Title: ARCH2108 Animals, plants and people : The process, recognition and progress of animal domestication
1 ARCH2108Animals, plants and people
The process, recognition and progress of
animal domestication
2What is a domestic animal?
- Domestic animals may be provisionally defined as
those kept and bred in and around human
habitation to be used constantly to human
advantage. - Hemmer, 1983/1990
- A domestic animal is one that has been bred in
captivity for purposes of economic profit to a
human community that maintains complete mastery
over its breeding, organization of territory, and
food supply. - Clutton-Brock, 1981
3In its most developed form the domestic animal
exhibits four principal characteristics
- 1. Its breeding is under human control.
- 2. It provides a product or service useful to
man. - 3. It is tame.
- 4. It has been selected away from the wild type.
- Mason, 1984
- Zoo animals meet criterion 1, but not the others
- Working elephants meet criteria 2 and 3, not 1
and 4 - Do laboratory animals meet all criteria?
4Fully domesticated mammals have undergone
parallel changes
- Increased colour variability
- Paedomorphosis
- Brain reduction
- Docility
- Earlier maturation
- Verarmung der Merkwelt
5Merkwelt
- A concept proposed by
- Jacob von Uexküll (1864-1944)
- Estonian biologist, regarded by many as the
founder of ethology. - - An animals world is partitioned into its
- Umwelt - what it experiences (environment)
- Merkwelt what it perceives (knowledge)
- Werkwelt what it does (actions)
6Verarmung der Merkweltcan be translated
Impoverishment of the Perceptual World
- In Hemmers model, domestication is a process of
- selection for docility
- which in turn involves reduction of
- stress, behavioural flexibility, aggression,
activity patterns, sensory awareness - - in sum,
- impoverishment of the Merkwelt.
7- Catecholamines
- produced by nervous tissue and adrenal glands
- stress hormones
- (increase heart rate, blood pressure, muscle
strength and alertness). -
- The most important are
- adrenalin (epinephrine)
- noradrenalin (norepinephrine)
- dopamine.
-
- Melanins
-
- are produced by the same biochemical pathways as
catecholamines. - Can we predict a link between pelage colour and
stress susceptibility?
8Keeler (1975)Research with colour morphs of Red
Foxes (Vulpes vulpes)
- Wild type Silver Pearl Amber Non-agouti Non-ago
uti/ Non-agouti/ - black silver dilution dilution/brown
Body wt. Adrenal wt. Catecholamine products in
urine Flight distance
9D.K.Belyaev (1917-1985)
- Bred silver foxes (Vulpes vulpes) at the
Institute of Cytology and Genetics in
Novosibirsk, western Siberia, Russia - Selected them only for tameness
- Phenotypic and physiological changes were
obtained as by-products
10Tame silver foxes
(About 18 generations)
11Phenotypic changes
Homozygous White Spotting (SS) About F8-10
12Belyaevs fox line also developed
- Curly tails
- Drooping ears
- Out-of-season breeding activity
- Longer moulting time
13Paedomorphosis
- Retention of juvenile characters into the adult
stage - Short face
- Broader skull
- Increased kyphosis (basicranial flexion)
- In cattle shorter, less inturned horns
- In sheep and goats shorter horns, even absent in
female - Playfulness
- Other juvenile behaviours barking in dogs,
kneading in cats
14Brain reduction
- Domestic species have brains reduced compared to
their wild ancestral species - Different domestic species or even breeds have
different degrees of size reduction - A few dog breeds have been selected for
re-enlargement
15Measuring brain size reduction
- On whole body samples
- Weigh body and brain
- Graph brain weight against body weight (usually
double logarithmic) - On skulls
- Measure cranial capacity (endocranial volume
ECV) - Take cube root
- Graph it against a size standardisation measure
- Calculate difference between intercepts of wild
and domestic samples
16Example camels
wild
Cube root of ECV
Domestic Bactrian
Domestic Arabian
Basal skull length
17Percentage brain size reductions(brain vs body
weight method)according to the Kiel school
- Laboratory mouse 0
- Laboratory rat 8.7
- Guinea pig 5-7 (different studies)
- Cat 23.4
- Ferret 32.4
- Dog 29-34 (different studies)
- Pig 33.6
- Sheep ca 30
- Llama and alpaca 19.0
18The Kiel school(Institut für Haustierkunde,
Kiel)Herre, Röhrs, Ebinger, Kruska, Fischer
- pool all wild specimens to calculate the
allometric slope and intercept for the wild
ancestral stock - Hemmer
- keeps samples from different wild populations
separate, and calculates slope and intercept for
just the population supposed to be the source of
the domestic form
19hence -
- Cat
- 23 reduction (Herre Röhrs, 1973)
- (recalculated as 18 by Röhrs Ebinger, 1978)
- 10 reduction (Hemmer, 1976), using just North
African/Middle Eastern wild cats as baseline - Dog
- 234 reduction (Herre Röhrs, 1973)
- (recalculated as 29 by Röhrs Ebinger, 1978)
- 10 reduction (Hemmer, 1976), using just North
Middle Eastern wolves as baseline
20Different regions of the brain have been
differentially reduced
- Forebrain Corpus Midbrain Cerebellum
Medulla - callosum
- Rat 10.1 6.3 3.8 5.7 3.6
- Cat 26.0 - - - -
- Dog 35.0 31.0 19.0 32.0
23.0 - Ferret 36.8 32.7 17.4 23.9
16.0 - Pig 36.0 32.6 26.1 26.0
24.6
21So, of total brain reduction -
- 71 (rat) to nearly 80 (others) is due to
forebrain, mainly neocortex - 7 is due to corpus callosum
- 2-3 is due to midbrain (primary sensory
stations) - 13 (rat) but only 9-10 (others) is due to
cerebellum (balance and muscular coordination) - 5.6 (rat) but under 4 (others) is due to
medulla
22Kruska (1980) measured reduction of different
sensory regions of the neocortex in pigs
- Sensory centres reduced in the order
- Optic
- Acoustic
- Olfactory
- Amygdala (concerned with rage control) reduced by
29 (somewhat more than olfactory bulbs)
23Feral populations have not increased brain size
- Cats
- Rabbits
- Ferrets
- Dogs, including dingos
- Pigs
- Goats
- Relative brain size can therefore be used as a
test for whether a wild-living population is
truly wild or feral
24Features favouring domestication in a wild
species (Hale, 1962)
- Group structure
- Large social groups, hierarchical structure,
males affiliated with female groups - Not territorial
- Sexual behaviour
- Promiscuous matings
- Male does not have to establish dominance over
female - Not monogamous
- Sexual signals behavioural, not morphological
25Features favouring domestication in a wild
species (continued)
- Parent-young interaction
- Precocial
- Defined imprinting period
- Female accepts other infants
- Responses to humans
- Short flight distance
- Tolerant to environmental changes
- Other
- Adaptable
- Unspecialised diet
- Limited agility
26Examples from Middle East
Why domesticate
- and why not
Goat?
Ibex?
or oryx?
or sheep?
or even gazelle?
27Comparison between those which were domesticated
and those which were not
- Sheep and goats
- Group size 10-20
- Hierarchies
- Leadership
- Males often part of female groups
- Form tending bonds when mating
- Short flight distance
- Very environmentally tolerant
- Generalised diet, wide adaptability
- Fair to low agility
- Foster abandoned infants
- Ibex, oryx and gazelle
- Group size 9-45
- Non-hierarchical
- No marked leader roles
- Males part of female groups in ibex, oryx not
gazelle - Mate in harems (ibex) or lek (oryx, gazelle)
- Long flight distance
- Ibex environmentally tolerant oryx, gazelle not
- Adaptable (ibex), specialist (oryx, gazelle)
- High agility
- Do not foster (ibex uncertain)
28But why the Ass and not the Onager?
Wild ass Equus africanus
Onager Equus hemionus
29Wild asses and onager both - live in
female-young herds - males are territorial -
mate in leks - are very agile - but
- Wild ass
- Short flight distance
- High environmental tolerance
- High dietary adaptability
- Onager
- Long flight distance
- Nervous, temperamental, specialized habitat
- Dietary specialist
30How did they come to be domesticated
anyway?Zeuners model
- Scavengers - pig, dog, duck
- Social parasites - reindeer, sheep, goat
- Crop-robbers - cattle, buffalo, elephant,
rabbit, goose - Pest-destroyers - cat, ferret
- Transporters - horse, ass, camelids
- - plus those that were systematically
domesticated - fowl, hyaena, ostrich, mouse, rat, canary
31Zeuner (1963) proposed that there were 6 stages
in the domestication of a species
- Loose ties species is essentially wild
- Captivity restriction of contacts with wild
population - Intentional breeding for tractability
- Planned development bred for economic and other
characters, development of breeds - Elimination of the wild species as competitors
32How can we tell if a set of remains are from wild
or domestic?
- Size changes
- Most domestic species are smaller than their wild
relatives (except for some specialized breeds) - BUT
- At end of Pleistocene there was a rapid size
reduction in most large mammals anyway
33How can we tell if a set of remains are from wild
or domestic? contd.
- Demographic changes
- Domesticators slaughter high proportion of
juveniles for meat and to keep the milk for
themselves (and most juvenile males, to select
high-quality stud breeders), so samples will have
a high proportion of immatures - BUT
- Wild predators select their prey to much greater
extent than is often realized, so natural kills
may be skewed towards immatures too.
34How can we tell if a set of remains are from wild
or domestic? contd.
- Changes in bone structure
- Daly, Perkins Drew (1971) claimed that, in
metapodials, tali, phalanges and scapulae,
domestic animals have more abrupt transition
between compact and spongy bone -
Wild (Suberde)
Domestic (Erbaba)
Sections of distal articular surfaces of goat
metapodials
35- and that the trabeculae are thinner, the
lacunae more rectangular.
Sheep tali
- BUT
- Daly et al.s material is archeological the
model is not tested on recent samples. - Soil conditions might have played a part.
- Watson, 1975
Domestic
Wild
36Centres of Origin
6
7
9
1
8
2
3
4
5
37Middle Eastern theatre of domestication
Cattle Sheep Goat Arabian camel? Pig Wild
ass? Cat?
Zagros
Mesopotamia
Anatolia
Levant
Lower Nile
38Southeast Asian theatre
Buffalo Mithan? Pig
Pig
Banteng Pig
39Central and South Asian theatres
Horse Bactrian camel
Yak
Humped cattle
40And, presumably, Spain
Rabbit Ferret?