Name _______________________ Period _________
Chapter 22: Descent with Modification: A Darwinian View of Life As you study this chapter, read several paragraphs at a time to catch the flow of ideas and understand the reasoning that is being described. In some places, the text describes a narrative or story of events that led to Darwin’s theory of evolution. Therefore, first read the narrative to absorb the big picture and then return to answer the few questions that accompany this material.
Define evolution broadly and then give a narrower definition, as discussed in the overview. Evolution: Descent with modification; the idea that living species are descendants of ancestral species that were different from the present-day ones; also defined more narrowly as the change in the genetic composition of a population from generation to generation
Concept 22.1 The Darwinian revolution challenged the traditional view of a young Earth inhabited by unchanging species
This section takes a look at the historical setting and influences on Darwin, and it sets the stage for our formal study of evolution.
How did each of the following sources view the origin of species? Aristotle and Scala Naturae: Aristotle viewed species as fixed. Through his observations of nature, Aristotle recognized “affinities” among organisms. He concluded that life-forms could be arranged on a ladder, or scale, of increasing complexity, called the scala naturae. Each form, perfect and permanent, had its allotted rung on this ladder.
The Old Testament: The Old Testament holds that species were individually designed by God and therefore perfect.
Carolus Linnaeus: Linnaeus adopted a nested classification system, grouping similar species into increasingly general categories. Linnaeus, adhering to the Old Testament belief that all species were designed by God, did not ascribe the resemblances among species to evolutionary kinship, but rather to the pattern of their creation.
Explain the role of fossils in rock strata as a window to life in earlier times. Many fossils are found in sedimentary rocks formed from the sand and mud that settle to the bottom of seas, lakes, swamps, and other aquatic habitats. New layers of sediment cover older ones and compress them into superimposed layers of rock called strata. The fossils in particular strata provide a glimpse of some of the organisms that populated Earth at the time that the layer formed.
How would Georges Cuvier have explained the appearance of the record of life shown in the rock strata?
Cuvier opposed the idea of evolution. He advocated catastrophism, the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present.
Copyright © 2011 Pearson Education, Inc.
Cuvier speculated that each boundary between strata represented a catastrophe, such as a flood, that had destroyed many of the species living at that time.
James Hutton and Charles Lyell were geologists whose ideas strongly influenced Darwin’s thinking. What were the ideas each of them contributed?
James Hutton : Hutton proposed that Earth’s geologic features could be explained by gradual mechanisms still operating today, such as valley formed by rivers. Charles Lyell: Lyell incorporated Hutton’s thinking into his principle of uniformitarianism, which states that mechanisms of change are constant over time. Lyell proposed that the same geologic processes are operating today as in the past, and at the same rate.
What is the importance of the principle of uniformitarianism? If geologic change results from slow, continuous actions rather than from sudden events, then Earth must be much older than the widely accepted age of a few thousand years.
Jean-Baptiste de Lamarck proposed a mechanism for how life changes over time. Explain the two principles of his mechanism.
use and disuse: The idea that parts of the body...
Please join StudyMode to read the full document