The Evolution of Primates

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The Evolution of Primates

• Chapter 22

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Primate Adaptations 1 2

• Placental mammals
• evolved from arboreal shrewlike mammals
• Five grasping digits
• including opposable thumb or toe

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Five Grasping Digits

• Feet Hands of representative Primates
• Lemur
• Tarsier
• Woolly Monkey
• Gorilla
• Figures on next 4 slides

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Hand
Foot
(a) Lemur (Eulemur mongoz)
Fig. 22-1a, p. 467
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Hand
Foot
(b) Tarsier (Tarsius spectrum)
Fig. 22-1b, p. 467
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Hand
Foot
(c) Woolly spider monkey (Brachyteles
arachnoides)
Fig. 22-1c, p. 467
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Hand
Foot
(d) Gorilla (Gorilla gorilla)
Fig. 22-1d, p. 467
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Primate Adaptations 3 4

• Long, slender limbs
• move freely at hips and shoulders
• Eyes located in front of head
• 3-D vision
• Depth perception

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Suborders of Primates

• Prosimii
• lemurs, galagos, and lorises
• Tarsiiformes
• tarsiers
• Anthropoidea (anthropoids)
• monkeys, apes, and humans

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• Humans are classified in the order Primates,
  along with lemurs, tarsiers, monkeys, and apes
• This classification is based on close
  evolutionary ties

Hominids
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• What is the difference between
• Anthropoids
• Hominoids
• Hominids

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Anthropoids

• Include monkeys, apes, and humans
• Branched into 2 groups
• New World monkeys
• Old World monkeys

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New World and Old World Monkeys
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Hominoids

• Include apes and humans
• arose from Old World monkey lineage
• 4 modern genera of apes
• gibbons
• orangutans
• gorillas
• chimpanzees

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Apes
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Hominids

• Humans and their ancestors
• Only one extant group Homo sapiens

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• Differences between modern apes and hominids?
• Hominid Skeletal Adaptations
• Adapted for standing erect and walking on two
  feet
• complex curvature of the spine
• short, broad pelvis
• foramen magnum at base of skull
• first toe aligned with other toes
• Examples on next slide

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Gorilla and Human Skeletons
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Human Skeleton

• Hominid Skull Adaptations
• lacks pronounced supraorbital ridge
• flatter than ape skulls in front
• has a pronounced chin
• jaw structure with teeth arranged in U shape
• larger brain than apes
• The human brain did not begin to enlarge to its
  present size and complexity until long after
  human ancestors had evolved bipedal locomotion

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ApeSkull
HominidSkull
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• Five (5) examples of early hominids
• Sahelanthropus
• Ardipithecus ramidus
• Australopithecus sp.
• A. anamensis
• A. afarensis
• A. africanus

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Sahelanthropus

• Sahelanthropus
• base of Human Evolutionary tree
• Specimens dated 6-7 million years ago
• small brain
• face and teeth had many characteristics of larger
  brained human ancestors
• May not have walked upright no fossil leg bones

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Australopithecines (Southern Man Apes)

• Include
• Ardipithecus and Australopithecus species
• Ardipithecus
• East Africa 5 mya
• bipedal (a hominid feature) based on toe bone
  shape
• Single species A. ramidus

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Australopithecines

• 3 examples of Australopithecus species (6
  species in total are widely accepted)
• A. anamensis
• 4.2 to 3.9 mya
• Combines apelike and humanlike features
• Exhibits sexual dimorphism
• Leg bone fossils indicate upright posture and
  bipedelism

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Australopithecines (cont)

• A. afarensis
• Includes 3.2 mya complete fossil named Lucy
• small-brained (more like primate)
• A. africanus
• 3 mya
• Walked erect
• human like hands and teeth
• Still small-brained

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Genus Homo

• Homo habilis first member of genus Homo
• 2.3 to 0.75 mya
• Brain size and dentition similar to modern humans
• Stone tool maker/user
• Some disagreement among researchers
• Alternate name Australopithecus habilis

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Genus Homo (cont)

• Homo erectus
• Current evidence puts origin in Africa 1.7my
  with later radiations into Europe and Asia
• Asia versions Peking Man and Java Man
• Persisted until 200,000 ya
• Taller and larger-brained than habilis
• Disagreements
• Earlier fossils H. ergaster
• Later fossils from asia H. erectus

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Genus Homo (cont)

• Archaic Homo sapiens
• 400,000 200,000 years ago
• Regionally diverse
• Brain size modern humans
• Exhibited culture (learned traditions)
  represented by complex tools and symbolic objects

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Genus Homo (cont)

• Neandertals (h dropped in common name, still
  used in scientific name)
• 1st discovered in Neander valley in Germany
• Lived throughout Europe western Asia 230,000 to
  30,000 years ago
• No consensus on whether separate Homo species (H.
  neanderthalensis) or a subspecies of H. sapiens

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Possible Evolutionary Relationships
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THE END