Primate Evolution3 November, 2009

Time, time, time….

Earth’s origin

Origin oflife

Themes

Bush analogy (vs. ladder)

“Extinction is the rule”

Incompleteness of the fossil record

“Once we were not alone”

The nature of the evidence Fossils Molecular- protein/DNA

Class- MammaliaDerived from a branch of the reptiles- the therapsids

~200 M ybp

Mammals Hair, mammary glands Anatomy

One jaw bone

3 middle ear bones

Specific arterial

structures

Initially small, rat-like, nocturnal insect eaters

Earliest Mammals

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

“Advanced” Mammals- the “Placentals”

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

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

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

fetus= “placenta”

Two parallel lineages:Marsupial mammals- kangaroo, wallaby, opossum

Eutheria- live bearing, placental mammals

The reality of the situation at ~ 65 M ybp

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

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

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

The reality of the situation at ~ 65 M ybp

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

~60 M ybpMammalian “explosion” of diversity

Including- Primates (taxonomic Order) Tree-dwelling Omnivorous Branchiate- swing by arms Dexterous hands Claws replaced by nails Opposable thumb Forward-facing eyes, binocular vision Parental care

~ 58 M ybpAncestral Primate

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

Lemurs

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

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

~ 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 ybpAncestral Old World Monkeys, et al

Old-World MonkeysBaboon, Macaque, Proboscis Monkey

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

featuresGibbon, Great Apes

~ 18 M ybpAncestral Hominoids

“Lesser Apes”• Tree-dwelling• Strong brachiating

Gibbons

The “Hominidae”Humans +Great Apes

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”

~ 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”

Bipedal

Large brain

Small canine

teeth

Later: Tool production Language Art

Importance of A. afarensis &“Once we were not alone”

“Robust” lineages

“Gracile” lineages

BG

G

A

F D

Chimp Gorilla

Two major historical mass migrations; including the recent “out of Africa”

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

Years before present (byp)