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Introduction to Evolution

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Title: Introduction to Evolution


1
Introduction to Evolution Chris Scott, Ph.D.
2
Evolution and Diversity of Vertebrates
3
Echinodermata
Cephalochordata
ANCESTRAL DEUTEROSTOME
Chordates
Urochordata
Notochord
Myxini
Common ancestor of chordates
Craniates
Petromyzontida
Head
Vertebrates
Chondrichthyes
Vertebral column
Actinopterygii
Gnathostomes
Jaws, mineralized skeleton
Actinistia
Osteichthyans
Lungs or lung derivatives
Lobe-fins
Dipnoi
Lobed fins
Amphibia
Tetrapods
Reptilia
Limbs with digits
Amniotes
Amniotic egg
Mammalia
Milk
4
Derived Characters of Chordates
  • All chordates share a set of derived characters
  • Some species have some of these traits only
    during embryonic development
  • Four key characters of chordates
  • Notochord
  • Dorsal, hollow nerve cord
  • Pharyngeal slits or clefts
  • Muscular, post-anal tail

5
Dorsal, hollow nerve cord
Muscle segments
Notochord
Mouth
Anus
Pharyngeal slits or clefts
Muscular, post-anal tail
6
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7
Tiktaalik the fishapod"
Tetrapod Characters
Fish Characters
Scales Fins Gills and lungs
Neck Ribs Fin skeleton Flat skull Eyes on top of
skull
Shoulder bones
Ribs
Scales
Neck
Head
Eyes on top of skull
Humerus
Ulna
Flat skull
Wrist
Elbow
Radius
Fin
Fin skeleton
8
  • Tiktaalik could most likely prop itself on its
    fins, but not walk
  • The first tetrapods appeared 365 million years ago

9
Cephalochordata
Urochordata
Myxini
Petromyzontida
Chondrichthyes
Actinopterygii
Actinistia
Dipnoi
Amphibia
Reptilia
Mammalia
10
Mammals are amniotes that have hair and produce
milk
  • Mammals have
  • Mammary glands, which produce milk
  • Hair
  • A high metabolic rate, due to endothermy
  • A larger brain than other vertebrates of
    equivalent size
  • Differentiated teeth

11
Early Evolution of Mammals
12
Early Evolution of Mammals
  • Mammals evolved from reptilian synapsids
  • These reptiles arose during the Pennsylvanian
    Period (310 to 275 million years ago). A branch
    of the synapsids called the therapsids appeared
    by the middle of the Permian Period (275 to 225
    million years ago). It was over millions of
    years that some of these therapsids would evolve
    many features that would later be associated with
    mammals.

13
Hominins and the Evolution of Humans
14
Primates
  • The mammalian order Primates includes lemurs,
    tarsiers, monkeys, and apes
  • Humans are members of the ape group

15
Derived Characters of Primates
  • Most primates have hands and feet adapted for
    grasping, and flat nails

16
  • Other derived characters of primates
  • A large brain and short jaws
  • Forward-looking eyes close together on the face,
    providing depth perception
  • Complex social behavior and parental care
  • A fully opposable thumb (in monkeys and apes)

17
Living Primates
  • There are three main groups of living primates
  • Lemurs, lorises, and pottos
  • Tarsiers
  • Anthropoids (monkeys and apes, including humans)

18
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19
  • The first monkeys evolved in the Old World
    (Africa and Asia)
  • In the New World (South America), monkeys first
    appeared roughly 25 million years ago
  • New World and Old World monkeys underwent
    separate adaptive radiations during their many
    millions of years of separation

20
(b) Old World monkey macaque
21
Apes
  • The other group of anthropoids consists of
    primates informally called apes
  • This group includes gibbons, orangutans,
    gorillas, chimpanzees, bonobos, and humans
  • Apes diverged from Old World monkeys about 2025
    million years ago

22
(a) Gibbon
(b) Orangutan
(c) Gorilla
(d) Chimpanzees
(e) Bonobos
23
(d) Chimpanzees
24
Last Common Ancestor for Humans and Chimpanzees
7 Million years ago
Lemurs, lorises, and bush babies
Tarsiers
ANCESTRAL PRIMATE
New World monkeys
Anthropoids
Old World monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees and bonobos
Humans
20
10
0
60
50
40
30
Time (millions of years ago)
25
What does Hominin mean?
  • Hominin is a creature that paleoanthropologists
    have agreed is human or a human ancestor
  • Hominins include all of the Homo species (Homo
    sapiens, H. erectus , H. heidelbergensis), all of
    the Australopithecines and other ancient forms
    like Paranthropus and Ardipithecus

26
Hominin Timeline
27
Evidence of Bipedalism from the fossilized skull
alone
28
Comparison of Hip and Foot Bones
longer ape pelvis is adapted for quadrupedal
locomotion
29
Evidence that Hominins walked upright 3.5 million
years ago
30
Footprints found near Lake Turkana, Kenya, show
that human foot shape and gait had been achieved
1.5 million years ago
Science, VOL 323, ISSUE 5918,  pages 1197-1201
(Feb. 27, 2009) Early Hominin Foot Morphology
Based on 1.5-Million-Year-Old Footprints from
Ileret, Kenya
31
Science, VOL 323, ISSUE 5918,  pages 1197-1201
(Feb. 27, 2009) Early Hominin Foot Morphology
Based on 1.5-Million-Year-Old Footprints from
Ileret, Kenya 
32
Hominin
  • Hominin comprises the genera Homo, and the two
    species of the genus Pan (the Common Chimpanzee
    and the Bonobo), their ancestors, and the extinct
    lineages of their common ancestor

33
Ardipithecus ramidus
34
Between 1993 and 2003 bones of numerous
Ardipithecus ramidus specimens were found in
Ethiopia
35
Ardipithecus ramidus
October 1, 2009, paleontologists formally
announced the discovery of the relatively
complete A. ramidus fossil skeleton first
unearthed in 1994. The fossil is the remains,
dated 4.4 million years old, of a small-brained
110 lb, 3 foot 11 inch female, nicknamed "Ardi",
and includes most of the skull and teeth, as well
as the pelvis, hands, and feet. Researchers
infer from the form of her pelvis and limbs and
the presence of her abductable hallux, that she
was a facultative biped bipedal when moving on
the ground, but quadrupedal when moving about in
tree branches. Based on enamal thickness the
teeth suggest she was an omnivore her dental
makeup is more generalized than those of modern
apes
36
Ardipithecus ramidus
http//www.sciencemag.org/content/326/5949/60.2.fu
ll Youtube version Visual Reconstruction of
Ardi movement
37
Australopithecus afarensis
Nickname Lucy's species Where Lived Eastern
Africa (Ethiopia, Kenya, Tanzania) When Lived
Between about 3.85 and 2.95 million years ago
(900,000 thousand years!) Features 4 foot 11
inches 100 lbs combination of bipedal and tree
climbing abilities small brain dental structure
of omniovore
38
Homo habilis (handy man)
39
Early Homo
  • The earliest fossils placed in our genus Homo are
    those of Homo habilis, ranging in age from about
    2.4 to 1.6 million years
  • Stone tools have been found with H. habilis,
    giving this species its name, which means handy
    man

40
Homo habilis (handy man)
  • Earliest known species of the hominin group that
    has the Homo genus
  • Lived from approximately 2.33 to 1.4 million
    years ago
  • Some fossils of H. habilis are found with shaped
    stone tools
  • Homo habilis has often been thought to be the
    ancestor of the more gracile and sophisticated
    Homo ergaster, which in turn gave rise to the
    more human-appearing species, Homo erectus.
  • In 2000 a relatively late 1.44 million-year-old
    Homo habilis and a relatively early 1.55
    million-year-old Homo erectus from the same area
    of northern Kenya challenged the conventional
    view that these species evolved one after the
    other
  • Instead, this evidence - along with other fossils
    - demonstrate that they co-existed in Eastern
    Africa for almost half a million years!

41
1.7 MY old Fossil of Homo ergaster
42
Homo ergaster characteristics
  • Fossils from 1.9 to 1.5 MYA show a new stage of
    hominin development
  • H. ergaster had a bigger brain than H. habilus
  • H. ergaster had long slender legs with hip
    structure adapter for walking
  • H. ergaster fingers were shorter and straighter,
    implying lack of tree climbing
  • Sexual diamorphism is reduced
  • Tooth structure implying more meat eating

43
Homo erectus
Homo erectus (upright man) is an extinct species
of hominid that lived about 1.9 million to
143,000 years ago (1.75 million years!!!) The
species originated in Africa and spread as far as
India, China and Java.
Homo erectus, female. Reconstruction based on ER
3733 by John Gurche, front view
44
Homo erectus
Features average height is 5 foot 9 inches,
weight was about 150 lbs oldest known early
humans to have possessed modern human-like body
proportions with relatively elongated legs and
shorter arms compared to the size of the torso.
These features are considered adaptations to a
life lived on the ground, indicating the loss of
earlier tree-climbing adaptations, with the
ability to walk and possibly run long distances.
Compared with earlier fossil humans, note the
expanded braincase relative to the size of the
face. The appearance of Homo erectus in the
fossil record is often associated with the
earliest handaxes, the first major innovation in
stone tool technology.
45
Homo erectus
Range Generally considered to have been the
first species to have expanded beyond Africa,
Homo erectus is considered a highly variable
species, spread over two continents (it's not
certain whether it reached Europe), and possibly
the longest lived early human species - about
nine times as long as our own species, Homo
sapiens, has been around!
46
Homo erectus
47
Homo heidelbergensis
700,000 200,000 first early human species to
live in colder climates, it was the first early
human species to routinely hunt large animals.
This early human also broke new ground it was
the first species to build shelterscreating
simple dwellings out of wood and rock.
48
Homo heidelbergensis
  • Comparison of Neanderthal and Homo sapiens DNA
    suggests that the two lineages diverged from a
    common ancestor, most likely Homo
    heidelbergensis, sometime between 350,000 and
    400,000 years ago with the European branch
    leading to H. neanderthalensis and the African
    branch to H. sapiens

49
Homo neanderthalensis
Homo neanderthalensis was a living species from
at least 400,000 to 30,000 million years ago
50
Homo neanderthalensis
  • The ancestors of Neanderthals left Africa about
    400,000 to 800,000 years ago
  • Neanderthals evolved over the millennia mostly in
    what are now France, Spain, Germany and Russia
  • They were thick-boned with a larger brain
    (comparable to humans, stronger than humans, they
    buried their dead, and they made hunting tools
  • Neanderthals went extinct, or were simply
    absorbed into the modern human population, about
    30,000 years ago

51
Homo sapiens Out of Africa
  • Our species is called Homo sapiens
  • During a time of dramatic climate change 200,000
    years ago, Homo sapiens evolved in Africa
  • Like other early humans that were living at this
    time, Homo sapiens gathered and hunted food, and
    evolved behaviors that helped them respond to the
    challenges of survival in unstable environments

52
Homo sapiens
  • Compared to other members of the genus Homo,
    Homos sapiens have
  • A lighter build of their skeletons
  • Large brains
  • A thin-walled, high vaulted skull
  • A flat and near vertical forehead
  • Much less (if any) heavy brow ridges
  • Smaller noses
  • Less heavily developed jaws
  • Smaller teeth

53
Homo sapiens and Homo neanderthalensis
  • The earliest known Homo sapiens in Europe lived
    in a southern Italian cave 45,000 years ago
  • Homo sapiens were also in what is now the U.K.
    about 44,000 years ago
  • Neanderthal fossils have been found in Europe and
    Asia as recently as 28,000 years ago
  • These studies show that Homo sapiens quickly
    spread over Europe and coexisted with
    Neanderthals

54
Homo sapiens and Homo neanderthalensis
  • In May 2010 (Science magazine) a draft sequence
    of the Neanderthal genome was published
  • Genomic comparison confirmed Homo sapiens and
    Homo neanderthalensis interbred
  • Most, if not all, of the interbreeding took place
    in the Middle East, while modern humans were
    migrating out of Africa and spreading to other
    regions
  • If your heritage is non-African, you are part
    Neanderthal!

55
Homo sapiens and Homo neanderthalensis
  • The Homo sapiens/Neanderthal combination likely
    enabled interbred Homo sapiens to survive in
    harsh, cold regions that Neanderthals previously
    had adapted to
  • Variability is very important for long-term
    survival of a species -- every addition to the
    genome can be enriching

56
  • Humans first arrived in the New World (North and
    South America) sometime before 15,000 years ago
    by travelling across the Alaska-Russia land
    bridge
  • In 2004, 18,000-year-old fossils were found in
    Indonesia, and a new small hominin was named
    Homo floresiensis

57
A timeline for some selected hominin species
58
  • Homo sapiens were the first animal group to show
    evidence of symbolic and sophisticated thought
  • Chimpanzees regularly crack open hard-shell seeds
    and nuts with a stone hammer against a stone or
    wooden anvil and they'll carry the appropriate
    rocks over a good fraction of a kilometer for the
    purpose. 
  • A chimp breaks off a long grass stalk or a reed
    so she may use it later, hundreds of meters away,
    more than an hour in the future, to lure
    delectable termites out of a log or termite
    mound.

59
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61
Gorilla using a stick to test water depth
62
In 2002, a 77,000-year-old artistic carving was
found in South Africa
63
Timeline
  •  
  • Approximate age of the Universe 14 billion
    years................................
    14,000,000,000
  • Approximate age of the Earth 4.5 billion
    years........................................4,500
    ,000,000
  • Approximate age of life on this planet 3.5
    billion years....................3,500,000,000
  • First tetrapods (Tiktaalik, the first
    fishapod).......................................
    .......365,000,000
  • Permian Great Extinction..........................
    ...............................................245
    ,000,000
  • Evolution of the first mammals and................
    .............................................240,0
    00,000
  • K-T Great Extinction (end of the
    dinosaurs)........................................
    .....65,000,000
  • Earliest fossil evidence of the first hominin
    (Sahelanthropus tchadensis).......6,500,000
  • Age of Ardi (Ardipithecus ramidus)
    fossils...........................................
    .........4,400,000
  • Earliest fossils of the genus Homo (Homo habilus,
    handy man)...................2,400,000
  • Approximate age of our species Homo
    sapiens...........................................
    ......200,000
  • Approximate age of the first human civilizations
    less than 8,000 years ago..........8,000
  • Approximate age of oldest discovered book
    ..................................................
    .....4,000
  • Start of mass produced books using the Gutenberg
    press (1440 AD)....................572
  • Number of years the iPad has been available to
    the public........................................
    ...2
  • The Epic of Gilgamesh is an epic poem recorded
    on 12 clay tablets from Ancient Mesopotamia (now
    Iraq)
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