history of our planet week 10

the Anthropocene

The neolithic: dawn of the Anthropocene?

• Neolithic = 6000 years ago – timings debated

• These technological changes happen at different times in different places

• Characterised by the ‘neolithic revolution’:

•    Shift from nomadic, hunter gatherers to agriculture and (semi) permanent settlement

• Domestication of plants

•   Animal husbandry

• Population increase

• Much of this was facilitated as understood science and engineering

Domestication of animals:

• Wolves = first animals to be domesticated

• Possibly as long ago as 36,000 years ago

• Undisputed evidence c. 14,700 years ago

• Dog mandible found in human grave in Bonn, Germany – DNA analysis confirms direct descent of modern dogs

•   Suggestions that wolves picked us

Had camps, food, fire, scraps etc.

• Worked together to hunt, increase efficiency

convergent evolution humans and dogs

• Evidence of ‘convergent evolution’ in humans and dogs

• Digestion, metabolism, neurology, cancer

• Suggests subjected to same environmental mechanisms for 1000s years as humans

• Cognitive similarity, greater than relatives

• Dogs better than reading facial expressions etc.

domestication of animals order

ungulates first then poultry

• Anthropogenic selection and evolution, during the neolithic

• Primarily food, but also working animals and pets

  Also, materials e.g. wool

Dawn of agriculture:

• Agriculture developed independently in multiple locations and at varying times

• Enabled by technological advancement – irrigation, deforestation and food storage

dawn agriculture - near east/ levant

• the ‘fertile crescent’ – some of the earliest agricultural domesticates

• emmer wheat and early hybridisation

•   legumes (lentil, pea, chickpea)

• wide range of environments (locations, altitudes) – favourable climate for agriculture

dawn agriculture - far east

• earlier in China, then India

• millet

• rice

dawn agriculture - the Americas

earliest in Mesoamerica (middle America) ,

• squash, beans and maize

• teosinte → maize

• potatoes

• later in south and north America – potatoes, sweet potato, chillies, cotton

why did agriculture develop?

• Cultural Progress Hypothesis.

•    Environmental Change Hypothesis.

• Population Pressure Hypothesis

• Accident and opportunity?

Cultural Progress Hypothesis.

• Agricultural life is inherently superior to foraging. 

•   Inevitable process of evolution - bio-culturally capable.

Environmental Change Hypothesis.

•   Obvious correlation of agricultural origins with end of Pleistocene

BUT not only climate event AND delay across globe e.g. N, America

    Population Pressure Hypothesis

•   Population growth forces foragers to adopt agriculture, because wild resources become so scarce that eventually farming is worth doing.

•   Need a ready source of food under your own control

  Accident and opportunity?

•    Natural distribution of suitable plants and animals

 

The neolithic revolution:

•   Domestication of animals + dawn of agriculture

•   When grow crops need to stay near them

•   Shift from nomadic, hunter gatherer lifestyle to sedentary settlement

• Increasing population

• Complex social structure

  •    Division of labour, trade, politics, early religion, property ownership

• Increasing anthropogenic effects on natural environment

  •   Irrigation, deforestation, waste production

•   Beginning of Anthropocene?

Early civilisations:

Correlation between development of agriculture and early civilisations

early civilisation developments

• Cradle of civilisation?

• Civilisation developed in 6 areas of the world independently

Neolithic in Britain and Ireland:

•   Period of monument building (e.g. Stonehenge, Newgrange) – ritual?

• Archaeology: use of pottery, domestication of plants and animals

•    Agriculture limited to certain areas (e.g. Wessex, East Anglia, Cumbria coastal plain) (mostly southern Britain), because of primitive technology

• Phase of deforestation, rise in cereal pollen and agricultural weeds

• Followed by period of abandonment, forests returned

vegetation changes with neolithic

Landscape-scale transitions in vegetation cover associated with neolithic revolution are visible in the pollen record

Expansion of agriculture:

• took 1000s ears for agriculture to expand across Europe – UK was behind

• Modern DNA analysis can help us examine the spread of agriculture in more detail

• Sikor et al (2014, PLoS Genetics)

Bronze and iron age in Britain and Ireland:

•   Improving technology (metal smelting) allowed greater range of environments to    be farmed

•   First major settlements and vegetation clearance/deforestation become permanent

•   Start of Iron Age (c. 2,700 years ago), most of southern Britain was under agricultural use

•   Previously unexploited areas of Wales, southern Scotland, northern England- woodlands were cleared

• 1086 AD: Doomsday book - only 15% of original forests remained

British and Irish field systems

•    bronze age field system in Britain and Ireland are the oldest in the world

• make up co-axial field systems

•    the first to set up field systems this way – increase efficiency, safety of animals, who owns what

Palaeoecology and conservation:

•   palaeoecology can challenge perceptions, provide sustainable conservation targets

• Dartmoor national park – natural wilderness or anthropogenic landscape

•   Prior to c. 4,500 years ago, Dartmoor was largely forested (Alder, Hazel, Oak)

•    4,500 – 3,000 years ago – increased evidence of anthropogenic burning

• 2000 years ago to present – dramatic reduction in trees, replaced by grasses

•   Entirely human induced

• Heavily modified landscape maintained by grazing and swailing (burning)

Roman Britian:

• Agriculture was imperative in roman culture

• Waste and pollution were already a problem in roman cities

•   “As soon as I had gotten out of the heavy air of Rome and from the stink of the smoky chimneys thereof, which being stirred, poured forth whatever pestilential vapours and soot they had enclosed in them, I felt an alteration of my disposition.”

• Seneca (AD 61)

• Greenland ice core record shows signs of roman pollution

Exeter:

•   Isca dumnoniorum

•    ‘flowing water’ (isca)

• First established c. 55 AD, town grew up around

• Western most edge of roman Britain

Last 1000 years:

Temp warmer now than at any point in recent past:

20,000 years

800,000 years

•   2050: 3 million?

•   2100: 10 million?

   Medieval period onwards:

• Evidence of climate variability over last 1000 years

•    Major climate events

• Acceleration of anthropogenic environmental change

•   Emergence of anthropogenic climate change

  1. Medieval warm period:

• Wine in Scotland

• Vikings to Greenland

•   ‘discovery’ of north America

   2. Little ice age:

• ‘frost fairs’ on Thames

•   Widespread famine and bread riots (basic bread crops failed); witch hunts (misogynistic product of the little ice age)

3. Recent compilations:

   Some variation but generally support idea of recent T change outside of natural climate variability

1. Medieval warm period

2. Little ice age

3. Recent compilations

•   Significant increase in number of palaeoclimate and palaeoenvironmental records available

• Particularly tree ring records

• Climate forcing over last 1000 years

•    Anthropogenic influence:

•   GHGs (fossil fuels, deforestation etc)

• Land cover (albedo) (reduction in ice)

•    Aerosols

•    Dawn of Anthropocene?

Dawn of the Anthropocene?

•     A proposed new geological epoch, separate from the Holocene, characterised by significant human impact and influence on the earth (eco)system, including but not limited to anthropogenic climate change

• Crutzen, 2002 – nature

When did the Anthropocene begin?

•     Early Anthropocene hypothesis

•    Industrial revolution

• Rapid acceleration period

Early Anthropocene hypothesis:

• Centre around idea that, based on length of previous interglacials (e.g. ipwichian) earth should be returning to glacial

• But c. 8000 years ago climate records demonstrated deviation from this trend

• Greenhouse gases changed due to early agriculture (why we follow red line)

• Early deforestation and agricultural expansion have been identified as a possible driver of global climate change (ruddiman 2003)

Early Anthropocene hypothesis: diagram

• Blue line = if didn’t have anthropogenic hypothesis

• Instead, are following the red line

Early Anthropocene hypothesis:   Disputed: 1

• Holocene is super interglacial

• Eccentricity 400ka cycle

• Previous was MIS 11 (hoxnian)

• Lasted c. 31,000 years

• Overdue glaciation hypothesis is invalid

•   Human pop 8000 years ago was few million, earth was essentially pristine – non substantial human ‘footprint’

• Created vital debate on role of human in climate

Early Anthropocene hypothesis:   Disputed: 2

• Early evidence of pollution

• Peatland in tierra del Fuego

• Trace metal evidence for pollution over last 4000 years

Dawn of Anthropocene – industrial revolution:

•   Crutzen (2002, nature) proposed industrial revolution as beginning of Anthropocene

• Late 18^th C – greenhouse gas concentrations in polar ice cores begun to increase

• Coincides with new steam engine designs by Newcomen (1712) and Watts (1784)

• Flow on effects – efficient land clearance – synthetic fertiliser, improved sanitation/ water supply etc

Dawn of Anthropocene – rapid pop growth

The great acceleration:

• Steffan et al (2011)

• Anthropocene beginning c. 1950

• Shifts in population, consumption patterns

•   Definition needed for: consistency,   Correlation, Establishment of natural baselines

Dawn of Anthropocene: humans

•   Humans no longer a temporary disturbance

• Humans shape and influence processes across most of terrestrial biosphere and increasingly more so the ocean and atmosphere

• Call for human activity as a system on a par with the biosphere, hydrosphere (anthroposphere)

• Formal end to Holocene? – Anthropocene

    Biodiversity:   Extinction:

• Rate of extinctions

•   5th/6^th mass extinction event?

• Humans are just 0.01% of all life but have destroyed 83% of wild animals

• Humanity has wiped out 60% of animal populations since 1970

•   More than 300 mammal species have been eradicated by human activities

    Biodiversity:  land use change.

• habitat loss

• 10% wilderness areas lost in last 2 decades

•   Coral reefs, first major ecosystem to be lost?

    Biodiversity: Biogeography:

•   Translocation of flora and fauna through human agency - intentional (agriculture) and accidental

• Homogenisation (homogenocene)

•   Invasive species

    Biodiversity: climate

• Atmospheric GHG concentration

  • Increases in co2 and ch4

  • Fossil fuels, cement production and flaring

  •   Deforestation and land use change

• Global average temperature

•   Ice sheets, glaciers, sea ice

•   Sea level rise

• Permafrost

• Climate driven habitat loss