First published in 1990, this is a compilation of several important papers that have contributed to the foundation of population genetics, evolutionary biology and human genetics. The collection includes Haldane’s first paper in genetics, which was published in 1915, reporting the first case of linkage in a mammal, and – fifty years later, in 1965 – his last paper in genetics on selection for a single pair of allelomorphs with complete replacement. Haldane’s Rule, the only idea named after him, was published in 1922 and is still valid today. Other papers, which include many Haldane firsts, such as the first estimation of a human mutation rate, first human gene map, first papers in population genetics, first estimate of the probability of fixation of a new mutation, and first measurement of mutation impact on a population, leading to the “genetic load” concept, are included. The volume also includes a paper presenting an ancient logical system for interpreting scientific results.