lecture 4 Flashcards
CULTURAL MODELS
“Aggrandizer” Model (B. Hayden):
- Occurs in regions of plenty
Human predisposition for acquisition and power
“Triple A” personalities:
Ambitious, Abrasive, Aggressive, Accumulative,
Aggrandizing
Domestication emerges as a strategy to
increase surpluses, wealth and power.
-argues that domestication is both biological and cultural
DO WE REALLY NEED ONE UNIFYING THEORY?
‘Neolithic transition’:
‘Neolithic transition’: Now recognized to be a more protracted
process
Move away from
deterministic models
‘Complex multi-scalar
regional puzzles’
(Zeder 2006)
Recognition of multiple
domestication areas
EVIDENCE OF INTENSIFICATION: Broad Spectrum Revolution - Push
’Low ranked’ items of food
Small(er) game, small seeded plants,
processing time
Enhanced processing of available resources
Marrow & grease processing
High proportions of juvenile animals
Fewer prime-age individuals
Reduction in the physical size of prey
Largest animals have been overhunted
EVIDENCE OF INTENSIFICATION: Risk Aversion - Pull
’Low ranked’ items of food
Small game and seeds more abundant and predictable
Enhanced processing of available resources
High utility bones left at kill site to reduce transport costs
High proportions of juvenile animals
Evidence of a growing and healthy prey population
Reduction in the physical size of prey
Associated with climate change not overhunting
CENTRAL QUESTIONS IN DOMESTICATION
Where? Origins, centres and number of domestications, diffusion
How? Domestication pathways, genes under selection
Why? Motivations for domestication, environmental/economic/cultural factors involved
DEFINING DOMESTICATION
- Intentionality
- balance of power
- locus of change
ANTHROPOCENTRIC DEFINITIONS
Domestication often defined as a point when a particular threshold was met in the human-animal/plant relationship.
Focus on the capture and taming of animals by humans, their separation from the wild population, and their reliance on humans for their maintenance
Plants and Animals have passive role: “Domestication is not a natural state – it exists** because humans (and not animals) wished it”** (Ducos 1989:29)
Domestic animals are “bred in captivity for the purposes of **economic profit to a human community **that maintains complete mastery over its breeding, organization of territory, and food supply”
“Domestication exists when (and only when) living** animals are integrated as object**s into the
socio-economic organization of the human groups, in the sense that, while living, those animals are objects for ownership, inheritance, exchange, trade, etc., as are the other objects
(or persons) with which human groups have something to do”
BIOLOGICAL DEFINITIONS
Domestication strictly (co-)evolutionary process – no consideration for human intentionality (Morey 1994)
- we also become domesticated dependent of these animals for confort/economic/food our culture changes for them as well
Changes in plant and animal morphology, physiology and behaviour are a result of new selective niche (i.e. human environment)
Focus on symbiosis & mutualism
‘Domestication’ open to non-human organisms
-ex:Ant-herding and aphids
-ex: Fungus-growing ants
A WORKING DEFINITION….
Domestication is a sustained multigenerational, mutualistic relationship in which one organism assumes a significant degree of influence over the reproduction
and care of another organism in order to secure a more predictable supply of a resource of interest, and through which the partner organism gains advantage over individuals that remain outside this relationship, thereby benefitting and often increasing the fitness of both the domesticator and the target domesticate.
Defined by the relationship, not the outcome!
DOMESTICATION VS MUTUALISM
Mutualism - Both species benefit:
* Plants/animals increase reproductive fitness
* Humans gain predictable resource base
Domestication is ‘goal-oriented’ –Initiated and sustained by humans
Choice of particular variants
Continue, intensify, or leave the relationships
Consciously manipulate partner species
DOMESTICATION IS STILL HAPPENING!
NEW SELECTIVE PRESSURES
Process of domestication fundamentally involves a new set of ‘selective’ pressures resulting from human intervention
Fundamental similarities to ‘Natural Selection’ as plants and animals adapt to the new ‘human’ environment
NATURAL VARIATION
Variation in a population is an essential component of both natural and artificial selection.
Variation is heritable - genotype
Selection acts on the phenotype
-phenotypes : Individual observable characteristics resulting from the interaction of the genotype with the environment
ex: genotypes; white fur
ex:phenotype : black fur to comuflage
SOURCES OF GENETIC VARIATION
Mutations: changes in DNA – detrimental, beneficial or neutral
Gene flow: movement of genes from one population to another
(i.e. migration, hybridization)
Sex: new gene combinations into a population though sexual recombination
Epigenetics: phenotypic trait variations caused by external or
environmental factors that regulate gene expression
-No change in the DNA sequence
-ex:
NATURAL
SELECTION
Process by which heritable traits that
make it more likely for an organism to
survive and successfully reproduce
become more common in a population over successive
generations.
FITNESS
** ‘Fitness’:** the genetic
contribution of an individual
to the next generation’s
gene pool
ex: a blind lap dog who has many puppies, eight of which live to adulthood - **as many of spring as possible **
‘Inclusive fitness’: the
fitness of an individual
organism as measured in
terms of the survival and
reproductive success of its
kin and genetics being able to pass down
COMPONENTS OF NATURAL SELECTION
- Variation: Organisms exhibit individual genetic variation
- Heritability: Some traits are consistently passed on from parent to offspring
- Competition (overpopulation): More offspring than local resources can support leading to a struggle for resources.
-
Differential survival and reproduction: Some individuals will
contribute more offspring to the next generation
ARTIFICIAL
SELECTION
Process by which heritable traits favored by human actions become more common in successive generations
Can be intentional or unintentional
UNINTENTIONAL SELECTION
Human actions create unintended
selection pressure
Heikegani or “Samurai Crabs,” (Heikea japonica)
Crabs with ‘Samurai’ faces thrown back favoring the survival of certain phenotypes
Also called ‘unconscious selection’
ex:harvesting bigger fruits
INTENTIONAL
SELECTION
“Selective breeding”: Plants or animals are bred for selected traits
Can utilize techniques such as
inbreeding, line-breeding, and out-
crossing.
Artificial Selection:
Traits favored by human actions
Unconscious/Unintentional
selection
* Provisioning,
* niche construction
* anthrophilly
* relaxation of sexual selection
Conscious/Intentional selection
* Selective breeding
* Improvement,
* Culling of individuals with undesired traits
SELECTION & EVOLUTION
Both natural and artificial selection
occur at the individual level, but evolution occurs at the population level
