Animal Domestication Dr. Carlos A. DriscollHorse Camel Animal Domestication Dr. Carlos A. Driscoll The screen versions of these slides have full details of copyright and acknowledgements

Animal Domestication

Dr. Carlos A. Driscoll

1The screen versions of these slides have full details of copyright and acknowledgements

1



WWF Chair in Conservation Genetics,

Wildlife Institute of India, Dehradun

2

Simple questions

• Evolutionary context of domestication

– Where did it take place?

– When did this happen?

– Who domesticated animals?

– Why did they do it?

– What is domestication?

– How did it come about?

•Neo-Darwinian domestication

3

Selection by natural means, “the survival of the fittest”

was not just plausible or possible, but probable




4

5

6




7

8

9

World population since 10,000 BC




10

Animal domestication events

DonkeyCow, pig

Turkey,

duck

Llama, alpaca,

guinea pig

Goat, sheep,

cow, pig

Pig, chicken,

water buffalo

11

• Sedentism

• Social complexity and stability

– Band: a small, highly mobile egalitarian society based on hunting and gathering and characterized by a lack

of formal governmental institution and economic specialization. Political dominance is gained through achieved

leadership rather than ascribed leadership; as many leadership positions exist as circumstances call

for and there are qualified persons to fill them

– Tribal society: is an egalitarian society larger and more complex than a band and often sedentary, that practices

either hunting and gathering or food production and has politically autonomous communities. Political dominance

is gained through achieved leadership rather than ascribed leadership, and sodalities are important in integrating

the social system

– Civilization: a complex sociopolitical form defined by the institutions of the state and the existence of a distinctive

“great tradition” (sets of elite values and behaviors that emerge from folk traditions and that are expressed

in distinctive rituals, art, writing, or other symbolic forms)

– State: a stratified society that has developed the institutions for effectively upholding an order of stratification.

States are strongly territorial, with complex, well-defined political leadership, hierarchies of settlement,

and often elaborate and highly specialized bureaucracies

• Accessibility to useful wild plants and animals

• Complex before others

The domesticating society

(Council of Biology Editors, 1994)

12 Terminal Pleistocene, more than 12,000 years ago

Barley

Einkorn

Emmer wheat

Pea

Chick pea

Lentil

Flax

Bitter Vech

Wild einkorn Wheat

12




13

14

15

Cow

Goat

Sheep

Pig

Barley

Einkorn

Emmer wheat

Pea

Chick pea

Lentil

Flax

Bitter Vech

Fig

Olive

�Horse

Camel

�

15




16

17

Goats

11,000

10,500

10,000

11,000

9,500 – 9,000 BP

10 - 11,000

Wild barley

Wild einkorn Wheat

Wild emmer

wheatFig

Olive

• Raising one’s own food required farmers

to stay in one place year round, forever

− Accumulation of goods

− Division of labor

− Stable platform for an intensification of selection

Cattle

Sheep

Pigs

17

18

Six criteria were first outlined in Francis Galton’s 1865 paper

‘The First Steps Towards the Domestication of Animals’

1) They should be hardy

2) They should have an inborn liking for man

3) They should breed freely

4) They should be found useful to the savages

5) They should be comfort loving

6) They should be easy to tend

‘Good’ domesticates - 1865




19

1) Flexible diet (Hardiness)

2) Good disposition (Inborn liking of Man)

3) Breed in captivity (Breed freely)

4) Comparatively fast growth rate (Useful)

5) Fair temperament, no panicking (Comfort loving)

6) Modifiable social hierarchy (Easy to tend)

‘Good’ domesticates – today (1)

20

21







7) Commensal initiative





2222

23







7) Commensal initiative


24

• Natural selection

– Process by which favorable heritable traits become more common

in successive generations of reproducing organisms, and unfavorable traits

become less common, due to differential reproduction of genotypes

• Sexual selection

– Intraspecific competition driven by the "struggle between the individuals

of one sex, generally the males, for the possession of the other sex”

• Artificial selection

– Selective breeding

Evolution today




25

•Natural selection

– Sexual selection


– Methodical

– Unconscious

Darwin’s view

26


– Methodical

� Intentional progress towards

a preconceived ideal

– Unconscious

� Unintentional changes

resulting from management

or interaction

Darwin’s view (2)

27


– Methodical

– Unconscious

– Weak

� Post-zygotic,

as in natural selection

– Strong

� Pre-zygotic




28

Darwin’s view (3)


− Methodical

− Unconscious

− Only humans

29

“Mr. Wallace … argues that man,

after he had partially acquired those

intellectual and moral faculties which

distinguish him from the lower animals,

would have been but little liable to bodily

modifications through natural selection

or any other means. For man is enabled

through his mental faculties “to keep

with an unchanged body in harmony with

the changing universe.” He has great

power of adapting his habits to new

conditions of life. He invents weapons,

tools, and various stratagems to procure

food and to defend himself. When he

migrates into a colder climate he uses

clothes, builds sheds, and makes fires;

and by the aid of fire cooks food

otherwise indigestible”

30

Pathways to animal domestication

• Commensalism – natural selection

• Traditional barnyard – unconscious/methodological

(artificial selection)

•Modern agribusiness – methodical

• Exploited captives – little to no selection

e.g. domestication of wolves




31

In genetic terms:

• The ongoing process of domestication is a form of evolution

• This process of changing population allele frequencies

over generations is applied to modifying organisms

such that they more readily accept human contact and control

• Domestication happens to populations, not to individuals

What is domestication? (1)

32


• Not an either/or game. Differs by species

• Phenotypic commonalities among domesticates include:

Dwarfs and giants

Piebald coat color

Reproductive cycle changes

Wavy or curly hair

Rolled tails

Shorter tails, fewer vertebrae

Floppy ears

Living with people/lack of fear

• Physiology, morphology and behavior

are an interconnected suite of traits

33

• Lack of fear of people

A heritable predisposition to tameness





34


A heritable predisposition to tameness


35



– A heritable predisposition to tameness

• Phenotype = genotype + environment

– Like other effects, domestication (phenotype) is influenced by genes

(genotype) and environment, and their interaction

• Like language

– Genes predispose us to learn language,

but nothing says we have to learn language

– Developmental window for learning language best

– Environment determines what language we speak

36

Innate

fear

Group

status

Fear

of exposure

Social ordering?

Generalized

fear/vigilance

Self

image

Fear

of disease

Domestication represents a suite of behaviors


…and a suite of genes




37

• Lack of fear of people through individual taming

• A cultural process

Culture is the transmission of behaviors or ideas

from one individual to another through learning

• Domestication did not come about through the individual

taming of captured animals or from the learned acquisition

of a ‘culture of domestication’

• It came about as a consequence of differential survival

and reproduction in a population

What is domestication NOT?

38

• 130 founders from farm population

– 30 males, 100 vixens

• The standard test includes five steps:

1) Observer approaching fox cage

2) Observer stays near closed cage

3) Observer is near open cage but does not initiate tactile contact

4) Tactile contact

5) Observer stays near closed cage

• Selection only for tameness; 5% males, 20% females

• Restricted human contact

Belyaev and Trut initiate Fox-Farm experiment in 1959

39

• Dramatic changes after 8 - 10 generations, almost 20% of foxes

were ‘tame’ and sought out human contact; By 20 generations

up to 35%

• Coat color changes

• Floppy ears

• Curled tails

• Estrus cycle change

•Mating behavior

• Highly social

Results of fox farm experiment




40

41

42

• Domestication is in fact heritable

•Morphological traits recapitulated by selection on behavior

• Genetic variation present in ‘wild’ population prior

to any selection for domestication

• A master set of 10 to 20 genes? Obviously pleiotropic

Some implications of the fox farm experiment




43

A digression on domestication

• If the animals in Africa are just as appropriate to domesticate…

•Why don’t we find widespread domestication

of African animals?

•Why did sedentism first arise in the Near East?

Historical efforts to domesticate new species failed

because they didn’t start from a wide enough genetic base,

and didn’t pursue selection efforts appropriately

44

Destabilizing selection

• “Selection for tame behavior seems to result in breaking up

previously integrated ontogenic systems and thus lead

to multiple phenotypic effects that seem genetically unrelated

to the selected character, namely tame behavior”

• “Destabilizing selection could break up normal patterns

of gene activation and inhibition and result in a great increase

in the range and rate of hereditary variation,

which again is subject to specific selective forces”

45

Evolvability

• Capacity of a system to evolve

• Depends on amount of variation open to selection

• Type of variation

• Tied to physiology




46

BSC

• Species: groups of actually or potentially interbreeding populations

that are reproductively isolated from other such groups

– Most species occupy distinct ecological niches

which is the keystone of evolution

• Subspecies: a geographically defined aggregate of local populations

which differ taxonomically from other subdivisions of the species.

Subspecies are reproductively compatible

– Evidence should include concordant distribution of multiple,

independent, genetically based traits. Members should share

a unique geographic range or habitat, a group of phylogentically

concordant phenotype characters, and a unique natural history

Mayr, 1940; O’Brien and Mayr, 1991

47

Behavioral genetics

Seeks to understand the roles of genetics and the environment

in forming individual behavioral variation

• It is difficult to define the behavior in question

• It is difficult to measure the behavior

• Heritability is influenced by environment

(ecophenotypic variability)

• Behaviors are complex traits involving multiple genes

– Pleiotropic, epistatic

48

References and further reading

• Salamini, F., H. Ozkan, et al. (2002). "Genetics and geography of wild cereal domestication

in the near east." Nat Rev Genet 3(6): 429-441

• Smith, B. D. (1995). The emergence of agriculture. New York, Scientific American Library:

Distributed by W.H. Freeman

• Trut, L. N. (1999). "Early Canid Domestication: The Farm-Fox Experiment."

American Scientist 87: 160-169

• Kukekova, et. al., (2008) Genome Research, 17 (3): 387-399

• Driscoll, C. A., D. W. Macdonald, et al. (2009). "From wild animals to domestic pets,

an evolutionary view of domestication." Proc Natl Acad Sci U S A 106 Suppl

• Driscoll, C. A. and D. W. Macdonald (2010). "Top dogs: wolf domestication and wealth." J Biol 9(2): 10

• Andersson, L. and M. Georges (2004). "Domestic-animal genomics: deciphering the genetics

of complex traits.“ Nat Rev Genet 5(3): 202-212

• Driscoll, C. A., J. Clutton-Brock, et al. (2009). The Taming of the Cat. Scientific American. 300: 68-75

• Driscoll, C. A., M. Menotti-Raymond, et al. (2007). "The Near Eastern origin of cat domestication."

Science 317(5837): 519-523.

• Lindberg et al., Current Biology vol 15 no 22




49

References and further reading (2)

• Dawkins R (2003) The evolution of evolvability. On Growth, Form and Computers: 239–255

• Dawkins, R., 1989, The evolution of evolvability, in: Artificial Life, C. Langton (ed.) (Addison Wesley,

Santa Fe NM) pp. 201-220

• Galton, 1865 The first steps towards the domestication of animals. Transactions of the Ethnographical

Society of London Vol. 3 1865 p.122-128

50

Documents

Animal Domestication Dr. Carlos A. DriscollHorse Camel Animal Domestication Dr. Carlos A. Driscoll The screen versions of these slides have full details of copyright and acknowledgements