Although estimating historical rates of left- handedness might seem easy, until recent years there has been very little systematic data. Modern work asking whether the historical rate of left-handedness might have changed systematically probably begins with that of Brackenridge (1981). However, quite the most important modern source on rates of left-handedness is the vast study by Gilbert and Wysocki (1992), which although never intended as a study of handedness has emerged as a key resource. In 1986, National Geographic magazine published a special issue on olfaction (Gibbons, 1986), which was accompanied by a “scratch and sniff” card, which readers were encouraged to scratch, report what, if anything, they could smell, and then, after completing a brief demographic questionnaire, return the card. Over 1.4 million people did so...More interestingly, there was also a strong relationship of handedness to year of birth, only about 3% to 4% of those born before about 1920 being left-handed, compared with about 11% to 12% of those born after 1950, a three fold difference...The group born in 1900 in the Gilbert and Wysocki data were therefore aged 86 when the study was carried out in 1986....An alternative explanation of the lower rate of left-handedness suggests that the elderly are more likely, because of social pressure, either to have been forced to shift from writing with the left hand to writing with the right hand, or they prefer to call themselves right-handed, because of a taboo against left-handedness (Hugdahl et al., 1993; Hugdahl, 1996). Both this and the differential mortality explanation become unlikely when one looks at the entire Gilbert and Wysocki database, which included unpublished data on individuals born between 1887 and 1899 (see McManus et al., in press a). These data on these very oldest respondents are shown in Fig. 3.1, and the heavy dotted line shows the fit of a mixture of two constrained Weibull functions. Now it is clear that the very oldest respondents have a higher rate of left-handedness than those who are somewhat younger, an effect which is significant (McManus et al., in press a), and is utterly at odds with explanations due either to differential mortality or greater social pressure to be right-handed. The best account of the Gilbert and Wysocki data is that it directly reflects the actual rate of left-handedness in the population.