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Biology, Seventh Edition Solomon • Berg • Martin

Chapter 21

The Evolution of The Evolution of PrimatesPrimates

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Mammals• Endothermic

• Body hair

• Feed young with milk from mammary glands

• Most are viviparous

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Placental mammals• Placenta exchanges materials

between mother and fetus

• Newborns are more developed than marsupials

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Primates• Five grasping digits

• Opposable thumb or toe

• Long, freely moving limbs

• Eyes in front of the head

• Relatively large brain

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

Primate hands and feet

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Suborder Prosimii• Lemurs

• Suborder Tarsiiformes• Tarsiers

• Suborder Anthropoidae• Monkeys, apes, humans

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

Primate evolution

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Anthropoids• Old and new world monkeys• Apes and humans

• Hominoids• Apes

–Gibbons–Orangutans–Gorillas–Chimpanzees

• Humans

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

New world monkey Old world monkey

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Hominids• Humans

• Extinct human ancestors

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• 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

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

Human and gorilla skeletons

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

Human and gorilla heads

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Sahelanthropus tchadensis• 6-7 mya

• May be the earliest known hominid

• Discovered in 2002

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Australopithecines• Bipedal

• Ardipithecus ramidus

• Australopithecus anamensis

• Australopithecus afarensis

• Australopithecus africanus

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

An interpretation of hominid evolution

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Homo habilis• Appeared 2.3 mya

• Human features not found in australopithecines

• Slightly larger brain

• Stone tools

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Homo erectus• Appeared 1.7 mya in Africa

• Larger brain than Homo habilis

• More sophisticated tools

• Maybe clothing, fires, shelters

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

Homo erectus skull

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Archaic Homo sapiens• Appeared 800,000 years ago

• Overlapped Homo erectus populations in Africa, Asia, and Europe and later Neandertals

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Neandertals• Appeared 230,000 years ago

• Short, sturdy builds

• receding chin and forehead

• Heavy supraorbital ridge

• Larger front teeth

• May be a separate species

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• 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

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Out-of-Africa hypothesis• H. sapiens evolved from African

H. erectus 200,000 to 100,000 ya

• Migrated to Europe and Asia

• Displaced more primitive humans

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• 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

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Molecular anthropology• Comparison of biological

materials from modern populations

• Mitochondrial DNA

• Generally supports the Out-of-Africa hypothesis

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Biology, Seventh Edition CHAPTER 21 The Evolution of Primates

• Cultural evolution• Transmission of knowledge

across generations• Enabled by large brain size• Agriculture• Industry• Rapidly expanding population

had degraded the environment