the way humans behave. "We can therefore conclude that our results indicate that our sense of fairness is a derived trait and may be unique to the human race. "If fairness considerations are important for cooperative activities such as trading goods and services and sharing, the question then is, when did they evolve in our species? And if fairness is important only in humans, the question is why only in humans?" ### 'Theft is an ultimatum game' is published in the journal Biology Letters on 15 August 2012.