Biology Sylvia S. Mader Michael Windelspecht Chapter 30 Human Evolution Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. 1

Outline 30.1 Evolution of Primates 30.2 Evolution of Humanlike Hominins 30.3 Evolution of Early Genus Homo 30.4 Evolution of Later Genus Homo 2

30.1 Evolution of Primates Primate evolution characterized by trends towards: –Mobile limbs –Grasping hands –flattened face –Stereoscopic vision –large, complex brain –Reduced reproductive rate 3

Primate Diversity 4 AFRICAN APESOLD WORLD MONKEYPROSIMIANS Tarsier, Tarsius bancanus NEW WORLD MONKEY Anubis baboon, Papio anubis ASIAN APES HOMININS Chimpanzee, Pan troglodytes White-faced monkey, Cebus capucinus Orangutan, Pongo pygmaeus Humans, Homo sapiens (top left): © Doug Wechsler; (top middle): © St. Meyers/Okapia/Photo Researchers, Inc.; (top right): © Martin Harvey/Peter Arnold/Photolibrary; (bottom left): © Paul Souders/Corbis; (bottom middle): © Tim Davis/Photo Researchers, Inc.; (bottom right): © Comstock Images/JupiterImages RF Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Evolution of Primates Mobile Forelimbs and Hindlimbs –Most primates have flat nails instead of claws –Sensitive pads on undersides of fingers & toes –opposable thumb allow primates to grasp/release tree limbs 5

Evolution of Primate Hand 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. c. Monkey d. Human sharp claws short thumb nails long thumb a. Tree shrew suction cup-like pads b. Tarsier fingers easily curve

Evolution of Primates Stereoscopic Vision –3–3-D vision –D–Depth perception –A–Allows accurate judgments about distance / position tree limbs –S–Some have color vision! 7

Stereoscopic Vision 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. binocular field Reduced snout does not block vision.

Evolution of Primates Large, Complex Brain –process more sensory input –In apes and humans The portion of the brain devoted to sight is larger The portion of the brain devoted to smell is smaller The portion of the brain devoted to communication is larger 9

10 Evolution of Primates Reduced Reproductive Rate –Increased age of sexual maturity –Extended lifespan –Lengthened gestation time allowing for forebrain development –Single births –Juvenile development period extended, emphasis on learned behavior and complex social interactions

Evolution of Primates Sequence of Primate Evolution –Hominins first evolved about 5 MYA –Hominids Include chimpanzees, hominins, gorillas, and organgutan –Hominoids Include hominids and gibbon –Anthropoids Include hominoids, Old World monkeys, and New World monkeys 11

Evolution of Primates Proconsul ancestral to hominoids Phylogenetic tree indicates humans most closely related to African apes Prosimians –Lemurs and tarsiers –First type of primate to diverge from common primate ancestor 12

Monkey Skeleton Compared to Proconsul Skeleton 13 © National Museums of Kenya Monkey Proconsul a. Monkey skeleton b. Proconsul skeleton flat palms and soles arched vertebral column short forelimbs narrow rib cage immobile shoulder joint Monkeylike features: short forelimbs narrow rib cage quadrupedal lifestyle Apelike features: flat vertebral column lack of a tail mobile shoulder joints larger brain relative to body size Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Evolution of Primates 14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Humans hominin Chimpanzees Gorillas common chimpanzee western lowland gorilla Orangutans Gibbons white-handed gibbon Bornean orangutan rhesus monkey Old World Monkeys capuchin monkey New World Monkeys Mammalian ancestor enters trees. Tarsiers Philippine tarsier ring-tailed lemur PRESENT Million Years Ago ( MYA ) Prosimians Anthropoids Hominoids Hominids Hominines Lemurs

Genomic Comparison of Humans & Chimpanzees Humans & chimps are closely related: –Similar chromosome number –Similar pattern of transposons and pseudogenes –DNA base sequence btwn humans and chimpanzees differs by only 1.5% 15

30.2 Evolution of Humanlike Hominins Hominin fossils: –anatomy suitable for standing erect / walking on 2 feet (Bipedalism) Skeletal differences btwn humans and apes occur because: –Humans: bipedal, apes: quadrupedal 16

Classification 17 ORDER: Primates TRIBE*: Hominini (hominins) Early Humanlike Hominins Later Humanlike Hominins GENUS: Homo (humans) Early Homo Later Homo Homo habilis, Homo rudolfensis, Homo ergaster, Homo erectus australopithecines Adapted to an arboreal life Prosimians, Anthropoids CLASSIFICATION SUBFAMILY: Homininae (hominines) Sahelanthropus, ardipithecines, Brain size greater than 1,000 cc; tool use and culture Homo heidelbergensis, Homo neandertalensis, Homo sapiens Brain size greater than 600 cc; tool use and culture * A new taxonomic level that lies between subfamily and genus. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Walking Erect 18 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display Sehelanthropus tchadensis Australopithecus afarensis Australopithecus boisei Homo habilis Homo sapiens Homo neandertalensis Homo heidelbergensis Homo erectus Homo ergaster Homo rudolfensis Homo habilis Australopithecus africanus Australopithecus afarensis Australopithecus anamensis Australopithecus aethiopicus Australopithecus boisei Australopithecus robustus Ardipithecus ramidus Sahelanthropus tchadensis Million Years Ago (MYA) (S. tchadensis): © Prof. Michel Brunet; (A. afarensis): © Friedrich Saurer/Alamy; (A. boisei): © Science VU/NMK/Visuals Unlimited; (H. habilis): © Herve Conge/ISM/Phototake; (H. sapiens): © 2007 Educational Images Ltd./Custom Medical Stock Photo

Human Evolution 19 Homo sapiensArdipithecus ramidus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Evolution of Humanlike Hominins Ardipithecines: –Evolved in Africa Ardipithecus kadabba (5.6 MYA) Ardipithecus ramidus (Ardi! 4.4 MYA) –App. size of chimpanzee –Small head / brain –Walked erect, but spent most of time in trees –Flexible wrists 20

Evolution of Humanlike Hominins Australopithecines: –Evolved /diversified in Africa 4-1 mya –Possibly direct ancestor of humans –Evidence of mosaic evolution Different body parts evolve at different rates – cm in height w/ small brains –Consumed seeds, fruits, roots, leaves –Tanzanian footprints 21

Evolution of Humanlike Hominins Australopithecines: –Eastern Africa Australopithecus afarensis- Lucy –Bipedal, humanlike, low forehead, large canine teeth, small brain –Southern Africa A. africanus, A. robustus, A. sediba(possible trans link) –Small brain, long arms, climbed trees –Humanlike pelvis and striding gate 22

Australopithecus afarensis 23 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Dan Dreyfus and Associates

30.3 Evolution of Early Genus Homo Homo habilis and Homo rudolfensis –Originated ~2 mya –May be ancestral to modern humans –Socially organized –Scavengers –Larger brain than A. afarensis –Omnivorous Consumed meat and plants 24

Evolution of Early Genus Homo Homo ergaster and Homo erectus –Found in Africa, Asia, & Europe –Dated between mya –Larger brain, flatter face than Homo habilis –Much taller than previous hominids –first appeared in Africa, migrated to Asia & Europe –First hominid to use fire! 25

Evolution of Early Genus Homo Homo floresiensis –18,000 year-old fossil discovered in 2004 –1 m tall, 25 kg adult female –Braincase 1/3 size of modern human –Used tools and fire –May have evolved from Homo erectus 26

Homo ergaster 27 neck of femur femur © National Museums of Kenya Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Homo erectus 28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30.4 Evolution of Later Genus Homo Most researchers believe Homo sapiens evolved from Homo ergaster –Out-of-Africa Hypothesis (replacement model) H. sapiens evolved from H. ergaster in Africa, then migrated to Europe Supported by fossil record and DNA data –Multiregional Continuity Hypothesis Similar evolution occurred in many different places Suggest genetic continuity will be found btwn modern and archaic populations 29

Replacement Model 30 modern humans archaic humans Homo ergaster Homo erectus archaic humans modern humans Million Years Ago (MYA) EUROPE (present day) AFRICAASIA Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Evolution of Later Genus Homo Neandertals Neandertal (Homo neandertalensis) skeletons 1 st discovered Neander Valley (Germany) Skeletons date back 200,000 years –Massive brow ridges w/ protruding nose, jaws, and teeth –Heavily muscled –Culturally advanced Manufactured variety of tools 31

Neandertals 32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © The Field Museum, #A102513c

Evolution of Later Genus Homo Cro-Magnons –Oldest fossils designated H. sapiens –Modern humans who entered Asia and Europe from Africa 100,000 years ago Made advanced stone tools Developed language using patterned sounds Hunter-gatherers –Collected food from environment rather than domesticating animals and growing food plants 33

Cro-Magnons 34 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Transparency #608 Courtesy Dept. of Library Services, American Museum of Natural History

Evolution of Later Genus Homo Human Variation Hypothesized adaptations evolved to local environment –Bergmann’s Rule - Animals in colder regions have bulkier body –Allen’s Rule - Animals in colder regions have shorter limbs, digits, and ears Comparative study of mitochondrial DNA –Suggests human populations have common ancestor < 1 mya 35

Ethnic Groups 36 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © PhotoDisc/Getty Images; b: © Sylvia S. Mader; c: © B & C Alexander/Photo Researchers, Inc. a. b. c.

Bicultural Evolution Began w/ Homo Culture encompasses –Human activities –Products passed from one generation to another outside of direct biological inheritance. Homo habilis (and Homo rudolfensis) made simple stone tools for hammering, chopping, and digging Homo erectus made stone tools, but flakes were sharper and had straighter edges. 37