Astrobiology of Earth: the emergence, evolution and future of life on a planet in turmoil (Oxford Biology) [Hardcover]

TITLE

To state in a title 'Everybody should read this' sounds perhaps a bit 'exaggerated' for a potential reader and it deserves good arguments. But in the case of this book I think this title is really adequate. The main point is that a science-based overview about the phenomenon of life on earth and in the universe is a basic knowledge for every other aspect of our life on earth and to my knowledge many, many people have still a view, which is far behind the actual available knowledge (Not only high school graduates but university graduates too are often lacking this basic and central knowledge, not to speak from all the others...). And although there are other books around which are dealing with the subject of astrobiology, the book of Gale belongs clearly to the leading ones.

POINT OF VIEW

My point of view is in the case of astrobiology that of an 'amateur' reader, but with some scientific training in other fields (computer science, psychology, linguistics, philosophy, theology...). My first encounter with astrobiology was through the book of Peter Ward and Donald Brownle "Rare Earth : Why Complex Life is Uncommon in the Universe" (2000), a fascinating book. Inspired by this I have read many papers and books related to the subject. Then I detected the book of Gale and I understand this as a thoroughly written updated summary of the subject with lots of references and many valuable web-links.

ASTROBIOLOGY

In everyday life our mind is usually caught by many daily processes which have time horizons spanning from minutes and hours to days or weeks, seldom to months, rarely to years. But, as astrobiology teaches us, the phenomenon of life can only be understood if we take into account not only hundreds or thousands of years, but millions and even billions of years. Without these perspectives we will not understand 'who' or 'what' we 'really' are. And in this sense is astrobiology the only scientific discipline today, which deals with the phenomenon of life within such a wide scope including - at least in principle - all others disciplines, which can contribute worthwhile knowledge to the subject.

DEFINITION OF LIFE

Every book on life has to give some definition what has to be understood by a term like 'life'. And it is perhaps a bit disturbing for a reader searching clear answers to read in chapter one that there is still no 'satisfactory definition' around, even if we limit such a definition to the phenomenon of life 'as it is known on earth' (p.17). But for a scientific minded reader this increases the trust into the book. Real knowledge is usually knowledge of conditions, probabilities, complexities which are not easily to 'simplify'. In case of 'biological life' we know many details which are associated with systems we call 'living', but we are lacking an overall general concept integrating all 'relevant' aspects and which is perhaps also applicable to extraterrestrial life. The list of properties given by Gale in his book is quite representative triggering more questions than answers.
This unsatisfying situation with no clear general concept of life reproduces in the context of the search for extraterrestrial life (chapter 10). In the latter case we have an additional complication by a term like 'intelligent' in the combination 'intelligent life'. To state what are signs of 'intelligent life' we have to have a clear definition of 'intelligence'. So far we have only some (simple) operational definitions of experimental psychology, which can be applied to human persons and to some degree also to animals. How can this be applied to extraterrestrial intelligent life? Gale mentions these methodological limits but does not discuss them in detail. He spends more time to discuss the possibilities and impossibilities for us humans to explore the extraterrestrial space for life. He shows with some details the limits and challenges to bring research into the universe.

THE UNIVERSE FROM THE PERSPECTIVE OF BIOLOGY

In several chapters Gale describes very nicely the basic mechanisms of the developments and behaviors of stars, planets, galaxies etc. and in which sense these properties influence 'life' as it is known so far. In summary this is a breath taking overall picture which reveals a complexity of dependencies which makes certain phenomena, especially the phenomenon of life on earth, a really 'rare' phenomenon. The famous Drake equation from chapter 10 (p.200ff) to compute the number of possible civilizations in our universe looks in this context as a very rough approximation to a space of possibilities which is hard to compute. Probably nobody at the moment can give numbers between 0 and some 10^n (with n between 2 to 5) with really hard evidences.

ORIGIN OF LIFE AND A TUMULTUOUS PLANET

The development of life on earth follows a plot which could not be more exciting if some author had to invent this plot for a movie. The development from atoms to biological important molecules and from these to first reproductive cells needed about 1 billion years and is still not completely transformed into a well accepted working theoretical model. Many questions are open. Gale describes the different perspectives of this 'chemical evolution' quite nicely in chapter 6 and adds in chapter 7 the complicated and changing conditions of earth. To read these dramatic conditions (climate, weather, atmosphere, volcanoes, radiation, ice ages, tectonics, etc.) it is very impressive to see how life forms did withstand and evolve nevertheless.

MECHANISMS OF EVOLUTION.

From the first appearance of unicellular organisms to multicellular systems it needed about 2 billion years, but then one can find 'suddenly' a kind of 'explosion' from 545 million years before present onwards manifesting a great variety of multicelluar organisms. Gale describes the theoretical models for evolution as well as the historical perspective of the development of these theories, without going too much into the details of the theoretical models. This seems acceptable; the reader gets a basic orientation and hints for further readings. Nevertheless it shows again that many important questions are not sufficiently solved!

HUMANS

The final chapter 9 about the evolution of humans includes besides the evolution as such many interesting material about the 'interaction' between humans and the environment earth. The dramatic population growth of the last 200 years, the impact on the atmosphere, species extinction, several severe pollutions of water and land, and many other topics demonstrate, that the sheer existence of humans changes the planet earth dramatically. The topic of 'climate change' is discussed too and Gale points out that the real facts are not as clear as the report of the Intergovernmental Panel on Climate Change (IPCC) has stated. He cites a list of about 30.000 scientists which criticize the official IPCC statement.

EPILOGUE

Summing up all the insights from the preceding chapters Gale points out that for now earth is the only place where humans can dwell. Whether we will be able in the future to 'colonize' other places beyond the earth seems to be for a long time not a 'real' option.

SOME CRITICISM

Taking into account the vastness and complexity of the subject I have no real criticism, because the book does a really good job to make 'visible' what is important for a basic understanding. But I want to add at least a suggestion. Following the limits of the definition(s) of life it is apparent that the defining hypotheses stem nearly all from experts from the area of biology, molecular biology, physics. But as we can see does the phenomenon of 'life' reveal a great richness of complexities within bodies and behavior too. To understand the 'essence' of life it is perhaps necessary to include these properties too. Moreover the listed properties so far are highly depending on the special chemistry 'used' until now for life-bearing structures. But if we would define life more as a 'principle' of using e.g. 'free energy', to be able to 'process information' then clearly life can be everywhere in the universe where we have free energy independent of the 'material' by which it is realized.