Primate Evolution 5 November, 2007
Time, time, time…. Origin of life Earth’s origin
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- Mammalia • Derived from a branch of the reptiles- the therapsids • ~200 M ybp
Class- Mammalia • Characteristics • Hair • Mammary Glands (w/ or w/o nipples) • “Warm blooded” • Egg layers- earliest form= “monotremes” • Lots of unique anatomical features (1 aorta, 3 middle ear bones, one jaw bone (dentary), etc…)
Mammals, continued… • 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 • Young “born” only partially developed • No eggs- internal (initial) development- rudimentary placenta • Well-developed nipples- young attach to complete development
Live bearing Mammals • “Eutheria” • True placenta • Offspring spend longer developing in mother
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)
Mammalian diversification • Explosive diversity of mammalian types in “vacuum” of rapid dinosaur extinctions- especially eutherians
~60 M ybp • 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 ybp Ancestral Primate • “Dry-nosed” primates • Mostly diurnal • Specialized hands and • feet for grasping • Tarsiers + Monkeys & Apes • (a.k.a. “Simians”) • First- cat-sized and arboreal • “Wet-nosed” primates • Mostly nocturnal • Tree-dwelling • Lemurs
~ 40 M ybp Ancestral Simian • Old-World Monkeys + others • Africa & Asia • Simple, no tail • Narrow nose • Tree-dwelling • Mostly diurnal • Flat fingernails • Baboon, Macaque, Great • Apes Atlantic Ocean • New-World Monkeys • N/S America • Long prehensile tail • Flat nose • Tree-dwelling • Mostly nocturnal • Capuchin, Marmosets, • Howler monkey
~ 25 M ybp Ancestral Old World Monkeys, et al • (Apes) “Hominoids” • Mostly arboreal • Africa, Asia • Other anatomical • features • Gibbon, Great Apes • Old-World Monkeys • Baboon, Macaque, Proboscis • Monkey
~ 18 M ybp Ancestral Hominoids The “Hominidae” Humans +Great Apes • “Lesser Apes” • Tree-dwelling • Strong brachiating • Gibbons
The “Hominidae”
The “Hominidae” The “Hominidae” ~ 14 M ybp Sivapithecus (Ramipethecus)- fossil ~ 14 M ybp Initially thought to be an early “homininae” The “Homininae” Evolved in Africa: Gorilla, Chimp, Pygmy Chimp, Human Orangutans Asia
The “Homininae” The “Homininae” ~ 7 M ybp The “Hominini” Humans, Chimpanzee, Pygmy Chimpanzee (Bonobo) • Gorillas • 2 (4?) species • Knuckle-walk • Intelligent • Western & Eastern • species (w/ subspecies)
The “Hominini” The “Hominini” 6- 7 M ybp The “Hominids” Humans + fossils leading to modern humans Molecular evidence- “Molecular clocks” Antibody specificity DNA hybridization Chimpanzee Larger, stockier More aggressive Male-dominated social groups Bonobo Gracile More cooperative, more sexual Female-dominated Social groups
The “Hominids” • Bipedal • Large brain • Small canine teeth • Later: • Tool production • Language • Art
BREAK TIME
B D G E F A
Raymond Dart- 1924Australopithecus africanus
Donald JohansenAustralopithecus afarensis
1994-East Africa & Chad
Importance of A. afarensis “Gracile” lineages “Robust” lineages
“Once we were not alone”
B Chimp Gorilla E D C G
Homo sapiens as the “wanderer”The “out of Africa” theory Years before present (byp)
