Tipping Points - Lecture 3 (the spread of agriculture)

what were early human diets

were hunter gatherers so they ate whatever foods were around in the local enviroment

how long ago was agricultrue developed

10,000 years ago

what is the definition of agriculture

the practice of cultivating the soil, growing crops, or raising livestock for human use

what were the drivers of the radical change in diet and lifestyle?

climate most likely

how stable was the early holocene climate

not very stable at all. it was warm with a change in precipitation - the saraha was wetter

how do we know that the sahara was wetter

cave drawings of water animals that live in less dryer areas of africa e.g girafes

what was happening to the sea level rise

ice was melting - eustatic sea levels

there was rebound and submergence - isostatic changes

this was very significant for coastal settlements in the early holocene

what is the neolithic revolution

the wide-scale transition of many human cultures from a lifestyle of hunting and gathering to one of plant and animal domestication agriculture and settlement allowing the ability to support an increasingly large populationwhe

what were the three main centres for spread of agriculture

China, Southwest Asia, Mesoamerica

what were the secondary centres

south america, eastern north america, sub-saharan africa, south asia and papua new guinea

what is the fertile cresent

the middle east - known for domesticating wheat and barley

what did mesoamerica domesticate

maize (corn ) was considered gold! - initially domesticated around 9000 years BP

what did china domesticate

rice

how were plants domesticated from the wild?

selective breeding by early human populations. likely collection and cultivation of wild plant species for food. desirable traits recognised and these plants deliberately propagated. repeated cycles of this lead to genetic changes

which direction did agriculture spread

westward. as it was suddenly discovered in neolithic settlesments!

what are the two theories for how agriculture spread

• demic model

• cultural diffusionist model

what is the demic model

The Demic model proposes that the spread of agriculture was primarily driven by the migration of farming populations ("demic diffusion"). It suggests that Neolithic farmers migrated from their places of origin, bringing with them the package of domesticated plants and animals that characterised the Neolithic way of life.

what is the cultural diffusionist model

suggests tat the spread of agriculture occured through the gradual diffusion of farming practices and technologies from their places of origin to neighbouring regions. It highlights the role of cultural exchange, trade networks, and interactions between Mesolithic hunter-gatherer groups and Neolithic farming communities in the adoption of agricultural practices.

what does dna sugest is the cause of agriiculture

as new farmers were moving through Europe, they were mixing with the local hunter-gatherers. As this Neolithic population moved west, we can track cumulatively increasing levels of the local hunter-gatherer signatures in the genetics - this wasn't just one population wiping the other out. Instead, they were mixing.

However, in the Baltic regions, there is a high degree of genetic continuity from the Mesolithic to the Neolithic, suggesting instead that these people probably acquired knowledge of farming and ceramics by sharing cultures and ideas — rather than genes — with outside communities.

what did the development of agriculture lead to

• a nearly global shift to more sedentary lifestyles, a massive increase in human population levels, urbanism, state formation and with it the support of specialized crafts, leading to the diversification of material technologies, including ceramics, later metals and the modern proliferation of compounds and plastics that we see today.

• The increased population densities of humans and livestock, clearance of forests for agriculture, and the transformation of soils means that the world we live in has become increasingly anthropogenic.

• Unlike Pleistocene hunter-gatherers, farming societies have transformed the surface of the earth and impacted the genomes and geographies of many other species, especially domesticated ones.

what is star carr

large mesolithic settlement site in ancient lake flixton swamps, probably not continuous more summer

food web of food and aquatic plants

what are the tipping points occuring here

the tipping points from neolithic (narrow range of animal protein, terrestrial diets and absence of marine) to a mesolithic diet (wider range of protein and more towards shellfish and small fish)

where does language spread from

majority of the origins of languages came from the farming centres

what do simulation modesl temmus

Local population pressure – due to immigration or climate change – is NOT a prime mover of agricultural development.  

 

More likely steady innovation and competition between different ways of life.  

 

A combination of innovation and evolutionary cultural spread? 

 

Manages to predict wehre the centres of agriculture developed. 

 

what is the ruddiman theory

Schematic summary of two views of Holocene climate. Natural hypotheses regard the nearly stable observed climate trend as natural in origin. But the anthropogenic hypothesis claims that climate would have naturally cooled and passed the threshold for early glacial inception if anthropogenic greenhouse gas emissions had not offset most of a natural cooling.

what is the evidence for the ruddiman theory

• comparison of holocene trends of ch4 and co2 with solar radiation and natural changes in co2

• Estimated that CH 4 emissions from northern paddies accounted for 70% of the increase in atmospheric CH4 recorded in ice cores during that interval.

• Population growth was rapid enough from c. 7000 BP, and land use clearance was extensive by c. 6000 BP, and had ‘transformed the planet’ by c. 3000 BP - they were cutting down trees to make way for agriculture

deforestation explains some of the co2 but not all of it - where did the rest of the co2 come from?

• indirect feedback from warmer atmosphere warms oceans. warmer water holds less co2, so more is emitted to atmosphere

• increased co2 venting from southern ocean (more space, warmer = less ice)

• it creates feedbacks!