Domestication quiz 1

Holocene

period when domestication took off about 11,000 years ago

Pleistocene

Ice Age

universalist explanations

climate pushing, population pressure, aggrandizement

climate forcing

universalist explanation, end of Ice Age, temperatures warming, grasslands expanding, larger estuaries create hyperproductive land, Oasis and Holocene Climate Change hypotheses

oasis hypothesis

Holocene is nasty, hypothesis of climate pushing, began in fertile crescent, "Younger Dryas" shrank habitable ecosystems, forced humans and other organisms together into oases

Holocene Climate Change hypothesis

Holocene is nice, hypothesis of climate pushing, productive landscapes more common and allowed humans to settle, understood local environment better ad exerted more control on plants and animals

population pressure

universalist explanation, rapid population growth so existing food procurement was not enough, started domestication, increasing density forced people to settle, create surplus

Beer Hypothesis

aggrandizement, universalist explanation, grains domesticated to make alcoholic beverages OR create surplus for feasts, counterargument is everyone had access to same resources

Domestication: how?

started with hunter-gatherer ethnography

cultivating/tending

burning, thinning, weeding, planting, grafting, fertilizing, irrigating

herd/pack management

protection from predators, culling, reproductive isolation, breeding, game management (long-term availability of what is being hunted)

social institutes

mobility, seasonality, infrastructure, communal labor, surplus, storage

ideology and ritual

taboos, sacrifices, ethic of care, notions of property, sacredness

human niche construction or ecosystem engineering

societies have tendency to cultivate landscapes (heart of domestication), modified ecosystems to increase abundance or predictability

wild progenitor

ancestral species that gave rise to domesticated species

crop wild species

wild plant closely related to domesticated crop

crop progenitor

wild plant selected by humans to become crop

agrobiodiversity

biodiversity in crops

center of origin

geographical region where organism first developed its distinctive properties

differential phytogeographic method

method for determining center of origin, create botanical taxonomy (including crop progenitors, subspecies, landraces/varieties), deliminate distribution of each, infer center of origin is region of greatest diversity

final step in DPM

infer center of origin is region of greatest diversity

Crop Evolution Lab

founded in 1966 by Jack Harlan at the University of Illinois with JMJ de Wet

center of diversity

revised name for center of origin

ex situ

out of context or place

weeds should be defined by their ecology

argument proposed by Harlen and de Wet in Some thoughts on weeds (1965)

ecological characteristics of weeds

pioneers of open soil and human habitations (camp followers, contest with men for soil), cosmopolitan (not picky)

disturbance and succession

growth process, start with nothing, something clears, lichens cover soil, grasses and perennials, small shrubs and shade-intolerant species, shade-tolerant and larger trees

intro to idea of human self-domestication by Harlan and de Wet

"If we confine the concept of weeds to species adapted to human disturbance, then man is, by definition, the first and primary weed under whose influence all other weeds have evolved"

adaptive syndrome

convergent evolution OR parallel evolution

adaptive syndrome of weediness: annuals

prolific seed production, germination heteromorphism (produce seeds that germinate differently, crop mimicry, developmental plasticity (ability of organism to modify parts of its body)

adaptive syndrome of weediness: perennials

propagation by difficult to remove roots, robust protection

mutualism

ecological interaction between species that is beneficial to both

portion of mutualistic definition by Zeder

"...human intentionality sets domestication apart from other forms of mutualism"

domestication (from Zeder)

a form of mutualism that is asymmetrically enhanced by the human ability to culturally transfer knowledge

fitness

number of surviving offspring, quantification for benefit

axes of variation

intentionality, control/power, locus of change

intentionality

axis of variation, domestication is incidental result of human variation vs. purposeful action

power/control

axis of variation, plants and animals "self-domesticated" vs. human-directed

locus of change

axis of variation, genetic isolation and fixed phenotypic change vs. behavior and development (plasticity) including changes in human socioeconomic organization

plasticity

change in behavior and development

process

component of domestication, gradual result from human modification of ecosystems and selective pressures

relationship

component of domestication, specific kind of mutualism driven by human culture

changes

component of domestication, differences in bodies and behaviors of plants and animals, generalized as adaptive syndromes of domestication

adaptive syndromes of domestication

changes in bodies and behaviors of plants and animals, evolve in response to specific anthropogenic environments and human practices

adaptive syndrome

set of like characteristics in distantly related organisms that result from convergent evolution

convergent evolution

distantly related organisms independently evolve similar traits to adapt to similar necessities

foliage in the fruit hypothesis

leaves function as fruit, entice animal disperser to consume seeds that are indigestible

advantages of dispersal in poop

reduces sibling competition, direct dispersal to nitrogen enriched openings (hotspots)

paper by Harlan et. al. (1973)

The adaptive syndrome of domestication in annual seed crops

annual seed crop

plant that starts with a seed and ends with seeds of its own in one growing cycle (wheat, rice, corn, grains)

cereals

grasses that produce grains (seeds of annual plants)

planting is key

how adaptive syndrome evolves

support for planting from Harlan (1970)

"It is the seeds that escape the harvester that contribute to the next generation..."

seed predator

exerts selective pressure on plant population to avoid getting eaten

seed disperser

opens up selective advantages for allowing seeds to be captured

Harlan et al capture hypothesis

assuming harvested seed is then planted, anything that makes it more likely for a given seed to be "captured" will enjoy a selective advantage

seed heads become non-shattering

example of selective advantage, most are harvested and then contribute to population next year, shattering lost

plant architecture becomes more determinate

example of selective advantage, less branches, easier to harvest with fewer, larger seed heads, "sun-flower effect"

seeds mature simultaneously

example of selective advantage, must mature at right time together, seeds that do before or after are not captured

Harlan et al seedling hypothesis

assuming harvested seed is then planted, anything that gives a seedling an advantage in a harden or field environment will be selected

seed size increase

example of seedling advantage, increases food store

germination inhibitors reduced

example of seedling advantage, tubercule vs. smooth (better)

problem with Harlan hypothesis

mechanism only works if a new field is opened every year

Mueller hypothesis

switch in seed dispersal drove changes

uniform germination with minimal germination + loss of seed protection + increase in seed size

= changes associated with switch from pre-existing seed dispersal strategy to dispersal by humans

Dimitri Belyaev

Russian scientist who pioneered the Farm Fox experiment, wondered if selecting for tameness would lead to morphological changes observed in domestic foxes

Farm Fox experiment

60+ year experiment selecting for fox tameness

tameness

docile, obedient, and tolerant of human presence

Zeder on tameness

"The leading-edge pressures on animals undergoing domestication are likely to focus on behavioral attributes rather than morphological traits..."

What makes an animal easy to domesticate?

tolerance of penning, dominance hierarchies, will breed in captivity, little wariness or aggression

commensal

ecological relationship in which one organism benefits and the other derives neither benefit or harm

domestication syndrome in mammals: traits connected to important behaviors

more docile, pregnant more frequently/non-seasonally, less sexual dimorphism, endocrine and neurological differences, juvenile behaviors for longer/changes in early development

domestication syndrome in mammals: unclear connection between traits and behavior

smaller brains and more nuanced differences, smaller teeth, differently shaped heads and faces, floppy ears, curly tails, multi-colored (piebald) coats, more variety in hair texture

breed

genetically isolated subpopulation of domesticated population, usually <50-100 generations old with markedly reduced genetic diversity due to human action

breeding

selection of parents and restriction of mate choice, complete control over reproduction

village dog niche

scavengers in towns/villages, cannot be afraid of people and people cannot fear them, can digest human food specifically grain

self-domestication hypothesis

theory of dog domestication, wolves commensal scavengers, more successful scavengers did not fear humans, population not unlike village dogs evolved in proximity to people

human-initiated hypothesis

dog domestication theory, hunters took pups from den after killing parents, pups with greater ability to thrive when raised by humans survived

Mezhirich, Ukraine

Pleistocene Eurasian village ~15,000 years ago

middens

dumps

evidence for human-initiated hypothesis

dogs cared for by and buried alongside Pleistocene people

under selection in human-initiated hypothesis

changes in early development

critical period of socialization

hallmarked by neuroplasticity, period during early development when exposure to novelty results in long-term familiarity, commences with ability to explore, ends with avoidance of novelty

CPOS in wolves

2-6 weeks of age, can only smell and still need to nurse for at least another 3 weeks

CPOS in dogs

4-8 weeks of age, can smell, hear, and see and no longer need mothers for food

mothering orphaned pups

people took wolf pups close to age of weaning to select for those that has later CPOS and ability to be weaned sooner

important to remember

every domesticated plant or animal has its own unique history just as each has its own unique biology

domestication syndrome in annual seed crops

seeds become non-shattering, fewer and bigger seed heads, simultaneous maturation of seeds, increased seed size, reduced seed protections

tef

smallest domesticated grain, exception to rule, ancient farmers selected plants with many branches and small seeds to avoid lodging (bending of stems near ground)

de novo domestication

breeding technique that genetically modifies wild plants to create new crops with desirable traits

tubers

underground storage organ of a plant (enlarged stem) that bears buds from which a new plant can arise, asexually reproduces to create clones

domestication syndrome of tubers

partial or complete loss of ability to reproduce asexually, increase in predictability, size, number of tubers, decrease in other plant parts (more tube), easier to harvest (clumped) and/or separate more easily, loss or reduction in toxicity and other defenses

advantage of tuber cultivation

can make as many of exact same plant as desired

instant domestication

given root crop sprang from single desirable mutant, cloned millions of times

interdisciplinary manioc research seeks to answer this question

How do people affect the genetics of a plant that is propagated through cloning?

landrace

variety of domesticated plant that has evolved in a particular place to suit particular cultural preferences and ecological conditions, genetically heterogeneous compared to varieties created by formal plant breeding

extensive agriculture

swidden, rotating crops

agroecosystem of Amazonian manioc

landraces grown in block within swidden plots, live storage, bees facilitate cross-pollination between landraces, ants stash seeds under swidden field, landraces propagated via stem cuttings (clones)

live storage

can harvest when needed

folk taxonomy

complex criteria to decide if volunteer crops belong to existing landrace or represent something new and if it should be cloned