Red and gray kangaroos, however, were the exception, preferring their left hands for tasks such as grooming and eating regardless of whether they were standing on two or four legs.
During the course of the research, scientists tested this long held assumption with not only kangaroos but also with bipedal marsupials that are apparently considered more true handed than humans.
For this study, the project leader and his team looked at eastern gray and red kangaroos that were living in the wild in Tasmania and Australia.
The researchers say this is the first demonstration of population-level “handedness” in a species other than humans, which are mostly right-handed.
The tree-dwelling ancestors of red and gray kangaroos would have primarily relied on their right side for navigating the treetops, which meant only their left hands were free for grooming and feeding. According to Malashichev, in “a special-assessment scale of handedness adopted for primates, kangaroos pulled down the highest grades”.
Red-necked wallabies also showed a strong preference for the left paw, with one interesting exception. The researchers said that one-handedness may be more associated to posture than heredity.
They found the quadrupedal species they observed did not show overall handedness-although some individuals might have a favored forelimb, each group overall was “fifty-fifty”, Giljov says.
The study of handedness in animals began six years ago, when the researches noticed that various species of frogs use different legs depending on the action.
What was previously thought to be a specific with primates, handedness proved to be a specific for certain species of wild kangaroos as well. In the case of the red-necked wallabies, they preferred using one hand for some tasks and the second hand for other tasks.
The Russian team was aided on location by Janeane Ingram, a wildlife ecologist and PhD student at the University of Tasmania.
Not all marsupials were found to exhibit such handedness. But scientists have found more and more evidence that other species have such preferences as well.
“Wallabies use their front paws when they stand upright and at those times they display handedness”, Malashichev told RBTH.
Because human handedness has shown associations with neuropsychiatric conditions, including schizophrenia and autism, the findings suggest further studies could yield important insights into such links, the researchers say.
At the beginning of the study, the scientists were not expecting to discover hand preference in marsupials, given differences in their brain structure when compared to other mammals such as primates.
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