During the early days of civilization, people used whichever hand can be used in finding food, climbing hills and mountains, building shelters, and even drawing pictures on the walls of their caves. Anthropologists theorized that handedness was shared evenly between left-handed and right-handed thousands of years ago.
Ancient artifacts unearthed all over the world proved that Stone Age men created instruments that could be used with either hand, whichever was convenient for them.
A study which cited that the right-handed lived longer than the left-handed was based on scrutiny of records of deceased baseball players which took note of the age at death for right-handers and left-handers. The kind of methodology however, has created doubts from many people up to this time.
The study failed to consider that there is a decline in the number of children forced to change handedness over the past decades, resulting in a much higher number of left-handed compared to 50 years ago.
British researchers made similar studies of numerous cricket players but their methodology was differently done which excluded the factor of forced handedness. It was revealed that there was no difference in mortality between the right-handers and the left-handers when unnatural causes were not considered.
A mixed opinion aroused on the belief that lefties are more accident prone. This was furthered supported by a Swedish study of military conscripts that showed no significant difference, except for motor vehicle-related accidents that have been attributed to right-layout inclination of driver controls.
Again a study done in 1980 by Halpern & Coren implied that left-handed people had an average life expectancy of 9 years less than right-handed people. However, the data was not considered credible since it was based only on second-hand information gathered from the next-of-kin of recently deceased persons who were right and left-handed. The findings of researchers revealed that left-handed average age of death was 66 and the right-handed average age was 75.
However, that second-hand survey data used in the Halpern & Coren study is not a reliable methodology and only a few number of sample sizes were used. The research made by Aggleton, Bland, Kentridge, & Neave in the British Medical Journal does not agree on the theory that left-handed people die earlier.
But there are some evidences that left-handed women may have a shorter life span than right-handed women. A recent Dutch study indicated that left-handed women had a 40 percent higher risk of dying from any cause. They have a 70 percent higher risk of dying from cancer, and a 30 percent higher risk of dying from diseases of the circulatory system.
Left-handed women also had a 2 times increased risk of dying from breast cancer, close to a 5 times increased risk of dying from colorectal cancer, and more than 3 times higher risk of cerebro-vascular mortality.
But to-date no valid reason is given by researchers why left-handed women are prone to diseases. This leaves the subject of life-expectancy of right-handed and left-handed people to some degree of uncertainty.