This chapter presents an overview of the various sets of data that provide insight into human handedness history and geography. The history of handedness before 1800 consists almost entirely of a few isolated points, which often are illuminated only briefly through indirect evidence that has to be treated with great care. Data on handedness from the prehistoric period and pre-literate societies are necessarily indirect, take many forms, and can be difficult to interpret. A classic epidemiological method for distinguishing the effects of genes and culture is to observe migrants between two countries which differ in some characteristic. The chapter provides a clear demonstration that rates of left-handedness vary between different countries. Most explanations in biology distinguish nature and nurture, which to a large extent can be conceptualized as genes and environment. Social pressure can take many forms, and it is useful to distinguish between direct and indirect social pressure.