Download Evolution of Cooperation - A Journey to Better Understand Change

The Evolution of
Cooperation
Mike Ignatowski
Dec 18, 2016
1
Topics

Evolution – how can cooperation evolve?
–

Biology
–

Computer simulation
Importance of cooperation at all levels
Society / Economics / Politics
–
Competition vs. Cooperation
2
Modern Developments

These new developments started with E.O.
Wilson’s book Sociobiology in 1975

Followed by The Selfish Gene by Richard
Dawkins in 1976

They entered a new phase with Axelrod’s book
The Evolution of Cooperation in 1984

Since then the field has taken off. We know much
more than we did 2-3 decades ago.
3
The Big Problem:
Explaining Altruism and Cooperation
in light of Evolution

Even Darwin recognized this was a problem. It did not fit
well into evolution by competition and natural selection
–

“…one special difficulty, which at first appeared to me
insuperable, and actually fatal to my theory.”
Some people claimed this was a basic flaw in applying
evolution to humans.
–
The existence of altruism and cooperation is a sign of divine
creation of humans
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Sociobiology Creates
Some Controversy
E.O. Wilson

Established a scientific argument for rejecting the
common doctrine of “tabula rasa” (blank slate).
–
–
–
Offends some liberals and conservatives, who both
favored the idea that human behavior is culturally
based.
Offends some religious people who believe that moral
rules are divine in origin.
Some people believe that sociobiology promotes
racism, misogyny (prejudice against women) and
eugenics.
6
Kin Selection

You can aid the survival of your genes by aiding
the survival of genetically related individuals
who have many of your genes.
–
Take risks to help your siblings and offspring
–
Take less risks to help more distant relatives
8
Social Insects
(ants, bees, wasps)

Exploits kin selection to an extreme

All members of the social nest are (generally)
descendents of one “queen” and thus very
closely related.

All of the workers are sterile
–
The only way to pass on their genes is to make sure
their queen is successful, and the colony is strong.
9
10
Reciprocal Altruism
“I help you, in the anticipation that
you will help me in the future”

Can extend beyond close relatives.

Generally viewed as “the next higher level of cooperation”

It has more complex ways of dealing with groups and
“cheaters”.
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The Evolution of Cooperation

1984 book by Robert Axelrod

1981 article by the same title
–
One of the most cited articles in the
history of the journal Science
The coolest computer experiment ever done
- Mike Ignatowski
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Prisoner’s Dilemma
Prisoner B Stays Silent
Cooperates (with A)
Prisoner A Stays Silent Each serves six months
Cooperates (with B)
Prisoner A Betrays B
Defects
Prisoner B Betrays A
Defects
Prisoner A serves ten years
Prisoner B goes free
Prisoner A goes free
Each serves five years
Prisoner B serves ten years
“Rational Strategy” (according to standard game theory)
–
You are always better off defecting no matter what the other
person does.
–
Leads to each person serving 5 years in jail
“Irrational Strategy” (according to standard game theory)
–
If both prisoners behave irrationally (cooperates with each other),
then they each only serve 6 months in jail
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A More Generalized Payoff Matrix
Cooperate
Defect
Cooperate
3, 3
0, 5
Defect
5, 0
1, 1
We’ll use this version in the following discussions
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Axelrod’s Computer Simulation of an
Iterated Prisoner’s Dilemma
1.
Start with a large population of agents with different “strategies”
2.
Repeatedly have each agent play each other many times
3.
Sum up the total points scored by each agent
4.
Remove the worst scoring agents (bottom 10%) from the population
5.
Duplicate the best scoring agents (top 10%) and add those back to the
population
Repeat again from step one
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Evolution of Population with Simple
Strategies
Generation 1
D
C
C
D C D
C
D
D C
Generation 6
Generation 3
D
C
D
D
D C D
D
C
D
D D D
D D
D
D
D D
Cooperate
Defect
Cooperate
3, 3
0, 5
Defect
5, 0
1, 1
C = Always Cooperate
D = Always Defect
D
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Axelrod Asked Experts to Suggest
More Complex Strategies

14 people responded

Wide variety of different strategies

Axelrod added other strategies
–
Always cooperate
–
Always defect
–
Random choice
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Early Generations

“Nice” agents (cooperate a lot) do poorly,
–

“Nasty” agents (defect a lot) do well
–

they are taken advantage of by “nasty” agents
take advantage of “nice” agents
Population ends with many “nasty” agents
–
–
Very few “nice” ones
Plus some mixed agents (do both C and D)
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Middle Generations

Nasty agents spend most of their time defecting against
other nasty agents
–


Each only gets 1 point
Mixed agents that can cooperate with other mixed
agents do better
–
Provide they defect against other nasty agents
–
Long strings of 3 points from joint cooperation
Mixed agents grow and replace the nasty agents
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Later Generations

Bad agents are all eliminated

Mixed agents dominate the population
spending all their time cooperating with
each other
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Evolution of Population with More
Complex Strategies
Generation 1
Mid Generations
D
C
M
D C D
C
D
M C
Later Generations
D
M
D
D M D
M
D
D D
M
M
M
M M M
M
M
M M
C = Nice agents
D = Nasty agents
M = Mixed C and D
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Two Important Observation
There is no universal ideal strategy.
1.
–
The best strategy for an agent always depends on the
behavior characteristics of the rest of the population
Cooperation is hard to establish unless there are
repeated interactions between agents
2.
–
Implications to social policy and foreign policy
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Real Life Example
A real life example of spontaneous instances of cooperation during
trench warfare in World War I
–
Troops of one side would shell the other side with mortars, but would
often do so on a rigid schedule, and aim for a specific point in the other
side's trenches, allowing the other side to minimize casualties.
–
The other side would reciprocate in kind.
–
The generals on both sides were satisfied that shelling was occurring
and therefore the war was progressing satisfactorily, while the men in the
trenches found a way to cooperatively protect themselves.
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General Characteristics of
Successful Cooperating Strategies

Nice
–

Retaliating
–

A successful strategy must not be a blind optimist. It must always retaliate. An example of a
non-retaliating strategy is Always Cooperate. This is a very bad choice, as “bad" strategies will
ruthlessly exploit such softies.
Forgiving
–

The most important condition is that the strategy must be "nice", that is, it will not defect
before its opponent does. Almost all of the top-scoring strategies were nice.
Another quality of successful strategies is that they must be forgiving. Though they will
retaliate, they will once again fall back to cooperating if the opponent does not continue to
play defects. This stops long runs of revenge and counter-revenge, maximizing points.
Non-envious
–
The last quality is being non-envious, that is not striving to score more than the opponent
(impossible for a ‘nice’ strategy, i.e., a 'nice' strategy can never score more than the
opponent).
In other words, be a “Provokable Nice Guy” – with forgiveness
25
Group Insiders and Outsiders
Consider the following new situation
1.
2.
Most interactions are with a small group of other
agents
Occasional interaction (non-repeating) with an
agent outside the group
Dominant strategy becomes:
•
•
Cooperate with group members
Defect against outsiders
Social Cohesion
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Reputation
Indirect Reciprocal Altruism
Consider a very large population
–
each agent only interacts with another given agent once or twice.
– Leads to a un-cooperative (nasty) population
But what if other agents can observe your past interactions with all
other agents?
–
Leads to cooperating Tit-for-Tat populations again
– Establishing a good “reputation” is key to an agent’s success

–
i.e. nice, retaliating, forgiving, non-envious
Note: Much of our casual conversation is about how other people
behaved – about monitoring their reputation.
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Ultimatum Game
$1,000 Split between two people
Person A: decides on the distribution

50/50, 60/40, 80/20 etc…
Person B: Accepts or rejects the offer

If rejected, neither person gets any money
(One time single play in private, no iterations, no public observation of your behavior)
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Ultimatum Game – cont.
“Rational” game theory suggests that:
Person A: Keeps $999, offers B $1
Person B: Accepts the offer

$1 is better than nothing

In reality, most people will offer 50% to 30% to person B

Most people acting as “person B” will reject any offer below ~20%-30%

There is a strong impulse to “punish” people if they decide on an unfair
distribution.

Most people don’t really understand the implications of this being a single
non-iterated event, or that it does not effect their reputation since it is done
in private.

Punishing has become a very strong impulse for preserving cooperation,
even at a cost to the punisher.
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Have we been characterizing
evolution wrong all these years?
1.
Mutations
2.
Natural Selection -> survival of the fittest
3.
Development of Increased Cooperation
The story of evolution has been a story of
increasing levels of cooperation across all
levels of biology.
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Genes / DNA

Why don’t we have thousands of lose genes (DNA
snippets) floating around in the cell nucleus?
–
Maybe early organisms did
–
And such DNA snippets tried to out reproduce each other,
using up much of the cell’s resources
–
Putting them on a single DNA strand prevented this
competition to independently reproduce.
–
A gene would only reproduce if the entire cell reproduced.
34
Eukaryotes

The transition to complex
cells with internal structures

Incorporated mitochondria
and chloroplasts into the
internal cell structure
–
Both have their own DNA, and
were probably separate
creatures at one time
35
Multi-cell Organisms

Lichen is as far as this got with
cells having different genetic
material

More complex organisms have cells with
identical genetic material

Most of these cells are “sterile” – they don’t
reproduce

Only specialized stem cells reproduce.
–
This helps avoid competition between mutations.
36
Multi-cellular Organisms - cont.

And of course only a very small set of cells
within a large organism can produce another
organism.

For the vast majority of cells, they can only
successfully reproduce if the entire organism
reproduces.
–
This results in a complex division of labor with all the
cells working together for the success of the organism
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Large organisms have really
become “colonies” of organisms in
a cooperating relationship

There are 10x more bacteria cells that
make up a functioning human body than
there are “human cells”.
–
Mainly in your digestive system
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Cooperation across the full spectrum of levels
Every major advance in evolution of life has been an
advance in cooperation at larger scales

Genetic level

Cellular level

Multi-cellular Organisms

Social: multiple multi-cellular organisms
39
Cooperation is very common among most
animals and insects.
40
A picture of monkeys reminding us of the incredible benefits of cooperation….
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The development of human levels of
cooperation is a rare event.
–
It leads to increased communication,
language, culture, shared knowledge….
–
It only happened once in the history of life
on Earth
–
It lead to a domination of the ecosystem
43
Most social evolution =
cooperation at larger scales
44
Rethinking Market Economies

Competition is their fundamental element

Enabling cooperation between large
groups is their fundamental element
–
Buyers / Sellers / Producers / Middle-men
–
The Modern Corporation
45
“Competition has been shown to be useful
up to a certain point and no further, but
cooperation, which is the thing we must
strive for today, begins where competition
leaves off.”
–Franklin D. Roosevelt
46

Competition must always happen within a
constraining cooperative effort.

Unrestrained competition unsustainable
47
Competition can lead to
poor results

Race to the bottom: safety & environmental laws

Wasteful consumption from status competition

Overuse of common resources

Competition within teams is generally bad

Hiding information: Cancer research…

Congress – government shutdown
48
Growing Cooperation
49
Cooperative open source revolution
50
Cooperation at greater levels

International Trade

International Treaties

Scientific
Facebook

1.7B users ( larger than any nation )
52
Rethinking Market Economies

Competition is the most important thing

Competition and cooperation are both
fundamentally important

Actually, cooperation is becoming the most
important thing
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