Domestication: Horses

Question 1

Which structures of the horse do we look at in terms of evolutionary purposes?

Answer 1

1) Teeth

2) Limbs

Question 2

Evolution of horse limb

Answer 2

Move away from pentadactyl limb

Only have one metacarpal

Question 3

Evolution of horse teeth

Answer 3

Ever erupting teeth

Question 4

Horse Evolution: General facts

Answer 4

All other species extinct
Earliest: 55mya
Most species evolved in NA
Modern horses belong to the genus Equus

Question 5

Genus’ of ancestral horses (9)

Answer 5

1) Hyracotherium
2) Orohippus
3) Mesohippus
4) Miohippus
5) Parahippus
6) Merychippus
7) Pliohippus
8) Dinohippus
9) Equus

Question 6

Genus Hyracotherium

Answer 6

Oldest known ancestor (55mya)
- Teeth: 3 incisors, 1 canine, 4 premolars, 3 molars
- Feet padded
- Forelimb: Digits II-V weight bearing 
                   Digits I vestigial 
- Hindlimb: II-IV weight bearing 
                   I+V vestigial

Question 7

Genus Orohippus

Answer 7

52-45mya 
Co-existed with Hyracotherium
Teeth: Crests more pronounced to grinding
Feet padded 
Forelimb: 4 digits
Hindlimb: 3 digits

Question 8

Genus Mesohippus

Answer 8

37-32mya
Teeth: 3 premolars (shaped like molars)
3-digits on each forelimb and hindlimb
- legs proportionally longer

Question 9

Genus Miohippus

Answer 9

32-25mya
Extra crest on upper molars
No difference in feet - still 3 “toes”

Question 10

Genus Parahippus

Answer 10

24-17 million years ago
Last evolutionary link between ancestral forest dwelling horses and derived plains-dwelling grazers
- 3rd digit larger, stronger, carries majority of body weight
- Elongated skull

Question 11

Genus Merychippus

Answer 11

17-11mya
First to look like a modern horse
High-crowned cheek teeth
- first known grazing horse

Question 12

Genus Pliohippus

Answer 12

12-6mya
3 digits present, medial and lateral barely visible stubs
“grandfather” of modern horse

Question 13

Genus Dinohippus

Answer 13

13-5mya

Closest relative to genus Equus

Question 14

Genus Equus

Answer 14

Only surviving genus
2 species of modern wild horse:
- Tarpan, extinct~1919
- Przewalski horse

Question 15

Modern domestic horse

Answer 15

Equus caballus

Question 16

How many founder stallions and mares were needed to explain mtDNA in current horse population

Answer 16

1 stallion

77 mares

Question 17

When/where/ how many times did domestication take place?

Answer 17

When? 3500-3000BC
Where? Eurasian Steppes (Kazakhstan)
How many times? Once

Question 18

Evidence for domestication of Horses (2)

Answer 18

1) Fatty lipids of horse milk found inside pots

2) Indicative bit wear on horse teeth

Question 19

The “Thoroughbred Gene”

Answer 19

SNP change from Thymine to Cytosine

- influences speed

Question 20

Types of “thoroughbred” gene and what are they best suited for?

Answer 20

C/C: Best suited to fast, short-distance sprints
C/T: Best in middle-distance races
T/T: Have better stamina (long distance)