David Lack's *The Natural Regulation of Animal Numbers* is a clear and balanced account of animal population dynamics, emphasizing the role of density-dependent factors in maintaining stable numbers. Lack discusses how limiting factors such as food supply, predation, and disease regulate population growth, noting that while mathematical models like the logistic curve provide useful insights, they are simplifications. He highlights the importance of natural selection in shaping reproductive rates and stresses the role of food availability in limiting population size. The book also addresses the impact of environmental factors like climate and migration on population dynamics, and explores topics such as clutch size, breeding seasons, and territorial behavior. While the book focuses primarily on birds, it also touches on mammals and insects. Lack acknowledges gaps in our understanding and emphasizes the need for further research. He concludes with a reference to a quote about population and family size, suggesting that human population control is influenced by factors beyond biological constraints. P.K. Whelpton and Clyde V. Kiser's *Social and Psychological Factors Affecting Fertility* is a comprehensive study of the factors influencing fertility in Western societies. The book discusses the decline in fertility in the West, attributing it to various social and psychological factors. The Indianapolis study, which formed the basis of this work, examined 1,444 couples and tested 23 hypotheses about factors affecting fertility. The study distinguished between planned and unplanned families, finding that economic insecurity was linked to smaller planned families but not to the spread of contraceptive use. The book highlights the complexity of fertility factors and the need for further research. It is a valuable contribution to the understanding of social and psychological influences on fertility.David Lack's *The Natural Regulation of Animal Numbers* is a clear and balanced account of animal population dynamics, emphasizing the role of density-dependent factors in maintaining stable numbers. Lack discusses how limiting factors such as food supply, predation, and disease regulate population growth, noting that while mathematical models like the logistic curve provide useful insights, they are simplifications. He highlights the importance of natural selection in shaping reproductive rates and stresses the role of food availability in limiting population size. The book also addresses the impact of environmental factors like climate and migration on population dynamics, and explores topics such as clutch size, breeding seasons, and territorial behavior. While the book focuses primarily on birds, it also touches on mammals and insects. Lack acknowledges gaps in our understanding and emphasizes the need for further research. He concludes with a reference to a quote about population and family size, suggesting that human population control is influenced by factors beyond biological constraints. P.K. Whelpton and Clyde V. Kiser's *Social and Psychological Factors Affecting Fertility* is a comprehensive study of the factors influencing fertility in Western societies. The book discusses the decline in fertility in the West, attributing it to various social and psychological factors. The Indianapolis study, which formed the basis of this work, examined 1,444 couples and tested 23 hypotheses about factors affecting fertility. The study distinguished between planned and unplanned families, finding that economic insecurity was linked to smaller planned families but not to the spread of contraceptive use. The book highlights the complexity of fertility factors and the need for further research. It is a valuable contribution to the understanding of social and psychological influences on fertility.