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CHROMOSOME CONNECTION 2
Comparison of Human and Ape Chromosomes


by Larry Flammer

Improved from his earlier version
on the Becoming Human Site*

 

*Directions for seeing the original
Chromosome Connection lesson
on the Becoming Human site

 

EVOLUTION

Human Patterns

SEEChromosome Connections: Compelling Clues to Common Ancestry
Article by Larry Flammer published in the American Biology Teacher (NABT journal, February 2013).
Students compare banding patterns on hominid (human and ape) chromosomes, and see striking evidence of their common ancestry. Additional comparisons test (and confirm) that common ancestry hypothesis. Students find the “molecular fossil” of telomere fusion in our cells. This engaging inquiry demonstrates the power of multiple lines of evidence.

 SYNOPSIS

Students are taken on a chromosome comparison "adventure", in which the banding patterns are compared on the chromosomes of humans and apes. Degrees of similarities, and some causes of their differences are explored. Inferences about common origins based on those similarities (like forensic bullet marks) are also examined in a compelling way.

 PRINCIPAL CONCEPT

Modern apes and humans evolved from a common ancestor.

 ASSOCIATED CONCEPTS

1. The evidence that humans have evolved from non-humans is stronger than that for evolution within most other groups.
2. Many features of modern organisms reflect the structure of their ancestors in ways that are not adaptive.
3. Scientific explanations confirmed by different lines of evidence are stronger, more likely to be accurate.
4. The degree of chromosome similarity between two species indicates the degree of their biological relationship.
5. Hypotheses about past events can be tested by looking for revealing patterns in the present.

ASSESSABLE OBJECTIVES

   Students will....

1. actively engage in the careful analysis of chromosome banding patterns.
2. identify examples of inversion in homologous chromosomes.
3. demonstrate their understanding that degrees of similarities in chromosomes correspond to degrees of evolutionary relationship.
4. associate degrees of similarity with the relative timing of evolutionary divergence.

 MATERIALS

  (Click Here to Download these items as PDF files)

Teacher Packet (these 4 pages as shown here)
Background Information sheet (2 pages)
Activity Packet (4 pages)
Page of Cutouts (to cut out and place in envelope)
Worksheet (optional form)
Teacher's Answer Key (1 page) Send request to Webmaster using your school email address.
Envelopes (1/team) for 7 paper cutouts to manipulate
Complete Chromosome Diagrams (karyotypes) of humans and apes (1 page, for overhead)
Primate Cladogram based on Chromosome Banding Patterns (1 page, for overhead)

 TIME

This activity can be easily completed in one 45 minute period.
STUDENT HANDOUTS Background Information sheet (2 pages)
Activity Packet (4 pages)
Page of Cutouts (to cut out and place in envelope)
Worksheet (optional form)

 

 

TEACHING STRATEGY

This activity can be effectively and easily inserted into any one of several parts of your course. For example:
1. Following your lessons comparing hominid and ape skulls and their chronology, introducing evolution.
2. As part of your evolution unit in which you can show this as one of several independent lines of evidence pointing consistently to a conclusion of evolution in general, and/or human evolution in particular.
3. As part of your unit on molecular biology, where you can point out the striking similarities in proteins and/or DNA sequences between different species, the patterns of which closely match the degrees of relationships based on morphology.
4. As part of your unit on genetics, where you take a look at chromosomes in general, or karyotyping in particular.
5. As a human example of how scientific understanding is strengthened (to be pointed out wherever you do this):
a. Scientists use the simplest explanation consistent with all their data (parsimony, or "Occam's Razor").
b. MILEs (Multiple Independent Lines of Evidence), all pointing to the same conclusion and explaining all the observations, provides a major strength in scientific explanations.

Students may work on this independently, in pairs, or small teams (3-4), as preferred. It could even be given as a homework assignment, and discussed/reviewed the next day.

PREPARATION:
1. Provide handout materials for every student. Print Background Information on both sides of a single sheet. Assemble and staple the 4 pages of the Activity Packet. To simplify checking student/team work, provide the formatted Worksheet, where students can record answers to questions asked in the Activity Packet. This will allow the Activity Packets to be re-used, especially if placed in plastic sleeves.

2. Prepare cutout pieces showing chromosomes and bullet marks for students to manipulate. These (7 pieces per envelope) should be cut out and placed in envelopes, making a classroom set of envelopes, with one envelope for each team, or each student, if preferred. You can have a lab assistant do this, or have your students do it the first time, but keep the envelope packets for re-use every period/year.

3. A NICE OVERVIEW: Try the PowerPoint presentation on Chromosome Comparisons (script and ppt). If tight for time, this would be a useful substitute (though not as good as students doing the lesson!) for the Chromosome Connection.

 

 

PROCEDURES

A dramatic introduction is always an impressive way to open a topic. What you do, or how you do it may depend on the context and the topics that preceded this one? However, a general approach could include dressing like an old-time detective (French coat and fedora hat, or a "Sherlock Holmes" outfit). If you can do a good "Inspector Clouseau" impression, go with it! Do something to suggest the science of investigating crimes. On the other hand, be sensitive to student experiences with violence You don't want to be perceived as glorifying violence.

However, you could have a spent bullet (obtained from police, or a firing range, or fake it!) that you could pull out of your pocket (in a plastic bag), hold up in front of the class, and ask "If this bullet was found at a crime scene, could we tell what gun it came from?" "How?" Some students will probably know that scratch marks can be compared to bullets fired from suspected guns. If not, give a brief description of how this is done, and the principles involved. Then hand out the lesson, and let them proceed on their own.

DISCUSSION: When completed, discuss the results with the class, getting responses from 2-3 different teams for each item, and discussing any differences in responses, ultimately bringing about clarification and reinforcement of the key points. [For appropriate responses and some points of discussion, email request (from school email address) to the Webmaster.] When finished, show your class the complete page of Chromosome Diagrams (karyotypes) of ape and human chromosomes (using overhead or PowerPoint). Note the striking similarities throughout. Then display and discuss the Primate Cladogram based on Chromosome Banding Patterns (overhead or PP). You can point out where and when various chromosome changes are thought to have occurred (based on chromosome morphology and DNA analyses).

ASSESSMENT

Use some or all of the Check Questions, along with a few additional questions in a quiz to see if they fully grasp the main concept. Be sure to test for the stated Assessment Objectives.

 

 

EXTENSIONS

& VARIATIONS   

For a quick interactive online experience in matching primate chromosomes, go to the Becoming Human website <http://www.becominghuman.org/>, click on "Learning Center," then click on "Activities." Select "Chromosome Connection," then click to begin. Follow the directions there to match the chromosomes. The lesson plan (same name) offered there was created for the site, and further modified and adapted for its version on the ENSI site, courtesy of the author. Take a look at the other two interactives and other features on the BH site.

An excellent followup lesson to this one is the Chromosome Fusion lesson, at http://www.indiana.edu/~ensiweb/lessons/c.fus.les.html, where students discover (online) the DNA evidence that confirms that our chromosome #2 resulted from the fusion of the two chromosomes still found today in the apes. Very compelling confirmation (MILE) of the findings in the Chromosome Connection lesson.

EVEN BETTER, EASIER-TO-USE VERSION: "The Mystery of the Matching Marks" includes an extensive PowerPoint presentation that will walk teacher and students through the process. Works like a CSI mystery and shows the process of science that tests a pre-historical event.

Other logical followup lessons: Explore the molecular differences in beta hemoglobin from humans, apes, and other primates, as done in "Molecular Sequences & Primate Evolution" on ENSIweb at: <http://www.indiana.edu/~ensiweb/lessons/mol.prim.html>. And, if not already done, do the "Hominid Cranial Comparison" lesson, using replica skulls of hominids (hominins and apes): <http://www.indiana.edu/~ensiweb/lessons/hom.cran.html>.

NOTE: New Taxonomy for hominids (apes and humans). Recent molecular and genetic studies on these species have made a strong case for their revised classification. See details at: <http://www.indiana.edu/~ensiweb/lessons/new.tax.html>.

The Chromosome Connection lesson could be done as part of a series of crime scene scenarios that serve as an engaging example of science: a process of digging out clues to figure out the most likely solution to a problem. In this context, the more familiar use of fingerprint comparisons could also be discussed. An excellent online resource for various forensic ideas and strategies can be found at <http://www.courttv.com/forensics%5Fcurriculum/>. There are also a couple of crime scene lessons on the ENSI site: "The Case of the Missing Computer Chip" at http://www.indiana.edu/~ensiweb/lessons/crime.html, and "A Crime Against Plants" at http://www.indiana.edu/~ensiweb/lessons/plcr.les.html. A excellent discussion of the role of evolution in crime scene studies can be found at <http://evolution.berkeley.edu/evolibrary/news/060301_crime>. It's called "Evolution at the scene of the crime", on the Understanding Evolution site (UC Berkeley)

Important point: Be sure to point out to your students that crime scene science is largely historical science, not the classical experimental science typically presented as if it were the only form of science. Fields in which historical science is used extensively include paleontology, astronomy, geology, evolution science, and forensic science. This is very useful and legitimate science where events cannot be repeated, so we look for clues and patterns, leading to hypotheses about which predictions can be made, and we then look for evidence to check the predictions.

 

 

RESOURCES

The interactive activity presented here is modified and adapted from the lesson of the same name on the Becoming Human website (for which it was created by Larry Flammer). It is a variation of a similar lesson comparing just chimp and human chromosomes: "Chromosome Comparisons" (by ENSI teacher Beth Kramer), at <http://www.indiana.edu/~ensiweb/lessons/chromcom.html>, and a simpler lesson by ENSI teacher Larry Flammer: "Chromosome Clues" in the PBS/WGBH-Evolution Teacher's Guide (page 24), available free from <http://www.pbs.org/evolution>. The lesson can be downloaded directly from <http://www.pbs.org/wgbh/evolution/educators/teachstuds/unit5.html>. If you would like a sharper Chromosome Clues diagram, contact the WEBMASTER. Each of these variations emphasizes different aspects, and they vary in the time needed and sophistication.

Alberts, Bruce, et al. 1989. Molecular Biology of the Cell. Garland Publishers. Chiasmata, p.848, fig. 15-11.
Flammer, Larry. 1983. "Karyotype Komparison." Classroom activity.
Klein, Richard G. 1999. The Human Career. Univ. of Chicago Press. p. 71.
Kramer, Beth. 1995. "Comparison of Human and Chimpanzee Chromosomes". Classroom activity.
Wallace, B. 1966. Chromosomes, Giant Molecules, and Evolution. New York: W.W. Norton & Co., Ch.2.
Yunis, J.J. and O. Prakash, 1982. "The origin of man: A chromosomal pictorial legacy". Science, 215, 1525-1529.

 ATTRIBUTION

Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.

The inspiration for this was the article by Yunis and Prakash in Science (1982), showing the striking similarities of ape and human chromosomes. The similarity of this and the patterns of bullet scratches was seen in an article by Frank T. Awbrey in Creation/Evolution (Vol.2 No.3, 1981), where he referred to the discussion of this concept by Bruce Wallace in Chromosomes, Giant Molecules, and Evolution (Norton, 1966). The present lesson grew out of a 1983 classroom activity by L. Flammer, ideas from an activity by ENSI teacher Beth Kramer, adaptations for the Becoming Human web site, and significant suggestions from Eugenie Scott and Eric Meikle of NCSE. Taxonomic revisions were provided by Martin Nickels, Professor Emeritus of Anthropology at Illinois State University (and one of the ENSI co-directors).

Posted 11 May 2006


 * Directions for seeing the original Chromosome Connection lesson
on the Becoming Human site:

First, go to the Becoming Human website, created by Lucy's discoverer Don Johanson's "Institute of Human Origins" at http://www.becominghuman.org/. Click on the "Learning Center", then click on "Lesson Plans", and finally select "The Chromosome Connection." This was created specifically for the site by Larry Flammer. All pages can be downloaded and printed for making classroom sets.
However, Improvements have been incorported in the version 2 on the ENSI site;
See List of Materials above.

For an interesting, interactive activity, go back to the Learning Center and select "Chromosome Connection", giving users a chance to match chromosomes (from different species) with similar banding patterns. This is a bit simplistic, and the banding patterns here do not match those in Yunis' study, but it does give users the feel for chromosome matching.

 

 

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