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Odyssey of Life, Part I—The Ultimate Journey
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Classroom Activity
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Objective
To put in correct order the developmental stages for a fish, chick, pig, calf, and human.
- copy of "Timing Is Everything" student handout
(PDF or
HTML)
Copy and distribute the "Timing Is Everything" student handout. Have students cut out and reassemble the squares in an order that correctly represents three developmental stages of the five animals depicted (fish, chick, pig, calf and human). When students finish, have them explain the reasoning behind their answers. To conclude, have a discussion about the similarities and differences students see in the embryos. Since these five animals look similar in their early embryonic stages, might all vertebrates look similar in those stages? What might that suggest? As an extension, have students research how the theory of evolution has been viewed from the 1800s through today.
stage 1: 8, 2, 4, 10, 3
stage 2: 1, 7, 15, 6, 11
stage 3: 14, 9, 13, 12, 5
Students may think that the embryos only look similar. Point out that the backbones and limbs of all four-limbed vertebrates (also called tetrapods) are identical in embryonic origin and underlying structure. Even though they may differ in final external form and function, the various tetrapod limbs (arms, legs, flippers, wings) are all built from precisely the same sets of embryonic tissues, are supported by the same sets of bones, and are moved by the same sets of muscles. These extensive homologies reinforce the scientific understanding that all tetrapods have descended, with various modifications, from ancient, long-extinct ancestors.
Note:
These illustrations are
representations—not exact depictions—of the embryonic stages of each of these five animals.
Book
Lewin, Roger. The Origin of Modern Humans. New York: Scientific American Library: Distributed by W.H. Freeman, 1993.
Looks at possible preludes to Homo sapiens, various hypotheses regarding the origin of modern humans, the idea of a Mitrochondrial Eve, the archeology of modern humans and the origin of language.
Web Sites
NOVA Online—Odyssey of Life
http://www.pbs.org/nova/odyssey/
Includes a cyberdebate about
how humans evolved; time-lapse sequences of growing human, pig, chicken and fish embryos; an
interview with photographer Lennart Nilsson; an essay about the commonalities among species; and an online activity that reveals what bugs live in, on and around us.
Talk Origins
http://www.talkorigins.org/
This newsgroup is devoted to the discussion and debate of biological and physical origins. Most discussions in the newsgroup center on the creation-evolution controversy, but other topics of discussion include the origin of life, geology, biology, cosmology
and theology.
The Visible Embryo
http://www.visembryo.com/
Follows human embryological
development over
40 weeks, providing
in-depth information about what occurs at each stage. Requires Shockwave or QuickTime plug-ins.
The "Timing is everything" activity aligns with the following National Science Education Standards:
Grades 5-8
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Science Standard C:
Life Science
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Structure and function in living systems
Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are, in turn, grouped together to form larger functional units, called organs. Each type of cell, tissue and organ has a distinct structure and set of functions that serve the organism as a whole.
Grades 9-12
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Science Standard C:
Life Science
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The cell
Cells can differentiate, and complex
multicellular organisms are formed
as a highly organized arrangement of differentiated cells. In the development of these multicellular organisms, the progeny from a single cell form an embryo in which the cells multiply and differentiate to form the many
specialized cells, tissues and organs that comprise the final organism. The differentiation is regulated through
the expression of different genes.
Biological evolution
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. The millions of different species of plants, animals and microorganisms that live on Earth today are related by descent from common ancestors.
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