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Explore the fascinating evolution of primates, including lemurs, monkeys, apes, and humans. Discover the key adaptations that differentiate primates from other mammals and the progression of hominid species leading to modern Homo sapiens. Consider different hypotheses on human origins and the impact of cultural evolution on our species.
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Chapter 21 The Evolution of Primates
Mammals • Endothermic • Body hair • Feed young with milk from mammary glands • Most are viviparous
Placental mammals • Placenta exchanges materials between mother and fetus • Newborns are more developed than marsupials
Primates • Five grasping digits • Opposable thumb or toe • Long, freely moving limbs • Eyes in front of the head • Relatively large brain
Suborder Prosimii • Lemurs • Suborder Tarsiiformes • Tarsiers • Suborder Anthropoidae • Monkeys, apes, humans
Anthropoids • Old and new world monkeys • Apes and humans • Hominoids • Apes • Gibbons • Orangutans • Gorillas • Chimpanzees • Humans
New world monkey Old world monkey
Hominids • Humans • Extinct human ancestors
Differences between ape and human skeletons • Human adaptations for bipedal life on the ground • Complex curvature of the spine • Shorter, broader pelvis • Foramen magnum at base of skull • First toe aligned with other toes
Sahelanthropus tchadensis • 6-7 mya • May be the earliest known hominid • Discovered in 2002
Australopithecines • Bipedal • Ardipithecus ramidus • Australopithecus anamensis • Australopithecus afarensis • Australopithecus africanus
Homo habilis • Appeared 2.3 mya • Human features not found in australopithecines • Slightly larger brain • Stone tools
Homo erectus • Appeared 1.7 mya in Africa • Larger brain than Homo habilis • More sophisticated tools • Maybe clothing, fires, shelters
Archaic Homo sapiens • Appeared 800,000 years ago • Overlapped Homo erectus populations in Africa, Asia, and Europe and later Neandertals
Neandertals • Appeared 230,000 years ago • Short, sturdy builds • receding chin and forehead • Heavy supraorbital ridge • Larger front teeth • May be a separate species
Homo sapiens • Appeared 100,000 years ago in anatomically modern form • Lacked heavy brow ridge • Prominent chin • Complex weapons and tools • European Homo sapiens known as Cro-Magnons
Out-of-Africa hypothesis • H. sapiens evolved from AfricanH. erectus 200,000 to 100,000 ya • Migrated to Europe and Asia • Displaced more primitive humans
Multiregional hypothesis • Modern humans evolved from separate populations in Africa, Asia, and Europe ~2 mya • Populations evolved separately but also interbred • One species with regional variations that still exist
Molecular anthropology • Comparison of biological materials from modern populations • Mitochondrial DNA • Generally supports the Out-of-Africa hypothesis
Cultural evolution • Transmission of knowledge across generations • Enabled by large brain size • Agriculture • Industry • Rapidly expanding population had degraded the environment