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Liaisons of Life: From Hornworts to Hippos, How the Unassuming Microbe Has Driven Evolution

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I don't often race through a book on natural history, preferring to read a chapter or two at a time, think about them, and then read a bit more. This book is an exception; I read it in one sitting. Why? Because the author makes a well-argued case that essentially all species are strongly symbiotic with others. (Nine out of ten cells in "your" body are fellow travelers, although they account for only ten percent of "your" body mass. You couldn't survive without many of the species, nor they without you.) More importantly, evolution in one species forces -- and can be caused by -- evolution in the symbiotes. Lots of positive feedback loops here, meaning that once a tiny change occurs, it may destabilize the system enough to cause it to fall into another stable configuration. Sooner or later, it may happen that one cannot live without the other. Still later, only vestiges of one may remain. This is a more subtle way new species can emerge - and perhaps a more common one -- than simple survival of the fittest.

The book also outlines the horizontal transfer of genetic information (from one living organism to another) to complement the much more widely known vertical transfer (from parent to child). This concept is not nearly as widely known as it should be in these days of genetic engineering.

On the whole, the book is well written, with plenty of detail to support its conclusions. Minor stylistic problems include an occasional overdose of "gee whiz" statements and rhetorical questions.

If you are looking for a pleasant way to get a really solid layman's grasp of evolution, read Darwin's Ghost, by Steve Jones, followed by this book and Wonderful Life: The Burgess Shale, by Stephen Gould. I'll bet that you'll reread all three of them. At least I have.

Suppose Darwin's theory of evolution is incomplete. Imagine that the missing link in this major scientific theory is one-thousandth of a millimetre long - a fraction of the size of a pinhead. In LIAISONS OF LIFE I explain how microbes - the collective term for bacteria, fungi and a disparate assortment of single-celled organisms called protists - have in fact been key players in the evolutionary process.

I started writing LIAISONS OF LIFE because I discovered an unwritten history of evolution that had been researched by academics such as Jan Sapp, and biologists such as Lynn Margulis, but not given the kind of treatment that makes a page-turning story for non-specialists.

LIAISONS OF LIFE provides a history and explanation of symbiosis, the scientific name used to describe long-term intimate associations between different organisms, usually involving microbes. It is the vital role of microbes, which were denounced by biologists long ago, that is now growing in popularity and forcing scientists to rethink the Darwinian theory of evolution.

Drawing on new evidence from creatures found in underwater volcanoes, termite mounds and the gaps between our teeth, LIAISONS OF LIFE suggests that staying alive is as much about bonding with your neighbours as it is about growing and reproducing. It shows how germs blazed the trail that was later followed by plants and animals.

Despite having been first proposed over a hundred years ago, the idea that liaisons with microbes were the driving force behind evolution has taken over a century to reach centre stage. I describe that, "It is no surprise that out of the three diseases virtually defeated by modern medicine - smallpox, polio, and measles - none are microbial (they are viral), whereas of the three biggest current killers - malaria, TB, and AIDS - two are." The reason for this is quite simple. Not enough research has been conducted on the microbe. Two of the microbe's biggest obstacles were its minuscule size and the manner in which it received notoriety. Instead of appreciating its contribution to cheese and wine and its insurance in the fertility of crops, the microbe was immortalised by medical research, where its presence was seen as a sure sign of disease.

LIAISONS OF LIFE explores the mixture of political prejudice, technological backwardness and blind ignorance that lead the revolutionary ideas of a handful of pioneers to be condemned as heresies, only to be celebrated today as some of the greatest discoveries in the history of science. Some of the precarious fortunes of the pioneers charted in the book include Beatrix Potter, H.G. Wells, Louis Pasteur, and Lynn Margulis.

I point out how three of the most important breakthroughs of the past century -- symbiogenesis theory, microbe-mediated immunity, and the Gaia hypothesis -- have all challenged traditional biological theories by uncovering the hidden powers of the microbial realm.

In short, I've tried to make LIAISONS OF LIFE a page-turning story of the symbiotic revolution in biology that has been written in a form accessible to everyone. I hope you enjoy it.

Natural selection is a powerful force, but I have long suspected that other factors were involved in the evolution of life. One of these factors is the tendency for organisms to form partnerships (symbiotic relationships that may benefit both). Often this starts as parasitism, but may become (through natural selection perhaps) a mutual dependency. Wakeford has eloquently summarized the growing evidence in this area. Lichens are one notable example which were ignored by most 19th Century researchers. Indeed, as Wakeford points out the Swiss botanist Simon Schwendener and the well-known children's book writer Beatrix Potter had shown that lichens are composite organisms, consisting of both fungus and alga. Both Schwendener and Potter were ridiculed by the scientific society of the day, but were later shown to be essentially correct in their views. Since then other scientists, including Lynn Margulis, have produced solid evidence that all multicellular organisms are essentially composite organisms, containing organelles like mitochondria and chloroplasts that were once independent organisms in their own right.

Together with new developments in genomic research involving the switching on and switching off of genes these ideas will certainly alter our thinking about biology. Because of this I think we will soon have a totally revolutionary view of how life originated and evolved. Not all of Darwin's ideas will survive and many if not most may be modified (as some already have been), but I think that Darwin, who was the ultimate in curious scientists, would have approved!

I recommend this book as a well-written very good introduction to the idea of symbiotic evolution.

From the NEW YORK TIMES BOOK REVIEW: "Tom Wakeford has a good eye for striking facts...'Liaisons of Life' is a tour of symbioses--of beneficial partnerships between different life forms. Wakeford concentrates on cases in which one of the partners is a microbe, and the rhizosphere is one of about six main examples in the book. The others include luminescent bacteria that colonize the eyes of deep-sea fishes, acting as torchlights in the dark; the ideas of the biologist Lynn Margulis about cell evolution; and the early scientific career of the children's author Beatrix Potter, who started out by working on lichens. The book is highly readable; it assumes little scientific knowledge; and it is written in an enthusiastic, personal style. You can sense that Wakeford, a biologist at the University of Sussex, likes the material he is writing about. The examples of symbiosis are all excellent pieces of research...Wakeford and the school of thought he writes about have uncovered some marvelous ecological stories, and they wonder whether competition is so important after all."

This book is about symbiosis and how prevalent it is. It is also about how politicized the concept has been historically. From the experience of nineteenth-century biologist and illustrator Beatrix Potter whose identification of lichen as symbionts went against the established dogma as filtered through the ideas of Pasteur, to "anti-communist" biology as practiced by some Western scientists who saw symbiosis as supporting the collective, it is amazing how purely political ideas successfully censored the scientific. Symbiosis has even been thought of as "feminine" and contrary to the noble interpretation of Darwinism as the survival of the fittest.

But Wakeford is able (after a fashion) to go beyond the politics and demonstrate in a most convincing manner that the symbiotic way of life is vastly more important and enormously more widespread than is usually imagined. Most of us know that legumes work symbiotically with rhizobia bacteria to fix nitrogen in the soil so that it is available to the plant, but what surprised me is to learn that 90 percent of plants host mycorrhizal fungi (p. 167) and are therefore symbionts. As Wakeford asks on the same page, "Can we continue to simply call them plants without acknowledging their fungal dimension? Is a cow an animal or a microbial fermentation vessel, when without the microbes, the cow would not exist?"

Good questions, and indeed, what about humans who have microbes in our guts that help us to digest our food? Are we in symbiosis with those microbes? Without the beneficial bacteria in our guts, the harmful bacteria would run rampant and we would be led to disease. Ants are not merely ants, they are farmers who harvest fungi gardens. They and the fungi are in symbiosis, living together, dependent upon one another for their survival. And what about termites, creatures who harbor microbes to digest the wood they eat? The broad, general message of this book is that cooperation between species is at least as important in evolution as is competition.

Reading this made me think that perhaps the idea of competition in evolution is merely an anthropomorphic delusion. Certainly Wakeford shows that our notions about parasites and who is feeding on whom, may be in error. He writes, "Rather than discrete categories, the terms _mutualist_, _parasite_, and _pathogen_ are better seen as fuzzy points on a continuum, along the length of which an association between two organisms may fluctuate. For many associations, the point they occupy on this continuum is as difficult to assess as it is to say who gains more...in a marriage between two human partners." (p. 184)

There is an old saying, that I got from somewhere years ago. It is, "Everything works toward a symbiosis." This book not only supports that idea, it even, taken further, supports the idea of Gaia, namely that all the living creatures on this planet form a single organism. I don't necessary believe this, the "strong" Gaia hypothesis, but I think the distinction between a planet that harbors organisms and a planet that is itself part organism, may be more a semantic distinction than anything else.

Because of all we have learned about microbial life in recent decades, it is becoming clearer and clearer that no organism is an island, and indeed, all of life is in symbiosis with the microorganisms that constitute the largest, most viable life form on this planet. Realizing this while reading Wakeford's fascinating arguments, I had a thought: the little green men from outer space are probably symbionts themselves, but more fully realized ones, like lichen, part "animal" and part "plant," deriving their energy directly through photosynthesis. And suddenly I had a vision of beings all seated as in meditation, taking a break to open the top of their heads, filled not with brains, but with cells capable of turning light into nourishment. How primitive and clumsy we might appear by comparison!

_Liaisons of Life_ by Tom Wakeford is a well-researched and very readable book on the importance of symbiosis in ecology and in evolution. Actually, to be more specific, it is a book about the importance of organisms' symbiosis with microbes (whether microbes with microbes or microbes with macroscopic organisms). The central tenets of this wonderful work are first that microbes (be they bacteria, protozoa, or fungi) are one of the most important innovative factors in evolution and are key parts of any ecology; Wakeford believed that the importance of the gene has been overemphasized. Secondly, interdependence among organisms is at least as important (if not more important) than competition between them; most organisms survive only by the "constant management" of their relationships with the microbes in and around them. Far from constant competition, it is often difficult to tell where one organism ends and another begins. Thirdly, this is a dynamic relationship; relationships can change, partners in symbiosis come and go, and the mutalist of today can become the parasite of tomorrow.

The acceptance of the importance of symbiosis and the beneficial role of microbes has been a long time coming. In the nineteenth century microbes first came to the attention of scientists thanks to the efforts of Louis Pasteur. It was he coined the word "germ" and single-handedly brought about the "antibacterial age," a time that lasted for several decades in which scientists saw microbes as things only to be eradicated. Additionally, views about symbiosis became tied up with the politics of the 1920s and 1930s, with bacteria and symbiotic relationships regrettably and very unscientifically becoming tied up with fears about Communism. It did not help that many pioneers in the field hailed from Germany and Russia.

Those who pointed out evidence of symbiosis often were met with derision and ignorant prejudice. Beatrix Potter was hounded out of biology in the 1890s for her views that lichens were made up of the alliance of two organisms; when the London scientific community treated her with disdain if not hatred she became instead a noted children's author and illustrator. Earlier in 1869 the Swiss botanist Simon Schwendener offered his "dual hypothesis" for the taxonomy of lichen, noting that they were both a fungus and an alga; his theories and works were treated with contempt and for a time calling someone a "Schwendenerist" was a term of abuse, meaning someone who waffled between two competing explanations for something. The idea that symbiotic organisms could be passed from one generation to another was for a time discredited thanks to associations with pre-Darwinian French evolutionist Jean-Baptiste Lamarck.

Wakeford provided numerous fascinating examples of symbiosis in nature. Many species of orchids for instance are so dependent upon fungal symbionts in their roots that they cannot survive without them. In fact mycorrhizal fungi - underground fungi that exist in a symbiotic relationship with the roots of plants - are essential in allowing many plants to get enough of many nutrients (notably phosphate). So essential are they that 90% of the plants on Earth have domesticated their own species of fungus. Mycorrhizal fungi can form vast underground networks, often linking more than one plant together. One researcher by the name of David Perry has said that the sharing of fungal symbionts between trees is so important they form a superorganism, what he termed a "guild." These fungal symbionts are known to allow one tree - perhaps suffering by being overly shaded - to draw upon the nutrients of another tree, thereby constituting a "mycorrhizal welfare state."

In addition to colonizing roots symbionts can colonize other parts of the plant; tall fescue grass, a dominant grass in the United States, has a species of fungus (_Acremonium_) that grows in the spaces between the grass's cells. This symbiont offers resistance to drought, increases seed production, and produces toxic alkaloid compounds that put off plant-eaters. So intimate is the relationship that grass seeds are infected while still in the seed coat.

Other examples of symbiosis in nature include the relationships of deep sea organisms with bioluminescent symbiotic bacteria, chemosynthetic symbiotic sulfide bacteria living in _Riftia_ tube worms around hydrothermal vents, the bacteria that allow shipworms and termites to digest wood (or in the case of anobiid beetles, it is a yeast-like fungus that allows them to eat wood), and the bacteria and protozoa ecosystem that exists in the four-chambered stomachs of ruminants such as cattle, sheep, and deer that allow these animals to digest grass. The most important examples of symbiosis though are undoubtedly the acquisition in eukaryotic cells of chloroplasts and mitochondria, a momentous evolutionary event, an example of an extremely intimate and permanent form of intracellular symbiosis which Wakeford skillfully explained.

Many species very actively manage their microbial associates. Corals bleach themselves - bleaching being the loss of the coral's symbionts, called _Symbiodinium_ - as a natural strategy to deal with changing environmental conditions. They do this to alter the makeup of their symbionts, to allow themselves to be repopulated by a new type of associate, one that perhaps is better suited for a changed environment. Researchers have discovered that leaf-cutter ants are continually domesticating new varieties of fungi by taking them into their nests; 862 types of nest fungi have been discovered, with evidence that ants periodically swap crop varieties with their neighbors.

As noted, the continuum between beneficial symbiont and parasite is a rather fuzzy continuum. Orchids for instance produce natural fungicides to keep their root symbionts from colonizing their stems; these and other plants can be overrun by their symbionts if they become weakened or malnourished. David Philip, the famous "bubble boy," had to live in a sterile environment because his body had no ability to cohabit with the numerous microbial associates in the human body (symbiotic bacteria make up a tenth of our body's weight and totaling 90 trillion cells outnumber our own body cells nine to one). If the intestines of any human are damaged formerly beneficial symbiotic microbes can create a life-threatening infection called sepsis.

Bacteria and fungi really get a bad rap. We generally think of them as belonging to George Bush's axis of evil. As a matter of fact, says author Tom Wakeford, the majority of these mini creatures are essential for life. This is an easy to read, highly accessible little volume on symbiosis. Symbiosis involves two or more life forms combining their efforts to add to the life benefit of each.

At the beginning of the book we bump into, of all people, Beatrix Potter of Peter Rabbit fame. She was actually a biologist who subscribed to the then dissident theory that some organisms were combinations of two separate entities. She believed that lichens, those lumpy gray/green things on rocks and tree trunks, were composed of a fungus and an alga. Her scientific peers were so scornful of this belief that she ultimately quit biology, and consoled herself by writing. This career change could be considered good or bad, depending on whether you are fascinated by lichens or prefer to read books about Mrs. Tiggy-Winkle.

We learn of the interesting symbiosis between plants, fungi, and bacteria. Nitrogen fixing bacteria provide the plants with necessary, accessible nitrogen. Part of the problem that plants then face is finding the rest of the nutrients that they need. They simply can't grow huge root systems to search and find patches of underground food. Various fungi solve this problem by linking up with plants. They then send tiny tendrils far afield that discover the nutrients and send them to the plant roots. Orchids in the tropics have become endangered species. People dig them up and send them to collectors in the other parts of the world. They are then planted in gardens where they promptly die. They require a certain fungus to survive, and that fungus is found only in the habitat where they originally grew.

The book is full of tales of symbiotic science. How do some insects thrive on nutrients from leaves that they can neither chew nor digest? What bacteria live in our bodies, and how do they help us? This is one of those great science books that both teach and entertain.

I read the paperback of the original 2001 publishing year. It sure makes for a fascinating reading: Symbiotic bacteria that change the sex of their host's offspring. Worms that don't eat because they have incorporated chloroplasts for energy acquisition. Ants that market fungi with other ant species. And the origin of sexuality. (Though there are varying concepts out there, I may remark.)

The author jibes at the historic science establishment for driving out enlightened heads who came up with the idea of symbiosis in the late 19th century or some 60 years later. ("You believe in symbiosis? You must be a communist!"). He also assures us that the vilification of all the bacteria and other little "bugs" does good for the pharma companies' pockets only.

This book is easy to read and makes fun, while at it. Unfortunately, it contains no pictures. And it is a fast read, with less than 200 text pages. Meaning, this book is a good one, but not very exhaustive. It's more of a welcome introduction to the subject. One thing kept me wondering: The title. There is no mention whatsoever of either hornworts or hippos other than in reference to the title. Actually, I had to look up elsewhere, what a hornwort is (some plant), first I mistook it for the hornwarts found on a toad's skin. I am completely flabbergasted, how this most arbitrary book title came about.

Keep in mind that the book isn't the freshest one on the market. Mitochondria are still thought to have an infectious origin, for example. Even though really separate organisms once, please read Power, Sex, Suicide: Mitochondria and the Meaning of Life for an advanced theory. For a theoretic re-thinking, including reconstructing taxonomy and theories about gaia, read Symbiotic Planet: A New Look At Evolution. About largely more hostile bacteria and the fight with anti-biotics read Good Germs, Bad Germs: Health and Survival in a Bacterial World. If you are interested in the specific symbionts on and in the human body, read the exhaustive (dry) textbook Microbial Inhabitants of Humans: Their Ecology and Role in Health and Disease. More on the parasitic road, read the very recommendable Riddled with Life: Friendly Worms, Ladybug Sex, and the Parasites That Make Us Who We Are and with little overlap Parasite Rex : Inside the Bizarre World of Nature's Most Dangerous Creatures. If you like a coffee table book of the nasty treat "enjoy" Human Wildlife: The Life That Lives on Us. If you are interested in human-to-human symbiosis read the chapter on conjoined twins in Mutants: On the Form, Varieties and Errors of the Human Body.

This book is a delightful tour through the realm of symbiosis at the microbial level. The author describes one incredible symbiotic relationship after another, in creatures ranging from bivalves to wild orchids.

Even though it appears to be aimed at the average reader, he does not 'dumb down' the text. (This is why I gave it the 5th star.) Latin species names are often used and words like 'oligotrich' and 'mycorrhizae' are strewn throughout the book, yet are explained well enough to make any science-phobe feel at home.

The book really focuses on describing symbiosis by example, and the non-trivial role of the microbial partners in those relationships. He also casts off the simplistic and anthropomorphic idea of "competition" in nature for a more natural, inclusive view. There is not much mention of Gaia (which is fine by me), and the latter part of the book relating to microbial symbiosis and evolution seems to pretty much recapitulate Lynn Margulis' theory of symbiogenesis.

(If symbiosis intrigues you, also see Lynn Margulis' "Acquiring Genomes" book for a more complete description of the intriguing theory of symbiogenesis, or Gerald Tannock's books for a professional-level description of all those hundreds of bacterial critters that occupy the human intestinal tract.)