chapter 55

Question 1

what causes increased complexity in an organism?

Answer 1

• differences in gene expression
• changed in space (tissue) and time (developmental stage)

Question 2

genetic toolkit

Answer 2

idea that same genes are used in different ways, leading to distinct morphological differences

Question 3

impact of ‘genetic toolkit’ gene expression in humans

Answer 3

• humans have 39 hox genes organized into 4 clusters
• mutations can be lethal
  eg
  Hox A1 (homozygous) = severe mental development delay
  HoxA13 = development of fingers and toes

Question 4

mesozoic era

Answer 4

age of reptiles, after precambrian supereon
triassic

jurassic
- reptiles
- angiosperm

cretaceous
- mammals, first placental mammals

Question 5

angiosperm

Answer 5

• flowering plants
• most have endosperm within seeds (nutritional)
• most make fruit with seeds
• most diverse group of land plants

Question 6

cenozoic era

Answer 6

age of mammals
- extinction of dinosaurs created ecological opportunities for mammals
- mammal success probably linked to diversification of angiosperm
- Homo sapiens appear

Question 7

what’s so special about seeds?

Answer 7

they’re a synapomorphy!
- before seeds, plants used spores
- spores have little stored food resources

Question 8

relationship/impact between angiosperms and animals

Answer 8

reciprocal relationship
- angiosperms evolved to depend on animals for pollination, defence and dispersal
- reward with nectar, fruit and shelter

DEVELOPMENTAL CHANGES
- NS favoured changes to help primates compete for angiosperm resources

Question 9

primate features

Answer 9

• adaptations for locomotion
• opposable thumbs, tails
• hind limb posture
• stereoscopic vision (depth perception), 3 colour vision
• nails
• big brain time

Question 10

primate phylogeny

Answer 10

ANTHROPOIDS
new world monkeys
- prehensile tails, no opposable thumbs
- no 3 colour vision (minus howlers)
- monogamy

old world monkeys + apes (hominoids)
- sexual dimorphism
- non monogamous
- grasping hands and feet

tarsiers
- BIG EYES. big as brain
- good ears
- long feet and fingers

prosimians
- small brain
- large smelling
- nocturnal

Question 11

general terms for monkeys

Answer 11

anthropoids: NWM, OWM, apes (humans too)
hominoids: apes (humans too)
hominins: human lineage after divergence from chimps and bonobos

Question 12

anthropoids

Answer 12

NWM, OWM, apes (humans too)

Question 13

hominoids

Answer 13

apes (humans too)

Question 14

hominins

Answer 14

human lineage after divergence from chimps and bonobos

Question 15

types of foraging

Answer 15

• collection (eg fruit)
• extraction (eg termites)
• hunting

Question 16

complex foraging

Answer 16

hunting and extractive foraging

• requires learning
• food flow between ages and genders
• food sharing (self-sufficient food production only in adults)
• division of labour

Question 17

complex foraging: effects of food sharing and labour division

Answer 17

lead to
- reduced sexual dimorphism
- less competition between males
when male parental care is important, males don’t compete as much for reproductive rights

Question 18

causes for evolution of locomotion in hominins

Answer 18

• environmental changes caused hominins to move to grasslands

Question 19

theories of bipedalism

Answer 19

possibly…
- kept hominins cooler
- leaves arms free to carry things
- response to increase dependance of offspring
- suspensory locomotion (uncommon) pre-disposed ape lineage to evoke bipedalism

Question 20

hominin features (4-6 mya)

Answer 20

ANCESTRAL
-small molars
- canines larger
- low brow ridge
- small brain case

DERIVED
- forward location of foramen magnum (brainstem hole)
- small canine teeth
- changed in femur, pelvis
- flatter face

Question 21

difference between ancestral and derived features

Answer 21

ancestral
- old features
derived
- features we see in ourselves today

Question 22

hominin features (2-4mya)

Answer 22

3 diff species

generally…
- small bipeds
- small teeth
- flat face

Question 23

difference between humans and other apes

Answer 23

• fully bipedal
• long juvenile period
• big brain time
• spoken language

Question 24

when did humans and chimps split? details of split

Answer 24

5-7 million years ago
posture
- foramen magnum (brain stem hole) moves forward
- pelvis repositioned for upright posture. flattened + flared
- abductors to stabilize pelvis
- longer legs, directly under body (fever-tibia alignment)
- narrow foot, larger big toe

Question 25

neanderthal morphology + origins

Answer 25

• faces that bulge in middle
• large brow ridge
• BIG big brain capacity (> humans)
• stocky, muscly bodies

adaptations may reflect adaptation to the cold

ORIGINS
- up to 400 000 years ago
- europe, western asia
-

Question 26

mitochondrial DNA + neanderthal

Answer 26

mitochondrial in humans more closely related to each other than to neanderthals
- therefore, no evidence of gene flow with neanderthals based on that part of genome
- evidence of gene flow in autosomal DNA

Question 27

what does the neanderthal genome sequence tell us?

Answer 27

• non- African humans shares ~2% of genome with neanderthals
• 1/5 of neanderthal genome in scattered over different non-africana genomes today
• modern humans from Africa shared very little

CONCLUSION
- gene flow with neanderthals may have happened after humans left Africa, but before populations in Europe and Asia diversified

Question 28

Denisovans

Answer 28

more related to neanderthals than AMH
- after divergence from neanderthals, both had occasional gene flow with humans