A groundbreaking study published in PLOS Biology by researchers from Oxford University has shed light on why approximately 90% of humans are right-handed. The analysis of over 2,000 primates revealed that two significant evolutionary changes—upright walking and increased brain size—may have shaped this preference. Initially, humans seemed biologically unique in their right-hand dominance, but when researchers included brain volume and limb proportions in their models, humans no longer appeared as exceptions among primates. The shift to bipedalism allowed hands to specialize in tasks like tool use, while brain expansion led to greater neurological specialization, strengthening the tendency toward right-handedness. The study suggests a two-stage evolutionary process: first, upright movement liberated hands for specialized use, and second, brain complexity intensified this preference. Interestingly, the extinct species Homo floresiensis, known for its small stature, displayed a weaker right-hand preference, possibly due to its anatomy. Despite these findings, questions remain about the persistence of left-handedness and cultural influences on hand preference.