A new study showed kangaroos have a dominant hand, and are almost always "left-handed."
The recent study is the first to show "true" handedness is not a feature unique to primates, but is present in bipedal mammals such as kangaroos, Cell Press reported.
"According to a special-assessment scale of handedness adopted for primates, kangaroos pulled down the highest grades," said Yegor Malashichev of Saint Petersburg State University in Russia. "We observed a remarkable consistency in responses across bipedal species in that they all prefer to use the left, not the right, hand."
Past studies have shown handedness is more prevalent in walking frogs than in jumping frogs, and marsupials that walk on all fours also show signs of the trait. Handedness was originally not expected to be seen in marsupials because they lack the neural circuit that bridges the left and right hemispheres of the brain seen in other mammals. Observations of captive kangaroos did not bring conclusive evidence of handedness, but the same wasn't true for wild animals.
"What we observed in reality we did not initially expect," Malashichev said. "But the more we observed, the more it became obvious that there is something really new and interesting in the wild."
The researchers observed wild kangaroos show a natural preference for their left hands when performing actions such as grooming, bending a tree branch, or picking a leaf; this was particularly true in eastern grey and red kangaroos. The researchers found less evidence of handedness in kangaroo species that often spent time in trees. In the future, the researchers hope to continue their studies and gain more insight into handedness among mammals.
"This will give us a better resolution for the evolutionary interpretations," Malashichev concluded.
The findings were published in a recent edition of the journal Current Biology.