Primate EvolutionPrimate Evolution5 November, 20075 November, 2007

Time, time, time….Time, time, time….

Earth’s origin

Origin oflife

ThemesThemes

Bush analogy (vs. ladder)Bush analogy (vs. ladder)

““Extinction is the rule”Extinction is the rule”

Incompleteness of the fossil recordIncompleteness of the fossil record

““Once we were not alone”Once we were not alone”

The nature of the evidenceThe nature of the evidence FossilsFossils Molecular- protein/DNAMolecular- protein/DNA

Class- MammaliaClass- MammaliaDerived from a branch of the reptiles- the Derived from a branch of the reptiles- the therapsidstherapsids

~200 M ybp~200 M ybp

Class- MammaliaClass- MammaliaCharacteristicsCharacteristics HairHair Mammary Glands (w/ or w/o nipples)Mammary Glands (w/ or w/o nipples) ““Warm blooded”Warm blooded” Egg layers- earliest form= “monotremes”Egg layers- earliest form= “monotremes” Lots of unique anatomical features (1 aorta, 3 Lots of unique anatomical features (1 aorta, 3

middle ear bones, one jaw bone (dentary), etc…)middle ear bones, one jaw bone (dentary), etc…)

Mammals, continued…Mammals, continued… AnatomyAnatomy

One jaw boneOne jaw bone

3 middle ear bones3 middle ear bones

Specific arterial Specific arterial

structuresstructures

Initially small, rat-like, nocturnal insect Initially small, rat-like, nocturnal insect eaterseaters

Earliest MammalsEarliest Mammals

Modern descendents- platypus (of Modern descendents- platypus (of Australia) & echidna (of New Zealand)Australia) & echidna (of New Zealand)

““Advanced” Mammals- Advanced” Mammals- the “Placentals”the “Placentals”

~ 100 M ybp- “Age of the Dinosaurs” ~ 100 M ybp- “Age of the Dinosaurs” (Cretaceous era)(Cretaceous era)

(older fossil?- ~ 130 M ybp, 1 meter in (older fossil?- ~ 130 M ybp, 1 meter in length)length)

““Live bearing mammals”Live bearing mammals” Internal developmentInternal development Some form of connection between mother and Some form of connection between mother and

fetus= “placenta”fetus= “placenta”

Two parallel lineages:Two parallel lineages:Marsupial mammals- kangaroo, wallaby, Marsupial mammals- kangaroo, wallaby, opossumopossum Young “born” only partially developedYoung “born” only partially developed No eggs- internal (initial) development- No eggs- internal (initial) development-

rudimentary placentarudimentary placenta Well-developed nipples- young attach to Well-developed nipples- young attach to

complete developmentcomplete development

Live bearing MammalsLive bearing Mammals““Eutheria”Eutheria” True placentaTrue placenta Offspring spend longer developing in motherOffspring spend longer developing in mother

The reality of the situation at The reality of the situation at ~ 65 M ybp~ 65 M ybp

Mammals (monotremes, marsupials & Mammals (monotremes, marsupials & eutherians) were all a very small part of eutherians) were all a very small part of animal diversityanimal diversity

Eutherians represented by a very small Eutherians represented by a very small number of small, nocturnal, shrew-like number of small, nocturnal, shrew-like animalsanimals

The “K/T Boundary” (cretaceous/tertiary)The “K/T Boundary” (cretaceous/tertiary)

The reality of the situation at The reality of the situation at ~ 65 M ybp~ 65 M ybp

The “K/T Boundary” (cretaceous/tertiary)- one of many The “K/T Boundary” (cretaceous/tertiary)- one of many historical “Mass extinctions” (many living groups, historical “Mass extinctions” (many living groups, including the dinosaurs)including the dinosaurs)

Mammalian diversificationMammalian diversification

Explosive diversity of mammalian types in Explosive diversity of mammalian types in “vacuum” of rapid dinosaur extinctions- “vacuum” of rapid dinosaur extinctions- especially eutheriansespecially eutherians

~60 M ybp~60 M ybpPrimates (taxonomic Order)Primates (taxonomic Order) Tree-dwellingTree-dwelling OmnivorousOmnivorous Branchiate- swing by armsBranchiate- swing by arms Dexterous handsDexterous hands Claws replaced by nailsClaws replaced by nails Opposable thumbOpposable thumb Forward-facing eyes, binocular visionForward-facing eyes, binocular vision Parental careParental care

~ 58 M ybp~ 58 M ybpAncestral Primate

“Wet-nosed” primates• Mostly nocturnal• Tree-dwelling

Lemurs

“Dry-nosed” primates• Mostly diurnal• Specialized hands and feet for grasping

Tarsiers + Monkeys & Apes (a.k.a. “Simians”)First- cat-sized and arboreal

~ 40 M ybp~ 40 M ybpAncestral Simian

New-World MonkeysN/S America

• Long prehensile tail• Flat nose• Tree-dwelling• Mostly nocturnal

Capuchin, Marmosets, Howler monkey

Old-World Monkeys + othersAfrica & Asia

• Simple, no tail• Narrow nose• Tree-dwelling• Mostly diurnal• Flat fingernails

Baboon, Macaque, Great Apes

Atlantic Ocean

~ 25 M ybp~ 25 M ybpAncestral Old World Monkeys, et al

Old-World MonkeysBaboon, Macaque, Proboscis Monkey

(Apes) “Hominoids”• Mostly arboreal• Africa, Asia• Other anatomical features

Gibbon, Great Apes

~ 18 M ybp~ 18 M ybpAncestral Hominoids

“Lesser Apes”• Tree-dwelling• Strong brachiating

Gibbons

The “Hominidae”Humans +Great Apes

The “Hominidae”The “Hominidae”

The “Hominidae”The “Hominidae”The “Hominidae”

OrangutansAsia

~ 14 M ybp

Sivapithecus (Ramipethecus)- fossil~ 14 M ybpInitially thought to be an early “homininae”

The “Homininae”Evolved in Africa:Gorilla, Chimp, Pygmy Chimp, Human

The “Homininae”The “Homininae”The “Homininae”

~ 7 M ybp

Gorillas2 (4?) species

• Knuckle-walk• Intelligent

Western & Eastern species (w/ subspecies)

The “Hominini”Humans, Chimpanzee, Pygmy Chimpanzee (Bonobo)

The “Hominini”

The “Hominini”

6- 7 M ybp

Molecular evidence- “Molecular clocks” Antibody specificity DNA hybridization

ChimpanzeeLarger, stockierMore aggressiveMale-dominated social groups

BonoboGracileMore cooperative, more sexualFemale-dominated Social groups

The “Hominids”Humans + fossils leading to modern humans

The “Hominids”The “Hominids”

BipedalBipedal

Large brainLarge brain

Small canine Small canine

teethteeth

Later:Later: Tool productionTool production LanguageLanguage ArtArt

BREAK TIMEBREAK TIME

D

F

GE

B

A

Raymond Dart- 1924Raymond Dart- 1924Australopithecus africanusAustralopithecus africanus

Donald JohansenDonald JohansenAustralopithecus afarensisAustralopithecus afarensis

1994-1994-East Africa & ChadEast Africa & Chad

Importance of Importance of A. afarensisA. afarensis

“Robust” lineages

“Gracile” lineages

““Once we were not alone”Once we were not alone”

Chimp Gorilla

CD

G

B

E

Homo sapiensHomo sapiens as the “wanderer” as the “wanderer”The “out of Africa” theoryThe “out of Africa” theory

Years before present (byp)