Grade Level: 9-12

Time Allotment: 3 45-minute class periods

Overview: Where did life on Earth come from, and how did it become what it is today?  Students will explore the answer to that question in this lesson on evolution.  The lesson begins with an overview of the history of evolutionary theory, and then takes students on a tour of three billion years of life on the planet using an online interactive timeline.  Students will learn, using video segments from the PBS series The Human Spark, how modern humans evolved from our earliest primate ancestors.  As a culminating activity, students will examine some of the factors that continue to contribute to the evolution of new species and life on Earth.

Media Resources:

The Human Spark, selected segments

Links in the Evolutionary Chain

An exploration of some of the different characteristics that distinguish different branches of the hominid “family tree,” such as brain and face size, ability to make tools, and location.

Human Nature

A look at the ways in which monkeys and apes are similar to humans, not just biologically but mentally and socially

Websites:

Evolution: Change: Deep Time

This interactive timeline from the PBS series NOVA’s extensive Evolution website shows geological and biological milestones on Earth starting 4.5 billion years ago.

Materials:

Deep Time Milestones Student Organizer (PDF) (RTF)

Deep Time Milestones Student Organizer Answer Key (PDF) (RTF)

Objectives

Students will be able to:

• Explain the history of evolutionary theory, and the theory of natural selection as developed by Charles Darwin;
• Identify milestones in the evolution of life on Earth over the past 3.8 billion years;
• Compare and contrast characteristics of modern humans with early human and primate ancestors, and analyze how this may have affected our evolutionary path;
• Define the terms genetic drift, speciation, biodiversity, and extinction, and discuss how these factors contribute to the evolution of species.

Standards

National Science Education Standards

Life Science

Content Standard C

BIOLOGICAL EVOLUTION

[See Unifying Concepts and Processes]

• Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.
• The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.
• Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.
• The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.
• Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.

Before the Lesson/Prep for Teachers

Prior to teaching this lesson, you will need to:

Preview all of the video segments and websites used in the lesson.

Download the video clips used in the lesson to your classroom computer(s) or prepare to watch them using your classroom’s Internet connection.

Bookmark all websites that you plan to use in the lesson on each computer in your classroom. Using a social bookmarking tool such as delicious.com or diigo (www.diigo.com) (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.

Prepare all classroom materials. Print out and make copies of the “Deep Time Milestones” student organizer for each student in your class.

a. Prepare for the Gallery Walk activity by writing the following questions at the top of flip chart pages or large pieces of paper (one question per page): Genetic Drift: When a new population is established by a very small number of individuals from a larger population there tends to be a lack of genetic variation.  This is called the Founder Effect.  What are some of the disadvantages to this lack of variation?

b. Speciation: It is speculated that the Homo heidelbergensis population split – some moving to Europe and evolving into Neanderthals, others remaining in Africa to become Homo sapiens.  What type of speciation is this, and what effect did it have on the human population?

c. Biodiversity: During the Cretaceous period, biodiversity levels were high.  Mammals, dinosaurs, birds, marine creatures, and plant life flourished all over the planet.  Then, a massive meteor impact 65 million years ago wiped out 60 – 80% of all species on the planet.  Why did some survive and not others?

d. Extinction: The most recent large scale extinction event, the Holocene, includes many plants and animals but most notably large mammals and rainforest species.  Many believe that humans are largely responsible for these extinctions.  Do you feel that humans have contributed to extinctions over the past 10,000 years?  Why or why not?

e. Natural selection: Survival isn’t always based on physical fitness, but on the way our brains work.  Things like social skills, language, and technological capability may have been what allowed us to dominate over our ancestors.  What skills do we have that our earlier or primate ancestors didn’t, and why might they have been passed down to younger generations?

Post the flip chart pages around the room prior to the Culminating Activity.  If you are not familiar with conducting a “Gallery Walk” in your classroom, review the procedure at the “How to Use Gallery Walk?” Web page.

Proceed to Lesson Activities.

Grade Level: 9-12

Time Allotment: 2-3 45 minute class periods

Overview

In this lesson students will enter the world of the genome, learning about human history and evolution by examining information about human, Neanderthal, and chimpanzee DNA.  Using web interactives and video segments from the PBS series The Human Spark, students will be introduced to the ambitious Human Genome Project, learn about the genetic similarities and differences between human beings and our hominid ancestors, explore how specific genes manifest themselves in different organisms, and discover how genetic information can help us trace a path of human migration all the way back to our earliest ancestors.

This lesson is best used with students who have already learned about cellular structure and function in biology class, as well as with students who are already familiar with Darwin’s theory of human evolution.

Media Resources

Websites

Journey Into DNA

This interactive from the PBS series NOVA explores the structure of DNA and the human genome.

Atlas of the Human Journey

This interactive timeline from National Geographic provides a comprehensive overview of the major y-chromosome DNA and mtDNA haplotypes found in humans over the past 200,000 years.

The Human Spark: Becoming Us, selected segments

Ratty Old Genes

This clip explores the extraction and interpretation of Neanderthal DNA.

Talk of Life

Using the FOX P2 “language gene” as an example, this clip explores how similar genes evolve differently in different animals

Objectives

Students will be able to:

• Identify parts of the genome and key terms relating to the genome;
• Explain genetic similarities and differences between humans, Neanderthals, and chimpanzees;
• Define gene expression;
• Explain how genetic research helps track human migration over time.

Standards

Life Science

Content Standard C

THE CELL

• Cells have particular structures that underlie their functions. Every cell is surrounded by a membrane that separates it from the outside world. Inside the cell is a concentrated mixture of thousands of different molecules which form a variety of specialized structures that carry out such cell functions as energy production, transport of molecules, waste disposal, synthesis of new molecules, and the storage of genetic material.
• Cells store and use information to guide their functions. The genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.
• Cell functions are regulated. Regulation occurs both through changes in the activity of the functions performed by proteins and through the selective expression of individual genes. This regulation allows cells to respond to their environment and to control and coordinate cell growth and division.

THE MOLECULAR BASIS OF HEREDITY

• In all organisms, the instructions for specifying the characteristics of the organism are carried in DNA, a large polymer formed from subunits of four kinds (A, G, C, and T). The chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular ”letters”) and replicated (by a templating mechanism). Each DNA molecule in a cell forms a single chromosome.
• Most of the cells in a human contain two copies of each of 22 different chromosomes. In addition, there is a pair of chromosomes that determines sex: a female contains two X chromosomes and a male contains one X and one Y chromosome. Transmission of genetic information to offspring occurs through egg and sperm cells that contain only one representative from each chromosome pair. An egg and a sperm unite to form a new individual. The fact that the human body is formed from cells that contain two copies of each chromosome—and therefore two copies of each gene—explains many features of human heredity, such as how variations that are hidden in one generation can be expressed in the next.
• Changes in DNA (mutations) occur spontaneously at low rates. Some of these changes make no difference to the organism, whereas others can change cells and organisms. Only mutations in germ cells can create the variation that changes an organism’s offspring.

BIOLOGICAL EVOLUTION

[See Unifying Concepts and Processes]

• Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuring selection by the environment of those offspring better able to survive and leave offspring.

Before the Lesson/Prep for Teachers

Prior to teaching this lesson, you will need to:

Preview all of the video segments and websites used in the lesson.

Download the video clips used in the lesson to your classroom computer(s) or prepare to watch them using your classroom’s Internet connection.

Bookmark all websites that you plan to use in the lesson on each computer in your classroom. Using a social bookmarking tool such as delicious.com or diigo (www.diigo.com) (or an online bookmarking utility such as portaportal) will allow you to organize all the links in a central location.

Proceed to Lesson Activities.

The Human Spark: Becoming Us, selected segments

Ratty Old Genes
This clip explores the extraction and interpretation of Neanderthal DNA.
(View full post to see video)

Talk of Life
Using the FOX P2 “language gene” as an example, this clip explores how similar genes evolve differently in different animals
(View full post to see video)

Downloadable QuickTime versions of the video segments:
(Note: To download a video, right click on the video title and click “Save Link As…’ or “Save Target As…”. On a Mac, press the CTRL key and simultaneously click the mouse, then save the link.)

Ratty Old Genes

Talk of Life

The Human Spark: Becoming Us, selected segments

Links in the Evolutionary Chain

An exploration of some of the different characteristics that distinguish different branches of the hominid “family tree,” such as brain and face size, ability to make tools, and location.

Human Nature

A look at the ways in which monkeys and apes are similar to humans, not just biologically but mentally and socially.

Neanderthal reconstruction Photo: Stefan Scheer, Neanderthal Museum, Mettman, Germany

There were thousands of years that Neanderthals and Homo sapiens inhabited the same regions in Europe. How much did these groups intermingle?

One answer comes from looking at early human DNA… Does it contain any genetic traces of interbreeding with Neanderthals?

The answer, apparently is no. The scientists behind a recent study published in the journal Cell sequenced the mitochondrial DNA of a Neanderthal who lived 38,000 years ago.

While the scientists have been congratulated for the feat — it’s difficult to build a reliable sequence using ancient DNA — the results show no evidence of intermingling.

Get the full story here.