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Biological Anthropology

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Primate Evolution Hominid Evolution. The work of Primate ... Mongoose, robins) Some primates (actually at least one-i.e. Panamanian tamarin) have claws ... – PowerPoint PPT presentation

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Title: Biological Anthropology


1
Biological Anthropology
  • Review
  • Part II

2
Part Two
  • Format
  • 10 Matching
  • 20 Multiple Choice
  • 4 Short Answer
  • Content
  • Chapter 5, 6, 7, 8
  • Hominid Evolution
  • Hominid Classification
  • Bipedalism

3
Primate Evolution? Hominid Evolution
4
The work of Primate Paleontologists and
Paleoanthropologists
  • Focus on various questions of primate evolution.
  • How did primates emerge?
  • What conditions favored them?
  • How and why did the early primates diverge?
  • Focus on ancestral line leading to humans
  • Fossil record is full of diversity as well as
    apparent extinctions
  • Most of the primate lineages of the past never
    left any descendants at all

5
What challenges do paleontologists face in the
study of primate evolution?
  • Reconstruction of primate evolution requires the
    finding of fossil remains
  • Fossils are difficult to find (needs to be
    exposed by erosion, strata uplifted, or in
    accessible areas)
  • Fossil record incomplete
  • Fossils fragmented/ damage
  • Rely on anatomical studies of living species to
    make inferences
  • Need to use dating techniques to estimate age of
    fossil remains (relies on chemistry, geology, and
    physics)
  • Need to study ancient plants and animals,
    geography, and climate to reconstruct environment
    of ancient primates

6
When did primates emerge?
  • It is generally agreed that the earliest primate
    may have emerged in the late Cretaceous Period/
    Early Paleocene (approximately 55 million years
    ago).

7
What was the environment like during the
Cretaceous Period/ Early Paleocene?
  • Paleocene Period marked a major geological
    transition from the Cretaceous Period.
  • About 75 of all animal and plant life vanished
    by early Paleocene (including dinosaurs)
  • Cretaceous Period
  • Climate was uniformly damp and mild? but temp
    began to fall
  • Seasonal and geographic fluctuations began to
    develop
  • Climate became much drier and cooler in many
    areas? vast swamplands disappeared
  • Change in climate as a result of CONTINENTAL
    DRIFT

8
Continental Drift
9
CONTINENTAL DRIFT Movement of continents over
the past 135 million years
  • In early Cretaceous there were two super
    continents
  • Laurasia North American and Eurasia
  • Gondwanaland Africa, South America, India,
    Australia, Antarctica
  • By beginning of the Paleocene era
  • Gondwanaland broke apart? South America drifting
    west away from Africa, India drifting east,
    Australia and Antarctica drifting south
  • Results
  • As the continents changed position, they moved
    into locations with different climatic conditions
  • The very movement of the continents affected the
    climate

10
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11
Climatic Changes resulting from Continental Shift
  • Large landmasses affect wind and weather patterns
    differently than smaller landmasses
  • Laurasia would have been different from weather
    in other continents
  • When continents collide, mountain ranges are
    formed? affect weather pattern
  • Clouds drop moisture as they meet a mountain
    range
  • Location of continents prevents the movement of
    ocean currents from the tropics to the poles, the
    earths climate becomes colder

12
How does this relate to monkeys?
  • Continental drift and climate change had profound
    effects on the evolution of primates
  • Changes in climate changes in vegetation
  • Large trees with fruit and seeds became common
    during the Paleocene Era
  • New kinds of plant life opened up sources of food
    and protection for new animal forms
  • Changes in climate emergence of new species of
    animals
  • New plant life provided an abundant food supply
    for insects
  • Primates evolved from mammalian radiations
    (extensive diversifications) ? insectivore order
    of mammals (including modern shrews and moles) ?
    abundance in insects as result of first deciduous
    trees and new vegetation coming with climatic
    changes
  • Insectivores were very adaptable? can take
    advantage of variety of habitats (under ground,
    in water, on ground, above ground)
  • Above ground adaptation may have been the most
    important

13
Arboreal Theory
  • Primates evolved from insectivores that took to
    trees
  • Favored vision over smell
  • Smaller snouts and declining importance of sense
    of smell
  • Eyes of early primates would have come to face
    forward
  • Vision more useful for animals searching for food
    in the maze of tree branches
  • 3-D binocular vision would be favored because an
    animal jumping from branch to branch would be
    more likely to survive if it could accurately
    judge distances
  • Tree climbing favor grasping hands and feet, with
    hind limbs becoming more specialized for support
    and propulsion
  • Shift in diet from insects to seeds, fruit, and
    leaves might have been important to biological
    changes

14
Weakness of Arboreal Theory
  • Tree living not good explanation for many primate
    features
  • There are living mammals that dwell in trees but
    seem to do very well w/o primate characteristics
  • Tree squirrel? claws rather than nails, lacks
    front facing eyes, smell not reduced, no
    opposable thumb
  • Other mammals have primate features but do not
    live in trees
  • Cats, hawks, owls, Australian marsupial mammals

15
Visual Predation Theory
  • Belief that some factor OTHER than moving about
    in trees may account for the emergence of the
    primates
  • Proposes that early mammals may have been
    basically insect-eaters which favored 3-D vision
    and other selectively advantageous features for
    hunting insects in the undergrowth of a forest
  • 3-D vision would allow predator to gauge preys
    distance accurately
  • Grasping feet and hands would allow predator to
    move quietly
  • Reduced claws b/c claws make it difficult to
    grasp very slender branches
  • Sense of smell reduced, not so much b/c it was no
    longer useful, but b/c the location of the eyes
    at the front of the face allows for less room for
    a snout

16
Weakness of Visual Predation Theory
  • Not all visual predators have forward facing eyes
    (ex. Mongoose, robins)
  • Some primates (actually at least one-i.e.
    Panamanian tamarin) have claws
  • Many primate eat more fruits than insects

17
Hominid Evolution
18
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19
Hominid ClassificationHomo genus to which
modern humans and ancestors belong
  • Ardipithecus first bipedal ape
  • Combination of ape like features and bipedal
    locomotion
  • Australopithecus Afarensis first bipedal hominid
  • Lucy
  • best represented by fossil record (2 dozen
    individual fossil remains)
  • Homo neanderthalenis not in human genus (close
    relatives)
  • Homo Habilis early species belonging to our
    genus, 50 of modern human brain capability
  • Homo Erectus 1st hominid species to be widely
    distributed in Old World (larger brain than Homo
    Habilis, smaller brain than Homo Sapiens)
  • Homo Sapiens all living people belong to this,
    can successfully interbreed

20
  • Hominid Classification Tree

21
What were the physical changes crucial to early
hominid evolution? Which was the most crucial
and why?
  • Expansion of brain
  • Modification of female pelvis to allow bigger
    brained babies to be born
  • Reduction of face, teeth, and jaws
  • Increased meat eating
  • Extended period of infant/child dependency
  • Most crucial bipedal locomotion

22
Bipedalism
23
Evolution of Methods of Locomotion
24
What are the prevalent theories for the evolution
of bipedalism?
  • Bipedalism may have been favored by natural
    selection for several reasons.
  • Upright walking could have provided improved
    range of vision over tall grasses.
  • Easier to see predators and prey
  • Bipedalism is more efficient than quadrupled
    locomotion for traveling long distances.
  • Bipedalism frees the hands for other tasks
  • Carrying food and using tools and weapons
  • Bipedalism may allow for better body cooling, as
    more skin is exposed to air and there is more
    opportunity to block the body from direct sun.

25
Diagram of CoolingBipedalism may allow for
better body cooling, as more skin is exposed to
air and there is more opportunity to block the
body from direct sun.
26
What are the anatomical features of bipedalism?
  • Skull
  • In both Ancient and Modern apes, the Spine enters
    the skull at the back
  • Human spines enters at bottom thru hole foramen
    magnum
  • Pelvis
  • Ancient and Modern apes have long flat Pelvises
  • Humans have bowl shaped
  • Hold Organs
  • Lower center of gravity for better balance on 2
    legs
  • Knee
  • Apes are straight from pelvis, Humans slant in.
  • Allow straight walking Maintain balance.
  • Foot
  • Enlarged ankle bones and arches to support
    pressure of walking

27
Remember the following
  • PELVIS!
  • FEET!

28
What are the cost or negative affects of
bipedalism?
  • Harder to supply the Brain with blood due to
    gravity
  • Greater stress on the hips, lower back, knees,
    and feet. (especially for females during
    pregnancy)

29
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