MonthDayLecture Oct13Fungi 16The coral reef 18Animals—worms 20Animals—vertebrates 23Mammals 25Primates to humans 27Exam review 30Exam

Chordates Echinoderms Arthropods Annelids Mollusks Rotifers Roundworms Flatworms Cnidarians Sponges Multicelled Ancestry Radial Ancestry Bilateral Ancestry Coelomate Ancestry Single-celled, protistanlike ancestors

Figure 26.2 Page 445 Mammals Birds “Reptiles” Amphibians Amniotes Tetrapods Lungfishes Lobe-finned Fishes Ray-finned Fishes Cartilaginous Fishes Jawed Vertebrates Lampreys Vertebrates Craniates Hagfishes Cephalochordates Urochordates Chordates

Unique characteristics of mammals: Mammary glands Sweat glands Hair Four-chambered heart Other notable characteristics: –Internal fertilization of eggs –Warm-blooded

Primates evolved from an ancestral arboreal insectivore about 60 mya

Early primates: Dexterous hands with opposable thumbs Nails instead of claws Eyes in front-good depth perception Daytime vision (less reliance on smell)

Great Apes--hominoids Gorillas Orangutans Gibbons Humans

Our closest living relative: the chimpanzee

The ladder...

From Primates to Humans “Uniquely” human traits evolved through modification of traits that evolved earlier in ancestral forms

Falling out of the tree

Before Isthmus of Panama formedAfter Isthmus of Panama formed 23-5 mya—the Miocene Warm, wet Cool, dry

Trends in Lineage Leading to Humans Less reliance on smell, more on vision

Trends in Lineage Leading to Humans Less reliance on smell, more on vision Modifications of hand allow fine movements

power gripprecision grip

Trends in Lineage Leading to Humans Less reliance on smell, more on vision Modifications of hand allow fine movements Bow-shaped jaw and smaller teeth

Trends in Lineage Leading to Humans Less reliance on smell, more on vision Modifications of hand allow fine movements Bow-shaped jaw and smaller teeth Longer lifespan and period of dependency

Trends in Lineage Leading to Humans Less reliance on smell, more on vision Modifications of hand allow fine movements Bow-shaped jaw and smaller teeth Longer lifespan and period of dependency Skeletal changes to allow bipedalism –Not as efficient as quadrupedal movement, but keeps eyes up and forward, keeps hands free

ANCESTRAL PRIMATES mya Between 10 and 5 mya, the adaptive radiation of first hominiods (apelike forms) Between 10 and 5 mya, divergences leading to gorillas, chimpanzees, and hominids EARLY HOMINOIDS EARLY ANTHROPOIDS HOMINIDS A. afarensisA. boisei A. robustus A. africanus Homo rudolfensis Australopithecus Ardipithecus ramidus A. garhiH. erectus H. neanderthalensis H. sapiens H. habilis CHIMPANZEE GORILLA ORANGUTAN GIBBON OLD WORLD MONKEYS NEW WORLD MONKEYS PROSIMIANS 4 mya3 mya2 mya1 myapresent

Fig , p.457

Earliest Fossils Are African Sub-saharan Africa appears to be the cradle of human evolution No human fossils older than 2 million years exist anywhere but Africa

Fig a, p.457 Tools made by australopiths and/or H. habilis

Reconstruction of Homo habilis in an East African woodland

Homo erectus 2 million-53,000? years ago Evolved in Africa Migrated into Europe and Asia from 2 million to 500,000 years ago Larger brain than H. habilis Creative toolmaker Built fires and used furs for clothing

Homo sapiens Modern man evolved by 100,000 years ago Compared to Homo erectus: –Smaller teeth and jaws –Chin –Smaller facial bones –Larger-volume brain case

Neanderthals Early humans that lived in Europe and Near East Massively built, with large brains Disappeared when H. sapiens appeared DNA evidence suggests that they did not contribute to modern European populations

40,000 years ago Estimated times when populations of early H. sapiens were colonizing different regions of the world

Where Did H. sapiens Arise? Two hypotheses: –Multiregional model –African emergence model Both attempt to address biochemical and fossil evidence

Multiregional Model Argues that H. erectus migrated to many locations by about 1 million years ago Geographically separated populations gave rise to phenotypically different races of H. sapiens in different locations (parallel evolution) Gene flow prevented races from becoming species

African Emergence Model Argues that H. sapiens arose in sub-Saharan Africa H. sapiens migrated out of Africa and into regions where H. erectus had preceded them (and likely outcompeted them) Only after leaving Africa did phenotypic differences arise

NEW GUINEA, AUSTRALIA PACIFIC ISLANDS SOUTHEAST ASIA ARCTIC, NORTHEAST ASIA NORTH, SOUTH AMERICA NORTHEAST ASIA EUROPE, MIDDLE EAST AFRICA Genetic distance (percent) One family tree proposed for H. sapiens

40,000 years ago Estimated times when populations of early H. sapiens were colonizing different regions of the world