Evolution: A Scientific American Reader

Evolution: A Scientific American Reader

Evolution: A Scientific American Reader

Evolution: A Scientific American Reader

Synopsis

From the Scopes "Monkey Trial" of 1925 to the court ruling against the Dover Area School Board's proposed intelligent design curriculum in 2005, few scientific topics have engendered as much controversy- or grabbed as many headlines- as evolution. And since the debate shows no signs of abating, there is perhaps no better time to step back and ask: What is evolution? Defined as the gradual process by which something changes into a different and usually more complex and efficient form, evolution explains the formation of the universe, the nature of viruses, and the emergence of humans. A first-rate summary of the actual science of evolution, this Scientific American reader is a timely collection that gives readers an opportunity to consider evolution's impact in various settings.

Divided into four sections that consider the evolution of the universe, cells, dinosaurs, and humans, Evolution brings together more than thirty articles written by some of the world's most respected evolutionary scientists. As tour guides through the genesis of the universe and complex cells, P. James E. Peebles examines the evidence in support of an expanding cosmos, while Christian de Duve discusses the birth of eukaryotes. In an article that anticipated his book Full House, Stephen Jay Gould argues that chance and contingency are as important as natural selection for evolutionary change. And Ian Tatersall makes two fascinating contributions, submitting his view that the schematic of human evolution looks less like a ladder and more like a bush.

With the latest on what's being researched at every level of evolutionary studies, from prospects of life on other planets to the inner working of cells, Evolution offers general readers an opportunity to update their knowledge on this hot topic while giving students an introduction to the problems and methodologies of an entire field of inquiry.

Excerpt

P. James E. Peebles, David N. Schramm, Edwin L. Turner and Richard G. Kron

Originally published in October 1994

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 . . .

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