Human Evolution Station Part I: Watch Video: http://www.pbs.org/wgbh/evolution/library/11/2/quicktime/e_s_5_56.html
Take notes and answer questions: 1. 2. 3. 4. 5. 6.
Explain the difference between a relative and an ancestor. What does it mean when we say we share a “common ancestor” with chimpanzees? What are the chemicals in DNA? What is the result of a mutation? What is the difference between human DNA and chimp DNA? Why didn’t Darwin make claims about Human Evolution? What changed that scientists make this claim now?
Part II: Read the following section, examine the images, and answer the questions. Evolutionary biologists are interested in understanding how humans fit into the history of life and how the processes of evolution have shaped us. Much scientific effort goes into studying human evolution, and as a result, our understanding of this area is moving forward rapidly, as new evidence emerges and hypotheses are tested, confirmed, discarded, or modified. The location of our very own twig: Humans on the tree of life This tree is based on morphological and genetic data. Chimpanzees and humans are closely related, with DNA sequences that differ by only 1%. This genetic similarity made it hard to figure out exactly how these two primates are related, but recent genetic studies have strongly suggested that chimpanzees and humans are each other's closest living relative. Note they are closely related on the family tree below. Who shares a common ancestor with both chimps and humans?
How did humans evolve? About six million years ago in Africa, the chimpanzee lineage and our own split. What happened to us after that split? The hominid lineage did not march in a straight line to Homo sapiens. Instead, the early hominid lineage gave rise to many other (now extinct) hominids. Examining the fossils, the artifacts, and even the DNA of these relatives has helped us understand how this complex hominid tree evolved, and how modern humans came to exist.
Here are some of the important events in human history, with approximate dates, which reflect the evidence currently available (both fossil and DNA evidence): 1) Before 5 mya (million years ago): In Africa, our ancestral lineage and the chimpanzee lineage split. 2) Before 4 mya: The hominid Australopithecus anamensis walked around what is now Kenya on its hind legs. 3) 3 mya: Australopithecus afarensis ("Lucy") lived in Africa. 4) 2.5 mya: Some hominids made tools by chipping stones to form a cutting edge. There were perhaps four or more species of hominid living in Africa. 5) 2 mya: The first members of the Homo clade, with their relatively large brains, lived in Africa. 6) 1.5 mya: Hand axes were used. Also, hominids had spread out of Africa and into much of Asia and Europe. These hominids included the ancestors of Neanderthals (Homo neanderthalensis) in Europe and Homo erectus in Asia. 7) 100,000 years ago: Human brains reached more or less the current range of sizes. Early Homo sapiens lived in Africa. At the same time, Homo neanderthalensis and Homo erectus lived in other parts of the Old World. 8) 50,000 years ago: Human cultures produced cave paintings and body adornment, and constructed elaborate burials. Also, some groups of modern humans extended their range beyond Africa. 9) 25,000 years ago: Other Homo species had gone extinct, leaving only modern humans, Homo sapiens, spread throughout the Old World.
Questions, continued: 7. What types of evidence are used to construct the theory of how humans evolved? 8. Are humans directly related to chimps?
