HUMAN FEET ARE STRANGE

Transcription

1 Shrt Film Great Transitins: The Origin f Humans Educatr Materials OVERVIEW HUMAN FEET ARE STRANGE The activity Human Feet Are Strange was develped t supplement the film Great Transitins: The Origin f Humans ( In the film, starting at time mark 9:40 minutes, paleanthrplgist Dr. Tim White describes the Laetli trackway, a set f preserved hminid ftprints in Eastern Africa discvered in Fssils f the hminid species Australpithecus afarensis have been fund near the Laetli ftprints. Since A. afarensis was the nly hminid species knwn t be living in the area at the time, it is assumed that the ftprints at Laetli were made by A. afarensis. Dr. White als says that, human feet, we re all used t them, but they re really strange. What des he mean by that statement, and what is the significance f the Laetli ftprints? Students will explre these questins in this activity. Students first study ftprints made by themselves r their classmates. The prints are made by cvering the sles f the feet with water-sluble paints and then walking n a 3 ft 10 ft sheet f paper ( classrm trackway ). They are then asked t analyze the shape f their feet and the psitin f their tes, arches, and stride. Next, students make bservatins and draw inferences frm an illustratin f the 3.6-millin-year-ld trail f Laetli ftprints ( Laetli trackway ), cmpare their wn ftprints with thse f the Laetli trail, and evaluate the evidence in supprt f the cnclusin that the Laetli ftprints were made by a fully bipedal human ancestr. This activity ends with a summary activity, which students can cmplete as hmewrk. KEY CONCEPTS AND LEARNING OBJECTIVES The fssil recrd prvides a histry f life n Earth and includes nt nly the fssilized bnes f dead rganisms but als trace fssils, such as ftprints. Bipedalism, r walking primarily upright n tw legs, is ne f the traits that distinguish mdern humans frm all ther mdern primates. The bservatin f living rganisms can prvide insights int traits and behavirs f extinct species. Students will be able t learn the difference between bservatins and inferences and draw inferences based n bservatins and ther types f evidence. CURRICULUM CONNECTIONS Curriculum NGSS (April 2013) HS-LS4-1 AP Bilgy ( ) 1.A.4 IB Bilgy (2016) 5.1 KEY TERMS Standards Australpithecus afarensis, bipedalism, great apes, hminid, hminin, Laetli, Lucy TIME REQUIREMENT This lessn was designed t be cmpleted within tw 50-minute class perids but may take lnger depending n the amunt f class discussin. Parts 1 and 2 f this activity can be cmpleted during ne 50-minute class perid. Part 3, the summary activity, may be cmpleted n a secnd day r as hmewrk. The 20-minute film Page 1 f 7

2 Shrt Film Great Transitins: The Origin f Humans Educatr Materials Great Transitins: The Origin f Humans may be viewed in class n anther day r assigned as hmewrk. T reduce the amunt f time fr the activity, sme teachers have vlunteers make the trackway (Part 1) befre the scheduled class time. SUGGESTED AUDIENCE This activity is apprpriate fr all levels f high schl bilgy, including AP and IB. PRIOR KNOWLEDGE Students shuld be familiar with the tree f life and that mdern humans belng in the primate grup, with mdern chimpanzees as the clsest living relatives. Further, students shuld have a basic understanding f evlutin, including the unifying thery that species descend, with mdificatin, frm ther species and that the fssil recrd is a way f knwing abut past events. MATERIALS Materials are fr a class f 24 students. Part 1 One handut per student, excluding the summary activity (Part 3), which yu will hand ut separately One 3 ft 10 ft strip f white paper fr the trackway Fur r five plastic, 33-galln trash bags t place under the trackway (ptinal, if the flr is carpeted) One rll f wide masking tape r duct tape Dark shade f washable finger paint r washable pster paint Fur dispsable aluminum baking pans large enugh t fit a large ft Fam paintbrush (ptinal) Tw basins f water fr washing feet Paper twels fr drying feet Fur chairs (tw at each end f the trackway) Meterstick Images f ther animals feet, including thse f primates and great apes (ptinal) Part 2 12 laminated cpies f the 10-inch versin f the Laetli trackway, which may be dwnladed at (Flammer et al., 1998; Randak, 1998) Nte: Instead f prviding printed cpies f the Laetli trackway, yu may want t prject it fr students t bserve. Hi-res versin f the entire trackway ( (Flammer et al., 1998; Randak, 1998) enlarged t 3 feet 12 feet, printed, and laminated (ptinal) Part 3 One cpy f the summary activity (Part 3) f the student wrksheet per student Page 2 f 7

3 Shrt Film Great Transitins: The Origin f Humans Educatr Materials PROCEDURE PART 1: MAKE A CLASSROOM TRACKWAY Nte: T reduce the amunt f time fr the activity, sme teachers have vlunteers make the trackway befre the scheduled class time. 1. Setup can be dne befre class r with the assistance f students during class: If the flr is nt carpeted, tape a 3 ft 10 ft strip f paper t the flr. Use either wide masking tape r duct tape t securely hld the strip f paper. Any paint spills will easily wipe up. If the flr is carpeted, tape enugh trash bags t the flr t frm a prtective layer under the strip f paper. The trash bags shuld extend beynd the paper as shwn in Figure 1. Place tw chairs at each end f the trackway. Place the aluminum pans and cntainers f paint s that they are easily accessible t the vlunteers when seated. Figure 1. Setup fr Ftprint Activity. 2. Intrduce the activity: Distribute Parts 1 and 2 f the student handut (pages 1 7). Then lead int the activity by telling students that in the film Great Transitins: The Origin f Humans ( paleanthrplgist Dr. Tim White states that human feet are strange (Part 1, Step 1). If yu can, prject sme images f ther animals feet, including thse f sme primates and great apes. As yu cmpare feet, ask students what they think Dr. White means. Write sme f the ideas n the bard. Next, tell students that they are ging t make a trail f their wn ftprints fr analysis. 3. Make the trackway: Ask fr tw vlunteers. They must be willing t take ff their shes and scks and have the bttms f their feet cvered with paint. (Optin: Divide the class int grups f three r fur students and have each grup make a set f tracks. Then cmpare all the sets the class made.) Page 3 f 7

4 Shrt Film Great Transitins: The Origin f Humans Educatr Materials The paint can be applied in either f tw ways. Yu shuld try them bth befre ding the activity in class. First, pur sme paint int the aluminum pans. Methd 1: Ask the vlunteers t dip their feet int their pans f paint. The entire bttms f their feet shuld be cvered with paint including the arches and tes. Methd 2: Using a fam paintbrush, have a student assistant cver the bttms f each vlunteer s feet with paint. Request tw students t help safely guide the vlunteers as they walk dwn the pathway. Cautin! Warn the students that the paint is slippery! With assistance frm the guides, first ne and then the ther vlunteer shuld step nt the strip f paper and walk t the ppsite end. Tell the secnd vlunteer t be careful nt t step n the prints left by the first vlunteer. The prints near the end will be faint. 4. Discuss bservatins and inferences: Let students bserve the ftprints and write dwn their bservatins n their handuts (Part 1, Step 3). Ask a vlunteer t use a meterstick t determine hw clse tgether the feet are (hrizntal distance) and hw lng the stride is (lngitudinal distance). Ask whether students can infer where mst f the weight was placed n the ft (i.e., n the heel r tward the tes, the big te r the small tes, n the utside r dwn the middle) and if s, what bservatins are they basing this inference n. The paint is usually darker where mre weight was placed n the ft. Recrd sme f the bservatins n the bard (Part 1, Step 3). Students shuld als recrd the similarities and differences between the tw sets f prints (Part 1, Step 4). Discuss the difference between an bservatin, which invlves using ne r mre f the five senses t cllect data, and an inference, which is an assumptin made frm an bservatin. Ask yur students t think abut what inferences they culd make abut the height r age f the individuals wh made these prints r hw fast the individuals were walking, if yur students had nt seen the ftprints being made. Fr example, ask these questins: Can yu infer anything abut the individuals abslute r relative heights? In general, the lnger the stride, the lnger the legs and the taller the individual. Can yu infer whether they were walking r running? In general, the stride length is lnger when running, and the ftprints usually shw that mre weight was placed n the ball f the ft. Can yu infer whether they are ld r yung? Differences in size can prvide a clue as t whether the individual was a child r an adult, but a small adult culd leave the same-sized prints as a larger child. Students shuld recrd the cnsensus answers t these questins in the space prvided n their handuts (Part 1, Step 5). Ask students t identify sme things they culd nt infer withut seeing the ftprints being made (Part 1, Step 6). Ask students hw a chimpanzee s ftprints might be different frm the nes their classmates just made. Mentin t students that when chimpanzees walk n tw legs, their feet are wide apart and Page 4 f 7

5 Shrt Film Great Transitins: The Origin f Humans Educatr Materials they put mst f their weight n the utside f their feet. Als, their feet dn t have arches like urs d, and their big tes splay ut t the side. What ftprints wuld their painted feet leave behind? PART 2: LAETOLI TRACKWAY 5. Intrduce the Laetli trackway: Hand ut r prject ne cpy f the 10-inch Laetli trackway illustratin t each grup f tw students. Explain t students that this is a small prtin f the verall trackway. The name n the illustratin says that it is a phtgrammetric plan, which means it s a map cnstructed frm a phtgraph. As explained in the student handut, the number f cntur lines within the ftprint indicates its depth. Help students understand that the depth f a particular area f the print indicates hw much weight was placed n that area. Refer them back t the inferences they made abut the ftprints in the classrm trackway mst f the weight was placed where the paint was darkest. Here, mst f the weight was placed where there are many lines clse tgether. Orient students t the trackway. There are tw sets f prints in the trackway, ne labeled G.1 and the ther G.2/3. 6. Make bservatins and inferences: Ask students t examine the tracks and t discuss with a partner what they see, as utlined in Part 2, Steps 8 10 f the student handut. After a few minutes, have the grups share their bservatins. During the discussin, reinfrce the difference between bservatins and inferences by asking students, Is this an bservatin r an inference? Students may have difficulty identifying exactly hw many individuals made these ftprints. Sme anthrplgists nticed that it lks as thugh there are tw distinct heel prints within each ft. Ask yur students if they can bserve the same. The scientists inferred that tw individuals made this set f prints, with a smaller individual stepping int the tracks f the larger individual. Ask, Hw wuld we knw that the smaller individual stepped int the print f the larger individual and nt the ther way arund? If the smaller individual had gne first, its prints wuld have been bliterated by the larger individual s prints. Lk at the ther set f prints labeled G.1-35, G.1-34, and G Ask, D these prints line up with the larger set f prints (the nes labeled G2/3)? What can yu infer based n this bservatin? Because the tw sets f prints are walking in step, it s likely that the ftprints were made at the same time, and that the individual wh made the smaller prints was walking very clse t ne f the tw wh made the larger nes. Cnsider ding a demnstratin: Yu might want t ask fr tw vlunteers t demnstrate hw far apart they wuld need t stand t prduce thse ftprints. Ask yur students t speculate: Hw might these three individuals have been related? They may have been family: a father, mther, and child. Page 5 f 7

6 Shrt Film Great Transitins: The Origin f Humans Educatr Materials PART 3: CHIMPANZEE AND HUMAN FOOTPRINT COMPARISON 7. Cmplete the handut: Distribute Part 3 f the handut, the summary activity. Have students refer t the ftprint characteristics in Table 1 and answer the questins fllwing the table. After time fr individual wrk, ask fr vlunteers t describe their answers t Part 3, Step 11, evidence that the Laetli ftprints were made by a bipedal primate (human) and nt a quadrupedal ne (chimpanzee). When yu discuss Part 3, Step 12, remind students that the rck in which the Laetli ftprints were fund is 3.6 millin years ld. This means that ur human ancestrs were fully bipedal by that time. Hwever, it is nt pssible t determine when bipedalism first evlved based n the Laetli ftprints alne. By examining ther fssil evidence, scientists have lked fr evidence f bipedalism befre and after the time f the ftprints t pinpint the rigin f this anatmical adaptatin. Scientists have analyzed a large bdy f evidence t recnstruct ur evlutinary past, including the fssils and DNA f many hminids. 8. Discuss the activity further: Ask students t cmpare the ftprints made by the vlunteers t thse n the Laetli trackway. What similarities d they ntice? What differences? Ftprints are affected by hw hard r sft the grund is. As yu discuss the questins abut the Laetli tracks, get yur students t think abut hw extrardinary they are because the grund had t be sft enugh t capture the prints, but nt s sft that all detail was lst. T help them understand, yu may ask them t think abut hw their wn ftprints are affected by the sftness f the grund. Have them imagine walking acrss a dry field and thrugh a thick, muddy field. Wuld either envirnment leave gd ftprints? What type f envirnment wuld leave gd ftprints, and what wuld have t happen fr thse ftprints t be preserved? Other questins yu may wish t discuss include: Hw d ftprints cntribute t evidence f hminid evlutin? Wuld walking as a bipedal prvide an advantage t an rganism? Why r why nt? RELATED RESOURCES Additinal classrm resurces related t the Great Transitins: The Origin f Humans shrt film can be fund n the BiInteractive website at A Click and Learn activity that explres human evlutin and features the fssil Ardi can be fund at Skeletns Reveal Human and Chimpanzee Evlutin, References and resurces that cver a wide range f tpics related t evlutin can be fund at the Understanding Evlutin website at References and resurces related t human rigins can be fund at the Smithsnian Institutin s What Des It Mean t Be Human? website, A mre in-depth activity related t the Laetli trackway, Ftsteps in Time, can be fund at the ENSIWEB website, Page 6 f 7

7 Shrt Film Great Transitins: The Origin f Humans Educatr Materials REFERENCES Flammer, Larry, Jean Beard, Craig E. Nelsn, and Martin Nickels. ENSIWEB (Evlutin/Nature f Science Institutes) Accessed September 15, 2015, frm Randak, Steve. Ftsteps in Time: Analysis f the Laetli Ftprints. ENSIWEB Accessed September 15, 2015, frm AUTHORS Mary Clvard, Cbleskill-Richmndville High Schl (retired); Sandra Blumenrath, PhD, HHMI Edited by Laura Bnetta, PhD, HHMI; Stephanie Keep, Cnsultant Reviewed by Briana Pbiner, PhD, Smithsnian Institutin; Paul Beardsley, PhD, Cal Ply Pmna Field Tested by Cindy Rust, Pst Falls High Schl, Pst Falls, ID; Jennifer Kaltenbach, Ridge High Schl, Oakland, NJ; Lisa Mueller, Lakeview High Schl, Battle Creek, MI; Patti Richardsn, Frest Hills Central High, Grand Rapids, MI; Katharine Gibsn, Kassn Rad BOCES, Syracuse, NY; Stacey Strandberg, Divine Savir Hly Angels High Schl, Hartland, WI; Judith Pint, Bergen Cunty Academies, Hackensack, NJ; Angela Lennx, Exeter High Schl, Exeter, NH Page 7 f 7