When Richard Dawkins published "The Selfish Gene" two decades ago, today one wonders if he had any inkling then of what his idea launched. The din of protest over the concept was loud and vituperous. Yet, a generation of research has proven him more correct than anybody imagined then. In this work, researchers Trivers and Burt have summarized the wealth of information derived over the years. Genes do far more, it seems, than simply act to replicate themselves. They intrude, divert, even kill parts of the genome to provide themselves with any and every opportunity to endure down the generations. Some genes wish to protect the genome, while others seek to damage it - both for selfish ends. In this impressive and detailed overview, we learn which types of genes strive for dominance and why.
Your body is a mosaic of cell collections. These can be winnowed down to two basic types - somatic cells and sex cells. This is essentially the case for all plants and animals, down to such simple types as protozoa. The sex cells, the gametes, have the role of carrying the messages that will build the new body of somatic cells and containing new gametes. None of this process is as straightforward as was formerly thought. Within every body, conflicts rage as genes contend for favoured conditions. The genome, that fundamental instruction mechanism, is the arena where various genes, some with a long evolutionary history, insert themselves to provide a different recipe for life. The successful ones have what the authors describe as "drive". These genetic elements contrive to be transmitted to a disproportionate fraction of the organism's progeny" - a victory over the 50-50 Mendelian ratio taught in introductory biology classes.
The authors try to follow these actions from the molecular to the evolutionary, but as they accept, the full lines of evidence either have not, or cannot be tracked completely. They provide a brief history of research in selfish gene elements, then go on to expand on this with more recent work. Their account addresses such questions as how does the selfish element accomplish its ends, when and how did it likely originate, how far does it spread and how quickly, does it produce co-adaptations, and what does it do to the host and its lineage? The twists and turns of these elements vary from mundane parasitics who use the host only to replicate to killers which can modify sex ratios. The classifications they use permit the book to be read in any order, with the reader's interests easily covered by their chapter organisation.
Selfish genes may be readily identified in many cases by their tendency to locate on the centromeres of a chromosome. This is a critical area, hence protected from intrusion. Many of the groups, which may contain hundreds of genes, once found the means to enter this zone. Meiosis and cell division convey these groups through the process of reproduction and body construction, thus allowing them to proliferate easily. Of the ten topical areas, one of the more fascinating is that of gene imprinting. Unlike the "imprinting" of newborn creatures choosing the first moving object it sees as its parent, gene imprinting is parent-specific gene expression. Either the male or female parent may contain such genes, but in either circumstance, once established, a dominance will result that is passed to future generations. In many cases that imprinting will drive the sex of the embryo, usually favouring female progeny over male. Is it this sort of gene structure that contributed to the change from solitary insects such as the ancestral wasps to the social forms, including bees, that we see today? Is the formation of our own bodies, which are but groupings of specialised cells, the result of selfish genes that have learned to work together? How does it all hold together?
Clearly, as the authors point out, it is the sexual species where selfish gene elements have made their greatest successes. Some of them may find and invade the gamete cells and drive how the resulting union follows. In a few cases, the intruders have developed ways of ejecting unwanted segments from the gametes or the fertilised egg itself. With these methods available, they may even kill embryos of multiple-birth species, leaving only those individuals who carry their coding. With meticulous care, the authors describe those about which something is known, while pointing to areas needing dedicated research. Inevitably, the issue of stem cell research looms large in their proposals.
While the book is well-organised, effectively illustrated, and containing a useful glossary, it is the references that give it a firm underpinning. Burt and Trivers have made contributions of their own, but the nearly one hundred pages of source material are an invaluable resource. The authors have gone so far as to expand the subject areas in a special section to aid searching for topics. An unequalled work, this book will long endure - to be supplanted only by the ongoing investigations they call for. [stephen a. haines - Ottawa, Canada]