Mammals, Primates and Humans

Question 1

7 shared, derived traits of mammals?

Answer 1

Mammary glands
Hair or fur covering the body
3 middle ear bones
Endothermy
Dentary-squamosal jaw joint
Specialized teeth
Larger brain

Question 2

What did mammary glands evolve from?

Answer 2

sweat glands

Question 3

What is hair made of and what does it do?

Answer 3

fine, cylindrical keratin fibres
- insulates, protects and functions in sensory perception

Question 4

Ear structure and origin?

Answer 4

middle ear bones formed from leftover jaw bones
- allows detection of higher frequency sounds
- eardrum is better protected as it is deep inside the head

Question 5

What is the dentary-squamosal jaw joint?

Answer 5

Dentary (lower jawbone with teeth) and squamosal (small cranial bone) meet to form the haw joint
Articular and quadrate are reduced in size and incorporated into the ear

Question 6

Teeth structure and function?

Answer 6

• adapted for different functions reflecting diet
• occlude closer than reptiles allowing fine grinding which increases surface area and digestion of food
• 2 sets of teeth; milk teeth and adult teeth

Question 7

What is the significance of a larger brain?

Answer 7

more development of neurocortex for higher functions such as
- sensory perception
- motor commands
- language

Question 8

Other characteristics of mammals?

Answer 8

• limbs positioned vertically under the body for better support, enables more efficient movement
• diaphragm contributes to lung ventilation
• copulate using intromittent organ for internal fertilization
• viviparous
• synapsids

Question 9

Significance of palate-bone partition between nasal and oral cavity?

Answer 9

allows mammals to chew and breathe simultaneously allowing efficient food processing

Question 10

What are the 3 lineages of mammals?

Answer 10

Order Monotremata, Order Marsupiala, Clade Eutheria

Question 11

Monotreme characteristics?

Answer 11

• oviparous but provide milk to young after hatching
• no nipples, milk secreted from specialized hair patches
• have cloacas
• lack teeth as adults
• feed on invertebrates

Question 12

Shared derived traits of Theria?

Answer 12

Viviparous development
Placenta consisting of extraembryonic membranes and uterus lining
Post-birth nursing from nipples

Question 13

Placenta function?

Answer 13

Provides initial nourishment to embryo by exchanging nutrients, metabolic waste and dissolved gases between the mothers and embryos blood.

Question 14

Marsupial characteristics and embryo development?

Answer 14

• embryo development in placenta in uterus is brief
• born as partially developed embryos and complete development in marsupium (mothers pouch)
• nipples and milk glands are inside the pouch
• males and females possess cloaca

Question 15

Eutherian characteristics and embryo development?

Answer 15

• more complex placenta (shared, derived trait)
• embryos complete development in uterus and placenta provides nourishment throughout development
• post-birth young suckle milk from nipples
• separate urinary and anal openings

Question 16

4 clades of Eutherians?

Answer 16

Clade Afrotheria
Clade Xenartha (SA)
Clade Euarchontoglired
- Orders Primates and Rodentia
Clade Laurasiatheria
- hooved mammals, marine mammals, bats

Question 17

4 shared derived characteristics of primates

Answer 17

Hands and feet adapted for grasping
Large brain and short jaws
Forward-looking eyes positioned close together
Complex social behaviours

Question 18

How are primate hands and feet adapted?

Answer 18

thumb/big toe is separate from other fingers aiding in grasping
- monkeys and apes have opposable thumbs
- enable fine manipulation facilitated by flat nails

Question 19

How is primate vision adapted?

Answer 19

eyes provide depth perception critical for judging distances
- stereoscopic vision: field of vision from each eye overlaps
- vision increased, smell decreased

Question 20

What are the 3 main groups of primates?

Answer 20

Lemurs, lorises and bush babies
Tarsiers
Anthropoids - monkeys, apes and humans

Question 21

What are hominioids?

Answer 21

Non-monkey anthropoids commonly called apes

Question 22

Ape characteristics?

Answer 22

• diverged from Old World anthropoids
• lack tails and have large brains
• gibbons (lesser apes) and hominids (great apes)
  Great apes - orangutans, gorillas, chimps, bonobos, humans

Question 23

What are humans? Phylogeny and characteristics?

Answer 23

• member of genus Homo
• descended from great apes
• large brains and bipedal
• monophyletic
• chimps and bonobos are closest relatives

Question 24

4 shared derived traits of humans?

Answer 24

Upright posture and bipedal locomotion
Larger brains
Reduced jawbone and jaw muscles
Shorter digestive tract

Question 25

Where did hominins originate and Ardipithecus traits?

Answer 25

Africa
- bipedalism but small brains
- long arms and grasping feet for arboreal life

Question 26

What are some trends in hominin evolution?

Answer 26

• bipedalism
• expansion of brain and increased brain complexity
• pelvis modification
• reduction of teeth, face and jaws
• extended infant and child dependency
• increased hairlessness
• increased reliance on meat
• emergence of tool use

Question 27

Factors favouring bipedalism? (3)

Answer 27

• Large mammalian predators
• Compeition from terrestrial primates
• Change in habitat; decline in arboreal environmnts and expansion of open grasslands

Question 28

Adwantages and disadvantages of bipedaism?

Answer 28

Advantages:
- enhanced visibility of predators
- energy efficient locomotion for long-distance travel
- better thermoregulation in open habitats
- freed hands for carrying infants and tool use
Disadvantages:
- vulnerable to foot injuries
- increased strain on hips, backs, knees and ankles

Question 29

Skeletal adaptations for bipedalism? (5)

Answer 29

Skull attachment - repositioning of foramen magnum for balanced skull placement atop vertebral column
Spinal curvature to align weight over pelvis
Pelvis reconfigured to support internal organs in upright posture
Legs lengthened for efficient locomotion with larger knee hoints for weight support. Legs repositioned right underneath body
Narrower foot shape, enlarged heel and larger big toe for stability and propulsion

Question 30

Australopith characteristics?

Answer 30

• fully bipedal - short, bowl-shaped pelvis and aligned toes
• short, small brains, large and portruding jaws
• sexual dimoprhism
• tool use

Question 31

What are the 2 types of Australopiths?

Answer 31

Robust - sturdy skulls and powerful jaws
Gracile - slender with lighter jaws

Question 32

What is the earliest species in Genus homo and its characteristics?

Answer 32

Homo habilis
- larger brain capacity
- shorter jaw
- short in stature

Question 33

Homo ergaster characteristics?

Answer 33

• first fully bipedal and large-brained hominin
• long, slender legs and hip joints adapted for long-distance walking
• smaller teeth, shift towards increased meat consumption
• more sophisticated tools
• decrease in sexual dimorphism; pair-pair bonding and reduced male-male competition

Question 34

Homo erectus characteristics?

Answer 34

• first hominin species to migrate out of Africa
• hunter-gatherer societies
• ability to control fire; significant cultural and behavioural complexity
• larger brain

Question 35

Homo heidelbergensis characteristics?

Answer 35

• evolved from Homo erectus
• similar to Homo sapiens in body proportions, dental adaptations and cognitive ability
• large-animal hunter with sophisticated tools
• Neanderthals and Homo sapiens likely evolved from H. heidelbergensis

Question 36

Neanderthal characteristics?

Answer 36

• cold-adapted hominins
• robust physiques, thick bones
• complex behaviours such as burying the dead and crafting hunting tools
• smaller brains than Homo sapiens
• coexisted with Homo sapiens

Question 37

Homo Sapien characteristics?

Answer 37

• large brains
• increased behavioural complexity (symbolic, sophisticated thought, artistic carvings)
• originated in Africa
• little genetic variation