bio evol REVISION Flashcards
Advantages BIPEDALISM (2) Energy & Hands
Energy efficient locomotion
(2 legs less E than 4)
-longer more rewarding journeys (more E reprod)
Free Hands
carry tools, weapons, food
^ hand dexterity, build shelters
Resources scattered further apart
Advantages BIPEDALISM (2) Thermo & Height
Increased Height
enhanced visual field –> see over tall grass (pred/l f)
improved ability to anticipate danger & find safe route
Thermoregulation
less SA exposed to direct sunlight upright position
- remain in sun for longer*
Challenges/Disadv BIPEDALISM (2)
Challenges in Childbirth
changes pelvic shape
narrower birth canal
larger cranium
increased risk of complications
Back/Joint pain
spine and joins required to support weight of whole body –> stress lower back
- increase susceptibility to injury*
Skeletal Changes (Foot)
Foot (arch)
arch –> shock absorber
also stores E and release when pushing off
E efficient, increase d & suc
hallux –> thrust –> reduced grasping ability
robust heel bone –> balance/stability maintain arches
Skeletal Change (pelvis)
Bowl-shaped - flater broader - suport abdominal organs
brings cog aover feet balance and stability
lilac blades are points of attatchement for strong locomotion muscles
- decreased energy needed to stabilise body*
Skeletal Change (femur)
Leg (femur & knee)
longer, straighter, thinner
^stride l, centres body w, E efficient
femur angles inwards (valgus angle) –> brings knees closer to COG, walking w/out swaying, more stable
Skeletal Change (Spine)
S-shaped
acts as spring, compressing slightly under pressure, absorbing shock
* increase endurance loco*
dist weight evently over lower body (reduce stress on internal organs)
supports upright posture
Cultural evolution positive feedback loop | meat –>
Meat/protein
–> greater nutrient absorbtion (more calories/E)
–> fuel brain development
–> increase cranial capacity (better communication, memory, tools, bonding)
–> more sucessful hunting
–> meat
Adv Cooked food
–> more digestible (reduced E making organs)
–> more calories E
(reduced time foraging, less food)
–> nutrient available for brain development
Brain dvelopment led to ..
Ability to form complex thought (solve prob/be creative)
–> more complex tools imagined & constructed
–> developemt of Broca and Wernickes areas (more efficient teamwork)
–> development in memory and communication
Adv of Fire
-warmth (migrate out of Africa into cooler climates)
-light @ night (extend hunting hrs)
-tool making (stronger, more resistant to wear)
-protection
-cooking
-social organisation (strengthen bonds)
Com cultural/biological evol.
Cultural evolution:
transmission of learned behaviour,
ideas and knowledge
transferred across space & time and
can occur between unrelated individuals.
Biological evolution:
occurs more slowly as favourable changes in genomes of individuals are
passed only to their offspring by natural selection
adv/disad agriculture
-abundant food supply
-additonal materials from animals
-sustain large pop
-more waste
-weather dependent
-spread of disease
-overall decline in health
Out of Africa Dispersal Theory
Modern humans (h.sapiens) originated in Africa from h.erectus & migrated out into Europe and Western Asia where they encountered, interbred and eventually outcompeted arcahic hominin populations who had left africa much earlier.
sapiens left africa in 2nd migration 100-50000yrs
Evidence of OOA
Africa –> oldest pop –> greatest genetic diversity (regional pops, decreased levels, short time to accumulate diff and small pop)
Mt DNA
Nuclear DNA (compare gene similarities –> fewer –> more closely related)
Multiregional theory
Modern africans, asians and europeans evolved in their separate regions.
sufficient gene flow between populations prevent diverging into separate pop
common ancestor –> H. erectus left Africa 1.8MYA
Evidence of Multiregional
modern sapiens = genetic diversity african pop –> evolving for just as long
var btw regional pop should be large, long time to accumulate diff
high levels gene flow between pop, cannot use fossils to determine whether interbreeding occured.
