TAILIEUCHUNG - Lecture Biology (6e): Chapter 26 - Campbell, Reece
Chapter 26 - Early earth and the origin of life. This chapter presents the following content: Life on Earth originated between and billion years ago, prokaryotes dominated evolutionary history from to billion years ago, Oxygen began accumulating in the atmosphere about billion years ago,. | CHAPTER 26 Early Earth and the Origin of Life Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section A: Introduction to the History of Life 1. Life on Earth originated between and billion years ago 2. Prokaryotes dominated evolutionary history from to billion years ago 3. Oxygen began accumulating in the atmosphere about billion years ago 4. Eukaryote life began by billion years ago 5. Multicellular eukarotes evolved by billion years ago 6. Animal diversity exploded during the early Cambrian period 7. Plants, fungi, and animals colonized the land about 500 million years ago Life is a continuum extending from the earliest organisms through various phylogenetic branches to the great variety of forms alive today. The diversification of life on Earth began over billion ago. Introduction Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Geologic events that alter environments have changed the course of biological evolution. For example, the formation and subsequent breakup of the supercontinent Pangea has a tremendous impact on the diversity of life. Conversely, life has changed the planet it inhabits. The evolution of photosynthetic organisms that release oxygen into the air had a dramatic impact on Earth’s atmosphere. Much more recently, the emergence of Homo sapiens has changed the land, water, and air on a scale and on a rate unprecedented for a single species. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Historical study of any sort is an inexact discipline that depends on the preservation, reliability, and interpretation of past records. The fossil record of past life is generally less and less complete the farther into the past we delve. Fortunately, each organism alive today carries traces of its evolutionary history in its molecules, metabolism, and anatomy. Still, the evolutionary episodes of greatest antiquity are the generally most obscure. .
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