Astrobiology of Earth The Emergence, Evolution and Future of Life on a Planet in Turmoil

by Gale, Joseph

• ISBN13: 9780199205813
• ISBN10: 0199205817
• Format: Paperback
• Copyright: 2009-05-15
• Publisher: Oxford University Press

Summary

The study of life in our universe has been given the name 'astrobiology'. It is a relatively new subject, but not a new discipline since it brings together several mature fields of science including astronomy, geology, biology, and climatology. An understanding of the singular conditions that allowed the only example of life that we know exists to emerge and survive on our turbulent planet is essential if we are to seek answers to two fundamental questions facing humanity: will life (and especially human life) continue on Earth, and does life exist elsewhere in the universe? Astrobiology of Earth adopts a unique approach that differs from most texts in the field which focus on the possibility of extraterrestrial life. In contrast, the central theme of this book is the fortuitous combination of numerous cosmic factors that together produced the special environment which enabled the emergence, persistence and evolution of life on our own planet, culminating in humanity. This environment has been subject to constant and chaotic change during life's 3.6 billion year history. The geologically very recent appearance of humans and their effect on the biosphere is discussed in relation to its deterioration as well as climate change. The search for extraterrestrial life is considered with a view to the suggestion that humans may escape a depleted Earth by colonizing the universe. This book contributes to our understanding of astrobiology from the perspective of life on Earth and especially human welfare and survival. Astronomical and geological phenomena are related in turn to their biological relevance and impact. This introductory text assumes little or no prior knowledge of more specialized scientific fields and is designed for undergraduate and graduate level students taking related courses in departments of biology, earth science/geology, and environmental science. It will also serve as a useful biology primer for astronomy majors.

Author Biography

Joseph Gale was born in London, UK but immigrated to Israel in 1948. He studied at The Hebrew University, Jerusalem, and then completed his advanced studies at the University of California and the University of Michigan, USA. He was a visiting professor at McGill University in Canada and the Ben Gurion University (BGU) in Israel. At BGU he headed a research department and served as Institute Director and head of the International Center. His environmental expertise and experience in military and commercial aviation led to participation in a NASA project for Controlled Environment Life Support Systems for space flight. He has published more than one hundred refereed papers and co-edited/authored two books. Presently he is Professor Emeritus at Hebrew University where he teaches a course on the Astrobiology of Planet Earth.

Table of Contents

Introduction	p. ix
Symbols and abbreviations	p. xv
What is life? Why water?	p. 1
What is life?	p. 1
Why water?	p. 8
Summary	p. 17
The universe from the perspective of biology	p. 19
Some special units of measurement used in astronomy	p. 21
Time	p. 22
Biologically significant events occurring in the universe	p. 23
Stars	p. 25
Galaxies	p. 27
Planets of other star systems	p. 30
Comets and asteroids	p. 31
A brief survey of some other denizens of the universe	p. 32
Galactic and Circumstellar Habitable Zones	p. 33
Summary	p. 35
The Solar System and life on Earth: I	p. 37
Main components of the Solar System	p. 37
Our star, the Sun	p. 37
The heliosphere and solar wind	p. 39
The Sun's short-wave EM radiation	p. 39
Solar radiation and the temperature balance of the Earth's surface	p. 43
Solar radiation and photosynthesis	p. 44
Short-wave solar radiation, signals, and vision	p. 45
The concept of a Circumstellar Habitable Zone (CHZ)	p. 47
Planets of the Solar System and life on Earth	p. 49
Some extraterrestrial sites in the Solar System which may support life	p. 51
Summary	p. 55
The Solar System and life on Earth: II	p. 57
Comets and asteroids	p. 57
Planetary satellites and life	p. 58
Earth-a unique planet of the Solar System	p. 64
Cosmic radiation and the solar wind	p. 73
Summary	p. 76
Early and present Earth and its circumnavigation of the Sun	p. 79
Early Earth	p. 79
Motions of Earth in its circumnavigation of the Sun	p. 87
Significance of the Moon to life on Earth	p. 91
Jupiter-Earth's guardian angel (perhaps)	p. 93
Summary	p. 95
Origin of life and photosynthesis	p. 97
What do we know, what can we know of the origin of life?	p. 97
Panspermia	p. 100
The empirical 'bottom-up' approach to understanding the 'rapid' appearance of life. Can we produce life in a test tube?	p. 102
Some conjectures	p. 105
Hypotheses concerning the origin of life on Earth	p. 107
The origin of photosynthesis	p. 109
The evolution of photosynthesis	p. 109
Consequences of lack of birth control in plants	p. 112
Summary	p. 114
Setting the stage for the evolution of life on a tumultuous planet	p. 115
Earth's 'third atmosphere'	p. 116
Oxygen, UV radiation, and early ice ages	p. 118
Some biological effects of the oxygen revolution	p. 119
Carbon dioxide in Earth's third atmosphere	p. 122
Composition of Earth's atmosphere in the late Quaternary period	p. 123
Major stress factors which affected the evolution of life	p. 125
Mass extinctions in the fossil record: local and planet-wide catastrophes	p. 130
Conclusions	p. 134
Summary	p. 135
Mechanisms of evolution: from first cells and extremophiles to complex life	p. 137
The dating problem	p. 137
Timing of the main events in evolution	p. 138
Some early ideas about evolution	p. 138
Some recent theories of the mechanism of evolution	p. 143
The continuing coevolution of molecular biology and evolutionary theory	p. 147
Extremophiles	p. 149
Summary	p. 154
The evolution of humans and their interaction with the biosphere	p. 157
Human origins	p. 157
Human population	p. 160
Homo sapiens sapiens (horribilis horribilis?) and the biosphere	p. 164
Politically correct environmental science	p. 171
How many people can the world support?	p. 181
A note on land and energy resources	p. 182
Summary	p. 184
In search of extraterrestrial life	p. 187
A short history of the origins of astrobiology	p. 188
The search for extraterrestrial life today	p. 192
Why not fly there and see for ourselves?	p. 193
Creating a micro-biosphere, to enable humans to travel in space	p. 195
Limitations to the exploration of space with robotic probes	p. 199
What is the probability of there being other intelligent civilizations in the universe?	p. 200
Human spaceflight to extra-solar star systems	p. 206
Summary	p. 207
Epilogue	p. 209
A workshop guide	p. 211
Notes added 'in press'	p. 215
References and Resources	p. 217
Index	p. 231
Table of Contents provided by Ingram. All Rights Reserved.