Study Reveals Upright Posture and Brain Size Key to 90% of Humans Being Right-Handed

For generations, the question of why 90% of humans are right-handed has puzzled scientists. Now, a groundbreaking interdisciplinary study led by the University of Oxford offers a compelling explanation, linking this unique human trait to two pivotal evolutionary milestones: the adoption of upright posture and the significant increase in brain volume. Published in PLOS Biology, the research analyzed data from over 2,000 primates, employing a sophisticated comparative phylogenetic framework. Unlike previous studies, this work rigorously tested long-standing eco-evolutionary hypotheses. The lead researchers, including Dr. Thomas Püschel, highlight that the statistical models, when adjusted for brain size and bipedal locomotion, reveal that human handedness is not exceptional among primates in the same way it appears at first glance. The study posits that bipedalism was the initial catalyst, liberating the upper limbs for refined, lateralized movements. As the brain evolved and grew larger, this bias towards using one hand, particularly the right, became more pronounced, culminating in Homo sapiens. The case of Homo floresiensis, with its smaller brain and mixed locomotion, serves as a fascinating contrast, showing a much weaker manual preference. This research provides a crucial piece of the puzzle in understanding what makes us uniquely human.

“

Our results suggest that it is likely related to some of the key characteristics that make us human, especially upright posture and the evolution of larger brains.