bio part 3

Question 1

Canine Honing Complex

Answer 1

In apes, canines interlock when mouth is closed, fitting into a space called a diastema (space separating teeth of different functions)
The canine shears or slides against the premolar when the jaw is closed
The 3rd premolar, is elongated and presents a sharpening edge for the canine

Question 2

Dentition: Dental arcade: Chimp

Answer 2

U-shaped dental arcade
Large canines, broad incisors

Question 3

Dentition: Dental arcade: Human

Answer 3

Parabolic dental arcade
Smaller anterior teeth

Question 4

Chimpanzee face

Answer 4

More facial prognathism
Prognathism= the degree to which the face projects forward

Question 5

Human face

Answer 5

Less facial prognathism
Smaller, shorter mandible

Question 6

Muscles of Mastication

Answer 6

Temporalis:
Masseter:
(zygomatic arch)
Sagittal crest

Question 7

Temporalis:

Answer 7

extends from its origin on the cranium, passes behind the cheek bone (zygomatic arch), inserts onto the top of the mandible

Question 8

Masseter:

Answer 8

extends from the cheek bone to the bottom of the mandible

Question 9

Sagittal crest

Answer 9

develops on the top of the skull
- Associated with flaring zygomatics
- To accommodate chewing force masseter muscle is enlarged and accompanies robust mandible for attachment

Question 10

Transverse section

Answer 10

Differences in size and shape of teeth
Differences reflect reduction in size of chewing muscles

Question 11

Suspensory Locomotion

Answer 11

Brachiation – small-bodied gibbons highly specialized
Quadrumanous – Orangutans employ 4 – handed climbing behavior and walk on sides of fist on ground
Knuckle-walking – Stabilized wrist joints for weight bearing

Question 12

Center of Gravity

Answer 12

mean location of mass in body
Fixed point through which the weight of the body is transmitted or balanced

Question 13

Center of Gravity humans

Answer 13

In humans, CoG is in the midline anterior to the sacrum
Bent-hip, bent-knee bipedal chimp
Resisting the tendency to fall forward
Shifting weight from side to side – ‘waddle’

Question 14

Position of Foramen magnum

Answer 14

hole in base of skull in which spinal cord travels
Positioned directly underneath the skull in bipeds

Question 15

Nuchal crest

Answer 15

Expanded bony shelf on the posterior portion of the skull for attachment of larger neck muscles

Question 16

Vertebral column
apes

Answer 16

C –shaped vertebral column
Vertebral shape helps position head in front and center of gravity anterior to pelvis

Question 17

Vertebral column humans

Answer 17

have S-Shaped vertebral column
Lumbar vertebrae become wider further down
Supports body weight and balance
Pyramidal configuration
Meets wider sacrum
(AIIS)

Question 18

(AIIS)

Answer 18

Anterior Inferior Iliac Spine

Question 19

Pelvis Shape

Answer 19

Short, wide bowl-shaped pelvis
Base of support of upright trunk and internal organs
Iliac blades are shortened compared to apes
Further stabilizes weight transmission
Reorientation of the blades

Question 20

Knee: Valgus angle

Answer 20

Femur is oriented at an angle from the hip to the knee
Line of weight transmission is carried on the outside of the knee joint
Enlarged articulation on the lateral aspect of the knee
Deep patellar groove for increased stability

Question 21

Foot

Answer 21

Heel strike on large calcaneus (heel bone)
Distribute weight across foot to hallux (big toe)
Toe-off with hallux
Transverse and longitudinal arches

Question 22

Locomotion in the Last Common Ancestor (LCA)

Answer 22

Stability in wrist joint suggests knuckle-walking
Recent fossil evidence suggests clinging and climbing adaptations

Question 23

All fossil evidence from 7 -3 ma comes from

Answer 23

Eastern Africa:

Question 24

Major evolutionary novelties of humans

Answer 24

Habitual upright walking (bipedalism)
Characteristics of the dentition
Elaboration of material culture
Significant increase in brain size
Long developmental period and long lifespan

Question 25

Lovejoy’s model for the origins of bipedality.

Answer 25

Shift in social organization?– Evidence is based on reduced canine and lack of honing complex (i.e. lack of sexual dimorphism)
Research team interpreted species as monogamous social structure

Question 26

Piltdown Hoax

Answer 26

Big, human-like brain, ape-like jaw
Suggested European (even better British) origins of our lineage
Quickly hailed as the human ancestor – other fossils disregarded

Question 27

Australopithecus

Answer 27

Found in South, East, and Central Africa
Definite bipeds and hominins
Small-brained (up to 500cc)
Trend for large posterior teeth

Question 28

Major trends seen in Australopithecus

Answer 28

Dentition – reduced canine size; larger cheek teeth; thicker enamel
Locomotion/posture – adaptations for bipedalism
Relative brain size – not substantially enlarged compared to apes
Body size - smaller than modern humans, with more sexual dimorphism

Question 29

Evolutionary trends: homo

Answer 29

Increase in brain size and capacity for tool making
Decrease in prognathism, and postcanine tooth size
Increase in body size

Question 30

Evolutionary trends: Paranthropus

Answer 30

Hypermasticatory complex
Increase in cheek tooth size
Decrease in prognathism

Question 31

Traits from homo and Paranthrophus that are in Austrolapithacus

Answer 31

Increase in brain size
Decrease in prognathism, and cheektooth size
Increase in body size
Greater stone tool production

Question 32

Cranial crests: Muscles of mastication

Answer 32

Heavy chewing complex:
Huge posterior teeth, molarized premolars, tiny anterior teeth, massive mandible
Large, powerful chewing muscles (temporalis, masseter)
Post-orbital constriction and large sagittal cresting
Wide zygomatics, huge faces in general

Question 33

Homology:

Answer 33

shared derived traits

Question 34

Homoplasy:

Answer 34

similar traits not derived from a common ancestor

Question 35

Homoplasy on the top:

Answer 35

regional evolution of heavy chewing

Question 36

WE use.. Homology of heavy chewing features on the bottom

Answer 36

We use Paranthropus