Napoleon Bonaparte, Babe Ruth and Lady Gaga were all lefties.
You might call them “southpaws,” the less-flattering “goofy-handeds” or, if you’re Australian, “mollydookers.”
And while there’s no comparable set of nicknames, throughout the world, roughly nine out of 10 of us have a strong preference for using our right hand for most tasks — whether it’s eating with chopsticks, swinging a baseball bat or texting.
Scientists have long pondered why that is.
Now, a new study from Oxford University suggests that humans overwhelmingly became right-handed thanks to two big changes that happened during our evolution: walking upright and brain growth.
The team analyzed data from 2,025 monkeys and apes representing 41 primate species, using a statistical approach that frames data analysis using probability to represent uncertainty.
They tested several theories about the origins of what is called handedness or, more scientifically, lateralization. They delved into factors like tool use, habitat, body size, social structure, diet, movement and brain size.
Their results found that humans’ early ancestors, such as Australopithecus [Aus·tra·lo·pith·e·cus], likely only had mild right-handedness, more like modern great apes. The stronger preference for using the right hand appears to grow significantly with the emergence of later primate species, species including Homo erectus and Neanderthals.
The researchers still have questions. For one: Why does left-handedness persist? Has human culture played a role?
Other animals, like parrots and kangaroos — both strong lefties — might also shed some light on these curious evolutionary patterns. Perhaps, when it comes to handedness, there is no real right way.