**The Natural Regulation of Animal Numbers by David Lack** David Lack's book, *The Natural Regulation of Animal Numbers*, provides a clear and balanced overview of the principles governing animal population dynamics. The book, primarily focused on birds but also covering mammals and insects, emphasizes the importance of density-dependent factors such as food supply, predators, and disease in regulating population sizes. Lack warns against the overreliance on mathematical models, particularly the Verhulst-Pearl logistic curve, which he sees as a simplified representation of reality. He highlights that population growth is rapid but gradually slows down due to these limiting factors. The book also discusses various special topics, including clutch size, breeding seasons, longevity, climate, and migration, and interprets these phenomena through the lens of natural selection. While the book does not delve deeply into mammalian populations, it exposes knowledge gaps and provides valuable insights into the complex dynamics of animal populations. **Social and Psychological Factors Affecting Fertility by P. K. Whelpton and Clyde V. Kiser** The book *Social and Psychological Factors Affecting Fertility* edited by Whelpton and Kiser examines the decline in fertility rates in Western countries, a phenomenon that began in the late 18th century and spread across the continent in the 19th and 20th centuries. The study, conducted in Indianapolis in 1941, tested 23 hypotheses about social and psychological factors influencing fertility using a sample of 1,444 "relatively fecund" couples. The study distinguished between planned and unplanned families, allowing for a more nuanced analysis of the factors affecting fertility. For example, while economic insecurity was found to be associated with smaller planned families, it did not significantly influence the spread of contraceptive practices. The book presents detailed results and discusses various factors such as ego-centered interest in children, fear of pregnancy, social mobility, and parental family size, offering a comprehensive look at the multifaceted nature of fertility decisions.**The Natural Regulation of Animal Numbers by David Lack** David Lack's book, *The Natural Regulation of Animal Numbers*, provides a clear and balanced overview of the principles governing animal population dynamics. The book, primarily focused on birds but also covering mammals and insects, emphasizes the importance of density-dependent factors such as food supply, predators, and disease in regulating population sizes. Lack warns against the overreliance on mathematical models, particularly the Verhulst-Pearl logistic curve, which he sees as a simplified representation of reality. He highlights that population growth is rapid but gradually slows down due to these limiting factors. The book also discusses various special topics, including clutch size, breeding seasons, longevity, climate, and migration, and interprets these phenomena through the lens of natural selection. While the book does not delve deeply into mammalian populations, it exposes knowledge gaps and provides valuable insights into the complex dynamics of animal populations. **Social and Psychological Factors Affecting Fertility by P. K. Whelpton and Clyde V. Kiser** The book *Social and Psychological Factors Affecting Fertility* edited by Whelpton and Kiser examines the decline in fertility rates in Western countries, a phenomenon that began in the late 18th century and spread across the continent in the 19th and 20th centuries. The study, conducted in Indianapolis in 1941, tested 23 hypotheses about social and psychological factors influencing fertility using a sample of 1,444 "relatively fecund" couples. The study distinguished between planned and unplanned families, allowing for a more nuanced analysis of the factors affecting fertility. For example, while economic insecurity was found to be associated with smaller planned families, it did not significantly influence the spread of contraceptive practices. The book presents detailed results and discusses various factors such as ego-centered interest in children, fear of pregnancy, social mobility, and parental family size, offering a comprehensive look at the multifaceted nature of fertility decisions.