Sex and the Origins of Death

William Clark has done a great job here of explaining the connection in evolution between the origins of sexual reproduction and the origins of death. To know that the original living organisms, and their single-cell descendents today, do not die from aging but are potentially immortal leads to interesting questions about ourselves and particularly the relationship between our soma (body) cells and our gametes ie those cells that can potentially take our DNA into the future beyond the death of the body. Clark uses the hypothetical case of a man's second major heart attack to explain necrotic cell death. He also covers the problems we are faced with today around determing 'death', brain death and dealing with persistent vegetative state etc. Taking another perspective he looks at the dried cysts and spores of simple organisms in the search for a clearer definition of life at the level of the cell. The type of cell death of particular interest is programmed cell death that arose along with sexual reproduction and multicellular organisms. Programmed cell death occurs in the developing fetus where excess cells quietly self-destruct. It also continues throughout life in, for example, the immune system. And ultimately body cells themselves are programmed to die once enough time has elapsed for the body's DNA to have passed on to new bodies. As Clark puts it, the only purpose of somatic cells, from nature's point of view, is to optimize the survival and function of the true guardians of the DNA - the germ cells. In the original living organisms the first somatic DNA was itself germline DNA. But programmed death is apparently necessary in order to realize the full biological advantage of sex as part of reproduction. Our DNA makes a hundred trillion copies of itself to ensure the transmission of just a few copies to the next generation. Then it directs the destruction of the other hundred trillion copies and we die. Death of cells is therefore not an a priori requirement of life but an evolutionary consequence of the way we reproduce ourselves and of our multicellularity. Perhaps the knowledge of our own mortality can be made more palatable when we see it as a price we all pay for the great and awesome diversity of life on our beautiful planet that has arisen from the evolution of sexual reproduction and multicellularity.

I delayed to read this book, put off by a reviewer who warned that it was difficult due to the author's use of scientific jargon. But that reviewer was wrong. There is a lot of jargon in this book: all clearly introduced, defined, and rarely used. In fact, the author presents things a little more simply than he could have! This is one of the better biology books I've ever read (and I read about a dozen each year) because of the issue it deals with: why, literally why, we die. It explains exactly what death is and why, in evolutionary terms, it happens. Here is another one of those subjects which for so long we could only explore through philosophical and religious speculation, now explained clearly, if so much less dramatically, by science. This, indeed, will be the starting point for religions of the future. Next time a child asks, "Why do people die?" I will have the answer, and an answer likely to appeal to the child's sense of wonder at the universe, likely to inspire her to learn more about her world. Topics covered include a basic introduction to cell biology, "accidental" cell death (necrosis), programmed cell death (apoptosis), the difference between prokaryotes and eukaryotes, sex (in this book, "sex" is simply genetic exchange, not the "sexy sex" we all obsess over; nothing titillating here), the difference between germ cells and somatic (body) cells, the causes of senescence (aging), progeria (a disease of premature aging), the various functions of different parts of the brain, biological and legal definitions of death, permanent vegetative states, biological definitions of life, and cryptobiosis (spores). In addition, embryology, immunology, cancer, metabolism, viruses, and neurology are lightly covered. All of that is well-explained; if you are curious, you will certainly be able to understand this book. By far the highlight of the book, the most interesting part, is the minute descriptions of the processes of cell death, incorporated into a detailed description of processes of the death of a human being. Let me recommend some other books that go very well with this one. Sherwin Nuland has written several, including "How We Die," which I've read and very highly recommend. It focuses exclusively on human death, and describes how various illnesses lead to death; it also deals with things from a more personal angle. "Sex and the Origins of Death" introduces us to a "gene's eye view" of life, which was popularized in Richard Dawkins' classic "The Selfish Gene," which I also strongly recommend, along with his other books. In addition, Matt Ridley's two best books are "Genome," as fine an introduction to genetics as a layperson could ask for, and "The Red Queen," which brilliantly explores the significance of sex for evolution. More distantly related to this book, Carl Zimmer's "At the Water's Edge" has the best account of embryology and evolution that I've read--though I haven't yet read Sean Carroll's "Endless Forms Most Beau

From the outset what UCLA's Wm Clark reports is staggering; Death is "not an obligatory attribute of life" and did not appear with the advent of it. Cellular aging resulting in death may not have occurred for more than a billion years after life's first entry on earth. Programmed cell death (PCD) which we suffer (displayed through wrinkles and forgetfulness) seems to have arisen about the time cells were experimenting with sex. Sex is an energy costly activity, engaged in because it rolls the genetic dice, inviting variations with each new offspring. An advantage because with environmental change what was well suited in the old world is often not suited for the new. Gene variations may result - through natural selection - in a few offspring amongst the dying progenitors that survive to save the species. For example, bacteria reproduce though cloning themselves, and can do so at a rate of 16 million per hour from one parent (take your antibiotics). But when the environment becomes harsh the parents spontaneously engage in sex, swapping genes with others as a gamble on survival.In a description of catastrophic cell death Clark displays a talent to meet or exceed even Sagan's best - clear, rich, compelling. Here heart attack and the wonder of cell machinery resist the inevitable as systems and their back ups struggle to counter power failures and starvation in a chain reaction of failing miracles. Like a community, some components are wholly unaware of disaster while others sacrifice themselves transferring energy to last lines of defense - pumps stationed in cell walls countering a siege of water pressing in about to wash them away. Such stunning, intentioned actions of this tiny, helpless, complex organism, the cell (of which we possess about 100 trillion - about as many cells as there are stars in the nearest 400 spiral galaxies including the Milky Way!) is starkly contrasted against our cell's decision to commit suicide. This happens when life is late, or as early as the womb when ancient relics of evolution are flushed out of us - like reminders of an ocean origin when interdigital webbing of our onetime fins are removed through PCD, leaving what's left between our fingers. Once the nucleus decides to pull the trigger, one last set of instructions emerge as its DNA begins disassembling. All the while a stack of unread instructions are being executed by unwary elements of the cell. The cell detaches from its neighbors, undulates, breaking into globules while still ignorant workers in these blobs work away, floating into a void where they are devoured by immune systems. Awful. But there are rays of hope for immortality. "Growth factors" are given to cells like lymphocytes to put a safety on their trigger. And there are executioners in this tragedy, T-Cells. Having spotted an invader they do not murder the foreigner, they command the interloper to kill itself, orders dutifully followed. T-Cells know the security code. Paramecium dodge death by let

I can't say enough about UCLA immunologist Dr. William Clark. Despite the brain stem grabbing title of this book (come on, sex and death?) set on a background of struggling sperms, this is a concise, informative primer on cellular biology; a broad subject. Fortunately Clark focuses on some of the more interesting aspects allowing the reader some specific retention from a virtual sea of information. There are probably about a dozen absolutely astounding facts in the anals of science and physics that bring perspective to the wacky world of reality. Clark zeroes in on the biological milieu and sheds some light on what sex and death signify at the biochemical level. For example, dividing bacteria are potentially immortal. They don't necessarily die (although outright death can occur) but simply divide, thereby making more copies of theirselves. Sex, Clark's thesis implores, was natures alternative to bacteria but carried the price of mortality with it. If this isn't an original sin analogy I don't know what is. All the bacteria today are in a sense immortal descendents of the bacteriodal creatures that existed billions of years ago. We, as humans didn't just pop up out of the aether either, but it is our germ cells that are the the catalysts for allowing us to be here in a potentially immortal lineage from the very same ancestors of bacteria. Not our bodies mind you, they're just disposable vehicles for the immortal sperms and eggs ( the ones that get regenerated and fuse with their counterpart in any event). We die, but our sperms and eggs (a few at least), like bacteria, persist in an immortal-like, time spanning existence. Gametes, however, aren't the only eukaryotic cells that are potentially immortal (yes Martha, immortality isn't just a transcendental idea) so are cancer cells. Cancer cells are those disposable body cells that go haywire and lose the genetic program to commit suicide. They become potentially immortal and in some cases revert back to a bacteria like haploid state. You see, body cells, like germ cells, need not die; they do so because they are programmed to. Our genes contain suicide programs in them and that is why we die; of course, if they didn't we'd be just a big wads of cancer: we'd be more like bacteria than people-ergo, death really isn't such a bad thing after all, it does in fact serve a very important purpose. You'll learn about cellular suicide mechanisms like telomere degradation and the Hayflick limit. This little book truly is fun reading. Clark always throws in a sidebar to illustrate his thesis. In this book he takes an old guy who has an attack of acute cardiac failure due to ventricular fibrillation and eventually ends up plugged into life support. Clark's hypothetical victim becomes essentially brain dead but can still breath and exhibit facial expressions doe to continuing brain stem function. What is life and death? Clark uses this imaginary heart attack victim is an effective backdrop to show a person alive