This updated and expanded edition provides cross-referenced definitions and articles that should prove useful to students in biological and related sciences, as well as to professionals and interested laypersons. This new edition reflects the rapid and dramatic developments in cell biology in recent years, and includes additional diagrams illustrating the intricacy of numerous cell mechanisms. There are expanded entries relating to human evolution and palaeoanthropology, while the principles, techniques and issues involved in gene mapping and manipulation receive improved treatment. Topical issues, such as selfish DNA, the Human Genome Project, mitochondrial Eve and sex, are also covered. Taxonomic entries have been modified in keeping with the five kingdom system and, where possible, in line with increasingly accepted cladistic principles.