2 Artificial Selection

Artificial Selection Domestication & Breed Development

Domestication Def. – wild species that becomes acclimatized to breeding and surviving in captivity  Reasons for Domestication 

 Food

source  Labor  Companionship

To Succeed with Domestication   

Adapt to environment Provide nutrition needs Meet social requirements  Must 

consider typical social organization of species

How to young learn to be adults

 Problems  



Vices, Aggression Impotence, Infanticide

Able to reproduce

Domestication of the Horse 

23,000 B.C.  Southern

France – archeological site  Food – cracked bones of as many as 100,000 horses

Start of Primitive Agriculture – 4500-3500 B.C.   

Less nomadic Depletion of local herds Domestication    



Means of dependable food supply Taming by-product of hunting Orphaned foal 2-12 months of age Adopt, raise and put to work

Ex. Turkestan – Turkmenes   

Lived on mare’s milk and horse meat - Raised fillies/ate colts Tethered mares in season for wild stallions to breed Earliest selection criteria – Milk Production

Domestication of the Horse 

Ass, Onager & Camel domesticated before the horse 



3000 B.C. drawings of Onager being ridden with a nose ring and jaw strap

Horse domesticated in numerous areas during similar time period 

3000-2300 B.C.

Signs of Domestication 

Caves of Sumeria (Perisian Gulf) – 2800 B.C.  First

signs of selective breeding  Drawings of horse heads in 4 horizontal rows  Different head profile types (convex, straight, concave) and mane types (erect, hanging and maneless) 

Central Asia – 2800 B.C.  Drawings

of horses hitched wearing snaffle-type bits

Signs of Domestication 

Jarrestad, Sweden – 3000 B.C.  Drawings

of mounted men on Tarpan-like and Przewalski-type horses using reins for control (Gotland and Fjord breeds?)  Kivik, Sweden – 2300 B.C. 



Horses and Charioteers

China & Mongolia – 2500 B.C.  Drawings

of horse at work and warfare

Earliest Selective Breeding 

Temperament  Those

that refused to obey returned to wild or used for meat  More agreeable animals remained in comparative safety of captivity  Bred to other docile animals to produce goodtempered foals

Earliest Selection Criteria 

Learning Ability - Trainability  Horse  

transferred reliance to man

Food, protection and companionship Learned to overcome fears –hunting lions, tigers, etc.

 Xenophon

– 430 B.C. – first recorded advocate of training by reward.

Other Traits 

Speed and Survivability  Withhold

water for several days  Release herd pointed in the direction of water  First to arrive were selected for breeding and training

Man Alters the Horse Flight Instinct  Confinement 

 No

longer a wandering grazer  Some adjusted less well - Stable vices 

Modification in Diet  Resulting

digestive problems

Man Alters the Horse 

Orthopedic Problems  1000

B.C. – Xenophon first asserted “no foot, no horse”  500 B.C. – Persians develop first ‘horseshoes’ – heavy cloth 

Other problems  Occurrence

of genetic abnormalities  May select beauty over functionality 

Small, dainty hooves

 Selection

versatility 

Breeds

criteria for performance reduced

Breed Development Breed = group with distinctive characteristics that are transmitted to their offspring.  Initial development through natural crosses and artificial selection 

 Environment

– important role  Adaptations of the 4 original types 

Results in many breeding groups

Breed Development 

Distinctive Characteristics  Extremes

in Climate, Topography and Vegetation  Conformation  Color  Performance 

Skills and Abilities – well promoted by breed advocates

 Intelligence  Disposition  Suitable  gaits

to Man’s Purpose

Formal Development 

Man bred early types to fix certain desirable characteristics  Little 

change if type was suitable

pony breeds are relatively pure – almost direct descendants of one early type

 Some

breeds took centuries

Outcrossing with numerous other breeds  Easiest to develop if trait can be fixed (set)  Get desirable and undesirable characteristics set 



One sire may have strong prepotence – good and bad

Genetic Evidence 

DNA of ancient wild horses found in permafrost  Sweden

& Estonia – 2000yr old remains, Alaska – 28000 yr old remains  Analyzed the mitochondria DNA 

Mutations occur at a known rate = molecular clock

 Maternal  

ancestry traced

Tested against 600 living horses From 25 breeds worldwide

Genetic Evidence Shows 

 

Minimum of 77 wild mares have been incorporated into the breeding stock at domestication Genetic diversity among the domestic horse is extensive Other major livestock species have a narrow genetic basis  Limited

number of wild populations  Limited number of geographic regions