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

Robin Dunbar at the 2008 Nobel Conference

Gustavus Adolphus College in Saint Peter, Minnesota hosted a conference last October focused squarely on the idea of “The Human Spark.” In fact, throughout our travels, the show’s production team met with many of the conference’s speakers! Webcasts of each presentation are available online for the general public.

Robin Dunbar from the University of Oxford discusses the social brain theory and what sets human beings apart from other apes.

Curtis Marean from Arizona State University talks about the implications of his archaeological work along the coast of South Africa for our understanding of human origins – not just anatomically modern humans, but modern behavior too.

Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology presents the implications of his work sequencing the Neanderthal genome.

In many ways, The Human Spark tells a story of evolution as we look at the emergence of different related species over vast quantities of time. British geneticist Steve Jones has lately made the provocative assertion that human evolution is coming to its end. Here’s his explanation for why.

He doesn’t say human beings have achieved perfection –- but he does suggest that our population is becoming much more uniform. Remember that evolution depends on random genetic changes for natural selection to work on. Jones argues that fewer older fathers in the developed world means less genetic variation. And the mutations that do occur don’t give anyone much of a competitive edge because we no longer live under the tough conditions our ancestors did. Populations are much larger and far less isolated than they were in the past, too, which cuts down the possibility that a random change can take hold in a small group.

Check out these sites for more info:

• Daily Mail: “Evolution stops here: Future Man will look the same, says scientist”
• BBC Radio: “Human evolution ‘has stopped’” (audio)
  
• Discover Magazine Blogs: “No More Evolution For You, Says British Scientist”

Jones doesn’t offer much by way of evidence to back up his position.

What do you think? Is evolution coming to an end? What evolutionary pressures do you think still exist? What could a future human look like?