Elephants associated the colour red with the Maasai
St Andrews University researchers found that elephants could recognise the degree of danger posed by different groups of individuals.
The study found African elephants reacted with fear when they detected the scent of garments previously worn by men of the Maasai tribe.
Maasai men are known to demonstrate their virility by spearing elephants.
Level of risk
The elephants also responded aggressively to red clothing, which is characteristic of traditional Maasai dress.
However, the elephants showed much milder reaction to clothing previously worn by the Kamba people, agriculturalists who pose little threat.
The psychologists said they had expected to find elephants might be able to distinguish among different human groups according to the level of risk they posed.
They said: "We were not disappointed. In fact, we think that this is the first time that it has been experimentally shown that any animal can categorise a single species of potential predator into subclasses based on such subtle cues."