Dogs process speech just like us, according to new research writes Mark Waghorn.

They use identical parts of the brain to understand the tone and meaning of words.

Our canine companions also do it in the same pecking order - picking up on the pitch first.

Language is considered to be a uniquely human ability - beyond even our closest primate relatives.

It's complex - communicating not only words but also inflection, gender and identity. Dogs are sensitive to these cues - suggesting they are more clever than we thought.

The groundbreaking study identifies extraordinary speech processing similarities between us and a dumb animal for the first time.

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Lead author Dr Anna Gabor, an ethologist at Eotvos Lorand University in Budapest, said: "Human brains process speech hierarchically - intonations at lower stages and next word meanings at higher.

"Dogs too process intonation and word meaning separately - and the order is also similar."

Four years ago the Hungarian team showed dogs - like people - use the right and left hemispheres to process intonation and words, respectively.

The latest study builds on this by revealing exactly what's going on in their grey matter when we talk to them.

Their sensitivity to human communicative signs is well known. Both the words and the intonation carry vital information.

For example, when we shout 'sit' many do just that. When we praise them they may notice the positive intent.

But despite years of research we know very little about their thought processes during these instances.

Using MRI (magnetic resonance imaging) scanners Dr Gabor and colleagues measured dog brain activity during a series of experiments.

They listened to both known words - 'clever', 'well done' and 'that's it' - and unknown, neutral ones like 'such', 'as if' and 'yet' both with praising and neutral intonation.

Dr Gabor said: "Repeating the same intonation led to activity decreases mostly in ancient sub-cortical brain regions.

"Repeating known words led to activity decreases in higher stage auditory cortical brain regions."

Humans also process speech using this same hierarchical sequence, she said.

Interestingly, older dogs distinguished words less than younger ones.

The findings published in Scientific Reports could shed light on the evolution of language.

Dr Gabor said: "Exploring speech processing similarities and differences between dog and human brains can help a lot in understanding the steps that led to the emergence of speech during evolution.

"Some years ago we discovered dog brains - just as human brains - separate intonation and word meaning. But is the hierarchy also similar?

"To find it out, we used a special technique this time - we measured how dog brain activity decreases to repeatedly played stimuli.

"During brain scanning, sometimes we repeated words, sometimes intonations. Stronger decrease in a given brain region to certain repetitions shows the region's involvement."

Researchers have long debated when humans starting talking to each other. Estimates range from 50,000 to more than two million years ago.

Words leave no traces in the archaeological record. Recent research has suggested it evolved early in human evolution to help our ancestors teach each other how to make stone tools.

Dr Attila Andics, principal investigator in the lab, said: "Although speech processing in humans is unique in many aspects, this study revealed exciting similarities between us and a speechless species.

"The similarity does not imply, however, that this hierarchy evolved for speech processing.

"Instead, the hierarchy following intonation and word meaning processing reported here and also in humans may reflect a more general, not speech-specific processing principle.

"Simpler, emotionally loaded cues - such as intonation - are typically analysed at lower stages - while more complex, learnt cues such as word meaning are analysed at higher stages in multiple species.

"What our results really shed light on is that human speech processing may also follow this more basic, more general hierarchy."