13. Human evolution

Question 1

Features of mamals

Answer 1

• 4-chambered heart
• mammary glands - parental care
• endothermic - with hair/fur
• most mammals - a placenta to feed the young in the mother

Question 2

Who are the 2 primate ancestors?

Answer 2

• plesiadapids

* adapids

Question 3

Adapids

Answer 3

• 1st true primates
• tree living
• nail instead of claws
• opposable toes and thumbs
• forward facing eyes
• fed mostly on insects and fruit

Question 4

Plesiadapids

Answer 4

• coexisted with dinosaurs
• lived in trees
• squirrel like
• claws, big incisor, small brains
• evolved into adapids

Question 5

Prosimians

Answer 5

• wet-nosed primates
• least specialised primates
• binocular vision
• much of brain is nasal area
• smaller brain and body mass

Question 6

What features do animals need for leaping in trees?

Answer 6

• binocular vision
- judge distance

• large brain for decisions
- control of locomotion and visual processing

• grasping digits (not paws)
- opposable thumbs

• upright posture
• smell not v. useful - reduced nose length

Question 7

What are the 2 main branches of primates?

Answer 7

• strepsirrhines: wet-nosed primates (least specialised)

* haplorrhines: dry-nosed primates

Question 8

How many groups of primates are there?

Answer 8

eight

Question 9

What are the eight groups of primates?

Answer 9

1. lemurs
2. lorises
3. tarsiers
4. new-world monkeys
5. old world monkeys
6. gibbons
7. orangutans
8. african apes and humans

Question 10

What groups are strepsirrhines?

Answer 10

Wet nosed (least specialised)
• lemurs
•lorises

a.k.a prosimians

Question 11

What groups are haplorrhines?

Answer 11

• tarsiers
• new world monkeys
• old world monkeys
• gibbons
• orangutans
• african apes and humans

a.k.a anthropoids

Question 12

What are tarsiers?

Answer 12

• intermediate primate species with species from both prosimians and anthropoids
• eyes bigger than brain
• grooming claw
• furry nose
• carnivorous - others are usually omniverous

Question 13

Examples of new world monkeys

Answer 13

• spider monkey
• tamarin
• howler monkey

Question 14

Examples of old world monkeys

Answer 14

• Gelada
• Colobus
• Baboon

Question 15

Lesser apes examples

Answer 15

• gibbon

Question 16

Great-apes

Answer 16

• orangutan

Question 17

What are humans’ closes common ancestors?

Answer 17

• chimpanzees
• social
• intelligent
• knuckle walkers

Question 18

What are some skeletal changes that occurred due to erect posture?

Answer 18

• arched feet
• arm length proportional to legs
• S-shaped spine
• bowl shaped pelvis
• femur angled inwards
• toes facing forwards - can walk for longer times

Question 19

New world monkeys

Answer 19

• tropical south america
• all tree dwelling
• prehensile tail (adapted to grasp or hold objects)

Question 20

Old world monkeys

Answer 20

• tropical africa and asia
• tail never prehensile
• more diverse habitats - some on ground

Question 21

Define prehensile

Answer 21

Capable of grasping

Question 22

What are the features of parenting in most mammals?

Answer 22

• birth trigger hormone oxytocin
• triggers mother to bond to infant’s smell, starts lactation
• vasopressin (similar hormone) - bonds males to smell of female

Question 23

What are the features of parenting in simians?

Answer 23

• reduced smell
• parental care lasts beyond lactation
• young females learn complex parenting skills - not just hormones controlling parents
• tactile relations release the reward hormone (Beta-endorphin) which reinforces bonding

Question 24

How long ago did we diverge from chimpanzees?

Answer 24

•diverged from humans only about 7-8 mya