Most kangaroos are left-handed.

Habitual use of one hand (handedness) is often thought to be predominant in humans and other primates, but studies of wild Australian kangaroos have found that they tend to use their left hand when feeding, grooming and other activities. Therefore, although most people are right-handed, most kangaroos are left-handed.

In addition to adding more information to kangaroo behavior, this study provides clues to a particular aspect of mammalian evolution. Yegor Malashichev, a biologist at the National University of St. Petersburg, Russia, said: “We found a very obvious handedness phenomenon. In biped kangaroos, most individuals prefer to use their left hand when performing various behaviors.”

Most kangaroos are left-handed.

Researchers say they didn’t expect to find handedness in kangaroos or other marsupials because their brains are different from those of placental mammals, including primates. Janeane Ingram, a wildlife ecologist involved in the study, said: “Anything that can prove the handedness of other bipeds will provide clues to the study of brain symmetry and mammalian evolution. Even in the scientific world, real handedness is believed to be predominantly present in humans and primates.”

Most kangaroos are left-handed.

Researchers observed seven species of kangaroos, including eastern grey kangaroos, red kangaroos, red-necked kangaroos and tree kangaroos, on the Australian mainland and Tasmania Island. They found that eastern grey kangaroos and red kangaroos like to wash their faces, pick leaves, bend branches and support their bodies with one hand in all activities. Red-necked kangaroos eat leaves with their left hand. They hold branches with their right hand and pick leaves with their left hand. However, the researchers found no obvious handedness in kangaroos.

Most kangaroos are left-handed.

Humans and kangaroos are not alike, but they share a common feature: they spend most of their time biped. Therefore, Malashichev and his colleagues speculated that bipedal walking was the cause of handedness, whereas quadruped animals showed no obvious handedness.

Because the connections between the left and right brains of kangaroos are different from those of other mammals, it is surprising to find handedness in kangaroos. The findings suggest that researchers may need to study kangaroo brains further and plan to know if other marsupials, such as koalas, are handy. In mammals, marsupials play a very special role, so studying their brain function may provide some interesting information about our evolutionary history.