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NOVA scienceNOW: Little People of Flores

Viewing Ideas

Before Watching

1. Use a map to locate where scientists found the Homo floresiensis skeletons. Review map skills by asking students how they would locate Flores Island, Indonesia on the map. Using a world map, have them locate Indonesia (the island chain northwest of Australia). If the map has sufficient detail, have them locate Flores Island (at the southeastern end of the chain, next to the island of East Timor). Have them determine its latitude and longitude (120-124º East, 8.5º South). Tell students that people may have been able to reach Flores Island during the Pleistocene ice ages, when sea level was considerably lower and many landmasses were connected by land bridges. Ask them from which major landmass Flores Island's first hominids might have arrived. (From Asia)

2. Review the system of scientific classification. Some scientists have proposed the idea that Homo floresiensis is a separate human species. To help students understand what 'species' means, review the system of scientific classification (i.e., kingdom, phylum, class, order, family, genus, species). Have students research the classification for humans (animalia, chordata, mammalia, primate, hominidae, homo, sapiens). As an extension, have students identify some of the animals found in each of the following categories: animalia (insect), chordata (alligator), mammalia (mouse), and primate (apes). Point out that this system goes from general to specific—more specific categories are subsumed by more general ones.

3. Show that the body's bones grow in predictable ways. When the Flores skeletons were discovered, scientists had to determine whether they were from full-grown adults or from people who were afflicted with diseases that interfered with their growth. Comparing the lengths of certain bones yields predictable ratios, such as one's height being equal to the finger tip-to-finger tip distance between one's outstretched arms. If a skeleton's bone ratios differ greatly from what is expected, that individual may have had a disease or genetic condition that affected his or her growth. To investigate whether the body's bones show predictable ratios when measured, have student pairs use a measuring tape to compare the lengths of different bones. (They can use a length of string to determine the distance and then measure the string length.) You can help students calculate the ratios by providing the table below or by copying it on the board.

   
   

   Measurement #1	Length #1	Measurement #2	Length #2	Length #1 / Length #2	Expected Quotient	Ratio
   Arm span (measure finger tip to finger tip with arms outstretched)		Height*			1	1:1
   Thigh (measure outer side, from hip to kneecap)		Height*			4	4:1
   Forearm (measure elbow to wrist)		Foot (measure heel to toe)			1	1:1
   Thumb Circumference (measure lowest part of thumb)		Wrist Circumference			2	2:1
   Wrist Circumference		Neck Circumference			2	2:1
   Head Circumference (measure around eyes)		Height*			7	7:1

   * remove shoes before measuring height

   To process the activity, write the names of the pair of bones being compared on the board. Next to each pair, have students write the values they determined when dividing the length of Bone #1 by the length of Bone #2. Students' numbers will differ from the expected result due to measurement errors or because of variation in bone length. Thus, while the expected result may be 1.0, students may get results of 0.8 or 1.2. However, scientists do not expect a data set to contain identical values. Rather, they are interested in seeing where the data points cluster. As a class, see if the student values cluster around the expected result. Discuss whether, when taken together, the class's numbers support the idea that certain body dimensions are proportional. Students should find this to be the case. Scientists use the fact that an animal's bone sizes are proportional to reconstruct full skeletons from mere bone fragments. Ask students if they think the ratios would hold for both children and for adults. How could they test their prediction? (Choose a pair of bones listed in the table. Measure these bone lengths on a child and an adult and calculate the ratios. If the two ratios are close in value, one can conclude that a body's bones grow proportionally, irrespective of age. Note: Some ratios for babies and young children will differ from those of older children because their heads are proportionally larger.)

After Watching

1. Brainstorm the advantages and disadvantages of being small. Evidence supports the idea that when animals migrate to remote islands, they can develop smaller body sizes over the span of generations. The segment mentions that the hippos, buffalo, elephants, elk, and deer found on remote islands are smaller than their mainland counterparts. Ask students to generate a list of ideas as to why being small might be an advantage on Flores Island. (Small animals require less food.) What might be some of the disadvantages for a species when this happens? (If larger animals reach the island, they may out-compete small animals for food and shelter. Also, they might eat the small animals.) Record students' ideas on the board.

2. Use the H. floresiensis controversy to model the scientific process. When the first Homo floresiensis skeleton was found, some scientists claimed that it represented a new species. Others maintained that it was from a Homo sapiens (i.e., modern human) with developmental problems. Scientists on both sides of the question presented evidence to support their views, and debate stalled. Subsequently, nine skeletons, all of small stature, were found, supporting the idea that H. floresiensis was a miniature species distinct from H. sapiens. (Have students think of an example from the video that shows how the H. floresiensis controversy illustrates each part of the scientific method (formulate hypothesis, define procedure, collect data, analyze evidence, and draw conclusion). Discuss how the amount of data influences a debate. (As with any experiment, increased amounts of data make it easier to identify meaningful patterns. Each skeleton served as one experimental trial; finding nine skeletons was equivalent to conducting multiple trials.) As an extension, discuss the advantages and disadvantages to having scientists pose different explanations for the same evidence. (It may lead to more research, which provides additional insight. Alternatively, it can lead to biased testing and biased consideration of the results.)

3. Research the human family tree. In the segment, scientist Bert Roberts says, "The human family tree now appears much bushier than people had first envisaged. We tend to think that we're the pinnacle of some kind of genus. But, in actual fact, we're just the last surviving twig." To help students better understand the human family tree, have the class create a 'timeline of humans.' Ask student teams to research one or two groups of the 11 different hominids (see the URLs in the Resource section) and find when and where their groups lived and which hominids they are most closely related to. Have them put their information on an index card or a poster. Organize the class's work in a timeline on a bulletin board. Draw connecting arrows to groups that are closely related. Is the family tree linear or branched? (Branched) What differences define each group? Where does Homo floresiensis fit in? How recently did H. floresiensis live? (18,000 years ago) How many hominids currently inhabit Earth? (One, just Homo sapiens.) Have students consider some of the reasons a species might become extinct. (Changing conditions alter the environment and make it uninhabitable; disease can devastate a species; other organisms can increase competition for food and shelter; major catastrophic events, such as an asteroid impact, can wipe out species or make the environment uninhabitable.)

Web Sites

Archaeology and age of a new hominid from Flores in eastern Indonesia
http://www.nature.com/cgi-taf/DynaPage.taf?
file=/nature/journal/v431/n7012/full/nature02956_fs.html
Discusses archeological findings for H. floresiensis at Liang Bua cave on Flores Island, Indonesia. (Requires site license or subscription to Nature.)

Asia: habitats and faunal barriers
http://www.loris-conservation.org/database/
distribution_maps/01_Asia_zoogeography.html
Maps Pleistocene land bridges in Asia.

Human Evolution
http://www.pbs.org/wgbh/aso/tryit/evolution/
Presents human evolution activity with an animated, interactive time line.

The Pleistocene: 1.8 million to 11,000 years ago
http://www.ucmp.berkeley.edu/quarternary/ple.html
Describes the Pleistocene Epoch, including the evolution and expansion of Homo sapiens.

Books

Gamlin, Linda. Eyewitness: Evolution. New York: Dorling Kindersley, 2000.
Traces discoveries that help explain life's diversity. Includes a section on human evolution.

Page, Martin, editor. Eyewitness Visual Dictionary: Animals. New York: Dorling Kindersley, 1991.
Describes animal classification.

Reid, Des, editor. Eyewitness Visual Dictionary: Human Anatomy. New York: Dorling Kindersley, 1996.
Presents annotated diagrams of human anatomy and the human skeleton.