Handedness, the idea that most members of a species have a dominant hand and will use it for everything was long thought to be the purview of only great apes (including us, humans). According to a study led by Yegor Malashichev, a zoologist at Saint Petersburg State University, we are not alone.  

Until now, we’ve discounted the notion of handedness in other species due to their need to use all limbs in order to move. However, in species that have developed the ability to walk upright (like humans and kangaroos), hands are freed to do other tasks, and with that comes a preference for a dominant hand. 

Malashichev and his team recorded limb preference in three species: the red-necked wallaby, the red kangaroo and the eastern gray kangaroo. They discovered that red-necked wallabies used their left hands while standing on two legs, feeding and grooming themselves, and that kangaroos preferred to use their left hand regardless of whether or not they were on two or four legs.

Malashichev believes that this preference developed as a result of the brain’s evolution, its need to assign everyday tasks to one side of the brain, emergency flight responses to the other, and that an early ancestor of today’s kangaroo needed to navigate treetops with its right side, leaving its left hand free to feed and groom with.

Malashichev's study was published June 18 in Current Biology.

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