Domestication: Dogs

Question 1

Dogs closest relative

Answer 1

Grey wolf (canis lupus)

Question 2

Did humans domesticate grey wolves of were dogs already dogs?

Answer 2

Dogs were already dogs
Dogs were domesticated before humans transitioned to agricultural societies
Dog was the first domesticated species

Question 3

Evolution of dogs:

Answer 3

60mya: Miacis
30-40mya: Cynodictis
40,000ya: Diverged from grey wolves

Question 4

What were the distinguishing factors of Cynodictis? (3)

Answer 4

1) Elongation of the limbs/feet -> running
2) Carnassial teeth specialized for shearing
3) Expanded cranium(+brain) -> intelligence

Question 5

Domestication (definition)

Answer 5

“process of developing a mutually useful relationship between animals and humans”

• Create reproductive isolation
• Driven by economic advantage

Question 6

6 Domestication criteria

Answer 6

1) Flexible diet
2) Reasonable growth rate
3) Breed in captivity
4) Pleasant disposition
5) Steady temperment
6) Modifiable social hierarchy

Question 7

6 similarities between dogs and humans which led to their domestication?

Answer 7

1) Hierarchical order
2) Work co-operatively
3) Strong kinship ties
4) Suspicious of outsiders
5) Care for + protect young even if not their own
6) Refined ability to interpret moods

Question 8

What is the reasoning for dogs being able to read human emotions as well as they do?

Answer 8

1) Left Gaze Bias
- Right side of human faces are better at expressing emotional state
2) Finger Pointing
- humans point at something, and dog looks

Question 9

Molecular level of dog domestication

Answer 9

• Dogs have upregulation of amylase gene (4-30 copies, wolves have 2)
• Eye contact stimulates oxytocin release in dogs and humans

Question 10

Belyaev’s Experiment

Answer 10

Silver foxes (1979)

• 20 generation of breeding, foxes sought contact with people, lick hands/faces, whine, wag tail, etc
• retention of juvenile fox traits (paedomorphosis)
• Pleiotropy

Question 11

Paedomorphosis

Answer 11

Retention of juvenile traits into adulthood

Question 12

Pleiotropy

Answer 12

One gene affects several others

Question 13

What are the roles of neural crest cells in domestication?

Answer 13

• Pathologies in neural crest cells led to ne phenotypes
• Caused many sources of variation in behavour, integument, and facial skeleton
• Mutations in SorCS1 can lead to behavioural disorders which are involved with synapse function

Question 14

How old the modern day dog-breeds?

Answer 14

No more than 500yrs old

Most about ~150 years ago