Visit our textbook-specific Online Learning Center Web site at www.mhhe.com/relethford8e to access the exercises that follow.
Family Trees
Go to the Museum of Science, Boston "Human Evolution: Interpreting Evidence" Web site. Click on the "Family Trees" link: http://www.mos.org/evolution/overlays/. This site points out that interpretation of the fossil record can differ greatly, depending on which scientist you talk to. Three scientists (Meave Leakey, Ian Tattersall, and Tim White) are represented. Their respective timelines of hominin evolution are represented graphically.
Click on each by selecting the box alongside the scientist's name. Notice that all are available as a single, downloadable .PDF file. (The individual scientists are not identified on the .PDF version, so make sure that you label each by comparing them from the Web version.)
Now compare each timeline side by side.
What are the most striking differences between them? Are there any similarities?
What do you think are some of the criteria each scientist used to develop their own schemes of hominin evolution?
Human Evolution
New Zealand's University of Waikato School of Science and Engineering Web site provides a brief, informative, and understandable overview of human evolution on a single page: http://sci.waikato.ac.nz/evolution/HumanEvolution.shtml#Theearliesthominids. Read each of the sections: Miocene Apes, The Earliest Hominids, The Australopithecines, Homo Species Trends in Human Evolution, Human Cultural Evolution, and Mitochondrial DNA.
Do the names for the fossils correspond with those in your textbook?
Which, if any, are different?
Why do some of the fossils have more than one name?
Look down the page and locate the "Taung baby" link. Click on it: http://www.d.umn.edu/cla/faculty/troufs/anth1602/pctaung.html. The site includes a photo of Raymond Dart holding the Taung (Australopithecus africanus) skull and a separate photo of the skull itself. A small African map identifies australopith sites.
How many sites are identified?
Where are most of the sites concentrated?
Origins of Humankind
http://www.pbs.org/wgbh/evolution/humans/humankind/index.html.
Watch the interactive "Origins of Humankind" Web activity from the PBS Evolution Web site. Complete the activity and see the Species Gallery for some of the most well-known specimens representing each species.
Why is the hominin family tree so tentative and unclear? How does it compare to the trees presented in your textbook?
Will it ever be possible to gather enough evidence to clarify the evolutionary relationships among these species?
If you could conjure up any fossil or molecular evidence you needed, what evidence would you like to find to answer these unresolved questions?
Palaeoanthropology: Hominin Revelations from Chad
Go to the journal Nature Web site and read the article on Sahelanthropus:http://www.nature.com/nature/journal/v418/n6894/full/418133a.html. This July 2002 article discusses the find: a cranium, jaw fragment, and some teeth. The fossil is compared for its significance to Raymond Dart's 1924 discover of the "Taung child."
What makes this particular find so significant?
Why was it so difficult to excavate this particular locale?
Absolute dating methods were not used at this site. Why?
What method was used instead?
Two hypotheses concerning hominin evolution are discussed: the linear, or "tidy," model and the "bushy," or "untidy," model. What is the difference between these models, and what are the evolutionary implications of each?
