Sydney - Wild kangaroos tend to favour their left paws during common tasks such as grooming and feeding, a study suggests.
The researchers say this is the first demonstration of population-level "handedness" in a species other than humans, who are mostly right-handed, the BBC reported.
The evidence comes from hours spent observing multiple species in the wild. Two species of kangaroo and one wallaby species all showed the left-handed trend; some other marsupials, which walk on all fours, did not show the same bias, the BBC said.
The research, published in the journal Current Biology, was conducted by Russian scientists from St Petersburg State University, who travelled to Australia to do the fieldwork. They collaborated with wildlife ecologist Janeane Ingram, a PhD student at the University of Tasmania.
Ms Ingram told the BBC the work had faced some scepticism.
"Unfortunately, even my own colleagues think that studying left-handed macropods is not a serious issue, but any study that proves true handedness in another bipedal species contributes to the study of brain symmetry and mammalian evolution," she said.
The study's senior author, Dr Yegor Malashichev, said there had been a widespread notion that handedness was a uniquely human phenomenon, until research in the past 10 to 20 years showed that asymmetry in behaviour and brain structure was surprisingly widespread.
But examples of left- or right-handedness tended to be specific to particular behaviours, and were not consistent across a population.
"As one of our reviewers pointed out, laterality is also obvious in how parrots hold their food or how your dog shakes hands," Ms Ingram said. "But these examples of lateralisation have not been proven at the population level."
The study found a consistent left-handed bias across eastern grey kangaroos, red kangaroos, and red-necked wallabies - no matter whether the animals were grooming, feeding or propping themselves up.
The researchers also argue that posture is an important factor. The left-handed trend was only seen in species that stand upright on their hind legs, using their forelimbs more regularly for tasks other than walking.