Credit: Andrey Giljov/Natl Geogr. Soc.

Kangaroos that use two legs to jump have a strong preference for which hand they use to scratch themselves, suggesting that pronounced handedness is not uniquely human.

Yegor Malashichev of Saint Petersburg State University, Russia, and his team observed seven species of marsupial (including kangaroos) in Australia — three that walk on four legs and four species that are bipedal. They found that two kangaroo species mostly used their left forelimbs for actions such as grooming (pictured is an Eastern grey kangaroo, Macropus (Macropus) giganteus). Red-necked wallabies (Macropus (Notamacropus) rufogriseus), which move on two legs, generally used their left forelimb for fine manipulation tasks, such as feeding, and the right forelimb for actions requiring greater physical strength, such as holding up branches when feeding.

Four-legged animals did not exhibit handedness, suggesting that two-legged locomotion is a prerequisite for this characteristic.

Curr. Biol. http://doi.org/5jh (2015)