It was part of a study into how humans recognise music
Researchers in Barcelona made rats listen to the “Happy Birthday” song for three weeks, all in the name of science.
Scientists at the Universitat Pompeu Fabra’s Center for Brain and Cognition played a piano version of the second half of the song to forty rats for ten minutes every day for three weeks.
It was part of efforts to work out whether other species share the same skill as humans in being able to identify songs even when things like the key or the tempo change, with the findings published in the journal Animal Cognition.
For forty days in a row, the rats listened to “Happy Birthday”, and were given a snack every time they heard the song.
Eventually, the animals began to expect a treat whenever they heard the tune, in the same way that you’d expect some cake if you heard colleagues or friends singing “Happy Birthday.”
Once the rats began to recognise the song, the experiment moved onto the next step.
The rats were then played variations of the tune. Sometimes it was faster, sometimes it was slower. Sometimes with a higher pitch, sometimes with a lower one.
They were also played versions of the tune with a different instrument, such as a violin.
If they managed to recognise that it was the same tune, then they would behave as if they were getting a snack, by poking their noses on the feeder.
The researchers found that the rats were able to recognise the song when the pitch or tempo changed, but not when a different instrument played the melody.
Juan Manuel Toro, one of the study’s authors, told Universitat Pompeu Fabra: “The results suggest that the ability to recognize patterns over changes in pitch and tempo present in humans might emerge from pre-existing abilities in other species.”
Whilst us humans are obviously able to identify much more complex variations in tunes, the study suggests that the ability to recognise a tune even when it’s on different instruments is a much more recent development in our evolution.
So the next time you hear “Happy Birthday” and expect cake, that’s your rat-like instincts kicking in.
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