“Teaching a Unified Account of the Past”
David Christian
San Diego State University
September, 2008
A Problem for Educators
• Fragmentation of knowledge– We teach different disciplines but not the links
between them
• A sense of meaningless:– For students this creates a sense of a world
without meaning
A problem unique to the modern world
• In all societies we know of, children were taught an account of reality that was– Unified
– Meaningful
– Based on the best available knowledge
– Contained in Creation Stories
• Was Australia 500 years ago (think about it!)– Educationally ahead of the US today?
Francis Firebrace, a storyteller of the Yorta Yorta Nation, N.S.W.
Things are changing!
• Now we are once again within reach of an account of reality that is– More unified– More meaningful– Based on the best of modern scientific knowledge
• I’ve taught such a course for 20 years– I call it “big history”– Others call it “the evolutionary epic”
or “a modern creation story”– A fundamental educational breakthrough?
Why the change? One vital factor:The “Chronometric Revolution”
• Before the mid 20th century all absolute dates based on written records
• As History became more “scientific” it needed rigorous chronologies– These used written evidence– Could only reach back 5,000 years– History came to mean “human history”– History and the Science split into
C.P. Snow’s famous “Two Cultures”
History and Science were no longer talking to each other!
XThere seemed to be no history to Science
There seemed to be little science in History!NO DATES MEANT NO DATES!
Enter the “Chronometric Revolution”Dating the Undateable!
• 1950s, Willard Libby pioneers C14 dating– 1953, Claire Paterson dates the earth– New Radiometric techniques
• Other techniques including dendrochronology
• New techniques in – Biology (genetic dating)– Cosmology
A Unified Chronology for the whole of Time!
• New Paradigms: – In Big Bang Cosmology, Plate Tectonics &
Genetics– Made the sciences more historical
• The Chronometric Revolution:– Provided absolute dates for the whole of time!– Linked cosmology, astronomy,
chemistry, geology, biology, human history
– Within a single timeline
Can History and Science get back together?
Now that dating was possibleWas dating possible?
A unified and meaningful Map of Time and the Universe
• Like traditional creation stories
• The emerging scientific creation story can help students– Map themselves onto reality– Understand their place in reality– See that modern knowledge is unified
• The story is saturated with meaning!
The Story
• You’ll meet it during this course of lectures
• Today: – an introduction and a “taster” to
Big History (aka the Evolutionary Epic)
The whole of time in 11 dates
1. The Universe appeared c. 13.7 bys ago
2. The Earth, c. 4.5 bys ago
3. First living organisms c. 3.8 bys ago
4. First multi-celled organisms c. 600 mys ago
5. Dinosaurs wiped out c. 67 mys ago
6. First “hominines” appeared c. 7 mys ago
7. Our species, Homo sapiens, c. 200,000 ys ago
8. First agricultural societies, c. 10,000 ys ago
9. First civilizations and written documents c. 5,000 ys ago
10. Industrial Revolution (and the USA!) c. 250 ys ago
11. Humans enter space c. 50 ys ago
Another way of seeing time:If the Universe began 13 years ago, then …
– the earth would have existed for about • five years [4.5 billion ys]
– large organisms with many cells for • 7 months [600 million ys]
– the asteroid that killed the dinosaurs would have landed • 3 weeks ago [67 million ys]
– Hominines would have existed for just • 3 days [c. 7 million ys]
– our own species, Homo Sapiens, for • 53 minutes [c. 200,000 ys]
– agricultural societies would have existed for • 5 minutes [c. 10,000 ys]
– the entire recorded history of civilization for • 3 minutes [c. 5,000 ys: that’s when most world history courses start!]
– modern industrial societies (and the USA!) for• 6 seconds [c. 250 ys]
– 1st humans in space and on the moon• 1 second [c. 50 ys] I live here!
Is there unity or meaning in this story?
• Many students feel it belittles them, and deprives them of meaning …
• After all our earth looks small from space …
Apollo 8 photograph of Earth from lunar orbit: Dec 24 1968
Or compared to the Sun?
1 million Earths could fit inside the Sun
Alfred Crosby describes the Earth as a “mote of debris” left over from the formation of the Sun [Children of the Sun, p. 2]
Or to the Milky Way?
An Artist’s Reconstruction of Our Galaxy
We are about 2/3 from the Center
How many stars in the Milky Way? About 100 billionHow many galaxies in the Universe? About 200 billion
Cesare Emiliani: There are as many stars in the Universe as there are “sand grains in all the deserts and beaches of the earth”
[Scientific Companion, 2nd ed., p. 9]
Depressed?
Despite this, it turns out there is plenty of meaning in the modern creation story
• One central theme: INCREASING COMPLEXITY
• The Universe began simple– Energy, matter, expanding space
• Over 14 bys more complex things appeared– Most of the Universe remains simple– But new, complex things have emerged:
• New forms of complexity– Galaxies and Stars (in that order!)– More chemical elements– Planets– Living Organisms– Modern Human Society
What is Complexity?A simple definition
1. Multiple Components: diverse, varied
2. Linking mechanisms: components linked together in precise patterns
3. New energy flows: and held together by flows of energy mobilized by the nature of the structure
4. New “Emergent Properties” :new rules, new types of entity appear when components are linked together in particular structures
5. Death: when the energy flows cease, the structure falls apart into its simpler components, ceasing to exist
Complexity exists at many scales
Figure 1 Brain tissue of a cat
Walle J. H. Nauta, Fundamental Neuroanatomy, ed.
Michael Feirtag (New York: Freeman, 1986), 9.
Figure 2 Supercomputer simulation of a clustering of galaxies.
Ron Cowen, “Galaxy Hunters: The search for cosmic dawn,” National Geographic 203, no. 2 (2003): 15.
And at different levels
• “There is a hierarchy, ranging from fundamental particles below the atomic level up through molecules and crystals to the macroscopic chunks which our unaided sense organs are built to appreciate. Living matter introduces a whole new set of rungs to the ladder of complexity: macromolecules folding themselves into their tertiary forms, intracellular membranes and organelles, cells, tissues, organs, organisms, populations, communities and ecosystems. ... At every level the units interact with each other following laws appropriate to that level, laws which are not conveniently reducible to laws at lower levels.”
• Richard Dawkins, The Extended Phenotype: the Long Reach of the Gene, Oxford: OUP, 1982, 1999, p. 112-3
Can we measure levels of complexity? Eric Chaisson’s Idea
• If forming complex things requires work
• And forming more complex things requires more work, then …– We should be able to measure complexity
objectively by measuring energy flows– “Free energy rate density” =
ergs per second flowing through each gram
Some Estimated Free Energy Rate DensitiesBased on: Eric J. Chaisson, Cosmic Evolution: The Rise of Complexity in
Nature, Cambridge, Mass.: Harvard University Press, 2001, p. 139
Generic Structure Free Energy Rate Density(erg s-1 g-1)
Galaxies (e.g. Milky Way) 1
Stars (e.g. Sun) 2
Planets (e.g. Earth) 75
Plants (biosphere) 900
Animals (e.g. Human body) 20,000
Brains (e.g. Human cranium) 150,000
Society (e.g. Modern human culture) 500,000
Stuart Kauffman: “the maintenance of order requires that some form of work be done on the system. In the absence of work, order disappears.” [From Complexity]
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
ergs/sec/gr
In Graph Form:
Estimated Free Energy Rate
Densities
Payoff? Modern Human Society is
a) extraordinarily complex &
b) depends on extraordinarily large energy flows
Interesting! Humans seem back at the center of the picture!
And the picture has meaning!
Humans are different
• “Although we are made up of the same chemicals, with the same physiological reactions, we are very different from other animals. Just as gases can become liquids, which can become solids, phase shifts occur in evolution, shifts so large in their implications that it becomes almost impossible to think of them as having the same components.”
Michael Gazzaniga, Human, Prologue
The Story of increasing complexity:Eight Thresholds
1. The Universe [Cosmology]
2. The first Galaxies & Stars [Astronomy]
3. New chemical elements [Chemistry]
4. Planets and our earth [Geology]
5. Life [Biology]
6. Human beings [History]
7. Agriculture [History]
8. Modern Society [History]
I’ll focus on the last three steps
Increasing human control of energy began deep in the Paleolithic
Chimp range: no change Range of
early humans250,000 BP?
c. 60,000 BP
50,000 BP?
15-13,000 BP?
4,000 BP?
1,000 BP?
New Sea-going
technologies
New hunting techniquesAdaptations to cold
Many new
technologies required
New ocean-going
technologies
Arctic technologies
Each migration = new ways of extracting energy
Paleolithic migrations based on comparisons of mitochondrial DNA
[see http://www.mitomap.org/WorldMigrations.pdf ]
Populations of Homo sapiens sapiens 100,000 BP - Now
100,000 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 00
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Years Before Pesent
Mill
ions
10,000 BP-Now
Slowly at first, human numbers grew as they entered new
environments
10,000 humans? 5,000,000 humans?
6,300,000,000humans?
Per Capita Energy Consumption increased
[Smils, Energy in World History, p. 236]
Paleolithic Era
Modern Era
Today each individual
consumes c. 60 times as much as 10,000 years agoPopulations have grown by 1,000 times, so total
energy consumption has
increased by almost 60,000
times
Our control of energy has increased rapidly in the last
centuryJohn McNeill, Something New under the Sun,
p. 15:
“We have probably deployed more energy since 1900 than in all of human history
before 1900. My very rough calculation suggests that the world in the twentieth
century used 10 times as much energy as in the thousand years before 1900 A.D.”
On land, humans now control 25-40% of all energy from photosynthesis![Vaclav Smil, The Earth’s Biosphere: Evolution, Dynamics, and Change, Cambridge, Mass.: M.I.T., 2002, p. 240]
From Alfred Crosby, Children of the Sun, p. 162
Biomass of mammals as a measure of energy control
[from Vaclav Smil, The Earth’s Biosphere, pp. 186]
0
20
40
60
80
100
120
Million tons carbon
Non-domesticated("Wild")
Mammals (5)
Humans (40) DomesticatedMammals (120)
Anthro
poge
nic
Mam
mal bio
mass
How complex is modern human society?Brains: 100,000,000,000 neurons (as many as stars in the Milky Way), each connected to hundreds of others, computing in parallelModern Human Society: 6 billion human brains, multiply connected through language, phones, and the internet, computing in parallel
Some Estimated Free Energy Rate DensitiesBased on: Eric J. Chaisson, Cosmic Evolution: The Rise of
Complexity in Nature, Cambridge, Mass.: Harvard UniversityPress, 2001, p. 139
Generic Structure Approximatelife span(Years)
Free EnergyRate Density(erg s-1 g-1)
Galaxies (e.g. Milky Way) billions 1
Stars (e.g. Sun) billions 2
Planets (e.g. Earth) billions 75
Plant species (biosphere) millions 900
Animal species (e.g. human body) millions 20,000
Large Brains (e.g. human brain) millions 150,000
Society (e.g. Modern humanculture)
centuries? 500,000
Complexity is not necessarily good!Perhaps complexity = fragility
More complexity more energy/resources for
humans less for other species
“Over the past few hundred years, humans have increased the species extinction rate by as much as 1,000 times over background rates typical over the planet’s history (medium certainty). Some 10–30% of mammal, bird, and amphibian species are currently threatened with extinction (medium to high certainty).”
“Baiji”, or Yangtse Dolphin: Now thought to be extinct
[From the Millennium Ecosystem Assessment, March 2005]
Human energy use now affects the biosphere
“Within a few centuries we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of millions of years.”
[Revelle & Suess, 1957, cited from Smils, The Earth’s Biosphere, p. 15]
HOW COMPLEX ARE WE ON COSMOLOGICAL SCALES?
Fermi’s question• If creatures similar to my governor are common• There should be millions in our galaxy• Some civilizations should be millions of years
more advanced than ours• Some must have left signals or objects for us to
detect• After 30 years of searching we have detected none• WHERE ARE THEY?
The Meaning of this Story:Human history may be one of the most complex phenomena in the Universe!
• “History” tells a story of one planet
• And one species’– Accelerating control of resources and energy– Leading to levels of complexity that may be
significant at cosmological scales– And may lead to our early retirement!
• A conclusion full of meaning!
Why so complex? a new adaptive mechanism?
• Adaptive mechanisms:– How living organisms acquire and pass on new and
more complex structures– How they mobilize more energy and become more
complex
• All other living organisms adapt genetically
• Humans find new ways of mobilizing energy without waiting for genetic change– How? Why are we so good at continually adapting?
New Adaptive mechanisms imply new “linking mechanisms”
• Linking mechanisms: – join once independent entities into new,
precisely structured and more complex, entities
• The Sun: – formed when gravity bound clouds of atoms
into a larger structure fuelled by fusion
The Structure of our Sun
Fusion takes place in the core
New supplies of hydrogen come from the outer layers
Heat from the centre travels outwards (taking about 1 mys!)
Energy from the core sustains its structure
Complexity in Human History: A Hypothesis
Humans “adapt” faster than other organismsbecause they use a new, more powerful, adaptive mechanism that links them within the complex structures of human societies:
Compare three adaptive mechanisms:1. Natural Selection: Slow, but recorded in DNA2. Learning: Fast change, but little communication so
non-cumulative3. Collective Learning: Fast change + linked through
language cumulative change HISTORY!
The Synergy of Collective Learning
0
200
400
600
800
1000
1200
10 20 30 40 50
Edges and VerticesModelling Synergy of Info-networks
No. of possibleEdges
No. ofVertices
As populations increase, possible exchanges between individuals increase even faster, and at an accelerating
rate
Basic “Graph Theory”: No. of “Nodes” compared to No. of possible links between “Nodes”
No. of Possible Links
No. of “Nodes”
The equation: if the no. of nodes is n, the number of possible links between them is (n x (n-1))/2.
Setting up a feedback loop
Collective Learning more energy more people more complexity
more collective learning …
Compare the history of Chimp energy use over 10,000 years
(1,000 Cals. Per person per day)
0
50
100
150
200
250
1,000 Calories perindividual per day
NOT MUCH SYNERGY HERE IN 100,000 YEARS!
With average human energy use(1,000 Cals. Per person per day)
0
50
100
150
200
250
1,000 Calories perperson per day
THIS IS SYNERGY!
A SIMPLE 3-PART PERIODIZATION1. The Paleolithic Era: feedback but limited
– Collective learning migrations to new environments– Energy control increases more humans, but …– Communities remain small little increase in complexity
collective learning slow2. The Agrarian Era: increasing positive feedback
– Collective learning domestication intensification– More energy from a given area: agriculture– Average community size increases population growth
social complexity more collective learning feedback!3. The Modern Era: positive feedback accelerates
– Collective learning global in scale + new technologies increase number of exchanges
– Energy control increases sharply; exploitation of fossil fuels– Average community size increases social complexity
RESULT?SOMETHING NEW APPEARS
IN THE COSMOS
• All the remarkable “emergent properties” of human society and human history are products of these processes
• Human Society counts as– A new phenomenon– A new level of complexity
A unified and meaningful account of the past
• Based on the best of modern science
• Coherent
• Full of meaning– Particularly if you happen to be
human!
• Highly teachable!
Thank You!
Eric Idle’s big history courseEric Idle’s big history course
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