"All wars arise from
population pressure." (Heinlein 1959 p. 145)
Major Reid (Heinlein's character in Starship
Troopers)was on the mark if you take "population pressure" to mean a
falling ratio of resources to population (roughly income per capita in modern
terms). There are sound evolutionary reasons why falling resources per
capita (or the prospect of same) usually drives human populations into
war. Wars and related social disruptions are here seen to be the outcome
of a behavioral switch
activated by particular environmental situations and mediated by xenophobic
ants engage in "wars"--that is, organized fighting between groups of social
animals. But--like humans--they don't do it all the time. Some
combination of environmental factors that probably includes time of the year,
temperature, and presence of ants from another nest turns on ant "war mode
evolutionary theory states that all physical characteristics and
species-typical behaviors (including behavioral switches for wars) are the
direct or indirect outcome of evolution.
The world is full of examples of behavioral switches.
Drop a rat in water and it swims. Bears hibernate during the
winter. Birds fly south or north depending on the season. It is
easy to see how behavioral switches evolved. Birds that flew the wrong
direction didn't leave many descendants. Perhaps the most spectacular
behavioral switch in the animal kingdom causes certain solitary grasshoppers to
become gregarious migratory locusts.
"At low population densities, these insects
behave like typical grasshoppers, to which they are closely related. But when
crowded, this insectan Dr. Jekyll transforms into Mr. Hyde. Chemical cues from
their feces and frequent disturbance of tiny hairs on their hind legs set off
the changes. The changelings aggregate in unruly mobs, feed in preference to
mating, grow longer wings and a darkened body, and irrupt into rapacious
swarms." (Lockwood 2003)
switch has such profound effects on body shape and behavior that for a long time
the different forms were thought to be different species.
Humans have behavioral switches too. Ones
we understand include maternal behavior (switched on by a flood of oxytocin
during birth), and Stockholm syndrome, where the brain chemicals released by
fear, abuse and minor acts of kindness cause rapid social reorienting to
captors. Robert Cialdini discusses a number of such behavior
switches (Cialdini 1984). For example, humans are hardwired to
reciprocate after being given something, even a flower. This was used
with huge success by the Krishna cult while begging in airports (p. 33).
My contention, simply put, is that the evolutionary
approach is the only approach in the social and behavioral sciences that deals
with why, in an ultimate sense, people behave as they do. As such, it often
unmasks the universal hypocrisies of our species, peering behind self-serving
notions about our moral and social values to reveal the darker side of human
nature. (Silverman 2003)
The understanding that emerges from applying
the profoundly powerful tool of evolutionary psychology to strange human
behavior is often so obvious that one marvels why it has not been known for
Consider the mysterious behavior of Elizabeth
Smart in Salt Lake City in 2003 or that of Patty Hearst when she was abducted
in 1974. In both cases the victims bonded to their captors and resisted
leaving them. The evolutionary origin of this psychological trait, known
as the Stockholm syndrome 
(or more descriptively as capture-bonding),
almost certainly comes from millions of years of evolutionary selection where
our ancestors--usually our female ancestors--were being violently captured from
one tribe by another. Those who had the psychological traits (ultimately
gene-based brain mechanisms) to socially reorient after a few days (i.e., bond)
to their captors often became our ancestors and passed on the trait. Those
who didn't have this trait all too often became breakfast. (Or were just
Being captured was a relatively common event
among our ancestors if their history is anything like the recent history of the
few remaining primitive tribes. 
In some of those tribes (Yanomamö, for instance) practically everyone in the
tribe is descended from a captive within the last three generations.
Perhaps as high as one in ten of our ancestors were abducted and incorporated
into the tribe that captured them. Once you understand the evolutionary
origin of this trait and its critical nature in genetic survival and
reproduction in the ancestral human environment, related mysterious human
psychological traits fall into place. Battered-wife syndrome is an
example of activating the capture-bonding psychological mechanism, as are
military basic training, fraternity bonding by hazing, and sex practices such
as sadism/masochism or bondage/discipline.
Another evolved psychological trait is the
drug-like reward many people get from intense attention. The evolutionary
origin of the attention-reward pathway is due to the way social primates
measure status. A certain amount of status is required before a hominid
male becomes attractive to females. (Status is approximately attention
integrated over time.) Perversion of this reward mechanism explains why
the behavior of cult members has many similarities to that of drug addicts. It also explains the origin of drug
addiction. (If you think about it, susceptibility to drug addiction has
to be a side effect of otherwise useful brain chemicals--it's hardly something
that could be directly selected.) I developed this theme in depth in "Sex, Drugs and Cults"
Species-typical behaviors evolved by natural
selection to maximize "inclusive reproductive success" in the EEA, that is the
Environment of Evolutionary Adaptedness. For humans the EEA existed
during the million of years our ancestors lived as hunter-gatherers on
savannas, on seashores, and in forests. It's a weighted composite of all
the places our hominid line lived and all their social environments back to
before we parted ways with the line that led to chimpanzees and
Species-typical behavior is generally good for
survival and "inclusive reproductive success" in the EEA. This is no
longer a radical viewpoint. See for example Gray's 2001 edition of his
psychology textbook, in which he discusses "Genetic and Evolutionary
Foundations of Behavior" in Chapter 3 (Gray 2001).
Except for a few remaining hunter-gatherer
tribes, we don't live in an environment resembling the EEA. Thus our
behavior may be a long way from optimal in other environments, as you will see
from the story below of the Southwest corn farmers.
In addition to the above-mentioned
psychological traits or mechanisms, evolution has left us with many others,
from our aesthetic preference for open parks with mowed lawns to the ease with
which we learn to fear snakes. Though the number is substantial, exactly
how many other traits we have is hard to determine. For one thing, some
of them may be called forth in the modern world even less often than
An example of such a trait is suicidal
self-sacrifice, particularly in war situations. For over a century after
Darwin formulated the first understanding of evolution, this and related
"altruistic" behaviors were hotly debated with next to no progress. Then,
in 1964, William Hamilton (in one of those jumps that seems so obvious
in retrospect) formulated the concept of "inclusive fitness." His
conceptual work started with bees. Because of the way sex is determined
in these insects, bees are particularly closely related, but the principle
works for any relative [Hamilton (1964a, 1964b), Haldane (1955), Smith,
Paraphrasing Hamilton, genes for psychological
mechanisms that make a person willing to die to save relatives should do better
than alternative genes under certain circumstances. As Hamilton put it, we should be willing to die if in doing
so we save more than two brothers, more than 4 half siblings or more than 8
cousins. Why? Because genes for this behavior would do better over
generations than the alternative since more copies of the genes would be saved
than are lost in the sacrificing individual. (Statistically, 2 brothers, 4 half
sibs, 8 cousins, etc., would share a copy of a gene for suicidal
self-sacrifice.) A milder statement of inclusive fitness is that we
should have evolved psychological traits to take life-threatening risks in
proportion to the number and relatedness of those we are risking our lives for.
Life seldom offers a clear choice in such stark
mathematical terms, but the psychological traits are there, honed by evolution
over millions of years. If you have ever wondered where humans get the
capacity to be suicide bombers, this is it.
Ants and chimpanzees engage in behavior similar
to human wars. Bees sacrifice themselves in the face of an immediate
attack. Mammal parents will take serious risks to save offspring, but
again only for immediate threats. In a time when birds and other primates
are found to be toolmakers, perhaps only the capacity for suicidal
self-sacrifice without an immediate threat sets humans apart from any other
animal. Why did we evolve it? And what turns on the
Answering the last first, memes. Memes
are replicating information patterns: ways to do things, learned elements
of culture, beliefs or ideas. The songs of whales and birds and a number
of primate skills such as cracking nuts or fishing for termites fit the
definition of memes, so they are not unique to humans. But the influence
of memes on humans is unique. People often die due to the
influence of memes. Of course the human susceptibility to memes is itself
a genetically evolved trait.
Going back to the question of why humans
evolved the capacity for meme-driven suicidal self-sacrifice, it is obviously
because the genes for such behavior did better in the EAA than alternate genes
due to Hamilton's inclusive fitness. But how?
1. War behavior in humans is not active
all the time so a behavioral switch is involved.
2. War is a species-typical behavior for
3. Evolution is the way war became a
species-typical behavior for humans
4. Evolution is a very slow process; thus
the influence of the last 10,000 years (since agriculture started) is
5. The psychological mechanisms behind
war behavior evolved during the several million years when our ancestors were
hunter-gatherers (in the EEA).
6. The driver for the behavioral switch
to war mode resulted from recurrent conditions in the EEA.
Origin of War
There is little doubt that human or human-line
groups have been making war on neighboring groups as far back as history and
archaeology can determine, probably before the common ancestor of human and
chimpanzees at least six million years ago.
"Through the years her work continued to yield
surprising insights, such as the unsettling discovery that chimpanzees engage
in primitive and brutal warfare. In early 1974, a "four-year war"
began at Gombe, the first record of long-term "warfare" in nonhuman
primates. Members of the Kasakela group systematically annihilated members of the
"Kahama" splinter group." (Goodall bio)
"It was both fascinating and appalling to learn that
chimpanzees were capable of hostile and territorial behavior that was not
unlike certain forms of primitive human warfare. War had always seemed to me to
be a purely human behavior. Accounts of warlike behavior date back to the very
first written records of human history; it seemed to be an almost universal
characteristic of human groups. [Wars] have functioned, at least ecologically,
to secure living space and adequate resources for the victors. To some extent
too, they have served to reduce population levels, thus conserving natural
resources." Goodall (1999 Chapter 9, "Precursors to War")
The (often unstated) assumption is that
behavior found in two related species was probably present in the ancestor
species, though the possibility cannot be ignored that the behavior evolved
independently in both sibling species. 
With respect to humans and our immediate
ancestors species, the question is what recurrent conditions in the EEA caused
a behavioral switch and the psychological trait(s) to evolve that resulted in
war's being a species-typical behavior for humans?
We have to be extremely careful in translating
from the modern world to that of hunter-gatherer tribes or the reverse
direction. Still, we can look at modern human behaviors and see if they
have logical support to have evolved in the EEA.
The most obvious way for a modern group of
humans to get into a state of war with another group is to be attacked.
Nothing unites a tribe or extended tribe (a nation) for war like being
attacked. Pearl Harbor or more recently 9/11 are prime examples, as are
other examples from tribes such as the Yanomamö.
It is easy to understand the evolutionary
origins of tribal responses to attack by predators--be they human or
carnivores. People with a (gene-based) tendency to viciously fight back
as a group when their group was attacked would be more likely to survive and
pass on those genes than ones who didn't respond and allowed themselves and
their relatives (with the same genes) to be slaughtered. Genes for
retaliation would continue to be favored in an environment where groups were
being attacked from time to time.
Defending from attack is easier to account for
than "unprovoked" attacks. Even if there are obvious resource gains to be
considered such as territory or food, if other people fight back, there is risk
to you and your genes of being hurt or killed while attacking. To balance
the genetic "accounts," the statistical risk to a representative hominid's
genes in going to war with a neighboring tribe must have been less than the
alternatives. William Calvin goes to the root of this problem when he
discusses Mama Bear and her cubs (Calvin 1990 chapter 3 .) Following
a Disney-like sequence of Mama Bear raising twin bear cubs every two years:
"Unfortunately, a little arithmetic shows
that this story doesn't have a happy ending. How many bears can the environment
feed? Obviously, that's the average bear population. And that means, on
average, only two babies per mother get to grow up and become a parent, out of
the dozen or two that she produces. The maximum population level is not set by
the birth rate but by the number of job slots afforded by the environmental
niche occupied by bears . . .."
"That means the average Mama Bear is
raising five-to-ten times more baby bears than can possibly survive, absent, of
course, miracles -- . . . "
Calvin goes on to point out that the extra
bears provide the substrate upon which evolution works, but they also cause the
population to periodically expand beyond resources for animals with few or no
predators. Sometime in the last several million years, perhaps as far
back as the time hominids started making sharp rocks, but certainly by the time
Homo Erectus had fire, the big cats were no longer effective at keeping hominid
numbers in check.
From what we know of primitive human mothers,
they were not as productive as bears--a well provisioned prehistoric human
mother probably produced a child every 4-5 years for 20-25 years as the !Kung
do (or at least did recently). But the end result was the same, the
environment was slowly filled to carrying capacity and beyond with
humans. With rare short-term exceptions, like the "miracle" 13,000 years
ago of tribes finding the American continents full of game and empty of people,
humans have always lived close to the ecological limit. For the last 6
million years hominid groups competed against other hominid groups for the same
game, roots, fruits and berries.
On top of the growth of human populations, the
productivity of the environment has never been stable. Several times in a
generation the rains fail or there is an exceptionally cold winter, or a fire
sweeps through. Such events disrupt human food supplies, abruptly
doubling (or worse) the harvesting area needed to feed a tribe.
When the population
increases over what the ecosystem can support, or some glitch in the weather
reduces the number who can be supported by it, fighting the tribe in the next
valley for resources is better for your genes than starving. (Almost anything
is). Tribes did not mathematically model the various outcomes, but our
genes have been selected to build brains that make such "genetic
cost-benefit" calculations on the basis of average expected outcome
without conscious awareness. (Capture-bonding does not involve conscious
awareness either--see Hearst's account.
In fact, our genes would
have been selected to go to war with the neighbors not when we are weak from
starvation, but when we anticipate hard times a-coming. Further,
like most psychological responses, this one is almost certainly tripped by relative
changes, here in income per capita, (originally game and berries), especially
by sharp downturns after a long ramp up (Cialdini 1984, p 249, quoting J. C.
A million years ago
tribes didn't have much choice of whom they fought--they had to be in walking
distance--though there is a historical case (Kroeber 1986) where warriors
walked over a hundred miles to fight. If you fought to a draw, some of
the mouths were no longer in a condition to eat and maybe that got you though
the lean times. If you won, you killed the males of the opposing tribe
and took their resources and women to the benefit of your genes.
If you lost, the males
in your tribe were usually killed, but because the winners normally took your
tribe's female children, your genes through these copies were still
better off in the "inclusive fitness" sense than starving. The Old
Testament stories of the Israelites may not be entirely accurate history, but
they do provide typical accounts of wars in a time closer to hunter-gatherer
culture, when war was a serious element of population control. For a recent historical example of
population reduction by war, in 1864 Paraguay went to war with 3 of its
neighbors. They were--needless to say--defeated.
nations in the world's military history exhibited such a degree of devastation
as the Paraguay of 1870. Its population, now estimated at only 221,000, had
suffered war casualties of at least 220,000 people. Among the survivors there
were only 28,000 men; women over fifteen were said to outnumber men at a ratio
of more than four to one." [Kolinski (1965) p. 198].
Going to war is
obviously a chancy business for genes. Unfortunately at times in our
collective past it was the only alternative to starving. In an evolutionary-psychology
model, the costs and payoffs of countless ecological crises and little tribal
wars have been statistically sampled over the last few million years and
recorded in human gene frequencies.
So how do you get from
falling income per capita or running out of game to a war? I can't point
to the exact parts of the brain that become activated when people are
anticipating future privation, but I expect the areas could be located using
functional MRI if some researcher were to go looking for them.
How do memes fit into this picture?
Chimpanzees, as Jane Goodall first discovered, can exterminate a neighboring
group without speech; their xenophobia seems to be wired in and active all the
time. Human groups, though, seem to require xenophobic memes that
dehumanize the target tribe to circulate among the attacking group for weeks to
months to work the warriors up to an attack. The model incorporates
amplifying xenophobic memes as a step in the causal chain leading to wars.
This is also part of the response to being attacked.
I suspect without being able to show it
directly that conditions of looming privation operate on brain modules to "turn
up the gain" (making an amplifying feedback loop) for xenophobic memes
propagating in a group. The connection between economic uncertainty or
hardship and aggressive, xenophobic or dehumanizing memes has been noted for a
long time, with the rise of the Nazi party in pre-war Germany as a typical
example. A mild example is that economic downturns are correlated with a
rise in neo-nazi and similar activity in the US. (Snap privation as
happened in the Irish potato famine or natural disasters occurs too fast to set
up the memetic amplification leading to war.)
Being attacked shortens the xenophobic meme
amplification process to almost nothing--sometimes with tragic
consequences. After 9/11 there were a number of cases in the US where
xenophobic attacks and killings occurred, often against people who were not
even Arab, but had features that their attackers identified as making them part
of the "attacking tribe."
Bad fit to non
We evolved the psychological traits leading to
war while living in tribes as hunter-gatherers, not in industrialized nations,
not even as primitive farmers. So it should come as no surprise that
psychological adaptations suited to limiting tribal populations don't work well
with more recent modes of life (technologies).
Steve LeBlanc (LeBlanc 1999) relates that after
expanding in a warm wet period, the corn-farming culture of the American
Southwest hit bad weather about 1260 CE. As expected from the model, the tribes
started warring with each other. The response they made of moving into forts
(pueblos) made them safer, but at the same time put much of their farming areas
out of reach.
This trapped the tribes in the feedback loop of
continuing privation and war mode for hundreds of years. LeBlanc states
that 23 of 27 groups of tribes vanished, died out or were absorbed into other
tribes. The few surviving groups (Zuni, Laguna, Hopi, Acoma) were still
at war with each other when the Spanish arrived in the 1500s.
War in complex urban societies is even
worse. War results in population crashes when the infrastructure
that keeps large populations alive is destroyed.
War mode impairs
In the EEA tribes were limited in size by how
far people could walk to collect food in a day. Because of this, the upper limit in the
most productive ecosystem was probably under 100 adults. A growing
tribe simply had to split when it reached a certain size depending on
the productivity of the ecosystem. (Tribe members didn't understand this
fact of life. Evolved social friction mechanisms overcame the
relationship ties and split the tribe as it approached the limit where it had
Thus for a given ecosystem tribes tended to be
about the same size. Making war on a tribe of roughly the same size was a
very risky business--if somewhat less risky for genes because they might exist
in the next generation even if the tribe didn't. Rational thinking would
not be in the interests of genes in such a situation. For this reason,
psychological mechanisms have evolved to switch human thinking
patterns--depressing rational thinking when xenophobic war memes start to
circulate or the tribe is attacked. This is the origin of the long list
of irrational acts and poor judgment that we see so often in the history of
The same depression in the ability to think
rationally lies behind suicidal self-sacrifice.
 Related irrational thinking occurs
when a tribe gets too large for efficient food gathering and social friction
mechanisms to split the tribe are being turned on.
It is apparent in interviews of baffled Rwanda
machete killers that they cannot explain why or how they entered the mental
state in which they did the killing.
As Bradley Thayer (Thayer 2004) points out the
genetic object of tribal wars was resources. One of the most spectacular
resource based wars in history was on Easter Island, famous for the
Moai statues. About 20 people settled Easter Island, a paradise of large
trees and vast numbers of sea birds. A few hundred years later
the population had grown a thousand fold, the last birds had been eaten, the
last tree had been cut down, and the population no longer was able to fish from
boats they had made from the trees. With the forest gone the soil
nutrients leached into the sea and the crops failed. (Diamond 2005 pp 79-119)
Such oral history as has come down (backed up
by a lot of field work) indicates that the highly related population split up
into the "long ears" and the "short ears." (Further indication that
any meme in the class that whips up warriors into "jumpin' up and down, yellin'
`KILL! KILL!'" will do.  )
The Easter Islanders went at each other with sharp rocks for two or three
Eventually the population was reduced to 5-10% of the peak. With much
lower demands the environment recovered to some extent and the rising income
per capita shut off "war mode." When Europeans arrived population had
perhaps doubled from the low point.
In short, humans go into war either because (1)
"war memes" build up in a population looking at bleak prospects or
(2) they are attacked. The two modes are additive and there are nasty
feedback paths, as we saw with the Southwest corn farmers.
Assuming we don't want war, what do we do to
keep it from happening?
Population growth lower than economic growth
keeps the mechanism that builds up "war memes" from being
activated. So how does that come about?
"When [globalization] comes into
traditional societies, which are pretty much defined by male control over
females, it suddenly alters the character of some of our most important
relationships and decisions: marriage, sex, births, family economics, the whole
shebang. And globalization has proven itself time and time again to empower
women disproportionately over men. That is a direct threat to the nature of
Empowering women and other factors such as
reliable birth control methods that go with the globalized high-tech life style
has the effect of lowering the birth rate to near or even below
replacement. Why isn't entirely obvious. The usual response of a
species finding itself in a rich, well-fed environment is to have lots of
offspring. Sarah Hrdy (Hrdy 1999) has given this topic a lot of thought
without reaching a firm conclusion.
There is no obvious evolutionary reason wealth
above a certain level should result in the demographic transition to a lower
human birth rate. Certainly the rationalizations for small families, such
as being able to send the children to college, didn't exist in the EEA.
It's a subject that deserves more study in the light of evolutionary
psychology. Perhaps it is an unrecognized side effect of a psychological
trait such as status seeking. In any case, as E. O. Wilson says, we are
What happens with lower birth rates in the
modern world is that after a 25-30 year delay economic growth can sometimes get
ahead of population growth. The effect of
rising income per capita is to turn off the psychological traits that give rise
to wars or related social disruption. As an example, the IRA has about
gone out of business in Northern Ireland. The reason is that the
birthrate there declined by about half a generation ago.
The psychological traits that lead to wars
evolved over the millions of years human ancestors lived in hunter-gatherer
tribes. War was the way populations stayed in balance with the ability of
the ecosystem to feed them. Typically populations built up and were
periodically reduced by wars.
In the modern world if a group does not have
the pressure of population growth in excess of economic growth, that group
won't start wars. It is the effect of low birth rates and relatively high
economic growth that has kept the democracies from starting wars. (At
least prior to 9/11.)
Of course they can still be attacked, which is
why the well being of other tribes (now nations) is important to your tribe
Even today this model might account for most if
not all wars.
"Social psychodynamics" and "psychohistory"
were mathematical models. They were fictional, but a real science of social
prediction based on evolutionary psychology will require mathematical
treatment. A mathematical/computer model is unlikely to provide exact
long-range predictions, there obviously being an element of chaos in
reality. It still could be of considerable use to governments if the
model could put numbers on the likelihood of a minor disturbance growing into
nationwide riots as recently happened in France. Models on the readiness
of a population to support a war, such as the Argentina and British populations
before the Falklands War, would also be of considerable interest.
Putting historically derived constants on the
factors leading to war is a project for the next paper--though it might take a
There are other models for predicting
wars. One of them is that wars are caused (somehow) when the percentage
of young men with poor prospects for reproduction exceeds some percentage of
the population. (Hudson 2004)
The Chinese have inadvertently provided a test
case. As a result of selective abortion favouring male children the
excess male population is well into the range where these theories predict
war. The EP model presented here predicts that the Chinese will not start
wars in spite of the excess males as long as their income per capita is rising.
Since the Chinese have done an astonishing job of getting the birth rate down,
that's a lot easier for their society to accomplish. Of course the
Chinese could still go into war mode by being attacked.
Going down the list of countries it is possible
to rate them for future problems just by looking at the direction of their
income per capita and future prospects.
To avoid wars in the long term, all cultures
(including Islamic cultures) will have to either
empower women or figure out some other way to reduce their population growth
to levels consistent with long-term economic growth.
Does the current mess the US is in fit this
Prior to the US attacking Iraq, it had been a
long time since a country in the developed world started a war. The 1982
Falklands War might have been the last time. The conditions under which
that war started and the way it was escalated by the British are consistent
with the model.
For various reasons, the Islamic world's income
per capita has been falling, partly because the culture is not particularly
accepting of western technology--including modern birth control--that empowers
women. The worst place in the world for falling income per capita before
the recent run up in oil prices was, of all places, Saudi Arabia, which saw a
nearly 75% fall in income per capita about equally due to falling oil prices and
rising population from a high birthrate. Saudi Arabia was the source of
most of the 9/11 suicide hijackers. Significantly birth control is
Saudi Arabia is not the only problem.
Stable or rising income per capita is rare in Islamic-Arab countries, and every
one of those is from resource extraction. The response to falling income
per capita in the modern world probably isn't nearly as deterministic as it was
in hunter-gatherer times; likely being influenced the particular memes already
circulating and the people who obtain "war chief" status
(i.e., bin Laden and Co.). Modern transport makes any "tribe" in the
world a possible target, with the largest "tribes" being the most likely
So falling income per capita provided the
conditions where the Al Queda meme set and related xenophobic memes motivate
warriors, and provide them support from the populations.
That's the origin of the 9/11 attacks.
Stupid, of course, but we evolved in little tribes where it made sense for
genes to build brains with the psychological trait of irrational thought in war
mode. If you were in a small tribe facing starvation, an insane attack on
a larger tribe where all the males of the little tribe were almost certain to
be killed was better for their genes than starving. Why? Because
most of the time the tribe's young women were booty and became wives (or second
wives) in the victorious tribe. And against the odds they might win.
At the rational level Osama bin Laden and his
followers had no idea why they were attacking, but what the underlying
evolved psychological mechanisms were "expecting" (if he lost) was
for him and all of his male relatives to be put to death and his sisters and
daughters to be absorbed as wives or extra wives into the tribe he had attacked
(which for genes--as we have seen--beats starving). But the mechanisms
were cheated out of their "expectation." It just isn't politically
correct to deal with enemy tribes today the way they did in biblical
times. (I speculate that "biblical treatment" has fallen out of
favor as a meta effect of wars in the advanced countries becoming rare due to
long periods of rising income per capita.)
One of my reviewers pointed out that bin Laden
and most of his terrorists were not facing personal privation nor were their
families. Many of them are college educated with good socio-economic
backgrounds and prospects. This is where xenophobic memes spilling over
from the rest of the culture have their effect. In those long ago tribal
days, even well fed warriors had to get caught up in the madness if they were
going to successfully attack a neighboring tribe for resources.
So the huge US "tribe" was attacked
on 9/11 by OBL's tiny "Al Qaeda tribe" and went into war mode due to
Additionally, though the US has not suffered a
lot in total income, in the last few decades there has been a massive internal shift
in income with a large fraction of the population facing bleak times.
(Few starve in the US, but the war-meme behavioral switch mechanism needs only
a relative drop to be activated.) To the extent a substantial
fraction of the population faces reduced prospects or thinks they are, they are
that much more willing to support war and/or circulate xenophobic memes such as
the rapture/Armageddon and fulfillment of biblical prophesy.
How did the US
get into this Iraq mess?
Once a tribe is attacked (and goes into war
mode) rationality really suffers. It's not different from the damage to
rationality that comes from the build-up of war memes in a tribe with bleak
prospects but it happens much faster. Under those circumstances, tribes
follow leaders who are often less rational than their supporters. In this
case the US had the misfortune of a leader who had a preconceived notion of
which country he wanted to attack. Also perceptions of being under attack
are more important than reality in activating behavior switches. "All you
have to do is tell them they are being attacked."
 In the months leading up to the
attack on Iraq, the message put out by the US administration was "be afraid, be
very afraid, we are about to be attacked with Saddam's weapons of mass
So the US military overran Iraq with high
support from the US population. Of course other than being Muslims (and
not even very radical ones at that), the Iraqi tribes had nothing to do with
9/11. Still, had the US been able to restore electricity and bring up the
economic prospects in Iraq in a few months, they might have gotten away with it
since a fair fraction of the population didn't care for the former
But the US failed to improve or even restore
the Iraq economy to the depressed pre-war levels. Now the bad economy in
Iraq is a powerful psychological mechanism supporting war memes, plus the fact
that Iraq was attacked which turns on war mode in the population and
wrecks their rationality just like the 9/11 attack did in the US. The
ongoing upheaval, especially the meme-driven suicide attacks, makes the
economic improvements needed to shut off war mode next to impossible. Of
course in a generation the people get used to the low economic level and some
minor economic up-trend could shut off war mode. That is what happened in
Lebanon and probably will happen in Iraq for those willing to wait 25 years.
And getting out?
Unfortunately understanding the evolutionary
psychology mechanisms behind wars hasn't (so far) led to an acceptable proposal
for what might be done about the current situation.
An unacceptable--even mad
proposal--would be to swap out the whole Iraqi population with Texans and
rapture believers. It's not impossible from a logistics point of view
(the US moves 25 million people through its airports in about a month).
The Iraqis would get a place where the power was on all day-- which would
improve their "income per capita" perception enough to shut off support for war
and related disruption. The Texans would have oil, which would certainly make
them happy, and with no fighting they could patch the country up in a year or
two. If there really are as many people looking for the rapture as the
polls show and some rapture leader got the idea that being closer to the Holy
Land was a good idea, a voluntary population swap might be oversubscribed.
But then what would you do? The US
doesn't need a 51st state in the Mid East full of people looking for the
rapture no matter how much oil it has.
Subsequent to finishing this article, I found
Azar Gat's excellent paper "The
Human Motivational Complex: Evolutionary Theory And The Causes Of
Hunter-Gatherer Fighting." I consider it entirely supportive.
Even more recently, January 2006, is the work
of Westen, D., Kilts, C., Blagov, P., Harenski, K., & Hamann, S.
"The neural basis of motivated reasoning: An fMRI study
of emotional constraints on political judgment during the U.S. Presidential
election of 2004." It is still, as of April 17, 2006 an unpublished
manuscript in revision. It is (from the press
release) a demonstration of the mechanism proposed in this article where
partisan mode (war mode) disrupts rational thinking.
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Lexington: The University Press of Kentucky
Abstract: Evolutionary psychology
and memetics are used to propose a model of war. Population growth leads
to a resource crisis. An impending resource crisis activates a behavioral
switch in humans allowing the build up of xenophobic or dehumanizing memes,
which synchronizes attacks on neighboring tribes. Hamilton's criterion of
inclusive fitness is invoked to account for the evolution of this species
typical behavior. War as an evolved species typical behavior in the EEA
for humans is discussed, first as an attack response and second as unprovoked
attacks. Unprovoked attacks are proposed to require the build up of
xenophobic or dehumanizing memes. Evolved brain mechanisms are proposed
to cause these memes to become more common when the subject population
anticipates "looming privation." The well-known reduction in the ability
of humans to think rationally in war situations is explained in evolutionary
terms as a divergence in interest between the individual and his genes.
The problem of avoiding wars is examined in terms of these mechanisms.
Population growth at a higher rate than economic growth is proposed as the
causal factor for wars in the modern world. This model and the "excess
males" model make different predictions about where future wars will
start. The model is then applied to analyze current events.
Keywords: Evolutionary psychology, memetics,
war, behavioral switches, xenophobic memes, dehumanizing memes, Stockholm
syndrome, capture-bonding, impaired rational thinking, inclusive fitness,
Thayer has written a substantial book, (Thayer 2004), where he explores arguments
for an evolutionary origin for wars and ethnic conflicts. I didn't find
his book till this article was nearly complete. Roughly 1/3
of the book is notes and references. Anyone who finds this article
inadequately referenced is advised to read Dr. Thayer's book. His
research into the literature is entirely supportive of this paper--though he
does not take the final step of proposing particular evolved mechanisms leading
The syndrome is
named after the famous Norrmalmstorg robbery of Kreditbanken at Norrmalmstorg,
Stockholm which lasted from August 23 to August 28, 1973. In this case, the
victims kept on defending their captors even after their six-days physical
detention was over. They showed a reticent behaviour in the following legal
procedures. The term was coined by the criminologist and psychologist Nils
Bejerot, who assisted the police during the robbery, and referred to the
syndrome in news broadcast. It was then picked up by many psychologists
Other famous cases include those of airplane hostages and kidnapped
people, such as Patty Hearst. After having been a hostage of a politically
engaged military organisation (the Symbionese Liberation Army), Patty Hearst
joined the group several months after she was freed. The syndrome is related to
bride capture and similar topics in cultural anthropology.
capture" was socially acceptable in England as late as the 15th century
and still is in a few remote corners of the world
speculative, but genes for intensely rewarding sex that induced rapid social
reorienting and bonding would be favored in capture-bonding situations.
It is also the
reason certain drugs--chemicals that happen to fit the endorphin and dopamine
receptors--are addicting. It makes no sense that humans would have
evolved the ability to become addicted. It does make sense that humans
would have chemically--mediated reward circuits that encourage behavior that
aids reproduction. The capacity to become drug-addicted is a by-product
of the attention-reward pathway. See also Blakesley (2002)
"To express the
matter more vividly, in the world of our model organisms, whose behavior is
determined strictly by genotype, we expect to find that no one is prepared to
sacrifice his life for any single person but that everyone will sacrifice it
when he can thereby save more than two brothers, or four half-brothers, or
eight first cousins...." (Hamilton 1964a p. 16)
biologist J. S. B. Haldane made similar statements. I am not sure who has
 The problem with this argument applied to
chimpanzees/bonobos/humans is that bonobos have not been observed to make war
on neighboring groups and humans are as closely related to bonobos as we are to
chimpanzees. Presumptively bonobos are capable of population growth to
press the limits of their environment to support them. If wars are not a
factor limiting bonobo numbers, it would be of great interest to find out what
are the limiting factors?]
interview with Larry King on CNN: "And, you know, I had no free will. I
had virtually no free will until I was separated from them for about two weeks.
And then it suddenly, you know, slowly began to dawn that they just weren't
there any more. I could actually think my own thoughts." From
Numbers, from The holy Bible, King James version Chapter 31
7: They warred against Mid'ian, as the LORD
commanded Moses, and slew every male.
8: They slew the kings of Mid'ian with the rest
of their slain, Evi, Rekem, Zur, Hur, and Reba, the five kings of Mid'ian; and
they also slew Balaam the son of Be'or with the sword.
9: And the people of Israel took captive the
women of Mid'ian and their little ones; and they took as booty all their
cattle, their flocks, and all their goods.
10: All their cities in the places where they
dwelt, and all their encampments, they burned with fire,
11: and took all the spoil and all the booty,
both of man and of beast.
12: Then they brought the captives and the booty
and the spoil to Moses, and to Elea'zar the priest, and to the congregation of
the people of Israel, at the camp on the plains of Moab by the Jordan at
13: Moses, and Elea'zar the priest, and all the
leaders of the congregation, went forth to meet them outside the camp.
14: And Moses was angry with the officers of the
army, the commanders of thousands and the commanders of hundreds, who had come
from service in the war.
15: Moses said to them, "Have you let all
the women live?
16: Behold, these caused the people of Israel,
by the counsel of Balaam, to act treacherously against the LORD in the matter
of Pe'or, and so the plague came among the congregation of the LORD.
17: Now therefore, kill every male among the
little ones, and kill every woman who has known man by lying with him.
18: But all the young girls who have not known
man by lying with him, keep alive for yourselves.
There are cases in
post-agricultural history where suicidal self-sacrifice made a major difference.
For example in 480 BCE Leonidas king of Sparta commanded 300 Greeks in one of
the pivotal events in modern human history: the battle of
Thermopylae. A small force (eventually wiped out to the last man) held up
over 100,000 Persians in a narrow pass for six days while the Greeks mustered
the forces that eventually defeated the Persians. The achievements of
Greece lie at the root of western culture. Without this sacrifice the
world would be very different.
(1984). p. 256: "It is easy enough to feel properly warned against
scarcity pressures; but it is substantially more difficult to act on that
warning. Part of the problem is that our typical reaction to scarcity
hinders our ability to think.
From the song
"Alice's Restaurant by Arlo Guthrie, 1966.
protein turned to the biggest animal left on the island for food, namely
humans. The island society collapsed in an epidemic of cannibalism....The worst
insult that an Easter Islander could say to another Easter Islander was `the
flesh of your mother sticks between my teeth.'"
Wilson International Center for Scholars)
"Of course the
people don't want war. But after all, it's the leaders of the country who
determine the policy, and it's always a simple matter to drag the people along
whether it's a democracy, a fascist dictatorship, or a parliament, or a
communist dictatorship. Voice or no voice, the people can always be brought to
the bidding of the leaders. That is easy. All you have to do is tell them they
are being attacked, and denounce the pacifists for lack of patriotism, and
exposing the country to greater danger."