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EVOLUTION

THE UNIVERSITY OF CHICAGO PRESS

Contents

THE EVOLUTION OF THE UNIVERSE.................................................................................................3The Evolution of the Universe P. JAMES E. PEEBLES, DAVID N. SCHRAMM, EDWIN L. TURNER AND RICHARD G. KRON.....................13The First Stars in the Universe RICHARD B. LARSON AND VOLKER BROMM...........................................................24Exploring Our Universe and Others MARTIN REES................................................................................32Searching for Life in Our Solar System BRUCE M. JAKOSKY......................................................................40The Fate of Life in the Universe LAWRENCE M. KRAUSS AND GLENN D. STARKMAN....................................................51Life's Rocky Start ROBERT M. HAZEN...........................................................................................61Misconceptions about the Big Bang CHARLES H. LINEWEAVER AND TAMARA M. DAVIS..................................................72The Evolution of the Earth CLAUDE J. ALLGRE AND STEPHEN H. SCHNEIDERCELLULAR EVOLUTION............................................................................................................87Uprooting the Tree of Life W. FORD DOOLITTLE.................................................................................99The Birth of Complex Cells CHRISTIAN DE DUVE.................................................................................114Viral Quasispecies MANFRED EIGEN.............................................................................................126How Cells Respond to Stress WILLIAM J. WELCH.................................................................................140Cell Communication: The Inside Story JOHN D. SCOTT AND TONY PAWSON...........................................................150Life, Death and the Immune System SIR GUSTAV J. V. NOSSAL....................................................................163Cybernetic Cells W. WAYT GIBBSDINOSAURS AND OTHER MONSTERS..................................................................................................171Rulers of the Jurassic Seas RYOSUKE MOTANI...................................................................................182The Mammals That Conquered the Seas KATE WONG................................................................................193Breathing Life into Tyrannosaurus rex GREGORY M. ERICKSON....................................................................203Madagascar's Mesozoic Secrets JOHN J. FLYNN AND ANDR R. WYSS................................................................213Which Came First, the Feather or the Bird? RICHARD O. PRUM AND ALAN H. BRUSH.................................................225The Terror Birds of South America LARRY G. MARSHALL..........................................................................234The Evolution of Life on the Earth STEPHEN JAY GOULDHUMAN EVOLUTION...............................................................................................................251An Ancestor to Call Our Own KATE WONG........................................................................................260Early Hominid Fossils from Africa MEAVE LEAKEY AND ALAN WALKER...............................................................269Planet of the Apes DAVID R. BEGUN............................................................................................280Once We Were Not Alone IAN TATTERSALL........................................................................................291Out of Africa Again ... and Again? IAN TATTERSALL............................................................................301Who Were the Neandertals? KATE WONG..........................................................................................310Food for Thought WILLIAM R. LEONARD..........................................................................................322Skin Deep NINA G. JABLONSKI AND GEORGE CHAPLIN...............................................................................330The Evolution of Human Birth KAREN R. ROSENBERG AND WENDA R. TREVATHAN.......................................................338Once Were Cannibals TIM D. WHITE.............................................................................................347If Humans Were Built to Last S. JAY OLSHANSKY, BRUCE A. CARNES AND ROBERT N. BUTLER..........................................355ILLUSTRATION CREDITS

Chapter One

At a particular instant roughly 15 billion years ago, all the matter and energy we can observe, concentrated in a region smaller than a dime, began to expand and cool at an incredibly rapid rate. By the time the temperature had dropped to 100 million times that of the sun's core, the forces of nature assumed their present properties, and the elementary particles known as quarks roamed freely in a sea of energy. When the universe had expanded an additional 1,000 times, all the matter we can measure filled a region the size of the solar system.

At that time, the free quarks became confined in neutrons and protons. After the universe had grown by another factor of 1,000, protons and neutrons combined to form atomic nuclei, including most of the helium and deuterium present today. All of this occurred within the first minute of the expansion. Conditions were still too hot, however, for atomic nuclei to capture electrons. Neutral atoms appeared in abundance only after the expansion had continued for 300,000 years and the universe was 1,000 times smaller than it is now. The neutral atoms then began to coalesce into gas clouds, which later evolved into stars. By the time the universe had expanded to one fifth its present size, the stars had formed groups recognizable as young galaxies.

When the universe was half its present size, nuclear reactions in stars had produced most of the heavy elements from which terrestrial planets were made. Our solar system is relatively young: it formed five billion years ago, when the universe was two thirds its present size. Over time the formation of stars has consumed the supply of gas in galaxies, and hence the population of stars is waning. Fifteen billion years from now stars like our sun will be relatively rare, making the universe a far less hospitable place for observers like us.

Our understanding of the genesis and evolution of the universe is one of the great achievements of 20th-century science. This knowledge comes from decades of innovative experiments and theories. Modern telescopes on the ground and in space detect the light from galaxies billions of light-years away, showing us what the universe looked like when it was young. Particle accelerators probe the basic physics of the high-energy environment of the early universe. Satellites detect the cosmic background radiation left over from the early stages of expansion, providing an image of the universe on the largest scales we can observe.

Our best efforts to explain this wealth of data are embodied in a theory known as the standard cosmological model or the big bang cosmology. The major claim of the theory is that in the large-scale average the universe is expanding in a nearly homogeneous way from a dense early state. At present, there...