13. Evolution of the human Musculoskeletal System

Question 1

what is EVOLUTION

Answer 1

the CHANGE in the HERITABLE CHARACTERISTICS of
biological POPULATIONS over successive GENERATIONS

Question 2

STEPS of EVOLUTION

Answer 2

GENETIC VARIATION
DESIGN VARIATION
PERFORMANCE VARIATION
FITNESS VARIATION

Question 3

what are PLEIOTROPIC EFFECTS

Answer 3

changes leading to UNWANTED SIDE EFFECTS

Question 4

when is CHANGE UNLIKELY

Answer 4

if COST to the change or NO BENEFIT

Question 5

types of SELECTION

Answer 5

NATURAL SELECTION
- how well ADAPTED to the environment

SEXUAL SELECTION

Question 6

GENETIC DRIFT is the..

Answer 6

change in the frequency of an existing gene variant in a population due to random chance

Question 7

STOCHASTIC EFFECTS occur by..

Answer 7

CHANCE

Question 8

what is PHENOTYPIC PLASTICITY

Answer 8

the change in phenotype (“appearance”)
without genetic change (“genotype”)

Some features are more plastic than others.
* Stature (height) is a plastic feature (but also highly heritable).
* Skin colour is a highly plastic feature (tanning not genetic)
* Digit number is not a plastic feature.

Question 9

CHANGE in STATURE over time (increased height) is due to

Answer 9

PHENOTYPIC PLASTICITY

not due to evolution/genetic changes

main factors:
* fetal growth
* infant nutrition
* infant infection

Question 10

Absolute body size affects..

Answer 10

BIOLOGICAL FITNESS

e.g. a larger body requires more energy; requires rich habitat
Dwarfism can be adaptive

Question 11

TINBERGEN’S 4 QUESTIONS: what is a PROXIMATE and ULTIMATE question

Answer 11

Proximate = HOW
Ultimate = WHY

Question 12

TINBERGEN’S 4 QUESTIONS: what is SYNCHRONIC and DIACHRONIC (questions)

Answer 12

Synchronic = NOW
Diachronic = HISTORY

Question 13

TINBERGEN’S QUESTIONS.
what is a HOW question

Answer 13

PROXIMATE

Question 14

TINBERGEN’S QUESTIONS.
what is a WHY question

Answer 14

ULTIMATE

Question 15

TINBERGEN’S QUESTIONS.
what is a NOW question

Answer 15

SYNCHRONIC

Question 16

TINBERGEN’S QUESTIONS.
what is a HISTORY question

Answer 16

DIACHRONIC

Question 17

ARBOREAL LIFE - GRASPING FOOT changed into…

(ARBOREAL = living in trees)

Answer 17

TERESTRIAL LIFE - A LEVERING FOOT

better for walking on land than climbing trees

(Terrestrial = on land)

Question 18

when did development of human features start

Answer 18

6-7 million years ago

(african apes split between humans and chimpanzees&bonobos)

Question 19

in Embryology, how are (5) FINGERS/TOES developed

Answer 19

APOPTOSIS of tissue

Syndactyly : when some fingers/toes still joined

Question 20

which GENES are for the fixed number 5 for fingers/toes

Answer 20

HOX GENES

Question 21

BIPED meaning

Answer 21

walking on 2 feet
(not on hands&feet - 4)

Question 22

why did we become BIPEDS (theories)

Answer 22

Load carrying
Infant carrying

possible
-tool carrying
- tool throwing
- food carriage

Social behaviour
Feeding

Question 23

how does SKULL SHAPE determine if they were a BIPED / important for bipeds

Answer 23

if CENTRAL POSITION of the FORAMEN MAGNUM

Question 24

how does TRUNK SHAPE determine if BIPEDS / important

Answer 24

LARGE ‘OPEN’ LUMBAR REGION (in humans)
- allows us to MOVE the UPPER and LOWER TRUNK SEPARATELY (thorax & abdomen)
- DE-COUPLING between them

important for terrestrial locomotion (biped)

Question 25

how is BODY POSTURE and SPINE SHAPE important for BIPEDS

Answer 25

humans: 2 concave curvatures - LORDOSIS & 2 convex curvatures - KYPHOSIS

Question 26

EVOLUTION of the GLUTEUS SUPERFICIALIS (in chimpanzees) to humans as BIPEDS

Answer 26

gluteus superficialis - HIP ABDUCTOR changed to become a HIP EXTENSOR in HUMANS as the GLUTEUS MAXIMUS

Question 27

EVOLUTION of FOOT from chimpanzees & orangutans (in trees) to becoming BIPEDS (humans)

Answer 27

the HALLUX (big toe) in orangutan: small and not aligned. other 4 digits for hooking onto branches in HUMANS: the HALLUX is LONG and ALIGNED with the other toes for EXTRA RIGIDITY for WALKING

Question 28

EVOLUTION of the ANKLE JOINT

Answer 28

SHAPE of TALAR TROCHLEA and PATH of the TIBIA is DIFFERENT 17 degree angle in chimpanzee 11.5 degree in humans

Question 29

a CLIMBING HAND has:

Answer 29

CURVED PHALANGES SHORT THUMB STRONG FLEXOR MUSCLES

Question 30

EVOLUTIONARY CHANGES in the hand: a 'manipulation' or 'TOOL USE' HAND is 'freed from locomotion' and has:

Answer 30

- STRAIGHT PHALANGES - LONG THUMB (Precision Grips) - SHORT FINGERS

Question 31

MEDICATION in animals

Answer 31

SELF-MEDICATION often TREATING PARASITES or PATHOGENS eg -Chimpanzees eating rough leaves toget rid of gastro-intestinal parasites - red colobus monkeys eat charcoal to get rid of Toxins

Question 32

Evolutionary medicine is a rapidly growing field that:

Answer 32

- uses the principles of evolutionary biology to better understand, prevent and treat disease - uses studies of disease to advance basic knowledge in evolutionary biology

Question 33

EVOLUTIONARY CHANGES for BIPEDS: (7)

Answer 33

- Skull shape / POSTITION of FORAMEN MAGNUM (central) - TRUNK SHAPE (large lumbar region) - BODY POSTURE & SPINE SHAPE - (superficialis) GLUTEAL MUSCLE (to gluteus maximus) - FOOT (HALLUX) - ANKLE JOINT - SHAPE of TALAR TROCHLEA and PATH of the TIBIA - HAND