Humans remain overwhelmingly right-handed

About nine in ten people preferentially use their right hand, a ratio that holds across cultures and time periods and stands out even among animals that show side preferences. An El País science feature by Patricia Fernández de Lis traces the puzzle through fossil clues and archaeology, arguing that the human skew toward the right hand appears to deepen as tool-making and complex communication emerge in the record. The piece places the question inside a broader story about brain asymmetry: what looks like a simple habit is tied to how tasks are divided between hemispheres.

According to El País, many species show individual biases—cats may favor a paw, parrots a foot—but humans are unusual in displaying a population-wide tilt. In chimpanzees the split is closer to two right-handers for every left-hander; in humans it is closer to eight or nine to one. The article links handedness to hemispheric specialization: in over 95% of right-handed people, the left hemisphere is primarily responsible for language, while the right hemisphere is more associated with functions such as face recognition and spatial orientation. Hand movement control and speech production sit in adjacent brain areas and share neural circuits, a proximity that makes it difficult to discuss “handedness” without also discussing communication.

One leading account described in the piece is that language began as gesture before it became vocal, with early complex communication relying on manual signs that were more often made with the right hand. Tool-making then supplies a mechanical reason the bias could have become self-reinforcing: knapping and other early techniques require coordinated roles for the two hands—one stabilizing, one striking at controlled angles and forces. El País notes that brain asymmetry can be inferred from endocranium imprints inside fossil skulls, with australopithecines from three to four million years ago showing asymmetry and a more pronounced pattern emerging around the time the first worked stone tools appear roughly 2.5 million years ago. The oldest stone flakes, the article says, indicate most early hominins used their right hand for tool-making.

The argument is not that any single factor “caused” right-handedness, but that teaching, imitation, and shared techniques could have amplified a small initial bias into a stable majority trait. Tool skills are culturally transmitted by observation and instruction; a group that standardizes on one side can make demonstration easier and reduce errors when novices copy experts. El País also points to parrots—highly vocal and social animals—as another case where population-level lateralization appears, suggesting that communication and social coordination may be the common thread rather than uniquely human anatomy.

Two million years after the first stone flakes, the evidence remains indirect: imprints in skulls, wear patterns, and the asymmetries implied by tools. The modern world still records the same blunt number—about 90% right-handed—without a single fossil that can settle the matter on its own.