Life As We Do Not Know It

Title: Life As We Do Not Know ItAuthor: Peter Ward
Publisher: Penguin Books 2007 (First published: 2005)
ISBN: 978-0-14-303849-8
Pages: 261

Peter Douglas Ward is professor of biology, earth and space and space sciences and adjunct professor of astronomy as the University of Washington in Seattle. He is associated with as the Astrobiology Institute of NASA and takes part in explorations for finding alien life in the solar system. This book is a treatise on what life is, what are its forms on earth, how it can originate differently in earth as well as other planets or moons, the probability of encountering life in these exotic places, and what should we prepared for, in case we indeed find alien life. The familiar form of earth life is based on DNA as its genetic code. This code helps to synthesise the 20 amino acids which are used for life’s functions. The number 20 is fixed for earth life (also called Terroan life, as defined by the author). But there are chances for life forms which don’t adhere to this pattern, which may code for different amino acids than the present 20. Ward says that these life forms may be present even on earth, but we have not found them out yet. In case we have seen them, we haven’t recognised them to be life forms. If such a confusion is inevitable, how are we to recognise even more alien life forms when (or if) we encounter them in other planets?

The first two chapters on ‘What is life?’ and ‘What is earth life?’ are excellent primers on the subject. The hydrothermal vents in deep ocean, where life was supposed to have started is a good topic to read. The characteristics of life are its reproducibility, development, evolution, metabolism, complexity and organisation and its autonomy. These is the definition of Paul Davies regarding life. NASA defines life as a ‘chemical system capable of Darwinian evolution’. The bewildering complexity of life forms on earth is brought into ample detail by the classification of Archaeans as a separate doman. They had long been overlooked because they closely resembled bacteria. But once their DNA was compared it became clear that these tiny cells were quite different from bacteria. Then there are extremophiles which make hot hydrothermal vents or such sulphurous sources their habitats. In the third chapter, titled ‘Life as we do not know it’, Ward discusses other possibilities like silicon life, in place of carbon life of which all life in earth is composed of. He also declares that silicon life is improbable, because silicon forms chemical bonds with other elements that are much weak than carbon’s and can be broken much easily. On the other hand, silicon-hydrogen and silicon-oxygen bonds are stronger than those of carbon, which may help it to produce long chains, thus supporting complexity.

Several recipes for life is described in the fifth chapter on ‘A Recipe book of life’. RNA life is theoretically plausible on earth, but we have not seen them so far. In alient environments, it may be more difficult for them to operate, as RNA is unstable at higher temperatures. It was an enigma for paleo-biologists to understand how RNA was formed in the first place. An explanation is given, as “in the presence of borate, simpler organic molecules that are common both on earth and in space (on comets, for example) combine to form complex sugars, including ribose” (p.94). An description of how cellular life evolved is also given, “Somewhere, perhaps amid the hydrothermal vents or may be in warm little ponds or somewhere else, microscopic bags of proteins, their lipid membrane walls separating them from the surrounding heated sea water or pore fluid of some sort, interacted with a different group of alients, perhaps nearly naked strands of DNA. Perhaps there were ribosomes already formed. In any event, the two types of assemblage merged into a single cell”. (p.97). Ward is an ardent proponent of life’s origin in hydrothermal vents and he refutes Darwin’s assertion that life might have formed in ‘warm little ponds’ or in the ‘primordial soup’ of early earth. He says, “What Darwin could not appreciate in his time was that the mechanisms leading to accretion of the earth produced a world that, early in its history, was harsh and poisonous, a place that was very far removed from the idyllic tide pool or pond envisioned in the 19^th and early 20^th centuries, but that did not have a reducing atmosphere or ocean” (p.111).

The next chapter on ‘Artificial synthesis of Life’ hovers on the efforts in this field including the synthesis of amino acids by Stanley Miller and Craig Venter’s efforts. Venter succeeded in synthesising amino acids different from the ones used by ordinary life and the different DNA of these organisms are sure to add fuzz to researchers’ lives in these labs. Since this book was published five years ago, nothing of much of Venter’s works are mentioned, but Venter himself finds a prominent mention at the appropriate place.

After these solid preliminaries, Ward moves on to the concept of ‘Panspermia’, the theory that life originated not in earth, but in some other planets from which the seeds of life travelled in meteors or comets and reached earth. In fact, not only earth, but any planet which receives the seedlings of life is an example of panspermia. He asserts that however hard NASA might have tried, there are microbes in the innumerable satellites and space probes which have impacted other planets and moons, the vikings, mars explorers, cassini-huygens probes are some of them. There is a slender, very slender chance that such random droppings on a foreign planet might have spawned life there. An investigation into the places in our solar system where life can originate constitute the next four chapters. The planet Venus is nearer to the sun and the surface is very hot for organic molecules. However, in the clouds of Venus, which are filled with sulphuric acid, there is a probability of some primitve life originating, as per some researchers. The case of Mars, is entirely different. There is evidence that Mars once had flowing liquid water, a hospitable temperature and all paraphernalia required for life. Though these favourable conditions are definitely not available at present, and the planet is barren, there may be fossils of early life forms there which a paleontologist may be able to pick up once one such person lands on the planet. Billions of years ago, when Sun’s energy output was considerably less that what is spits out at present, the three planets of Venus, Earth and Mars might have been habitable. In fact, there is very good probability that the conditions on Earth and Mars were identical 3.5 billion years ago when life first originated on Earth. The third place to look for is Europa, one of Jupiter’s moons which has a planet-girdling ocean of ice, which might harbour liquid water under the icy crust. The depth of the ocean is nearly 100 kilometers, 10 times that of Earth’s, and hence any life forms which might be present there should have resolved the problem of sustaining under the enormous pressure experienced at such great depths. The fourth option is that of Titan, Saturn’s biggest moon. Unlike the others, Titan is quite large (nearly equal to Mercury) and has an atmosphere which is very thick and consisting of methane and other hydrocarbons. It may also contain a sea of ammonia which is not impervious to life, not even to some form of earth life. The huygens probe which landed on Titan in 2005 gave details of the hydrocarbon rivers and seas and the atmosphere there. Ward also hints that of all the places in the solar system, Titan may be the place where we may indeed detect life. But its metabolism and chemistry will be radically different from the CHON life forms which we encounter in earth (CHON stands for Carbon, Hydrogen, Oxygen and Nitrogen). Ward also says in a lighter vein that a biochemist shall be the first person landing on that moon, just as it should have been a paleontologist who first sets foot on Mars.

The book ends with an admonition to politicians who sanction bio-chemical weapon research which may sound the death knell for this planet and its myriad life forms. The viruses and other monsters developed at these labs may go out of hand and cause irreversible effects on plants and animals. We should tread carefully on this area and more money should be spent of search for life at other places in the solar system.

A very good work, eminently readable and which presents the state of research in the chosen field in a concise and easy-to-understand format. The book is attractive to experts and lay people alike. The good sense of humour of the author is evident in every page of the book. Some excellent photos sourced from NASA’s archives give accurate and state-of-the-art information on planets and moons, especially Mars, Europa and Titan. The only drawback which can be made out of this book is the usage of outdated temperature and distance scales used. The temperature is always given in fahrenheit and distance is in miles. While this may be more than sufficient for those readers in the U.S where metric system does not exist, a book which caters to the international public should at least have taken care to give the values in celsius and kilometers also. Such myopic vision was uncharacteristic to an author and a book which sought to widen our view even beyond earth! Even with this discrepancy, the book is recommended and should receive a warm welcome from collectors of science works.

Rating: 3 Star