A U.S biologist has found human behaviour could be driving the evolution of animals' brains by changing the habitats in which they live.

The research suggests the brains of some animals have got bigger in tandem with the industrialisation of their habitat - making some city animals smarter than their rural peers.

Evolutionary biologist Emilie Snell-Rood discovered white-footed mouse and meadow voles living in cities, had on average brains that were six per cent larger than the brains of animals collected from farms in the countryside.

Associate Professor Snell-Rood, of the University of Minnesota's College of Biological Sciences, believes animals are showing 'complex cognitive responses to both urban and rural areas with cranial capacity tracking human-induced change in some cases'.

She is interested in whether small animals will be able to cope with the conversion of prairies to agriculture or forests being replaced by cities to ultimately cope with human-induced change.

Previous research found a link between brain size and the ability to adapt to urban environments in birds, but did not investigate whether the change of environment caused the evolution.