Chapter 2: Biology and Evolution

Biology and Evolution

Chapter 2: Biology and Evolution

Detailed Chapter Outline

I.CHALLENGE ISSUE AND CHAPTER OUTLINE

II.EVOLUTION AND CREATION STORIES

A common part of all cultures is a mythology that explains how humans came about on earth
Mythologies and creation stories differ from evolution, which relies upon scientific language
Creation stories depict the relationship between humans and the rest of the natural world
Evolution is the scientific way to explain how species appear and change over time
Evolution is based on testable ideas, which separates it from creation stories
Evolution is not ‘just’ a theory
Evidence for evolution is so overwhelming that most scientists accept it as fact

III.THE CLASSIFICATION OF LIVING THINGS

How humans have classified the world and life forms have changed over time and continue to exhibit variation
Early classification systems, such as the Great Chain of Being, were challenged based on early European exploration
Avoiding the biases of the Great Chain of Being, Carolus Linnaeus developed the Systema Naturae classification system
Linnaeus’ classification system was based on:
Body structure
Body function
Sequence of bodily growth
Modern taxonomic systems retain Linnaeus’ classification structure; however, they are also based on protein structure and genetic material
Modern taxonomic systems are also based on cross-species comparisons, which enable the examination of analogies and homologies

IV.THE DISCOVERY OF EVOLUTION

A.European exploration and European industrialization challenged previously held ideas on species “fixity” or that species did not change over time

B.Ideas such as “Catastrophism” were invoked to help explain the disappearance of certain species, while still being faithful to religious doctrine

C.Charles Darwin, however, formulated the Theory of Natural Selection “that has withstood the test of time”

a.Darwin’s theory was influenced by the works of Erasmus Darwin and Thomas Malthus

b.Darwin’s Theory of Natural Selection culminated in his seminal text On the Origin of Species (1859)

D.While Darwin provided the idea behind how species change over time or evolve, parts of his theory were incomplete

a. Two questions haunted Darwin’s theory:

“How did the variation arise in the first place?”
“What was the mechanism of heredity by which variable traits could be passed from one generation to the next?”

E.Contemporary and historical advancements in heredity, molecular genetics, cellular biology, and population genetics provide support for Darwin’s evolutionary theory

V.HEREDITY

A. The work of Gregor Mendel would eventually advance the field of cellular biology and molecular genetics

B.Gregor Mendel was instrumental in explaining:

a. Particulate inheritance

b. Law of Segregation

c. Independent Assortment

C.Other components of contemporary/historical genetic research that support Darwin’s Theory of Natural Selection are:

a. Chromosomes

b. Deoxyribonucleic acid (DNA)

c. Genes

d. Alleles

e.Cell Division

i.mitosis

ii. meiosis

f. Heterozygous and homozygous

g. Genotype and phenotype

h. Dominance and Recessive

i.Polygenetic inheritance

VI.EVOLUTION, INDIVIDUALS, AND POPULATIONS

A. At individual levels, the study of genetics illustrates how parents pass traits on to their offspring

At the level of the group or population, the study of genetics reveals evolutionary processes and how they affect the levels and patterns of biodiversity on earth
Four evolutionary forces active at the population level are:
Mutation
Genetic Drift
A particular type of genetic drift is the “Founder’s Effect”
This was likely to have been significant in human evolution given small population sizes
Gene flow
Natural Selection
Adaptation in natural selection is the collection of beneficial adjustments that a population makes to the environment
It can only act on pre-existing genetic variation
Mutations are the ultimate source of new genetic material due to the constant induction of new genetic material
A well-studied case of human adaptation to particular environment types is sickle-cell anemia
The presence of high rates of sickle-cell anemia correlate with world regions that have high rates of malaria
In these malarial environments sickle-cell was an adaptive and beneficial genetic trait
In world regions without high rates of malaria, sickle-cell anemia became a disadvantageous trait

VII.ADAPTATION AND PHYSICAL VARIATION

Biological diversity is often studied and mapped out in clines
This approach of analyzing the spatial distribution of certain human traits enables anthropologists to identify the correlation between the trait’s adaptive function and its relationship to the environment
For example, people in cold climates tend to exhibit greater body bulk and people in hot climates tend to be tall and slender

VIII.CHAPTER SUMMARY

Learning Objectives

By the end of this chapter, having fully read it and reviewed the central themes, students should be able to:

1.Describe Darwin’s Theory of Natural Selection.

2.List and discuss the four main evolutionary forces that are responsible for the vast biological variation present in human and non-human populations.

3. Explain the differences between Creation stories and evolution.

4.Trace the history of species classification, from the Great Chain of Being to the modern taxonomic system.

5.Compare the similarities and differences between Linnaeus’ classification system and contemporary taxonomic systems.

6.Differentiate analogies and homologies.

7.Explain how European exploration and Europe’s industrial revolution were key factors in the emergence of evolutionary theory.

8.Trace out the history of Charles Darwin and how he formulated his Theory of Natural Selection.

9.Understand the importance behind Gregor Mendel’s experiments with pea plants.

10.List and discuss the main processes and components that explain heredity.

a.Genes

b.Law of Segregation

c. Independent Assortment

d. Chromosomes

e. DNA

f.Alleles

g. Mitosis

h.Meiosis

i.Homozygous and Heterozygous

j. Dominant and Recessive

k. Genotypes and Phenotypes

11.Explain how population genetics work and their role in evolution.

a.Mutation

b. Genetic Drift

c.Founder’s Effect

d.Gene Flow

e. Natural Selection

f.Adaptation

12.Describe the importance of sickle-cell anemia in understanding how evolution works and how traits are context dependent.

13.Describe the role of clines in understanding how and why traits are spread across geographic space.

Key Terms

Adaptation

Alleles

Analogies

Chromatid

Chromosomes

Clines

DNA

Dominance

Evolution

Founder’s Effect

Gene Flow

Gene Pool

Genus (Genera)

Genes

Genetic Drift

Genome

Genotype

Hemoglobin

Heterozygous

Homologies

Homozygous

Law of Independent Assortment

Law of Segregation

Mammals

Meiosis

Mitosis

Mutation

Natural Selection

Phenotype

Polygenetic Inheritance

Population

Primates

Recessive

Sickle-cell Anemia

Species

Taxonomy

Lecture Suggestions

1.Discuss the often contentious relationship between evolution and creationism.

2.Illustrate how science and evolution attempt to answer different questions than religion and religious doctrine.

3.Describe the role of biology in human adaptation to various environmental conditions. In regards to our physical limitations, discuss the ways that culture has allowed us to circumvent our biologies and live in various types of environments.

4. Explore the history of Darwin and why his Theory of Natural Selection was, on the one hand, “simple or obvious” and, on the other hand, so controversial.

5. Examine different examples of clinal distribution. Provide examples outside the text that illustrate both gradual and discontinuous clinal distributions. Have your students attempt to explain why these physical characteristics might be distributed across geographic space in these patterns.

6.Compare the differences between Linnaeus’ classification system and contemporary taxonomic systems.

7.Examine each of the four main processes of population genetics and evolution.

8. Further discuss in class the importance behind Thomas Malthus’ concept of Carrying Capacity and how it greatly influenced many of Darwin’s ideas on competition, selection, and evolution.

9.Explain the importance of mutation in natural selection.

10.Provide your students with a real or fictive genotypic and phenotypic makeup of a breeding parent generation. Have your students determine, based on their knowledge of heredity and dominant and recessive traits, what genotypes and phenotypes would emerge in the second and third generation.

InfoTrac Exercises

1.The debates surrounding evolution and creationism are heated at times and if you simply used creationism as your keyword, you would get hundreds and hundreds of returns. Narrow the field by using the keywords intelligent designcreationismevolution. Explore the articles that come up and see the diversity of arguments that center on this debate.

2. Using the keywords great chain of being, find Stephen Jay Gould’s article “Bound by the Great Chain.” What are the historical foundations for this particular view of evolution and how does Gould handle the concept in this article?

Internet Exercises

1. Dennis O’Neil’s Anthropology Tutorials at Palomar College provides lessons and activities to test students’ knowledge of evolution, biological adaptation, and human variation. Go to and focus on the evolution and biological adaptation tutorials. Take the associated Flashcard Quizzes to see what you know and what you need to work on.

2.The mapping of the human genome has arguably been one of the more ambitious projects in human history. Go to the Human Genome Project’s website and write a one to two page paper on what the project is and what are the main goals of the project. Follow the “What’s Next?” link to see the future of this project.

3.Based on your exploration of the Anthropological code of ethics and the code of ethics as set forth by the AAA and those possibly discussed in class, what are some of the ethical, legal, and social issues brought about by the Human Genome Project?

4Students may sometimes confuse genetic drift and gene flow, or be unable to fully understand the importance of genetic drift to evolution. Besides having a tremendous wealth of information, the website explains and explores the role of genetic drift. You can use the “Search the Archive” link on the website and use