Screws and screwdrivers - like tin openers, scissors, corkscrews, card machines, and mobile phone apps - are designed for 90% of the population: right-handed people.

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Tightening a screw (clockwise) with your right hand requires supination (palm up) at the elbow, and external rotation at the shoulder. This outward turning motion aligns with how we naturally apply force.

For left-handers, though, tightening a screw requires pronation at the elbow and internal rotation at the shoulder. This turning inward motion is an inherently weaker movement pattern, and provides less stability at the wrist.

Left-handers do, however, recapture an advantage when loosening screws, as rotating counterclockwise aligns with their natural biomechanics.

As for the 1% blessed with ambidexterity, they get the best of both worlds: tighten with the right, loosen with the left.

At school, they told us to pursue a career that suits our natural talents and dispositions. My only talents were a strong right wrist and a superhuman tolerance for endless screwing. Fast forward 12 years and over a million screws later, I have most certainly mastered the art of screwing, and could do it drunk, blind, upside-down, in my sleep.

Fixing the loose screws in my head, though... not so easy.