chapter 2 – human evolution
DESCRIPTION
Chapter 2 – Human Evolution. Today’s Objectives. How do humans differ from apes? Skeleton, organs, culture Why was Homo erectus so successful as an early hominid? What happened to Neandertals? Be able to briefly trace the cultural development of: tools, fire, clothing, shelter, art - PowerPoint PPT PresentationTRANSCRIPT
Chapter 2 –Human Evolution
Today’s ObjectivesHow do humans differ from apes?
Skeleton, organs, cultureWhy was Homo erectus so successful as an early hominid?What happened to Neandertals?Be able to briefly trace the cultural development of:
tools, fire, clothing, shelter, artWhat is so important about the Upper Palaeolithic?
Theories of Evolution
Origin Myths/CosmologiesGreek – PrometheusGenesis
Left: Prometheus and AthenaTop: God and Adam
Western examples
Carl Sagan’s Universe Calendar
24 days = 1 billion years1 second = 475 years
“Big Bang” January 1Milky Way May 1Solar System September 9Life on Earth September 25Humanlike Primates December 31, 10:30pm
Milky Way
Theories of Evolution
Darwin and Wallace, 1850sEvolution theory holds that existing species of plants and animals have emerged over millions of years from simple organisms.Darwin, On the origin of species, 1859Influenced by the principle of uniformitarianism
Charles Darwin
Theories of Evolution - CorollariesDarwin’s principle of natural selection
“Natural selection is the gradual process by which nature selects the forms most fit to survive and reproduce in a given environment.”
For natural selection to work on a given population, there must be variety within that population and competition for strategic resources.
The concept of natural selection argues that organisms which have a better fit within their environmental niche will reproduce more frequently than those organisms that fit less well.
Theories of Evolution - Corollaries
Random genetic drift is the loss of alleles from a population's gene pool through chance.
Mutation introduces genetic variation into a breeding population.
Gene flow occurs through interbreeding: the transmission of genetic material from one population to another. Gene flow decreases differences and inhibits speciation, the formation of new species.
Theories of Evolution - CorollariesMendel’s principle of inheritance, 1856
The science of genetics explains the origin of the variety upon which natural selection operates.
By experimenting with successive generations of pea plants, Mendel came to the conclusion that heredity is determined by discrete particles, the effects of which may disappear in one generation, and reappear in the next.
Other TheoriesCreationism accounts for biological diversity by referring to the divine act of Creation as described in Genesis.
Catastrophism is a modified version of Creationism, which accounts for the fossil record by positing divinely authored worldwide disasters that wiped out the creatures represented in the fossil record, who were then supplanted by newer, created species.
Intelligent Design states that modern physics and cosmology have uncovered evidence for intelligence in the structure of the universe and this intelligence seems to act with us in mind and that the universe as a whole shows evidence of design.
Early Primates
Prosimians (65mya)Monkeys (35mya)Apes (23mya)Hominids (5mya)
Early Primates - TraitsCommon physical primate traits:
Dense hair or fur coveringWarm-bloodedLive youngSuckleInfant dependence
Common social primate traits:Social lifePlay Observation and imitationPecking order Common Primate Traits
Primate Family Tree
Crown lemurOrangutan
Evolution of BipedalismAnatomical changes
Neck (1), chest (2), lower back (3), hips and
pelvis (4), thighs (5), knees (6), feet (7)
Theories
Tool use and bipedalism (Darwin/Washburn)
Energy efficiency and bipedalism (Isbell/Young)
Radiator theory (Falk)
Body temperature and bipedalism (Wheeler)
Habitat variability and bipedalism (Potts)
Reproduction and bipedalism (Lovejoy)
Canine reduction and bipedalism (Jolly)(Click for interactive skeleton)
Pre-hominid Evolution
Reconstruction of Australopithecine
Ardipithecus ramidus 4.4 - ? mya
A. anamensis 4.2 - 3.9
A. afarensis 4.2 - 2.5
A. bahrelghazali 3.5 - 3.0
A. africanus 3.5 - 2.5
P. aethiopicus 2.7 - 2.3
A. garhi 2.5 - ?
P. boisei 2.3 - 1.3
P. robustus 2.0 - 1.0
BipedalismToolsLanguage
Hominid Evolution
Homo habilis (2.0 – 1.6mya)
H. rudolfensis (2.4-1.6mya)
H. erectus (1.9-27kyBP)
H. heidelbergensis (800-
100kyBP)
H. neanderthalensis (300-
30kyBP)
H. sapiens (130kyBP – present)
Sca
le:
Mill
ions
of
Years
BP
Hominid EvolutionMajor Homo advances:
Brain sizeBetter bipedalismHuntingFire (H. erectus)Tools
• Oldowon (H. habilis)• Acheulean (H. erectus)• Mousterian (H.
heidelbergensis)• Solutrean (H. sapiens)
Built shelters (H. heidelbergensis)Clothing (H. neandertalensis)Language (Neandertals?)
Homo habilis
Artist’s representation of a Homo habilis band as it might have existed two million years ago.
612 cc brain
2.3 - 1.6 mya
first toolmaker
prognathic face, brow ridge
probable meat-eater
possibly arboreal
discovered in 1960 by Leakeys
no speech
H. habilis v. H. erectusFinds in east Africa indicate that Homo habilis was not very different from the australopithecines in terms of body size and shape.The earliest Homo erectus remains indicate rapid biological change.
The fossil record for the transition from H. habilis to H. erectus supports the punctuated equilibrium model of evolution.H. erectus was considerably taller and had a larger brain than H. habilis.
Homo erectus1891 - Eugene Dubois discovers H. erectus in JavaDubois calls it Pithecanthropus erectus initially, also dubbed “Java Man”finds in China called Sinanthropusdates from 1.9 mya to 27,000 years B.P.994 cc brain size (compare to 612 for H. habilis)Acheulean tool industry
Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya.
Homo erectus – 1.9mya to 27k yBPWhy was H. erectus so successful?
Less sexual dimorphism = possible pair bonds, marriageLess hair on body = wearing of furs, other clothingWearing of furs = ability to live further north
Quick adaptation to environment without physical changesCulture is main reason H. erectus was so successful
• organization for hunting• ability to protect against
predators• control of fire?• possible campsites• tools (Acheulean industry)
Distribution of H. erectus
Homo neanderthalensisdiscovered in the Neander Valley (Tal) near Dusseldorf, 1856massive brain--about 1,400cc on averagelarge torso, short limbs, broad nasal passageslater remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teethretained occipital torus, some mid-facial prognathism
The skull of the classic Neandertal found in 1908 at La Chapelle-aux-Saints.
Neandertal Culture
Homesites – In caves, also in
the open (near rivers,
framed with wood and
covered with skins)
Burial – Is there evidence of
purposeful burial and ritual?
Language – Could
Neandertals talk or not?
Tools – Mousterian tradition
Top: Reconstruction of Neandertal burial from Shanidar caveBottom: Mousterian tools
What happened to Neandertals?
H. neanderthalensis coexisted with H. sapiens
for at least 20,000 years, perhaps as long as
60,000 years
What happened?
Neandertals interbred with H. sapiens
Neandertals were killed off by H. sapiens
H. sapiens drove Neandertals into extinction by
competition
Homo sapiens
Archaic – 100,000 to 35,000 years BP
Sometimes called Homo sapiens and Homo sapiens neanderthalensis
Modern – 35,000 years BP to present
Anatomically modern
Sometimes called Homo sapiens sapiens
Cro-Magnon ManCro-Magnon humans
35,000 years B.P. in western Europe to 17,000 years B.P.1,600 cc cranial capacityName comes from a hotel in FranceNot a different species, just old Homo sapiens from Europe
Artist’s reconstruction of a Cro-Magnon man
Archaic H. sapiens Culture Art
Traces of art found in beads, carvings, and paintingsCave paintings in Spain and southern France showed a marked degree of skill
Female figurines27,000 to 22,000 years B.P.Called “venuses,” these figurines depicted women with large breasts and broad hips• Perhaps it was an example of an ideal
type, or perhaps an expression of a desire for fertility
Archaic H. sapiens Culture
Cave paintingsMostly animals on bare wallsSubjects were animals favored for their meat and skinsHuman figures were rarely drawn due to taboos and fears that it would somehow harm others
Cave paintings from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France
Upper Palaeolithic – Hotbed of Culture
40 – 10k yBPShelters
15,000 yBP UkraineSome made with mammoth bonesWood, leather working; carpentry
ToolsFrom cores to bladesSpecializationComposite toolsBow and arrow
Domestication of dogs Gathering rather than hunting became the mainstay of human economies.
Top: Straw Hut
Left: Mammoth bone hut
Bottom: Tool progression
Modern Homo SapiensRegional-Continuity Model (Milford Wolpoff, UMich)
Humans evolved more or less simultaneously across the entire Old World from several ancestral populations.
Rapid-Replacement Model (Chris Stringer, NHM London)Humans evolved only once--in Africa from H. heidelbergensis ancestors--and then migrated throughout the Old World, replacing their archaic predecessors. Also called the “Out of Africa” and “Killer Ape” hypothesis.
Social Organization
Hunter-gatherer analogySmall group, low population density, nomadism, kinship groups
MigrationNorth America was the last colonized by hominids.Beringia (land bridge) between Russia and AlaskaAsian origin of Native Americans30,000 to 12,000 years B.P. was first migration
Human Variation
Modern humans vary in skin color, hair color, and eye color.Will talk about anthropological conceptions of race and ethnicity later in the semester (April 23).