From Barrie Wells
In her piece about excavations in a Yorkshire churchyard, Georgina Ferry writes that archaeologists have produced even higher estimates of left-handedness than the most recent 13 per cent, recording 16 to 19 per cent rates in medieval skeletons (Â鶹´«Ã½, Science, 26 August).
Castles built in this period took advantage of the dominance of right-handedness for their defence, through the design of spiral staircases. The defenders may be assumed to be the ones further up the staircase. It is easier for a right-handed person to wield a sword from above if the staircase descends counterclockwise as viewed from above. This design was therefore adopted to put the attackers at a disadvantage.
However, castles with five or more spiral staircases often have one constructed in the opposite direction. Presumably it was accepted that 20 per cent was around the break-even point, that there would be about this many left-handers defending the castle.
It is presumably at least partially due to evidence of this kind that it has long been believed that the level of left-handedness will approximate to 20 per cent once social pressures have been removed. However, I would be interested to know whether the study of a single churchyard (at Wharram Percy in Yorkshire) significantly adds to this belief.
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Left-handedness is sometimes said to run in families. If there is indeed a genetic effect, does a single churchyard at a time of limited travel and intermixing represent a realistic sample?
