Chapter 2 Human Evolution

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Chapter 2 Human Evolution
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Todays 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
• What is so important about the Upper
  Palaeolithic?

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Theories of Evolution

• Origin Myths/Cosmologies
• Greek Prometheus
• Genesis

Western examples
Left Prometheus and Athena Top God and Adam
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Carl Sagans Universe Calendar

• 24 days 1 billion years
• 1 second 475 years
• Big Bang January 1
• Milky Way May 1
• Solar System September 9
• Life on Earth September 25
• Humanlike Primates December 31, 1030pm

Milky Way
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Theories of Evolution

• Darwin and Wallace, 1850s
• Evolution theory holds that existing species of
  plants and animals have emerged over millions of
  years from simple organisms.
• Darwin, On the origin of species, 1859
• Influenced by the principle of uniformitarianism

Charles Darwin
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Theories of Evolution - Corollaries

• Darwins 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.

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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.

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Theories of Evolution - Corollaries

• Mendels 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.

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Other Theories

• Creationism 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.

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Early Primates

• Prosimians (65mya)
• Monkeys (35mya)
• Apes (23mya)
• Hominids (5mya)

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Early Primates - Traits

• Common physical primate traits
• Dense hair or fur covering
• Warm-blooded
• Live young
• Suckle
• Infant dependence
• Common social primate traits
• Social life
• Play
• Observation and imitation
• Pecking order

Common Primate Traits
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Primate Family Tree
Orangutan
Crown lemur
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Evolution of Bipedalism

• Anatomical 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)
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Pre-hominid Evolution

• 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
• Bipedalism
• Tools
• Language

Reconstruction of Australopithecine
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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)

Scale Millions of Years BP
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Hominid Evolution

• Major Homo advances
• Brain size
• Better bipedalism
• Hunting
• Fire (H. erectus)
• Tools
• Oldowon (H. habilis)
• Acheulean (H. erectus)
• Mousterian (H. heidelbergensis)
• Solutrean (H. sapiens)
• Built shelters (H. heidelbergensis)
• Clothing (H. neandertalensis)
• Language (Neandertals?)

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Homo habilis

• 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

Artists representation of a Homo habilis band as
it might have existed two million years ago.
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H. habilis v. H. erectus

• Finds 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.

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Homo erectus

• 1891 - Eugene Dubois discovers H. erectus in Java
• Dubois calls it Pithecanthropus erectus
  initially, also dubbed Java Man
• finds in China called Sinanthropus
• dates 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.
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Homo erectus 1.9mya to 27k yBP

• Why was H. erectus so successful?
• Less sexual dimorphism possible pair bonds,
  marriage
• Less hair on body wearing of furs, other
  clothing
• Wearing of furs ability to live further north

• Quick adaptation to environment without physical
  changes
• Culture 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
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Homo neanderthalensis

• discovered in the Neander Valley (Tal) near
  Dusseldorf, 1856
• massive brain--about 1,400cc on average
• large torso, short limbs, broad nasal passages
• later remains show decrease in robustness of the
  front teeth and face, suggesting use of tools
  replaced teeth
• retained occipital torus, some mid-facial
  prognathism

The skull of the classic Neandertal found in 1908
at La Chapelle-aux-Saints.
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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 cave Bottom Mousterian tools
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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

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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

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Cro-Magnon Man

• Cro-Magnon humans
• 35,000 years B.P. in western Europe to 17,000
  years B.P.
• 1,600 cc cranial capacity
• Name comes from a hotel in France
• Not a different species, just old Homo sapiens
  from Europe

Artists reconstruction of a Cro-Magnon man
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Archaic H. sapiens Culture

• Art
• Traces of art found in beads, carvings, and
  paintings
• Cave paintings in Spain and southern France
  showed a marked degree of skill
• Female figurines
• 27,000 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

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Archaic H. sapiens Culture
Cave paintings from 20,000 years ago at
Vallon-Pont-dArc in southern France (left) and
from Lascaux, in southwest France

• Cave paintings
• Mostly animals on bare walls
• Subjects were animals favored for their meat and
  skins
• Human figures were rarely drawn due to taboos and
  fears that it would somehow harm others

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Upper Palaeolithic Hotbed of Culture

• 40 10k yBP
• Shelters
• 15,000 yBP Ukraine
• Some made with mammoth bones
• Wood, leather working carpentry
• Tools
• From cores to blades
• Specialization
• Composite tools
• Bow 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
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Modern Homo Sapiens

• Regional-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.

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Social Organization

• Hunter-gatherer analogy
• Small group, low population density, nomadism,
  kinship groups
• Migration
• North America was the last colonized by hominids.
• Beringia (land bridge) between Russia and Alaska
• Asian origin of Native Americans
• 30,000 to 12,000 years B.P. was first migration

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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).