The overwhelming human preference for the right hand is largely determined by genetic and biological factors that shape the brain before birth, though evolutionary pressures like tool use and combat may have provided a survival advantage that solidified this trait in the majority of the population.
The vast majority of humans, roughly 85 to 90 percent, are right-handed, a ratio that remains remarkably consistent across cultures, suggesting a strong biological influence rather than just environmental conditioning, though certain societies enforce right-hand use. Scientists believe this preference begins in the womb, with studies showing fetuses favoring their right arm as early as the 10th week of gestation, sucking their right thumb more frequently, thus suggesting that right-handedness is the default outcome encoded by dozens of genes.
Left-handedness is thought to arise from random developmental variation, while evolutionary theories propose that the majority proportion may have stabilized because right-hand dominance offered advantages in ancient combat, such as the ability to strike an opponent’s heart, counterbalanced by the strategic, unpredictable advantages enjoyed by the left-handed minority.
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