People and
Planet Earth
4 Plant and Animal
Domestication
From last week;
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1. subantarctic lakes
2. asteroid impacts and plate
tectonics
3. evolution of whales
Subantarctic lakes
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There are nearly 400 known
subglacial lakes in Antarctica. The
largest is Lake Vostok. It’s 500 m
below sea level, 250 km long and
50km wide. Lake temp. is about -3C.
Water is replenished every 13,000
years. Presence of water related to
pressure of ice and geothermal heat.
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In another lake, Lake Whillans,
there are over 4000 species of
microbes. No photosynthesis so
they survive by processing
methane, sulphur and iron.
Asteroid impact and plate tectonics
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Most of the literature focusses on the
early Earth and the premise that at
around 3.6 billion years ago a large
asteroid (1000 km diameter)
fractured the crusted Earth to initiate
PT.
The ‘kink’ in the Hawaiian seamount
chain has also been interpreted as a
product of impact.
Evolution of whales
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Whale evolution probably began
around 50 MY ago from the same
animal group that contains the
hippopotamus.
The earliest ancestor appear to be
Eocene.
Whales derive from the Pakicetidae,
the first cetaceans.
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Human impact on environment seems
to have been modest until the Late
Pleistocene/Early Holocene. By then
humans had developed increasingly
sophisticated material technologies
and complex social arrangements.
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We saw earlier that our first major
impact may have been our role in
the extinction of the Late
Pleistocene megafauna.
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The transition from the LP to the
Holocene is marked in a large
number of places by a major change
in human-biosphere interactions –
the domestication of plants and
animals.
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In 1987, Jared Diamond described plant
and animal domestication as ‘The Worst
Mistake of the Human Race’ (Discover
Magazine).
He claimed that the process brought with it
malnutrition, starvation, epidemic disease
and class and gender divisions.
This suggests that conscious decisions
were to adopt domestication over foraging.
As we shall see, it wasn’t that simple.
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Before we get into this, we need a few
basic definitions;
Cultivation – the use and management of
plant resources which may or may not
involve domestication.
Domestication – the use and
management of plant and animal
resources in such a way as to make them
dependent on human intervention for
establishment and survival.
Agriculture – most assume that this is
related to the scale of activity and the
complexity of the manipulation.
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These changes began with a stone
technology, in the Neolithic. The
process of domestication has been
called the Neolithic Revolution, but
in most places the changes were the
consequence of long and increasing
interactions between people, plants
and animals; perhaps an inevitable
extension of hunter-gatherer
economies.
Interactions between people and their food
plants
Domestication has been described
as an ‘evolutionary continuum of
plant-people interaction.’
 Simply, humans applied selective
pressures. Initially, these would
have been accidental; a
consequence of food gathering,
for example.
Emmer wheat
Accidental selection for non-shattering
wheat
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What was domesticated?
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Where and when did it happen?
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How and why did it happen?
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What was domesticated?
Plants and animals existing in close
proximity to humans – components in the
foraging economy, weedy species around
camp sites, etc.
For plants, these were species that were
(a) pre-adapted to domestication, (b)
mostly disturbance related, (c) genetically
flexible (polyploidy), and (d) were
commonly self-fertilizing.
The earliest plant domesticates were
cereals. Plants less easily manipulated
were domesticated later. These include
crops grown as vegecultures and tree
crops.
Species of wheat (Triticum) from the Middle
East
Rice
The world’s major food crops
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For animals, suitable animals were those
that;
Were dietary generalists
Had a strong herding instinct
Were unaggressive
Were non-territorial
Were promiscuous maters
Were easy breeders
Had a fast growth rate
Were multipurpose animals
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Where and when?
First, it’s useful to consider how ‘where’ is
determined. What lines of evidence suggest
domestication?
(a) settlement form and function
(b) animals remains (type, age, size of
bones,etc). Zooarcheology.
(c) archeobotanical remains (carbonized plants
remains, pollen, etc.)
(d) impressions and residues on pottery and
tools
(e) food procuring and processing tools
(f) isotopic composition of human bone,
dentition, coprolites, etc.
Crop marks – Bronze age hut circles and
enclosures
Magnetometer survey
Ground penetrating radar
Skara Brae, Orkney, a Neolithic village about 5000
years old
House interior, Skara Brae
Bronze Age urn burial
Carbonized materials recovered by flotation
Pollen grains
Corn pollen
Farming tools – sickles and scrapers
More tools – sickles, manos and
metates (mortars and pestles)
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Where?
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Plants and animals seems to have
been domesticated in several widely
spaced locations in a variety of
environments. This suggests
independent origins.
A number of ‘hearths of
domestication’ are recognized.
Some are small but others are less
defined (centres and noncentres).
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Early centres of food production
What was domesticated and where
Centres of animal domestication
Fertile Crescent
Nowhere else had the same richness of
plants and animals available for
domestication
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When?
Depends on what is taken as a reliable
indicator of domestication, and the ability
to date items considered to represent the
process (14C and AMS).
Until recently is has been assumed that
the earliest domestication was that of
wheat and barley in the Fertile Crescent,
perhaps 10,500 BP. New AMS dates on
rice from China may change that view.
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How and why?
These are the most difficult questions to
resolve.
Domestication can be seen as a
consequence of mostly accidental
selection pressures that make plants and
animals increasingly dependent on human
intervention. People become critical for
protection and reproduction. How does
this work?
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For plants, increasing interaction meant;
(a) general increase in size (for plants)
and in the size of the part used by
people (seed, root, etc.)
(b) genetic changes (polyploidy)
(c) reduction in ability to disseminate
naturally
(d) loss of delayed seed germination
(e) simultaneous crop ripening
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(f) loss of protective mechanisms
(g) increased diversity in form and function
(local races) . The most common rice
species is Oryza sativa, but there are
probably over 80,000 races.
(h) changes in life style (annual to
perennial)
Corn and its progenitor Teocinte
For animals, increasing
interaction meant;
 (a) increasing dependence on
humans for food, protection, etc.
 (b) increasing selection for certain
attributes (meat, wool, hides, etc.)
 (c) changes in life cycles, etc.
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Why?
The most difficult question to answer.
Why would people who had existed
as foragers for so long and apparently
successfully change their basic
system of food procurement?
A number of hypotheses have been
proposed.
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A. Environmental Change;
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The Pleistocene-Holocene boundary was a time
of rapid environmental change. Perhaps
traditional foods were no longer available and
alternatives needed to be found.
Some have suggested that the Younger Dryas,
an early Holocene episode of rapid climate shift
may have been responsible.
This coincidence only works well for the Middle
East and China.
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In many other places the process is obvious
only well into the Holocene.
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B. Population Pressure;
Simply put, increasing population forced
foragers to adopt agriculture. On what
grounds? More food per unit area?
How would they know?
In general, population pressure is
considered a consequence not a cause.
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C. Coevolution;
Here domestication is seen as a
natural consequence of long-term
interaction between people, plants
and animals.
Many of the things domesticated were
pre-adapted.
Part of the answer, but it doesn’t
explain when.
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D. Optimal Foraging;
This hypothesis suggests that
changing food supply associated
with overexploitation may have
forced people to adopt alternative
food sources and different production
strategies.
All of these hypotheses have merit,
but no single one is sufficient.
Consequences
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In essence, plant and animal
domestication allowed the emergence of
‘civilization’.
Food surplus brought population
increase, sedentism and urbanization.
Stratification of society.
Centralized government.
Organized religion.
Art, writing, warfare, colonization, etc.
Environmental degradation.
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Next week we’ll take a look at
some of those early societies ; at
how and where they were
established and why they
declined.