By Jonathan WebbScience reporter, BBC News
Baby chickens have left-right number bias like humans, say researchers - Video courtesy of Dr Rosa Rugani, University of Padova
Scientists in Italy have found that baby chickens associate low and high numbers with left and right, respectively - just like humans.
In a series of experiments, 60 newborn chicks were shown patterns of shapes representing different numbers, before choosing a direction.
Humans are known to use a "mental number line" to think about quantities but this innate left-right association has not been seen in animals before.
The work appears in Science magazine.
Dr Rossa Rugani, who led the experiments at the University of Padova, said it was impossible to know exactly what drove the chicks' choices - but the results were clear.
"All we can judge is behavioural responses. Therefore, we don't actually know if it is a real 'number line' but it strongly resembles what is observed in the human number line," she told BBC News.