humans and may have formed the evolutionary basis of some of the advanced language abilities of humans."
Professor Fischer added: "I think these findings make you humble to some degree because you have to see that we share a lot with other animals."
Words of caution
We humans are always on the lookout for language ability in other animals, but is Rico really demonstrating that?
Alex Kacelnik, a behavioural ecologist from Oxford University, UK, believes he might not be.
"If the research is judged for its value for understanding the limits of animal rationality then it should be considered very important," he told BBC News Online. "But we should be careful about making generalisations with human language."
Rico is good at linking concepts, Professor Kacelnik believes, but that does not mean he has a special predisposition to understand language.
"From the point of view of Rico, there may not be anything special about sounds," he explained. "We don't know that Rico has a particular ability to link sounds to objects, rather than link any arbitrary stimulus to objects.
"I suspect it would be the case that if we used 200 different smells Rico would perform better."
He continued: "Sounds were used in this experiment because they are convenient for the researchers.
"Rico probably has the general ability to connect things - not a language ability."