Biology: A Global Approach
Chapter 21 How Evolution Works 2
Concept 21.1 The Darwinian revolution challenged traditional views of a young Earth
inhabited by unchanging species 2
Endless Forms Most Beautiful 2
Scala Naturae and Classification of Species 2
Ideas About Change over Time 3
Lamarck’s Hypothesis of Evolution 3
Concept 21.2 Descent with modification by natural selection explains the adaptations of
organisms and the unity and diversity of life 4
Darwin’s Research 4
Ideas from The Origin of Species 4
Key Features of Natural Selection 5
Concept 21.3 Evolution is supported by an overwhelming amount of scientific evidence 6
Direct Observations of Evolutionary Change 6
Homology 6
The Fossil Record 7
Biogeography 7
What Is Theoretical About Darwin’s View of Life? 7
, Chapter 21 How Evolution Works
Concept 21.1 The Darwinian revolution challenged traditional views of a young Earth
inhabited by unchanging species
Endless Forms Most Beautiful
There are three key observations about life.
- organisms are well suited (adapted) for life in their environments.
- the many shared characteristics (unity) of life
- the rich diversity of life.
For now, we will define evolution as descent with modification, a phrase Darwin uses to
summarize the process by which species accumulate differences from their ancestors and
they adapt to different environments over time. Evolution can also be defined as a change in
the genetic composition of a population from generation to generation.
We can view evolution in two related but different ways: as a pattern and as a process. The
pattern of evolutionary changes is revealed by data from many scientific disciplines. These
data are facts, they are observations shows that life has evolved over time. The process of
evolution consists of the mechanisms that cause the observed pattern of change. These
mechanisms represent natural causes of the natural phenomena we observe. The power of
evolution as a unifying theory is its ability to explain and connect a vast array of observations
about the living world.
Scala Naturae and Classification of Species
Aristotle (384-322 bce), viewed species as fixed (unchanging). He concluded that life-forms
could be arranged on a ladder, or scale, of increasing complexity, later called the scala
naturae.
Carolus Linnaeus (1707-1778), a Swedish physician and botanist who sought to classify life
diversity, in his words, ‘for the greater glory of God’. Linnaeus developed the two-part, or
Chapter 21 How Evolution Works 2
Concept 21.1 The Darwinian revolution challenged traditional views of a young Earth
inhabited by unchanging species 2
Endless Forms Most Beautiful 2
Scala Naturae and Classification of Species 2
Ideas About Change over Time 3
Lamarck’s Hypothesis of Evolution 3
Concept 21.2 Descent with modification by natural selection explains the adaptations of
organisms and the unity and diversity of life 4
Darwin’s Research 4
Ideas from The Origin of Species 4
Key Features of Natural Selection 5
Concept 21.3 Evolution is supported by an overwhelming amount of scientific evidence 6
Direct Observations of Evolutionary Change 6
Homology 6
The Fossil Record 7
Biogeography 7
What Is Theoretical About Darwin’s View of Life? 7
, Chapter 21 How Evolution Works
Concept 21.1 The Darwinian revolution challenged traditional views of a young Earth
inhabited by unchanging species
Endless Forms Most Beautiful
There are three key observations about life.
- organisms are well suited (adapted) for life in their environments.
- the many shared characteristics (unity) of life
- the rich diversity of life.
For now, we will define evolution as descent with modification, a phrase Darwin uses to
summarize the process by which species accumulate differences from their ancestors and
they adapt to different environments over time. Evolution can also be defined as a change in
the genetic composition of a population from generation to generation.
We can view evolution in two related but different ways: as a pattern and as a process. The
pattern of evolutionary changes is revealed by data from many scientific disciplines. These
data are facts, they are observations shows that life has evolved over time. The process of
evolution consists of the mechanisms that cause the observed pattern of change. These
mechanisms represent natural causes of the natural phenomena we observe. The power of
evolution as a unifying theory is its ability to explain and connect a vast array of observations
about the living world.
Scala Naturae and Classification of Species
Aristotle (384-322 bce), viewed species as fixed (unchanging). He concluded that life-forms
could be arranged on a ladder, or scale, of increasing complexity, later called the scala
naturae.
Carolus Linnaeus (1707-1778), a Swedish physician and botanist who sought to classify life
diversity, in his words, ‘for the greater glory of God’. Linnaeus developed the two-part, or
