Skull Chamcteristics of Human Ancestors and Relatives, from (—) = Most Primitive to (++) Most Advinced Genus and species Teeth Jaw Structure Cranium Cranium Muscle Attachments Nose Australopithecus afasi Homo habilis Homo erectus Homo sapiens யோகானை Pan troglodytus 5. The first true hominids found in the fossil record have been assigned to the genus Australopithecus (from the Greek stralis for “southern and pithecus for “ape” because the first specimens were found in southern Africa). Some of the oldest known fossils of Australopithecus are of the species A afures. The most famous skeleton has been named Lucy. Lucy and others of her species lived approximately 3.6 to 29 million years ago 6. Now turn your attention to the skulls of the Home lineage. There is debate about the lineage of our own genus, Homo (“Man”), Homo habilis, the early toolmaker, lived in eastern and southern Africa from about 1.9 to 1.6 million years ago. Homo erectus upright man”) also arose in Africa. However, it was Homo crecies whose populations left Africa in waves between 2 million and 500,000 years ago. Some still lived in southeast Asia until at least 53,000 years ago. Our own species, Homo sapiens (“Wise man”), seems to have evolved from Homo erectus ancestors by 100,000 years ago (a) What changes from primitive to advanced characteristics do you see in the evolution from A. afarensis to Homo habilis? (b) What is the trend in cranial capacity between the ancestral A. afarensis and Homo erectus? c) Between Homo erectus and Homo sapiens? 7. Finally, study the skulls of the modern human form (Homo sapiens) and our nearest living relative, the chimpanzee (Pan troglodytes). Fossil evidence, biochemistry, and genetic analyses indicate that chimpanzees and humans are the most closely related of all living primates. In fact, comparisons of amino acid sequences of proteins and DNA sequences show that chimpanzees and humans share about 99% of their genes! Other evidence shows that the separation from the hominid line of the lineage that led to chimpanzees and other great apes occurred about 6 million years ago (a) How does the chimpanzee skull compare with the skull of Australopithecus afarensis? What features are most alike? Which are most different? (b) How does the chimpanzee skull compare with the human skull with respect to primitive and advanced anatomical features? 220 EXERCISE 17

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