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Genes and Environment > W5 > Flashcards

W5 Flashcards

1
Q

describe mammals in terms of subclass and key traits

A

subclass Theria: marsupials and subclass Eutheria: young fed by placenta to an advanced stage

traits:

  1. fusion/reduction of bones
    - single jaw bone and bones to amplify sound in the ear
    - opposing and specialised teeth
    - solid strong pelvic girdle
  2. endothermic with hair/fur insulation as well as sweat glands
  3. 4 chambered heart
  4. mammary glands for parental care
  5. most mammals have a placenta to feed the young in the mother
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2
Q

describe the human ‘order’

A
  • primates
  • 4th largest of 18 orders of eutheria
    eg. orangutan
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3
Q

describe how, from a geographical and lineage perspective how mammals came about

A
  • mammals evolved from a seperate group of reptiles and became dominate after a meteor wiped out all animals greater than 25kg
  • before the meteor: a warm earth period
  • after the meteor: a 30 MY hot earth period
  • resulting in more rain and more forests with trees everywhere
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4
Q

describe the human primate ancestor

A

Plesiadapids:

  • coexisted with dinosaurs
  • lived in trees during the warm earth era
  • squirrel like
  • claws, big incisors and small brains
  • evolved into adapids

Adapids: (1sts true primates)

  • 56-40 MYA
  • tree living during the HOT EARTH period
  • nails instead of claws
  • opposable toes and thumbs
  • forward facing eyes
  • bigger Brains
  • fed mostly on insects and fruit
  • similar to modern promisians
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5
Q

describe the wet nosed primates: promisians

A

eg. mouse lemur: nocturnal insectivore probably similar to early primates
- lemurs: only in Madagascar

facts:
- least specialised primates

traits:
1. hands, binocular vision
2. long nose because smell is important
\+wet nose with a split lip
\+scent making used
3. much of brain is nasal area
4. smaller brain and body mass
5 simple social groups
6. often several young
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6
Q

describe the slow loris

A
  • 3 species of lorises in SE Asia
  • 4 pottos in Africa are similar
  • all nocturnal
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7
Q

describe the bushbaby

A
  • like other mammals, prosimians have a reflective eye layer
  • nocturnal insectivores
  • 11spp. in africa
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8
Q

describe the traits required for leaping in trees

A
  1. binocular vision to judge distance, forward facing eyes protected by ring of bone
  2. large brain for decisions, especially visual processing, control of locomotion
  3. grasping digits; not paws. therefore have opposable thumbs and 1 toe. as well as flat nails and pads
  4. can use upright posture
  5. smell not v. useful, hands to mouth. therefore have reduced nose length
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9
Q

describe primate phylogeny

A
  • eight groups with almost all in tropical forests. these have increasing specialisation and behavioural organisation
  • wet nosed have the least specialisation, lemurs and lorises
  • dry nosed include: tarsiers,
    SIMIANS~~~~~
    new world monkeys, old world moneys,
    HOMINOIDS~~~~~~
    gibbons, orang-utans, African apes+humans
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10
Q

describe the dry nosed group in terms of key traits, and in reference to an example

A
  • also called anthropoids
  • reduction of use of smell
  • dry nose and no split lip
  • flatter face
  • mostly diurnal
  • no reflective eye layer

Tarsiers:

  • SE Asia
  • dry nose features, but same ecology as many wet noses such as nocturnal insectivore: has huge eyes
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11
Q

what are the key traits of simians

A
  • dry nose: no split lip, therefore has less smell
  • has more complex sounds: communication
  • no reflective eye layer
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12
Q

what are the key traits of monkeys and apes

A
  • diurnal (lost eye layer)
  • most eat fruit and leaves
  • one baby is enough
  • unified uterus
  • embedded placenta
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13
Q

what are the key traits of new world monkeys

A
  • found on tropical south america
  • all tree dwelling
  • prehensile tail (spider monkey)
  • 12 premolars
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14
Q

what are the key traits of old world monkeys

A
  • tropical Africa and Asia
  • 8 premolars, narrow nostrils like apes
  • tail never prehensile
  • more diverse habitats- some on ground eg. baboons and proboscis monkey

special features:

  • visual animals
  • colour vision
  • sexual displays
  • complex socieities
  • elaborate child care
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15
Q

describe the parenting change

A

most mammals:

  • birth triggers hormone oxytocin
  • triggers mother to bond to infants smell, starts lactation
  • vasopressin bonds males to smell of female

in simians:

  • reduced smell
  • parental care lasts beyond lactation
  • young females learn complex parenting skills
  • so executive brain, not hormones controls parenting
  • tactile relations release the reward hormone beta endorphin- reinforces bonding
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16
Q

describe hominoids in terms of locations, lineage, special features and structure

A

location: tropics of Africa and Asia
lineage: diverged from Old world monkeys 25MYA
special features: ripe fruit specialists so have lost the VIT c gene

  • mostly larger than monkeys
  • larger brains
  • extended childhoods
  • no tails:
    + adapted for brachiation
    +long arms, shorter legs
    + flat chests
    +shoulder blades at back
    +rotating arms
17
Q

describe the great apes in terms of examples

A

classification for apes: pongidae

eg. orang-utan hangs out in dene forests in SE asia
- humans split from orang-utans +/-12MYA
eg. Gorilla (2 species)
- diverged form us and chimps +/- 9MYA
eg. chimpanzees using a tool
- diverged from humans 8-7 MYA
- occurred when Africa became dryer and when Ardipithecines began walking on 2 legs
eg. Bonobo chimps
- social ties: like the chimpanzee it expresses aggression and dominance. like the bonobo it demonstrates sexual acts and relationships
- humans have social setup DNA like bonobos

18
Q

describe the classification of hominoids

A

superfamily: Hominoids(apes and hominids with no tails and brachiation)

family:

  1. hylobatids
  2. pongids
  3. hominids (adapted to stand erect and walk)

genus:

  1. Hylobates (eg. gibbons)
  2. pongo (eg. orang-utan), pan (chimps), gorilla
  3. homo
19
Q

describe the story of the walking ape

A
  1. the hominids had an origin 7MYA: Pliocene, pleistocenes, holocene.
  2. the planet then cools and the trees became more widely spaced
  3. footprints discovered in 1978 of bipedal walkers from 3.5mya. probably Australopithecus afarensis
  4. the prints showed heel to toe striding where the weight shifts over the big toe. from the stride, the height was estimated to be 1.2m
20
Q

list the skeletal differences due to erect posture

A

lots of changes needed

  1. neck under skull vs behind, this was to balance the head on the spine
  2. S shared spine vs arch, this absorbs shock as feet hit the ground
  3. pelvis was bowl shaped and was wide rather than long, this supported the abdomen, muscles to femur for balance and forward and back

limbs:

  1. knuckle walking in apes: therefore the arms were long and the legs short, with the fingers curled over. however, in humans, this became shorter arms and longer legs
  2. heel bones support weight
  3. arched foot rather than flat; this absorbs shock
  4. femur angled inwards
  5. big toe points forward
  6. knee joints point forward
21
Q

describe skull differences

A
  1. Head:
    A. cranial capacity: chimps 400ml vs humans of 1400 ml. B. Human skull had baby shape whereas the ape and face grows more
  2. weaker jaw muscles whereby the gene MYH16 for muscle protein became mutated. this lead to smaller jaw muscles and allowed for a larger and thinner skull
  3. brain growth: Genes APSM and HAR1 F & -R mutated. this lead to more neurons branches in the developing brain. in Lucy’s skull, it was found that the duplication of gene SRGAP2 which controls conscious thought is 3.4MYA. this second version of gene interferes with the original and allows nerves to grow more connections and migrate further
  4. more energy to the brain: 3 gene changes caused this leading to wider arteries and more glucose shunted from blood to brain
22
Q

describe differences in the teeth

A

this occurred due to dietary differences:

  1. shape of palate became rounded rather than rectangular
  2. size of canines and diastema became more rounded/ smaller and disappeared
  3. wear on molars
23
Q

describe the first walking apes in terms of time, why walking became advantageous and what initiated this

A
  • 7-4MYA
  • Why did walking become advantageous?
  • as africa began to cool and dry, apes that could move faster between trees had an advantage
  • what made apes good climbers?
  • long arms and fingers
  • long toes and a prehensile big toe
  • skill like normal ape
  • what was similar between these apes and humans?
  • s scurried spore with the neck under the skull
  • heel, arched feet, toes can bend up
  • pelvis like chimp but hip joint to support erect body
24
Q

describe Lucy: Australopithecus afarensis

A
  • actual bones from discovery are 3.5MYA and model came from a reconstructed skeleton
  • this species came from 4-3 MYA in eastern africa
  • about 1.5m high
  • more erect, big toe was forwards and the femur was angled inwards
  • had long arms and curled fingers, legs were only just longer than arms. thus, suggesting they climbed trees too
  • better bipedalism would allow longer travel, spotting predators and transport of food
    had a human like knee joint
25
Q

describe the pelvis and contrast between chimpanzees, Australopithecus and humans

A

chimpanzee: pelvis shape is important for walking, to attach the leg muscles and birth of infants
australopithecus: wider pelvis then chimp. and also wider birth canal. was the intermediate

humans are born premature compared to apes, to fit.

26
Q

describe how Lucy was an example of a intermediate between apes and humans

A
  • canine size intermedate
  • diastema small but present
  • palate arch partly rounded
27
Q

describe the skull of Lucy

A
  • ape like
  • low forehead
  • prominent brow ridges
  • projecting face
  • cranial capacity of 400-500 ml which is within the ape range
    note: upright walking came long before the enlargement of the brain in human evolution
  • perhaps made tools
28
Q

describe homo habilis

A
  • 2.3-1.4MYA in east Africa
  • few fossils: skulls and bits
  • cranial capacity 510-612ml
  • H.rudolfensis had a 700ml brain, few fossils
  • larger brain region for speech, so maybe language and perhaps coop hunting and culture
  • 2nd duplication of SRGAP2 gene, so more growth of neurons, connections and brain functions

olduwai stone tools:

  • simple cracked stones, often carried far from natural rock sites
  • found with butchered animals bones
29
Q

describe h.erectus

A

1.8-0.4MYA in africa, 1.77 MYA in georgia
also called h.ergaster
eg. Turkana boy who was 1.6m teenager 1.8mya IN E Africa

  • pelvis very like modern humans
  • similar to modern humans but heavier
  • tall, built for running
  • cranial size much bigger at 650-900 ml
  • 1200ml by o.6MYA
  • flat top, prominent brow ridges
  • occipital ridge at rear
  • jaw protrudes, but less than h.habilis
30
Q

describe h.erectus acheulean stone culture

A
  • developed in Africa split with asian H.erectus
  • established camp sites, s tone working
  • more elaborate tolls than olduvai
  • but style and manufacture unchanged for mYA
  • especially the hand axe which was found everywhere and used many ways like a Swiss army knife
31
Q

why was H.erectus so successful

A
  • less sexual dimorphism=possible pair bonds, marriage
  • less hair on body = wearing of furs and other clothing
    . therefore, could live further north in Eurasia
  • could adapt to environment fast without evolutionary change
  • archulean tools= organisation for hunting. thus, also could protect against predators
  • so culture is a main reason for success
  • control of fire: possible campsites

first out of Africa during a warm period: found 1.8-0.3MYA In gerogia, java, china

32
Q

describe the Denisovans in Asia

A
  • in 2011, dna from a finger and a tooth showed a seperate human evolved in Asia
  • it seems modern humans interbred with them. as their genes are 5%melanesians, aboriginals and native Americans
  • we gained important immune genes against local diseases
33
Q

describe homo.neanderthalensis

A

• Europe, western Asia 300,000 – 28,000 yr ago
- Long before modern H. sapiens • 1400 -1500 ml brain – bigger than us! • Homesites, burials, art.
• Males heavier than modern humans.
• Distinctive skull shape: modest brow ridge,
mid-face projection, deeper orbit, no jutting chin.
• Larger eyes, brain focus on vision & movement
• Occupied warmer southern Europe
• H. sapiens first occupied cold plains +/- 45,000 ya
(hunting mammoths etc)
• We coexisted with them for +/- 20,000 yr!
• Mt-DNA - no gene mixing w modern humans
but nuclear DNA mixing - yes!
Big Hulks? male Neanderthals & sapiens females

34
Q

describe homo-spaiens

A

Archaic: 225,000 to 35,000 BP Modern 35,000 - now

1st signs of jewellery & art +? tide records.
70 Kya, S. Africa (At beachcomber cave)
Omega 3 fatty acids in seafood – good for brains

• Evolved in Africa
• High domed skull, Flat face
• Small /no brow ridges
• Rounded back of skull
• Mean cranial capacity1400ml 
- jutting chin: Allows space for tongue to form complex sounds, and more language
• FOXP2 gene mutation:
- better memory for vocalisation & grammar

Genes and Environment (12 decks)

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