13. Evolution of the human Musculoskeletal System Flashcards
what is EVOLUTION
the CHANGE in the HERITABLE CHARACTERISTICS of
biological POPULATIONS over successive GENERATIONS
STEPS of EVOLUTION
GENETIC VARIATION
DESIGN VARIATION
PERFORMANCE VARIATION
FITNESS VARIATION
what are PLEIOTROPIC EFFECTS
changes leading to UNWANTED SIDE EFFECTS
when is CHANGE UNLIKELY
if COST to the change or NO BENEFIT
types of SELECTION
NATURAL SELECTION
- how well ADAPTED to the environment
SEXUAL SELECTION
GENETIC DRIFT is the..
change in the frequency of an existing gene variant in a population due to random chance
STOCHASTIC EFFECTS occur by..
CHANCE
what is PHENOTYPIC PLASTICITY
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.
CHANGE in STATURE over time (increased height) is due to
PHENOTYPIC PLASTICITY
not due to evolution/genetic changes
main factors:
* fetal growth
* infant nutrition
* infant infection
Absolute body size affects..
BIOLOGICAL FITNESS
e.g. a larger body requires more energy; requires rich habitat
Dwarfism can be adaptive
TINBERGEN’S 4 QUESTIONS: what is a PROXIMATE and ULTIMATE question
Proximate = HOW
Ultimate = WHY
TINBERGEN’S 4 QUESTIONS: what is SYNCHRONIC and DIACHRONIC (questions)
Synchronic = NOW
Diachronic = HISTORY
TINBERGEN’S QUESTIONS.
what is a HOW question
PROXIMATE
TINBERGEN’S QUESTIONS.
what is a WHY question
ULTIMATE
TINBERGEN’S QUESTIONS.
what is a NOW question
SYNCHRONIC
TINBERGEN’S QUESTIONS.
what is a HISTORY question
DIACHRONIC
ARBOREAL LIFE - GRASPING FOOT changed into…
(ARBOREAL = living in trees)
TERESTRIAL LIFE - A LEVERING FOOT
better for walking on land than climbing trees
(Terrestrial = on land)
when did development of human features start
6-7 million years ago
(african apes split between humans and chimpanzees&bonobos)
in Embryology, how are (5) FINGERS/TOES developed
APOPTOSIS of tissue
Syndactyly : when some fingers/toes still joined
which GENES are for the fixed number 5 for fingers/toes
HOX GENES
BIPED meaning
walking on 2 feet
(not on hands&feet - 4)
why did we become BIPEDS (theories)
Load carrying
Infant carrying
possible
-tool carrying
- tool throwing
- food carriage
Social behaviour
Feeding
how does SKULL SHAPE determine if they were a BIPED / important for bipeds
if CENTRAL POSITION of the FORAMEN MAGNUM
how does TRUNK SHAPE determine if BIPEDS / important
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)
how is BODY POSTURE and SPINE SHAPE important for BIPEDS
humans: 2 concave curvatures - LORDOSIS
& 2 convex curvatures - KYPHOSIS
EVOLUTION of the GLUTEUS SUPERFICIALIS (in chimpanzees) to humans as BIPEDS
gluteus superficialis - HIP ABDUCTOR
changed to become a HIP EXTENSOR in HUMANS as the GLUTEUS MAXIMUS
EVOLUTION of FOOT from chimpanzees & orangutans (in trees) to becoming BIPEDS (humans)
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
EVOLUTION of the ANKLE JOINT
SHAPE of TALAR TROCHLEA and PATH of the TIBIA is DIFFERENT
17 degree angle in chimpanzee
11.5 degree in humans
a CLIMBING HAND has:
CURVED PHALANGES
SHORT THUMB
STRONG FLEXOR MUSCLES
EVOLUTIONARY CHANGES in the hand:
a ‘manipulation’ or ‘TOOL USE’ HAND is ‘freed from locomotion’ and has:
- STRAIGHT PHALANGES
- LONG THUMB (Precision Grips)
- SHORT FINGERS
MEDICATION in animals
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
Evolutionary medicine is a rapidly growing field that:
- uses the principles of evolutionary biology to better
understand, prevent and treat disease - uses studies of disease to advance basic knowledge
in evolutionary biology
EVOLUTIONARY CHANGES for BIPEDS:
(7)
- 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
