Although approximately 90% of all humans are right-handed, cats, rats, and mice that show handedness seem to be equally split between right- and left-pawedness.
Human asymmetrical behavior patterns involve the foot, eye, and ear as well as the hand. In each case, humans show the same rightward bias they show toward handedness.
Left-handedness has also been called mancinism, sinistromanuality, and cackhandedness. Other colloquialisms for left-handedness include skivvy-handed, scrummy-handed, kaggy-fisted, cawk-fisted, gibble-fisted, southpaw, cunny-and ballock-handed.
According to tradition, an itchy left hand indicates you will lose money. An itchy right hand indicates you will receive money.
Increased levels of testosterone in the womb has been shown to increase the chances of becoming left-handed. This may explain the correlation that seems to exist between left-handedness and some immune disorders, as testosterone has been linked to immune disorders.