Scientists have decoded the puzzle of why wolves cannot be tamed, while dogs can gladly become "man's best friend", even though the two share similar genes.

New research by evolutionary biologist Kathryn Lord at the University of Massachusetts suggests the different behaviours are related to the animals' earliest sensory experiences and the critical period of socialisation.

Until now, little was known about sensory development in wolf pups, and assumptions were usually extrapolated from what is known for dogs, Lord explained.

To address this knowledge gap, she studied responses of seven wolf pups and 43 dogs to both familiar and new smells, sounds and visual stimuli, tested them weekly, and found they did develop their senses at the same time. However, these two subspecies enter the critical period of socialisation at different ages.

Dogs begin the period at four weeks, while wolves begin at two weeks.