Chapters 5 and 6

1
Chapters 5 and 6

• Primate and Hominoid Evolution

2
Chapter Outline

• Macroeveolution and the process of Speciation
• Mammalian Primate Evolution
• Beginning of Bipedalism

3
Macroevolution and the Process Of Speciation

• Macroevolution focuses upon the formation of new
  species (speciation) and on the evolutionary
  relationships between groups of species.
• A species is usually defined as a population or
  group of populations capable of interbreeding and
  producing fertile offspring.

4
Speciation

• Speciation is inferred in the fossil record when
  a group of organisms takes on a different
  appearance over time.
• Over time, as the two populations come to differ
  from each other, speciation occurs in a branching
  fashion known as cladogenesis.
• In anagenesis a single population accumulates new
  mutations over time until it is considered a
  separate species.

5
Punctuated Equilibria

• A model of macroevolutionary change that suggests
  evolution occurs via long periods of stability or
  stasis punctuated by periods of rapid change.

6
Evolutionary Relationships

• Derived and ancestral
• Derived features are characteristics that define
  a group of organisms that did not exist in
  ancestral populations (bipedalism)
• Ancestral features are characteristics possessed
  by an organism or group of organisms due to
  shared ancestry (bilateral symmetry)
• Convergent evolution means that two species came
  up with the same idea (wings on butterflies and
  birds) but they do not share evolutionary history

7
Nondirectedness of Macroevolution

• Evolution is not directed. Macroevolution
  evolution happens because circumstanc allows it.
• If a meteor hadnt hit the earth and the climate
  hadnt changed drastically (cooling), dinosaurs
  wouldnt have become extinct and allow mammals to
  flourish. Mammals just happened to have the
  traits (warm bodies, etc) that enabled them to
  live through climate change. It was not
  preordained by nature. If a massive, abrupt
  climate change hadnt occurred, dinosaurs (not
  humans) might very well still walk the earth.

8
Mammalian Primate Evolution

• Climate changes led to the appearance of primates
  about 65 million years ago (Paleocene Epoch).
• These were small, arboreal, nocturnal, insect
  eaters.
• About 23 million years ago, hominoids, the
  primates that include all living and extinct apes
  and humans began to appear in Asia, Africa, and
  Europe.
• Genetic studies have confirmed that the African
  apes are our closest living relatives.
• Bipedalism preceded brain expansion, and played a
  pivotal role in setting us apart from the apes.

9
Theories about Primate Evolution

• Climate change led to life in trees, which was
  responsible for visual acuity and manual
  dexterity (those who couldnt grasp branches or
  judge distances died)
• The visual predation theory indicates that
  predators of the small tree-dwelling primates
  could not reach them in their trees

10
True Primate Bodies, Advance of Anthropoids

• Start 55 million years ago in the Eocene Epoch
• Enlarged braincases, slightly reduced snouts,
  forward position of eye orbits, postorbital bar
• Earliest anthropoid primates appeared 45 mil.
  Years ago
• By 23-34 million years ago, anthropoids
  diversified and expanded (from fossil found in
  Egypt)

Aegyptopithecus
11
Continental Drift

• According to the theory of plate tectonics, the
  movement of continents embedded in underlying
  plates on the earths surface in relation to one
  another over the history of life on earth.
• This enabled the early primates to spread to all
  the continents before they split adaptive
  radiation

Untold tragedies of continental drift
12
Continental Drift
13

• Mammals were preadapted (possessed the biological
  equipment to take advantage of new opportunities
  after the extinction of the dinosaurs).
• Being homeotherm instead of isotherm was useful.

• Adaptive radiation refers to rapid
  diversification of an evolving population as it
  adapts to a variety of available niches.
• This did not happen until mammals were present on
  the earth for 100 million years.

14
Golden Age of Hominoids (Miocene)

• Old World anthropoid dental pattern (2-1-2-3) and
  Y5 molars
• No tail
• Broad, flexible shoulder joints
• From the Miocene Epoch (5 to 23 million years
  ago)
• Are Miocene apes the missing link between humans
  and other African apes? Hard to say b/c only
  skulls have been found and bipedalism is a
  pre-req for being a hominid

15
Molecular Clock

• The hypothesis that dates of divergences among
  related species can be calculated through an
  examination of the genetic mutations that have
  accrued since divergence.

16
Human Evolution

• Humans and their ancestors are distinct among
  hominoids for bipedalism, a form of locomotion on
  two feet.
• In the past 30 years studies have confirmed that
  the African apes (chimpanzees, bonobos, and
  gorillas) are our closest living relatives.
• Between 8 and 5 million years ago, humans,
  chimpanzees, and gorillas began to follow
  separate evolutionary courses

17
Bipedalism

• Inclusion of any fossil specimen in the human
  evolutionary line depends upon evidence of
  bipedalism it is a derived characteristic
• IT CAME FIRST!!!
• Bipedalism predates the larger brains known for
  humans (Piltdown man fraud)

18
Changes in Anatomy Associated with Bipedalism

• Skull centered above spinal column through
  foramen magnum
• Spinal column convex and concave curves that
  maintain upright posture, center of gravity above
  the legs not in front of them
• A chimps spine has a single arching curve,
  humans curve with the various vertebra

• Pelvis chimps are elongated, humans are wider
  and shorter lower limbs curve inward to maintain
  gravity
• Feet arched, no opposable toe

19
Australopithecines

• The genus including several species of early
  bipeds from southern and eastern Africa living
  between about 4.3 and 1.1 million years ago, one
  of whom was directly ancestral to humans.

20
Australopithecus afarensis

• Lucy and Lucys baby (3.3 mil. Yr. old)
• Looked like an ape from the waist up and a human
  from the waist down
• Lucys forearm is shorter than an apes, but
  larger than a humans
• Fully bipedal, but fingers and toes indicate she
  was adapted to climbing trees
• Large jaws, brow ridge, chinless, small brain,
  backward sloping skull
• Canines smaller than a humans, larger than a
  chimps, maintains diastema

chimp
human
Australo.
21
Robust Australopithecines

• Several species within the genus
  Australopithecus,who lived from 2.5 and 1.1
  million years ago in eastern and southern Africa.
• Known for the rugged nature of their chewing
  apparatus (large back teeth, large chewing
  muscles, and bony ridge on their skull tops for
  the insertion of these large muscles).
• They died out were not the predecessor of humans

22
Gracile Australopithecines

• Members of the genus Australopithecus possessing
  a more lightly built chewing apparatus.
• Likely had a diet that included more meat than
  that of the robust australopithecines.
• Their less robust jaws and skull enabled them to
  eat different foodsthey were more naturally
  adaptive

23
Bipedalism was Risky Business

• Bipedalism must have been useful for our
  ancestors who had to make it in the forest AND in
  the savannah
• Bipeds are slower than quadrapeds,
• Their underbelly shows
• They were an easy meal for a carnivore
• They could have done it to carry food, to avoid
  heat stress
• Bipeds might have just developed through
  macromutation and then it stuck around b/c it
  ended up being useful b/c bipeds can walk long
  distances

24
Chapters 7 and 8

• Early Homo and the Origins of Culture and
• Pre-modern Humans and the Elaboration of Culture

25
Chapter Outline

• Who is Homo?
• Differences between Homo and Australopithecenes.
• Tools and Culture
• Elaboration of Culture
• Neandertal

26
Homo habilis

• Handy man.
• The first fossil members of the genus Homo
  appearing 2.5 million years ago, with larger
  brains and smaller faces (less robust chewing
  apparatus) than australopithecines.

Discovered by the Leakey Family in the Olduvai
Gorge in association with tools
27
Lumpers or Splitters

• Scientists frequently argue about where in the
  fossil record any particular fossil belongs
• Lumpers put all fossils that look alike into the
  same category, figuring that its impossible to
  say whether the ancient remains are a separate
  species or not
• Splitters focus on the variation of the fossil
  record and interpret minor differences in skull
  or skeleton as indicative of a separate species
• Is it a species difference or simple sexual
  dimorphism?

A. afarensis. Leftmale, rightfemale
28
Differences b/t early Homo and Australopithecus

• 2.4 mil. Yrs ago, Homo went in a different
  direction from Australopithecus
• Homo enlarged brain size, ability to cool the
  brain (major heat generator), smaller teeth,
  human-like brain shape, evidence for stone tool
  making, meat eating

• Robust aust. Co-existed with Homo
• They had huge jaws and back teeth for processing
  plant food, brain size didnt change, no evidence
  of stone tool use, specialized in eating plant
  food (no meat)

29
Lower Paleolithic Tools

• Early stone tools (2.6 mil. To 200,000 years ago)
• Made with the percussion method (using a
  hammerstone to remove flakes, make a blade)
• People who made these were thinking they knew
  how a tool could be made, used the best raw
  materials, know about flaking, shows thinking and
  planning

30
Oldowan

• The first stone tool industry.
• Beginning between 2.6 and 2.5 million years ago.
• Critical industry for making meat RELIABLY
  available
• We, as our ancestors, cannot use our nails and
  teeth to rip through skin and fur we need tools
• This provided a reliable and efficient food supply

31
Hunting or Scavenging?

• Homo was a scavenger
• Cut marks from tools are made on top of chewing
  marks from animals
• In fact, Homo was probably the third animal to
  get at a kill (tertiary scavenger)
• Homo would drag parts of the animal to a
  tool-making site for butchering
• They ate marrow, which provides lots of fat and
  proteinmore so than lean muscle meat

32
Homo erectus

• Upright man. also, the traveler
• A species within the genus Homo first appearing
  just after 2 million years ago in Africa and
  spreading through the Old World.
• Had a brain close in size to that of modern
  humans.
• Had sophisticated behaviors including use of fire
  for warmth, cooking, and protection.

33
H. Erectus traveled
Green indicates where H. erectus went

• Homo erectus is found in Africa, Asia, and Europe
• Homo erectus walked out of Africa onto other
  continents
• Once out, did Homo erectus stay a discrete
  species or did he become different species?
• The lumpers say no, the splitters say yes

34
Physical Characteristics of H. erectus

• Bigger brain (1,000 cc)
• Low vault of cranium, head long and narrow
• Shape of brain very modern-like (especially in
  speech area)
• Brain asymmetrical
• Massive brow ridge
• Sloping forehead, receding chin
• Smaller teeth, but powerful compared to modern
  standards
• More muscular than modern humans and greater
  height
• Less sexual dimorphism

H. habilis
H. erectus
35
Relationship b/t H. habilis and H. erectus

• H. erectus derived traits
• Increased body size, reduced sexual dimorphism,
  human body form

• H. erectus ancestral traits
• Long neck, low angle of thigh bone, long low
  vault of brain, constriction of skull behind the
  eyes, smaller (than human) brain size

36
Culture of Homo erectus

• Acheulean tools standardized, shaper points,
  regular cutting edges, diversified tool kit
  (cleavers, picks, knives, axe)
• Fire able to stay warm in cold conditions
  (outside of Africa), helps thaw carcasses,
  predigest food, stay up after dark (socialize?)
• Hunting able to organize a hunt, run animals off
  cliffs, etc.
• Possible sea-faring craft (Indo)
• Rock carvings (India)
• Symbolic art indicates language was
  hypothetically possible

37
Homo sapiens

• Between 400,000 and 200,000 years ago, evolving
  humans achieved the brain capacity of
  contemporary Homo sapiens.
• Several variations of the genus Homo existed
  around this time, including the Neandertals.

38
Levalloisian Tradition

• The pace of culture accelerated with the
  appearance of Homo sapien
• Levalloisian tradition involves preparing a core
  by removing small flakes from the stones surface
• This produces a more efficient, sharper-edged
  blade
• They fastened these blades to sticks
• Sometimes painted them

39
Neandertal

• A distinct group within the genus Homo inhabiting
  Europe and Southwest Asia from approximately
  125,000 to 30,000 years ago.
• Represented as the classic cave men.
• They had modern-sized brains with faces and
  skulls that were very different from later
  fossilized remains.
• Extremely muscular, short limbs

40
Neandertal Culture

• The use of fire was essential to their survival
  in cold climates.
• They lived in small bands or family units, in
  the open and in caves.
• They likely used language to communicate.
• They buried their dead, reflecting ritual
  behavior.
• Fossil remains of an amputee discovered in Iraq
  and an arthritic man excavated in France imply
  they cared for the disabled.

41
Mousterian

• The tool industry of the Neandertals and their
  contemporaries of Europe, Southwest Asia, and
  northern Africa from 125,000 to 40,000 years ago.
  
• Mousterian tools are lighter and smaller than
  those of earlier traditions.
• Previous industries obtained only two or three
  flakes from an entire stone core, Mousterian
  toolmakers obtained many smaller flakes, which
  they retouched and sharpened.

42
H. sapiens

• Evidence indicates that at least one population
  of archaic H. sapiens evolved into modern humans.
  
• Whether this was due to the biological evolution
  of a new species or a simultaneous worldwide
  process involving all archaic forms is debated.

43
Recent African origins hypothesis

• The hypothesis that all modern people are derived
  from a single population of archaic H. sapiens
  from Africa.
• These H. sapiens replaced other archaic forms due
  to superior cultural capabilities.
• Also called the Eve or out of Africa
  hypothesis.

44
The Multiregional Hypothesis

• The hypothesis that modern humans originated
  through a process of simultaneous local
  transition from Homo erectus to Homo sapiens
  throughout the inhabited world.

45
Upper Paleolithic

• The last part (40,000 to10,000 years ago) of the
  Old Stone Age, featuring tool industries
  characterized by long slim blades and an
  explosion of creative symbolic forms.
• Technology called Aurignacian tradition

Cave painting of a bull and a horse in Lascaux
Grotto, near Montignac, France.