Illustrations of three fancy pigeons.

FIGURE 16–8 Artificial Selection Darwin used artificial selection in breeding fancy pigeons at his home outside London.

Farmers would select for breeding only trees that produced the largest fruit or cows that produced the most milk. Over time, this selective breeding would produce more trees with even bigger fruit and cows that gave even more milk. Darwin called this process artificial selection. In artificial selection, nature provides the variations, and humans select those they find useful. Darwin put artificial selection to the test by raising and breeding plants and fancy pigeon varieties, like those in Figure 16–8.

Darwin had no idea how heredity worked or what caused heritable variation. But he did know that variation occurs in wild species as well as in domesticated plants and animals. Before Darwin, scientists thought variations among individuals in nature were simply minor defects. Darwin's breakthrough was in recognizing that natural variation was very important because it provided the raw material for evolution. Darwin had all the information he needed. His scientific explanation for evolution was now formed—and when it was published, it would change the way people understood the living world.

16.2 Assessment

Review Key Concepts

    1. Review What were Hutton's and Lyell's ideas about the age of Earth and the processes that shape the planet?

    2. Apply Concepts How would Hutton and Lyell explain the formation of the Grand Canyon?

    1. Review What is an acquired characteristic? What role did Lamarck think acquired characteristics played in evolution?

    2. Evaluate What parts of Lamarck's hypotheses have been proved wrong? What did Lamarck get right?

    1. Review According to Malthus, what factors limit human population growth?

    2. Draw Conclusions How did Malthus influence Darwin?

    1. Review What is artificial selection?

    2. Infer Could artificial selection occur without inherited variation? Explain your answer.

WRITE ABOUT SCIENCE

Creative Writing

  1. Imagine you are Thomas Malthus and the year is 1798. Write a newspaper article that explains your ideas about the impact of a growing population on society and the environment.

End ofPage 458

Table of Contents

Miller & Levine Biology
About the Authors
Changing the World of Biology Education
Contents
Diversity of Life: A Visual Guide DOL•1–DOL•64
Labs and Activities
Features
UNIT 1 The Nature of Life
1 The Science of Biology
2 The Chemistry of Life
Unit Project
UNIT 2 Ecology
3 The Biosphere
4 Ecosystems and Communities
5 Populations
6 Humans in the Biosphere
Unit Project
UNIT 3 Cells
7 Cell Structure and Function
8 Photosynthesis
9 Cellular Respiration and Fermentation
10 Cell Growth and Division
Unit Project
UNIT 4 Genetics
11 Introduction to Genetics
12 DNA
13 RNA and Protein Synthesis
14 Human Heredity
15 Genetic Engineering
Unit Project
UNIT 5 Evolution
16 Darwin's Theory of Evolution
17 Evolution of Populations
18 Classification
19 History of Life
Unit Project
UNIT 6 From Microorganisms to Plants
20 Viruses and Prokaryotes
21 Protists and Fungi
22 Introduction to Plants
23 Plant Structure and Function
24 Plant Reproduction and Response
Unit Project
UNIT 7 Animals
25 Introduction to Animals
26 Animal Evolution and Diversity
27 Animal Systems I
28 Animal Systems II
29 Animal Behavior
Unit Project
UNIT 8 The Human Body
30 Digestive and Excretory Systems
31 Nervous System
32 Skeletal, Muscular, and Integumentary Systems
33 Circulatory and Respiratory Systems
34 Endocrine and Reproductive Systems
35 Immune System and Disease
Unit Project
A Visual Guide to The Diversity of Life
HOW TO USE THIS GUIDE
THE TREE OF LIFE
Bacteria
Protists
Fungi
Plants
Animals
Appendices
Appendix A Science Skills
Appendix B Lab Skills
Appendix C Technology & Design
Appendix D Math Skills
Appendix E Periodic Table
Glossary
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q, R
S
T
U
V
W
X, Y, Z
Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Credits
Go to previous page Go to next page