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ANTH 102 > Finals Study Guide Chapter 10 > Flashcards

Finals Study Guide Chapter 10 Flashcards

1
Q

How do we identify hominins

A

Six million years ago, climate and geographic change led to the evolution of hominins.
Characteristics of humans include:
Bipedalism
Differences in dental anatomy from apes
Large brains relative to body size
Long period of juvenile development
Dependence on a material and symbolic culture
Hominins shared some of the features of humans and also some features of contemporary chimpanzees

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2
Q

Why did bipedalism evolve?

A

1 feeding adaptations
Arboreal bipedalism
Ground feeding
Survived better when the trees began to dwindle during the cooling and drying period of the late Miocene
2. Energetics
Bipedalism saves energy
3. Thermoregultion
Less solar radiation
Earliest hominids are found in a wooded environment challenging this as an explanation for why bipedalism originated
4 carrying and provisioning
Provisioning mates rather than competing with other males for mates may explain reduction in canine size in early hominins

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3
Q

Who were the early hominins? How do we know

A 
-Early hominins were
Tree dwelling
Small toothed
Small brained apes
Walked on 2 legs
- Later hominins were
Quiet adept at bipedal locomotion 
Evolved enormous teeth for savanna diet
- We evolved a larger brain later
- All of the above occurred before 2mya, exclusively in Africa
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4
Q

Hominins diversification

A
  1. 2-4 mya, hominins diversified into many different species, and different genera as well
  2. All fossils are found inside Africa
  3. All of these hominins have relatively small brains
  4. All show skills for upright walking
    • Some hominins retained tree-climbing
  5. Chimpanzee-sized, sexual dimorphicabilities (canine reduced)
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5
Q

Terms used in Paleoanthropology

A

Terms used in Paleoanthropology
• Key bones referenced in fossil hominins
• Skull: mandible, maxilla
• Arm: humerus, radius, ulna
• Leg: femur, tibia, fibula
• Hands and feet: carpals/tarsals,
metacarpals/metatarsals, phalanges • Pelvis: ilium

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6
Q

Femur is a feature of

A

Bipedalism

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7
Q

Sagittal crest

A

Big bony intrusion in the top part of your head

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8
Q

Foramen magnum

A

Connects to spinal cord

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9
Q

Brow ridge

A

Not a lot of humans have this. But some primates have it

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10
Q

Cranial v. Post cranial

A

Cranial- skull

Post cranial- body from neck to toes

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11
Q

Identify traits that unique to humans

A
  1. We walk on two legs (bipedalism)
  2. We have small canines and large molars with thick enamel (2-1-2-3)
  3. We have large brains
  4. We have very slow life histories and a long juvenile period
     Cooperative breeding: rely on help from others to assist in the raising of the young
  5. We talk and have elaborate symbolic culture
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12
Q

Biped pelvis

A

Pelvis in a biped - ilium is short and stout

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13
Q

Biped skull

A

Skull in biped is in foramen magnum position

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14
Q

Biped spine

A

Spine in biped is in lumbar lordosis

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15
Q

What It Takes to Be a Biped

A
  1. Bipeds mean you have to be able to balance
    • When you take a step, your body is forced to balance for a short time on a single leg
    • Force of gravity wants to pull your entire body away from the weighted leg
    • Torque (twisty force) causes you to wobble from side to side when you walk
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16
Q

What it takes to be a biped -pelvis

A

Pelvis
Abductor mechanism- muscles in your hip
Muscles contract on the same side as the weighted leg when the opposite leg is lifted, to balance the torque created during one legged balance.

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17
Q

Biped - Femur

A

Long femoral neck aligns the attachment of the abductors on the femur to the attachment of the wide, flaring ilia
• Cortical bone distribution (uneven in human, more even in chimpanzees and gorillas)

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18
Q

Biped - knee

A

Knee
• Bicondylar angle (slants downward and inward)
• Keeps the feet, knees, and hips balanced and aligned
• Also seen in Australopithecus afarensis

19
Q

Biped - Foot and ankle

A

Foot and ankle
• Nongrasping big toe
• All other primates do
• Realignment of the big toe with the other toes was an important shift in
our ancestors away from a climbing,arboreal niche toward a terrestrial,
bipedal one

20
Q

Biped - Arches

A

Arches
Cushion the blow of walking
Also help to store and return energy

21
Q

Sahelanthropus

A 
Location: in Chad, Africa
 Ancient environment: once a lush, forested region 
Age: 6–7 mya
Hominin?
• Foramen magnum suggests bipedality 
• Chimpanzee-sized brain 
• Small canines 
• Flat face; large browridge
22
Q

Hominin means

A

More human like

23
Q

Orrorin

A

Location: Kenya, Africa
Ancient environment: once a mix of woodland and savanna
Age: 6 mya
Another fossil species that has been claimed to be the earliest hominin
Hominin?
• Long, curved fingers and robust arm bones suggest arboreal movement • Femur suggests bipedality
• Neck of the femur is quite long, which indicates that this animal had a
balancing abductor mechanism
• Teeth chimpanzee like
• Quite similar to those of modern apes, enamel is thicker like that found in members of our lineage

24
Q

There is a tendency to think that as one moves back in time to the common ancestor of humans and chimpanzees, the fossils should look more and more chimpanzee like, but that is not the case.

A

True

25
Q

Humans did not evolve from chimpanzees any more than chimpanzees evolved from humans.

A

True

26
Q

We share a common ancestor

A

That was neither human nor chimpanzee

27
Q

These early fossils are evidence that chimpanzees and gorillas

A

evolved, too.

28
Q

Ardipithecus kadabba

A

Ardipithecus kadabba
Location: Ethiopia, Africa
Age: 5.2–5.8 mya
Hominin?
• Toe bone suggests bipedality (human-like in shape)
• Canine sharpens against lower premolar
• Quite primitive and ape like, with larger, sharper canines, than those found in later hominins

29
Q

Ardipithecus ramidus

A

Location: Ethiopia, Africa
Age: 4.4 million years old
Hominin?
• Mixture of primitive and derived features
• Existed around the time of the last common ancestor of humans and chimpanzee
• Bipedal based on skull, pelvis, and foot
• Climbing based on hand, foot, and pelvis
• Small brain and small canines

30
Q

Describe teeth of Ardipithecus ramidus

A 
Incisors
• Smaller than frugivorous chimps 
Canines
• Not sharpened
• Not dimorphic 
Molars
• Thicker enamel than African apes; thinner than humans
31
Q

What type of mating system did Ardipithecus ramidus have

A

Pair bonding

32
Q

Small, dull canines are not at all beneficial to a male primate engaging in battles over access to females.

A

True

33
Q

A. ramidus: Postcranial Anatomy

A 
-• Hand
• Not knuckle walking
• Supports the hypothesis that gorillas and chimpanzees have independently evolved knuckle walking, from a non-knuckle-walking Miocene ancestor
-• Foot
• Grasping toe
• Stiff foot for bipedalism 
-• Pelvis
• Ilium adapted for bipedalism
• Lower part apelike
34
Q

Hominin

A

-Any member of the family Hominidae, including all species of Australopithecus and Homo.

35
Q

Ilium

A

-One of the three bones in the pelvis.

36
Q

Femur

A

-The thigh bone.

37
Q

Foramen magnum

A

-The large hole in the bottom of the cranium through which the spinal cord passes

38
Q

Zygomatic arches

A

-cheekbones

39
Q

Tibia

A

-The larger of the two long bones in the lower leg.

40
Q

Humerus

A

-The bone in the upper part of the forelimb (arm).

41
Q

Endocranial volume

A

-The volume inside the braincase.

42
Q

Subnasal prognathism

A

-condition in which the part of the face below the nose is pushed out

43
Q

Diastema

A

-A gap between adjacent teeth.

44
Q

Sagittal crest

A

-A sharp fin of bone that runs along the midline of the skull that increases the area available for the attachment of chewing muscles.

ANTH 102 (17 decks)

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