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Genes and Environment > Lecture 13-14 - Human Evolution > Flashcards

Lecture 13-14 - Human Evolution Flashcards

1
Q

When did mammals become the dominant species in Earth?

A

65 million years ago, (Crustaceous –> Tertiary Period)

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2
Q

Describe the characteristics of mammals.

A
  • Fusion, reduction of bones
  • Endothermic
  • 4 chambered heart
  • Mammary glands - assist in parental care
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3
Q

Most mammals have placenta to feed young IN THE MOTHER, except for _________. (2)

A
  • Subclass Theria

- Subclass Eutheria: Young fed by placenta until advanced stage

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4
Q

Mention two of the ancient primate ancestors. Describe their appearance.

A

Plesiadapids:

  • Coexisted with dinosaurs
  • Squirrel like
  • claws, big incisors

Adapids (1st true primate):

  • 56-40 MYa
  • Tree living
  • opposable toes and thumbs
  • facing forward eyes
  • Similar to modern-prosimians
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5
Q

Describe the characteristics of prosimians (wet-nosed primates).

A
  • binocular vision
  • Split lip -> wet nose
  • simple social groups
  • have reflective eye layer
  • exp. lemurs
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6
Q

Describe features required for the complex task of leaping between trees.

A
  • Binocular distance: to judge distance (forward facing eye)
  • Larger brains: visual processing, etc
  • Opposable thumbs and toes: for grasping
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7
Q

Mention the members of the dry-nosed group

A
  • Tarsiers
  • New World Monkeys
  • Old World Monkeys
  • Gibbons
  • Great Apes
  • Human
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8
Q

Explain how the reflective eye layer helps with night vision in prosimians.

A

Presence of reflective eye layer behind the retina help reflect light that has passed through back again to the retina. This allows more chance for the light to be detected by the retina, helpful in a low light environment.

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9
Q

Describe features of tarsiers.

A
  • reduction of use of smell
  • dry nose, no split lip
  • flatter face
  • mostly diurnal (no reflective eye layer)
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10
Q

Describe features of simians.

A
  • no split lip –> able to form more complex sounds
  • diurnal (lost eye layer)
  • unified uterus –> one baby is enough
  • embedded placenta –> prevent miscarriage
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11
Q

Differ between New and Old World Monkeys.

A

NWM:

  • all tree dwelling
  • prehensile (grasping) tail
  • have 12 premolars

OWM:

  • some on grounds
  • tail never prehensile
  • have 8 premolars
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12
Q

Explain how parenting is different for simians and other mammals.

A

In most mammals, birth triggers the hormone oxytocin which triggers the mother to bond to the infant’s smell and also induces lactation. However, bond usually stop beyond lactation. Vasopressin also leads to bonding between male an female.

In simians, smell has reduced importance and parental care last beyond lactation Brain, not hormones, controls parental behaviours. Tactile relationship induces endorphins - promotes and enforces bonding.

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13
Q

Hominoids diverged from Old World monkeys around _______.

A

25 million years ago.

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14
Q

Describe features of hominoids.

A
  • loss of tail
  • ripe fruit specialist (lost Vitamin C gene)
  • larger brains
  • extended childhoods
  • no tails: adapted for brachiation (arm swinging)
  • long arms, shorter legs
  • shoulder blades at the back
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15
Q

Chimpanzee diverge from humans about ______.

A

8-7 million years ago

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16
Q

Describe skeletal differences due to erect posture.

A
  • Neck under skull
  • S-shaped spine, not bent
  • Pelvis bowl shaped, not narrow & long
  • arms shorter, legs longer
  • femur bone angled inwards (pressure to knee)
17
Q

Describe differences in teeth and skull between ape and humans.

A

Skull:

  • humans have larger cranial capacity
  • weaker jaw muscle
  • more protruding jaw in ape

Teeth:

  • Rounded palate in humans, square in apes
  • Less diastema (gaps) in humans
18
Q

First walking apes appear around ______. Describe their features.

A

7-4 mya

  • good climbers
  • long arms, fingers, and toes
  • but have wide pelvis bones
  • S-curved spine
19
Q

Australopithecus afarensis ‘Lucy’’ dates back to ______. Describe features.

A

3-4 mya.

  • Walked erect
  • big toe forward facing
  • legs just longer than arms
  • biped
  • pelvis starts to be bowl shaped
  • small diastema, palate partly rounded
  • ape-like skull
20
Q

Later Australopithecus (such as A. africanus) dates back to ______-. Describe features.

A

3-2 mya

  • less protrusion of brow ridges
  • similar skeleton to A. afarensis
  • no diastema, more rounded arch, but still long jaw
21
Q

Homo habilis dates back _____. Mention a distinctive feature of this species.

A
  1. 3-1.4 mya

- increase in cranial capacity

22
Q

Homo erectus dates back to ______. Describe features.

A

1.8-0.4 mya

  • pelvis similar to modern humans
  • built for running
  • large cranial capacity
  • less protrusion in jaw
  • use of stone tools
23
Q

Explain reason why H. erectus successful in proliferation and spreading.

A
  • less sexual polymorphism -> easier mating
  • less hair on body -> use of clothes -> able to adapt further north
  • control of fore and stone tools
24
Q

Homo neanderthalensis dates back to ______. Describe features.

A

300 to 28 thousand years ago

  • heavier than modern humans
  • distinctive skull shape - brow ridge
  • larger eyes
  • larger cranial capacity than modern humans
25
Q

Homo sapiens dates back to _______. Describe features.

A

225000 years ago - now

  • high domed skull, flat face
  • small to no brow ridges
  • jutting chin -> complex sound
  • rounded back of skull
26
Q

Humans migrated to the Americas around ________.

A

18000 years ago.

Genes and Environment (26 decks)

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