Human Instinct:
By Robert Winston
       
Before life began there was just primeval soup, and in the soup there was a mixture of molecules, particularly
carbon dioxide and methane, both carbon-based, and water from the gases hydrogen and oxygen.  From these
simple inorganic molecules and atoms it is relatively easy to make amino acids.  It is postulated that these amino
acids- the building blocks from which all proteins are composed, essential to life on this planet- started to form
chains.  Similarly, relatively simple carbon-containing compounds such as sugars and purines were also formed.  
All of these substances are the basic components of necleotides, and hence DNA.  Proteins were made which
possibly broke up and recombined randomly.  Eventually, by chance, there appeared a few molecules that could
make copies of themselves.  By combining other amino acids as raw material, they happened to be able to copy
their own chemical structures.  These molecules, which we can call replicators, spread throughout the primeval
soup, reproducing and increasing in number.
      
But some replicators did not last long.  The replication process might have been flawed, thus they made copies
that were riddled with errors; the errors built up and eventually, in the final generation of copies of copies, the
molecules could no longer replicate themselves.  Like a lengthy game of Chinese whispers, the last molecule in
the line was effectively gibberish.  Others might have been able to make exact copies, every single time, but they
would never change and never evolve.  They would produce molecule after molecule, copy after copy, without
ever developing into something more complex, until they ran out of the simple proteins that provided the raw
material for replication.  So exact replication did not guarantee success.  Once again, they were an evolutionary
dead end.
      
Long-term success needs a happy medium.  It needs a molecule that replicates and makes just enough errors to
evolve and adapt to the conditions in which it lives.  If one particular variation of this replicator runs out of raw
materials, or maybe gets 'eaten'- used as raw material to feed another kind of replicator- there will be other
variations which may be more successful.  Just like the bacteria that mutate and develop immunity to antibiotics,
these early replicators will develop immunity to being eaten.
      
Eventually there was one especially prosperous replicator.  By chance, the mechanics of this molecule struck a
perfect balance in the copying process- not too exact and not too careless.  This replicator had enough
adaptability to spread, flourish and eat up all the other kinds of replicators while still retaining its own core ability
to reproduce itself.  We have a name for the modern descendants of this fantastically successful replicator- DNA.  
Its offspring  are contained within every single cell in every single plant and animal on this planet.
      
Along the long, twisted double helix of the nucleotides of the DNA replicator lie the parcels of coded information
we call genes.  Over time, genes mutate and change randomly.  Most mutations are pointless, or, worse, are
damaging to the survival chances of the genes, but some are helpful, and evolution has shown which genes are
good and which are bad.
      
There is no species of free-swimming DNA in the world's oceans.  The closest that we know about are simple
viruses, strands of replicators enclosed by a protective sheath of protein.  The instructions for making the
protective jacket are encoded in the DNA and these organisms are the precursors of every other kind of animal.  
The point is that every organism, including human beings, is a kind of protective jacket for DNA.  Our cells, which
in turn group together to make tissue, bone, skin, blood and nervous systems, are all integral components of our
DNA's extraordinarily complex survival machine.  The human boday and mind are adaptations 'designed' to
further the survival of our DNA replicators.  The individual organism merely becomes a machine for carrying the
genes, and the microbe, plant or animal is not the real focus of natural selection.
      
Natural selection is all about the spread of successful genes at the expense of not-so-successful genes.  These
genes do not have to make life pleasant for their or anyones else's survival machines.  As long as the genes can
replicate, life for its host organism can be miserable, painful, or just plain dull.  Genes do not care.  Selfishness is
therefore a cardinal quality in a gene in which paradoxically its own survival comes before the survival of the host
organism.  Many people assume that because our genes are selfish, so are human beings in their relationships
with one another.  This is only partly true.  Gene-centered evolution tells us that co-operation and altruism can
often be as beneficial to our genes as can competition.
      
Five million years ago, our hominid ancestors climbed down from the trees in the thinning forest to try their luck on
the savannah.  They were forced by an encroaching Ice Age to adapt to a new environment, a place with fewer
natural resources and little protection from predators.  Here, a slow and vicious drama of natural selection would
be played out over two hundred thousand generations as the ape-men struggled to compete with animals that
were faster, stronger, hardier, more poisonous and fundamentally more suited for violence, mayhem and weather
of savannah life.
      
It was on the savannah where our minds and instincts evolved in order to adapt to the conditions.  We adapted
quite well, but we must not make the mistake of thinking that evolution is perfect and that it will lead necessarily to
the best possible outcome.  Evolution is imperfect because it always involves change.  It cannot retrace its steps
and completely reorganize the system.  Everything builds upon itself, and each step of the way there must be an
evolutionary pressure to move in one direction or another.
      
Our brain, and the mind it housed, appears to have been our secret weapon and the solution to the problem of
survival.  An increasingly complex architecture began to develop.  Over the next three million years our brains
tripled in size.  Today, there is tension between our Stone Age instincts and the stresses and strains imposed by
post-industrial civilization.  We are pushed and pulled in all directions by many different biological, cognitive and
cultural forces.  Some of these may oppose one another, and some may pull in the same direction.  It is entirely
possible for two instinctual tendencies to act at odds to each other.  But that does not mean these forces cannot
coexist; it just means that the track through space is more difficult to understand.  It is impossible to model human
behavior because there are too many factors involved and tiny shifts in initial conditions can have dramatic long-
term effects.  Not to mention that humans apparently have free will.
      
      
The Brain
       
The human brain takes up 20 percent of the available oxygen and energy in our blood.  Its greedy energy
requirements work out as being ten times as much for its size as any other organ in the human body.  Moreover,
the brain is an engine that runs continuously day in, day out, but without the ability to store energy.
      
The tripling in size of the human brain was an enormous and unprecedented evolutionary leap.  This
extraordinary growth is at the very heart of our five-million-year-long story.  Human beings are clearly not typical.  
Our brains account for 2 percent of our body weight, three times larger than one would expect for a primate of our
size.  It has been shown that humans have by far the highest ratio of brain size to body size, but interestingly, the
other animals that score relatively high in this field tend to live in complex social groups with much interaction with
other members of the same species.
      
The growth of the human brain was not simply a scaling up of the old model, but instead there was an out-of-
proportion expansion of an area of our brain called the prefrontal cortex and its relation to other parts of the
cortex.  The cortex is responsible for high-order types of thinking and planning that we associate with the very
essence of humanness.  More importantly, this scaling-up is not just in terms of the actual size of the cortex, but in
its complexity and the degree to which it is connected and controls other regions of the cortex.  In other words, the
prefrontal cortex began to branch out to the places other parts of the brain couldn't reach, affording it and its
higher functions with a new dominance in the evolving brain.
      
We know that our human minds have a tremendous capacity to learn skills and pick up new knowledge, but it is
what is at the heart of this learning process that counts.  In order to learn, we must communicate with others, and
the social nature of hominids and early humans was vitally important: how they lived as a group, found food as a
group, protected and communicated with one another.  It is difficult to catch large prey alone.  Once prey is
caught it makes sense to share the kill, otherwise much of the meat will go to waste.  In large groups, sharing
meat and other foods would have acted as a kind of insurance policy: if today you don't manage to catch
anything, then tomorrow others will share their food with you.  And while living, hunting and gathering in groups
would have meant everyone had a better chance of getting fed and therefore surviving, the process relied on the
hominids being able to communicate with one another.  It implies an ability to predict how others will react, and to
keep track of alliances and rivalries.  Look at our own every day behavior.  Though we cannot literally read other
peoples minds, we spend a great deal of our daily lives listening carefully to what people say, watching their
faces, eyes and body language and trying to make sense of their behavior.  Most of us are naturally skilled at it.  
Abilities like planning, memory, communication and consciousness of ourselves and others almost definately
constitue the twist in human evolution that marked us out from all other animals.
      
Group living takes brainpower.  You need to remember who everyone is, to begin with.  Then you must learn the
relationships between individuals.  You need to communicate, to forge links of trust and reciprocity, and to
remember where you stand in each relationship.  It has been proposed that the size of the primate brain is in
proportion to its ability to handle a certain size of group.  It has been shown that there is a linear relationship
between the relative size of the neocortex and the average social group size.  The predicted natural human group
size is in the range of 125 to 150.  Approximations to these figures crop up in many studies of group size among
all kinds of different societies.  Our circle of community, whether we are urban socialites or rural recluses, reflects
the limits of our cognitive capacity.
      
      
Competition
       
Social Darwinism is a common misuse of evolutionary theory.  There is no reason why in modern society moral
rectitude, intellectual vigor and physical capability should translate to increased reproductive potential.  
Contemporary human society most certainly does not operate according to the laws of natural selection.  For
natural selection to work, those with physical or mental traits more suitable to their environment or lifestyle must
have more children than those who do not.  Intelligent, strong-willed or talented people do not on the whole leave
more offspring in the world than the average; nor are accomplished athletes necessarily more successful at
having babies than couch potatoes.
      
The Social Darwinists were also wrong to suggest that natural selection should act as a guide to the way we ought
to live.  There is no logical reason why there is anything morally worthwhile about the process of natural selection;
it is, by its very nature, morally neutral, a biological process based on random mutations.
      
Now it's pretty obvious that 'survival of the fittest' doesn't describe the way we live in modern society, but for most
of the evolutionary history of Homo sapiens things were very different.  Survival of the fittest, the perpetual lottery
of human survival, of human being pitted against human being, is an accurate picture of natural selection.  
Competition between members of the same species is the engine that drives natural selection.  Each step along
the way was a product of competition between contemporaries, humans who breathed, ate, made tools, perhaps
even talked to one another.  They were competing for mating opportunities and for resources such as food, water
or shelter; for the chance to survive and further their genes by reproducing.
      
Where competing for mates is concerned, nature has shown that we are likely to develop a tendency for
competitiveness and aggression.  These traits are a product of 'sexual selection'.  Natural selection, it is worth
reiterating, is the process whereby traits are selected which enhance the survival of any particular individual.  
Anything that allows us to live longer, eat better and protect ourselves and our kin from danger so that we and
they can reproduce could be a possible adaptive mechanism and a product of natural selection.  Sexual selection,
on the other hand, is the process that favors your genes chances of survival if you have an increased number of
mates, and therefore a larger number of offspring.  Anything that increases your chances of having sex will be
adaptive by sexual selection.  At its heart, sexual selection is all about competition and conflict within the species.
      
Sexual selection acts more powerfully on males than it does females simply because males have to compete more
fiercely for mating rights.  In today's world, men do take more risks than women, both in their day-to day lives and
in terms of their liking for dangerous activities.  Men are also more likely to impose 'handicaps' on themselves.  
This doesn't just mean making oneself a target of a predator, but to poison oneself with drugs and alcohol, to
exert energy on pointless and dangerous activities, or to spend precious resources without any discernible gain in
survival or fitness.  The instinct has become so ingrained that risk is a fundamental element of human psychology,
whether or not we are actively looking for a mate.  Human beings delight in their excess, find more and more
ingenious ways of putting themselves in jeopardy and adopt as many expensive habits as they can afford.  On a
more positive note, men do perform many more heroic acts than women, and it has also been suggested that
through this evolutionary process they have developed to be more ambitious.
      
In the small, tightly knit groups of our ancestors on the savannah, they needed to be able to read the intentions or
desires of others and convince them of certain courses of action.  They had to understand the social power
structure of the group and of kinship, possibly making alliances in the process.  You can see how devious
individuals would be much better at securing more than their fair share of resources, assuming they did not get
caught.  In a small group, getting caught lying or cheating is extremely damaging to one's future prospects.
      
More brain power is required to be a manipulator than to be manipulated.  Once a form of behavior appears that
exploits the gullible, there will be a selection pressure to match this exploitation with counter-exploitation,
something that requires greater intelligence.  The arms race would continue, turning brain-power into an essential
evolutionary property, each Machiavelli being outdone by the next.  Considerable brain capacity, particularly
enlargement of the cortex, seems to be necessary for the efficient memory individuals need in order to build
extensive social knowledge and rapidly learn new tactics in interaction.
      
One may also extend this theory to sexual conquests.  Perhaps sexual selection does have an answer for why
both men and women have equally sized brains.  The human brain itself can be seen as a mechanism of sexual
choice; perhaps as men evolved more highly complex brains to woo females, women too had to develop bigger
brains in order to understand and choose their man.  It seems that a complex combination of sexual selection and
the need to interact with others socially and to make use of a certain Machiavellian intelligence may well account
for how we've ended up with such large brains.
      
      
Fight or Flight
       
Our early hominid ancestors lived in a very dangerous environment.  When they first made it out onto the African
savannah, they were vastly outnumbered by vicious and hungry predators.  To stand the best possible chance of
survival, all animals have to protect themselves from danger and death, so they need a means to be alert to
threats at all times, to fear them and to fight or flee in response to them.  The imperative is self-preservation as
well as the survival of the species.  In evolutionary terms, a fearless animal would be much less likely to survive
and pass on its fearless genes.
      
It's certainly a reflection of just how vital the fear reaction really was for the survival of our ancient ancestors that a
special, dedicated brain system evolved to deal with it.  The location of the amygdala gives us a clue to the
precise nature of its role in processing fear.  It has connections to the autonomic nervous system- which controls
physiological reflexes such as your heart and breathing rates- as well as other brain regions that process sensory
input.  It's like a neurological crossroads, the hub of a network of pathways in the brain, a special 'rapid response
unit', primed to act quickly when presented with danger.  The amygdala's connection to the eyes and ears is a
special ultra-fast pathway which means it has access to raw and unprocessed sensory information.  There is no
involvement of a higher, conscious brain, no cognitive processing that tells the amygdala what to do.  So it turns
out that our most primeval emotion, to advance or retreat, is triggered so fast that it precedes all conscious
thought and awareness.  This results in a large number of mistakes being made, but evolution dictated that it is
better to be safe than sorry.  It is also interesting to note that there are far more connections leading from the
amygdala to the prefrontal cortex- the area of the brain responsible for planning and reasoning- than there are
going in the other direction, which may be one reason why we sometimes find it so difficult to exert conscious
control and logic over our fear.
      
E.O. Wilson, one of the founders of sociobiology- the study of the evolution of animal social behavior- compared
the hard-wired fear we have of certain things, to exposing an image on photographic film.  After exposure the
image is present but invisible; it appears only when the film is developed.  The image may be developed to
varying degrees of darkness or lightness, with a different tint or contrast, or perhaps not developed at all, but the
picture itself remains the same.  Our instinct for fearing snakes has always been imprinted on the film and all that
remains is for the film to be developed.  Indeed, putting the rarer forms of human phobias aside, the vast majority
fall into one of four very clear categories, all of which would have indeed had meaning for our ancestors on the
savannah: firstly a fear of animals such as snakes, spiders, and insects; then a fear of natural environments such
as height or the dark; fear of blood or injury; and finally a fear of dangerous situations such as being trapped in a
tight space.  For early humans, feeling such threats would clearly have been a useful mechanism for prolonging
survival: those who possessed the ability to sense and evade these dangers were more likely to live and
reproduce, passing these fears on to future generations.
      
      
Violence
       
Psychiatrists believe that many persistent criminals suffer from a condition called anti-social personality disorder,
or ASPD, which is essentially a milder form of what’s known as psychopathy.  The outward signs of ASPD include
impulsiveness, recklessness, a habit for getting into fights, deceitfulness, an inability to conform to social norms
and a lack of remorse when crimes have been committed.  The suggestion that a disposition to violence is
pathological has two implications: firstly, that it may somehow be cured, and secondly, that violence had no useful
role to play in our evolutionary past.  Territory, mates and food- these were the basic and essential commodities
for life on the savannah.  Now, imagine what might have happened during a conflict over a water hole on the
savannah, or for that matter in a confrontation over who gets a parking space in a supermarket parking lot.
      
It turns out that our ancient fight-or-flight is not only initiated by feelings of fear, but also by feelings of anger.  The
flow of adrenalin and rising blood pressure are necessary conditions for engaging in violence (or for running away
from a violent opponent).  In tribal or hunter-gatherer societies where there is no central authority, violence is
certainly not considered to be pathological.  In fact, the most successful members of the group in terms of wealth,
status or number of children are often those who engage in the most violence against those both in and out of the
group.
      
Game theory shows that neither an all-Hawk population, nor an all-Dove population is stable.  The only stable
populations must contain a mixture of Hawks and Doves; this is called an evolutionarily stable strategy (ESS).  It
would describe a population in which any mutation would not knock the population off balance; it would always
gravitate back to the ESS.  The mixture is not necessarily the best possible outcome, but it is stable, and that is
what counts.  Thus, two very different strategies can live alongside each other, and the individuals involved do not
need to adopt the same strategy in every instance, so long as the overall strategies employed by the population
stay balanced around the ESS.
      
The pecking order in any group of animals will be a fair indicator of who would win in any given confrontation.  The
construction of a pecking order has the effect of significantly reducing the number of violent confrontations.  
Among great apes, monkeys and other social mammals such as wolves, body language will signal immediately an
individuals rank in the system: dominant animals will have a more erect posture and will tend to be nonchalant and
confident in how they carry themselves; subordinates will appear nervous, averting their gazes and lowering their
heads.  As we know, these outward signs are common in humans.
      
Winston believes that Homo sapiens have evolved a capability to be violent and that we are able to choose
warfare as a strategy, depending on the conditions and ecology in which we live.  Our capacity for warfare
appears to be adaptive, and it seems logical that natural selection has rewarded those who had the instinct to
fight or defend when attacked.  And once one group of early humans takes up arms, the rest have to follow; they
have no choice if they want to live and thrive.
      
Human history has been driven by warfare.  We need only trace the movements of peoples, borders and nations
to realize that war is the main process by which the modern world has been constructed.  As technology
developed, our ability to conduct large-scale organized violence was refined.  As the scale of war grew, soldiers
fell victim to increasingly advance weapons.  Our intellects and superlative problem-solving abilities have been put
to work constructing extraordinary methods of fighting and killing our fellow humans.  Einstein pointed out the
scale of destruction made possible by his discoveries: `I know not with what weapons World War 3 will be fought,
but World War 4 will be fought with sticks and stones.`
      
      
The Birds and the Bees
       
At a rate of one a month, over the course of around thirty or so fertile years, a woman may release just four
hundred ripe ova from puberty to menopause.  Assuming one of the four hundred eggs she ovulates is fertilized,
the baby she bears will take nine months to gestate, which represents a huge biological investment.  If we take
into account the time taken to raise the child, breast-feed it and attend to its every need until it slowly gains self-
sufficiency, then it becomes clear why women must be careful as to who provides the other half of the genetic
package for any particular child.  If she makes a mistake and becomes pregnant by an unsuitable mate and father
who does not protect his family, she will be in trouble.  She will have wasted massive resources.  Such a waste
would have been even more critical on the savannah, where a high infant mortality rate would reduce the chance
of genetic continuity.
      
An adult human male may produce around a hundred million sperm every day.  He could father hundreds, if not
thousands, of babies if he was given the opportunity.  His role in any given conception simply involves a few
minutes in the sack, ejaculation and maybe a cigarette later.  From the male perspective, it's evolutionarily
desirable to impregnate as many females as possible.  From a female perspective, it pays to be cautious and to
choose a mate with great care.
      
Because of the way we are built, men tend to have more extra-marital affairs than women do.  In a long-term
relationship, a sense of loyalty, the mores and morals of any particular culture and the unwritten rules of the
institution of marriage often dissuade the man from attempting to sleep with other women.  But if he refuses an
opportunity at extra-marital sex, it is as much a case of overcoming physical temptation as it is a moral choice.  
Women, on the other hand, generally have less interest in sleeping with a complete stranger.  They aren't built to
seek out sex with a large number of men.  They are much more interested in quality rather than quantity.  They
have relatively few eggs, so they've got to be choosy about who gets to fertilize them.  Women, as we know, do in
fact have affairs though.  One way of explaining female infidelity is that it's a woman's way of hedging her bets.  
The security of knowing there is more than one 'provider' for you and your children is not to be taken lightly,
especially in the harsh desert environment where scarcity of resources is an ever-present and dangerous threat.  
In addition, a lover provides an extra insurance policy: if your husband dies or is killed on the hunting grounds,
there is someone else to help you take care of the kids.  So, from the point of view of material subsistence and
wealth, lovers can be profitable.  Adultery, for women, is also about dipping into the genetic pool.  Illicit adultery is
one way of introducing different DNA into the litter without destroying the stability of the family structure; and the
more desirable the man, the more desirable his genes, and vice versa.
      
It is a fact that every single one of our ancestors had sex, and reproduced successfully.  Of all the human instincts
we possess, sex shouts the loudest.  We are obsessed, and even when our behavior isn't overtly sexual, we
spend a great deal of time engaged in activities which are, in a fundamental way, connected with sex and
reproduction: money, career, appearance, friendships, and competition.  All these aspects of human life are
bound up in a web of sex-related impulses, whether we realize it or not.  As far as our genes are concerned,
reproduction is the whole point, thus evolution favors the ability to reproduce over all other considerations.
      
For men on the savannah, 'future reproductive value', or the ability a potential mate has to produce many babies
in the future, is the utmost consideration.  Infant and child mortality must have been high, and the most dangerous
journey humans would have faced was one of only four inches.  A woman who is young, fertile and healthy has a
better chance of bearing a number of children who themselves will be successful and will go on to reproduce.  
Also, waist-to-hip ratio may have been able to tell a man something about a woman's ability to reproduce.  After
puberty, estrogen causes increasing amounts of adipose fat to be laid down on women's thighs, buttocks and
breasts- fat which once was likely to be important for survival for both mother and child in conditions of scarcity.  
Even today, once a woman's fat deposits drop below a certain percentage of her body weight, she will stop
ovulating.  Men who were attracted to young, healthy females who possessed an hourglass figure would have
been more likely to choose one as a mate and would thus increase their chance of having lots of healthy children,
who would be predisposed to possessing these inclinations as well.  Indeed, men the world over, from all sorts of
different cultures, consistently prefer younger women, as well as those whose hip measurements are much bigger
than their waistlines.  The preferred waist-to-hip ratio appears to remain the same across the board, at .7.
      
Men also desire chastity.  The worst situation, evolutionarily speaking, in which a man can find himself, is
unknowingly bringing up someone else's children.  The evolutionary consequence for the male if this happens is
disastrous.  He would expend time, energy and resources for a child who does not carry his genes.  Conversely, a
competitor who impregnates another's mate has all the benefits of passing on his genetic inheritance with none of
the drawbacks of having to provide for the baby and its mother.  There is a constant tension between the desire
for sex and the need for a faithful mate.  When a man attempts to persuade or seduce a woman into having sex,
though he probably isn't conscious of it, he is setting a kind of 'test' to check the woman's self-restraint.  
Throughout history, many cultures have prized virginity when it comes to choosing a long-term female mate, and
this is due to the high evolutionary price of getting cuckolded.
      
For women, the factors that consistently come up in surveys testing what the most important qualities a man must
have to stimulate female interest are age, level of education, and income.  All these are predictors of financial
stability.  Women are much more focused on the long-term than men- particularly when it comes to the financial
future.  Having a mate that can provide for them and their child would have been essential on the savannah.  This
is not to say that appearance doesn't matter though.  The traditional visual stereotype of a healthy, testosterone-
rich male, tall, square-jawed and muscular, is certainly sought after.  Through the ages men's dress has tended to
accentuate these traits: the square, boxy shoulders of a suit, or the molded muscular curves of Roman armor,
which flatter and augment the physique of the wearer.
      
Women also like men who take risks, especially those who take risks on the behalf of other people.  Women
interpret heroism as an ability to protect them and their offspring.  In a world where danger was lurking around
every corner, cave and hillock in the form of sabre-tooth tigers as well as predatory males from rival bands of
early humans, bravery was a cardinal quality much in demand in a mate.  But, it has been determined that the
female long-term mating strategy avoids those males who take selfish or unnecessary risks.  So all in all, women
are interested in character, commitment and security when it comes to choosing a potential mate.
      
Pheromones may very well influence our choice of a mate.  We can literally sniff out suitable mates.  There is a
payoff in having a mate who is genetically dissimilar from oneself.  We all carry defects in our DNA, but providing
we do not mate with someone who has the identical defect in their DNA at the same point on a particular
chromosome, our children will nearly always be protected.  The normal DNA sequence from the defect free parent
compensates.  This is reflected in incest being taboo in practically every known culture.  The dangers of
inbreeding are too much to bear, and individuals who practiced it have tended to die out.  Our pheromones have
developed to be a very effective guide to healthy breeding.  The phrase 'animal attraction' seems quite applicable.
      
When two people finally do sniff each other out and fall in love, there is a period of time- on average lasting for
around eighteen months to three years- during which passion is at its height.  It is a time of exhilaration, of being
'high' in a natural and pleasure-filled state of excitement.  This state of mind has a lot to do with a love-drug called
PEA, or phenyl ethylamine.  The chemical is produced in the brain in large quantities during this fiery period of
ardor and amour, and its effects are somewhat similar to amphetamines, or speed.  PEA collects at the nerve
endings and helps the electrical impulses jump across the gap, or synapse, from one nerve cell to another.  When
nerve cells in your limbic system are fuelled by PEA, you'll feel high, full of energy, and sometimes euphoric.
      
PEA is not just present in the limbic systems of love-struck couples; it accompanies other intense experiences
too.  Parachute jumpers' PEA production goes through the roof during free-fall, an experience they describe as
accompanied by a feeling of great exhilaration.  Very commonly, people who have just jumped experience a
period of heady elation for some time afterwards.  The emotional high, whether it's caused by love or throwing
yourself from a plane, stimulates PEA production.  We fall in love to get our PEA injection, like an addict finding
his next fix.
      
Love is literally a drug, and a highly addictive one at that, and like all addictions there is a law of diminishing
returns.  The positive effects wear off after a certain period of time; the nerve cells of our brains become tolerant
to the unusually high levels of PEA, and we come back down to earth.  Once the honeymoon's over, passionate
romances tend to mellow into 'attachments'.  In this phase of the relationship, rather than producing PEA your
brain starts to pump out endorphins, brain opiates that are more like morphine than speed and serve to calm the
mind, kill pain and reduce anxiety.  From that point on the survival of our relationships depend on other feelings
and desires: sexual attraction, of course, friendship and interdependence.
      
There is also evidence that the action of the hormone oxytocin may have an important part to play in the way we
form attachments to the opposite sex.  Levels rise during touching and cuddling, the extra oxytocin making you
increasingly sexually receptive.  In both sexes, the levels of the hormone peak at orgasm.  But that's where the
similarity ends, because it seems the combination of other hormones with oxytocin results in the age-old battle of
the sexes running rife at this point.  It's believed that estrogen somehow amplifies the effect of the oxytocin in
women after orgasm, so most women become very affectionate, want to cuddle and feel that strong emotional
bond with their partner.  Men, on the other hand, mostly just want to snooze, and that may be because
testosterone inhibits the bonding effects of oxytocin after orgasm.
      
Sexual jealousy is an impulse we've almost certainly inherited from our ancestors on the savannah.  A less
suspicious species than ours would have become extinct many years ago.  The whole point of monogamy, to be
harshly utilitarian, is that a partnership provides protection and resources for your own biological children.  It's not
surprising that the danger and fear of cuckoldry casts a dark shadow across much of men's sexual psychology.  
The cuckolded male is depositing energy, time and resources into someone else's genetic bank account;
somewhere deep in our male psyche is a voice which says, 'Avoid this scenario at all costs!'
      
Homo sapiens are unusual in that a woman's monthly period of fertility is hidden.  This modesty has two major
consequences.  The first is that humans desire and are able to have sex on any day of any month, whether or not
a woman is fertile.  We are extremely rare in this respect, since most other species save their sexual energy for
the time when it can be used most profitably.  The second is that in a monogamous coupling, men have constantly
to be on their guard because female infidelity is potentially dangerous at any time.  They can never relax, and
what's more, they can never leave their mates to their own devices.
      
Concealed ovulation is a clever ruse.  It goes hand in hand with internal fertilization.  While women can all be sure
that they are the true genetic mothers of their children, men face constant uncertainty ('mama's baby, papa's
maybe').  Just possibly, both concealed ovulation and internal fertilization evolved as mechanisms to ensure a
woman's mate was attentive all month long.  They reduce the risk of desertion by the male, which itself reduces
the risk of the male forging relationships with other women.
      
Women, too, feel jealous, but for different reasons.  They are more concerned about their mate diverting care,
attention and material resources to another woman.  So while men are more worried about their partner having
casual sex with another man, women are more concerned about an emotional involvement which may lead to the
disastrous scenario of abandonment and poverty.  Jealousy rests on a hair trigger.  It can arise from the most
innocuous of circumstances and be fired by the faintest hint of infidelity.  Obviously, there are exceptions to these
general descriptions of male and female tendencies, but our instincts are always there, whispering in our
unconscious.  They push and pull our behavior a little bit this way then a little bit that way.  Studies across many
different cultures show that sexual jealousy is universal and that men and women do in fact react differently to
extra-marital sex and to emotional involvement.
      
It is an obvious but important observation that jealousy begets violence.  Domestic violence is a common
consequence of sexual jealousy.  13 percent of all homicides involve the husband killing his wife, or vice versa,
and male sexual jealousy is the overwhelming cause of these, even in cases where the wife kills the husband.  
Note that jealousy need not be based on actual infidelity, just the suspicion of infidelity.
      
On an everyday basis in our relationships, jealousy probably really does help us to cope with a whole host of
small but real threats.  Unconsciously or otherwise, it's probably what motivates us to ward off rivals with nasty
stares or even threatening words or to shower our partner with affection when we feel he or she may be on the
verge of straying.  Jealousy is a double-edged sword: it can keep a long marriage stable over many years, or it
can drive a man to beat his wife.
      
High levels of testosterone are one reason why men are generally more aggressive than women.  It seems
probable that as our ancestors evolved over millions of years, the males- who were sometimes hunters,
sometimes scavengers and always defenders of the group- evolved some successful biological mechanisms to
fulfill these roles.  We know that with violent predators to fight off, hominid males had to be strong and powerful.  
We also know that testosterone builds muscle bulk and thus physical strength.  But aside from its effects on
muscles, a man's daily production of testosterone also has a huge impact on many aspects of his behavior, not
the least his sex drive.  Testosterone certainly accounts for higher sex drives in men and may have evolved hand
in hand with their desire to impregnate as many women as possible in order to spread their genes.  Testosterone
gave them the power to go and do it, so to speak.
      
The traditional sociological view of rape is that it is a pathological form of behavior, a crime committed by
dysfunctional individuals.  Most people can surely never have imagined that rape could be described as 'useful',
from the point of view of evolution, but controversially that is what some researchers have suggested.  It could
have been in a man's interest to employ force as a means of coercing a woman to have sex.  Rape could have
been a fruitful strategy from the point of view of a man's genetic inheritance.  
      
There exist strong correlations between levels of male hormone and dominance.  When someone wins any kind of
match they will have higher levels than their losing opponent, and will also tend to have higher than average
levels before their next match.  Elevated testosterone may help explain why the chances of a woman conceiving
from a single act of rape are more than twice those of a woman who engages in a single act of consensual sex.  
Some scientists have also suggested that rape increases secretion of stress hormones in the body and that these
may trigger ovulation if the rape takes place somewhere near the middle of the menstrual cycle.
      
Laws and cultural and moral norms are put in place to repress and contain our 'animal instincts'.  In traditional
village cultures for instance, rape within the group is met by fierce revenge or severe punishment- as it is in
practically all human civilizations.  But among hunter-gatherer or tribal cultures that wage war on neighboring
groups, when rape is committed outside the group it is often called something different, and this kind of rape is
not seen as a crime.  Among the warring bands of early humans, it is just possible that rape was more
commonplace than we think.  It is unpleasant to consider it, but rape could even have become part of the male
sexual instinct.  After the rape the baby would be raised in another group entirely, making it so the male didn't
need to waste any resources.  The genes that predispose a man to commit rape in these situations would become
more and more successful.
      
Women could be looted just like any other resources.  There is a strong proprietary nature about the male sexual
instinct, and this ties in with that strong need to avoid being cuckolded.  It is also believed that since women must
invest so much more of their biological resources and energy in bearing and raising children, they are, in effect, a
limited resource themselves.  Men have evolved to monopolize females, just as any animal would contest its
territory in the struggle for survival, for instance.  Over the ages, that monopoly has translated into what has been
considered to be a man's right.  Women have often been thought of as representing commodities, and have been
treated as such.  There has often been the idea that women 'belong' to their husbands.
      
Human males tend to be slightly bigger than females.  That simple fact reveals something fascinating about our
hominid ancestors.  Our ancient male forefathers probably had to fight for mating rights, suggesting that early
human groups were commonly practicing polygamy- in other words, a proportion of the males would monopolize
all the females.  Men fought over women, inevitably, as they still do.
      
An ethnographic survey of 849 human societies across the globe, including all traditional tribal and hunter-
gatherer groups showed that 708 of these are polygamous or allow the powerful or wealthy males to indulge in
polygamy.  It seems that, from a strictly evolutionary point of view, the competitive nature which pushes a man to
pursue power and status is strongly related to sex- and the number of women he can have sex with.  Throughout
history, tyrants and despots have kept harems whenever possible.
      
As the structure of Western society changed and life became more democratic and egalitarian, polygamy was
reduced.  But societies, ancient or modern, don't always order their affairs according to human instinct.  The
institution of marriage may in fact be a reaction to our innately unfaithful tendencies that are thought to be
undesirable or destructive to society.  The harem system is dangerous, particularly for males low in the pecking
order.  In the main, our instincts for competition mean that males excluded from the system do not take their fate
quietly and are likely to be a source of aggression and violence.
      
The relative sizes of men and women suggest promiscuity, harems and polygamy, but there are excellent reasons
for supposing that monogamy, or at least 'serial' monogamy, has always been the most popular family set-up.  On
the savannah, when conditions were hostile, a male human or pre-human hominid might have found it difficult to
maintain and protect more than one sexual partner and their respective children.  Rarely might he have been in a
position to commandeer enough resources to care for and supply a large group of females, as well as protect
them from being snatched by rival males disgruntled at the lack of available sexual partners.  It seems quite
probable that it wasn't until humans constructed dwellings, with some sort of semi-permanence, that this pattern
changed.
      
It has been suggested that we are designed to be monogamous only for as long as it takes to raise a single child
through infancy.  Between 40 and 50 percent of marriages in the US and UK end in divorce.  A worldwide pattern
shows that divorce peaks at around four years into marriage and then decline.  It is a pattern that does not seem
to alter despite different cultural norms, marriage practices, divorce procedures or relationship difficulties.  This is
also reflected in the fact that very few known societies have banned divorce, the Catholic Church being the most
notable exception.  Whatever the individual reasons for separation, we know that relationships do often break
down, and the four-year mark is a statistical watershed, even when there are children in the mix.  There is no
instinctual force which keeps couples together for a lifetime; 'till death do us part' is more often than not a hope
beyond hope, a tradition which from an evolutionary perspective has little relevance to the realities of human
relationships.  It seems that while we're socially monogamous, the truth is, by nature, we're sexually polygamous.
      
      
Kin Selection
       
Feelings of love for one's children seem to be ingrained in our subconscious; babies do not just get attached to
their parents, their parents also get attached to them.  The loving relationship between parent and child is, on the
face of it, an obvious biological adaptation.  Those children who are doted on and cared for are more likely to
survive the ravages of childhood and last until they are sexually mature and able to reproduce themselves.  Love,
in this sense, follows the genetic pathway; our genes survive through our children, and so on through our
children's children.
      
It is important to remember that natural selection actually selects successful genes rather than successful people,
and those genes spread throughout the population.  This has an all-important effect on our individual behavior
towards kin.  Our children carry our genes; in fact we share 50 percent of our genes with them.  We also share 50
percent of our genes with our siblings, because each brother or sister receives half of his or her genes from
either parent.  The percentage decrease as our blood relationship becomes more distant.  Because our relatives
carry a portion of our genes, it is in our interest to help them survive, prosper and reproduce.  It doesn't matter
that these genes will find success in another person's body.  The fact that our own genes find success, whoever
happens to be carrying them, is what is important.  From our genes’ point of view, any organism that contains
copies or partial copies of itself is worth preserving.  So, in essence, blood is thicker than water.
      
We have very few children and make an enormous investment- in terms of time, energy and resources, even
placing ourselves at risk of injury or death- in each of them to ensure their survival.  Our generosity even extends
beyond our children to our close relatives, but the closer the blood relation the more we are willing to do for them.  
This is a direct result of kin selection and an inescapable consequence of the fact that we share the most genes
with our parents, children and siblings.  The mathematics of kin selection predict that a parent who shares one
half of his or her genes with a child would be willing to die for two children or two siblings (or four grandchildren, or
eight cousins).  But behavior doesn’t adhere to such mechanical calculation.  Kin selection gives us a
predisposition only, one that makes us more likely to place ourselves in danger to save our children.  When a
mother dives into a surging river to save her infant, she does not consciously or unconsciously make a
calculation; she simply dives in (or not, as the case may be).
      
Evil stepmothers have been a staple in myths and fables from every conceivable age and corner of the world.  So
entrenched is the theme of the wicked step-parent in stories around the world that it is not surprising to find the
pattern reflected in the grim realities of domestic murder and abuse.  The vast majority of children killed in
domestic situations are murdered by step-parents or adults who are involved in a sexual relationship with the
child's parent, whether or not they take a parental role in their adoptive family.  In fact, one study showed that a
child living with at least one non-biological parent was an incredible seventy times more likely to be murdered than
a child living with both its biological parents.  It is a simple fact of evolutionary biology: parents don't want to waste
their precious resources on children who are not their own genetic offspring, nor do they want to share the limited
resources they have found for their own offspring with someone else's if they can possibly help it.  
      
      
Babies
       
We tend to imagine the co-existence of a mother and her unborn baby as a model of co-operation and harmony.  
But this fanciful image of the mother-child union hides a more complex reality.  The mathematics of kin selection
predict that during the nine months of pregnancy the mother’s body will inevitably be in conflict with the fetus, and
vice versa.  After all, the mother and baby are not genetically identical; in fact, they are related by only half the
same genes.  Moreover, because the baby carries genes from its father, it is not even immunologically compatible
with its mother.  Strikingly, it is a piece of foreign tissue.  Implanted anywhere else in the body at any other time, it
would be immediately rejected by the mother’s immune system.  The baby in utero is almost the perfect parasite.  
There are evolutionary changes that help the fetus develop more effectively, but these are at the expense of the
mother, and therefore at the expense of brothers and sisters who may be born in the future.  One example of this
is the mother’s blood supply through the placenta.  When the embryo implants in the mother’s uterus, it actually
‘invades’ the uterine wall, especially the walls of the maternal arteries, altering their structure so that they are no
longer receptive to their usual control from the mother’s body.  These arteries can then carry their precious cargo
of oxygen, hormones and nutrients directly to the fetus without the mother’s body interfering.  If the mother’s body
tries to restrict the amount of nutrients reaching the fetus, this will lower the levels reaching her own tissues.  And
because the fetus has plugged directly into the mother’s blood supply, it is also able to secrete chemicals that are
easily transferred through the placenta and around the mother’s body; among these are hormones which act as
the fetus’s means of maintaining the pregnancy.  They will compete with the mother’s body for nutrients after she
eats each meal and are able to trigger the placenta to produce enough progesterone to maintain the pregnancy
even if one of the mother’s ovaries shuts down completely.  Meanwhile, the mother’s body is frantically releasing
its own growth factors to limit the fetus’s invasion into her tissues.
      
So the effects of genes expressed in the fetus are countered by changes in the mother’s gene expression.  It
makes perfect evolutionary sense.  If the mother is in danger, so are all her future children, and the danger has to
be weighed against the well-being of the current inhabitant of her womb.  Two opposing genetic forces are
engaged in an evolutionary battle.  Biologists used to think that what’s good for the mother is good for the baby.  
We now know that’s not necessarily the case.
      
Within the developing fetus there is another powerful skirmish going on.  This one involves both the mother’s and
father’s genes.  Each cell in a normal developing embryo contains forty-six chromosomes in the form of twenty-
three pairs.  One half of each pair is from the mother, and half is from the father.  We effectively have two copies
of the instruction manual, and for each step of the development process we need to refer to only one of the
manuals at any one time.  Which manual is used is generally thought to depend on which of the two particular
variants of each gene (called ‘alleles’) we have received is dominant.  If one is dominant and its opposite number
is recessive, then the dominant allele will win out.
      
It would appear, then, as if a complete half of our full compliment of genes is effectively passed over.  But as we
know, genes have evolved to maximize their chances of survival, and the maternal and paternal genes have
slightly conflicting interests during the gestation of the fetus.  From the point of view of the father’s genes, there’s
a strong interest in building a ‘bigger’ baby.  Larger babies will be more able to survive the pregnancy, and when
they’re born they are more likely to be healthy and so will have a better chance of surviving infancy.  But from the
mother’s point of view- or, strictly speaking, from the mother’s genes’ point of view- the baby should be healthy
but not too large.  An oversized baby will drain the mother of precious nutrients during the pregnancy and is much
more likely to present a threat to her health when it’s born.  The chances of a mother dying during childbirth are
actually quite high, and the bigger the baby, the higher the chances.  So the mother’s genes are looking for a
happy medium between the size and the viability of the fetus.
      
Some maternal or parental genes have evolved an extraordinary ability to turn themselves ‘on’ during the
development of an embryo, whether or not they are dominant or recessive.  The process is called imprinting.  A
very small number of genes appear to be ‘marked’, or imprinted, according to whether they came from the mother
or father, and this marking triggers the gene to become active at a certain point in development.  One such
imprinted gene, IGF2, makes a growth hormone, rather similar to insulin, which has a role to play in the
development of the cells in the early embryo and the placenta.  When the hormone becomes active in the
placenta it increases the amount of nutrients that can be passed through from mother to child.  It is not surprising,
therefore, that the gene is paternal.  It seems the father is delivering an imprinted gene that strives to increase
the growth rate of the developing fetus.  The mother switches on a gene for a receptor whose role it is to mop up
excess protein produced by the paternal gene IGF2.  In effect, her genes are countering the effect of the paternal
IGF2, reducing the amount of nutrients getting across the placenta.
      
The process of imprinting reveals that parents are engaged in a battle for control over the development of their
baby.  The outcome, it should be stressed, is not a happy compromise which aims to reconcile these conflicting
interests.  Without the benefit of modern medical technology, childbirth leads to a high mortality rate for the
mother, partly because the size of the average newborn does pose a grave risk.  According to the World Health
Organization, 1,600 women die around the world every day giving birth- that’s over half a million every year.  And
in the developing world, where medical resources and Caesarean section are not always available, a good
proportion of these deaths can be loosely associated with the relatively large size of the human baby and its
consequent need to have a very good blood supply.
      
We humans are born prematurely.  Given that so much of a human's development takes place after the child is
born, it follows that it will be completely dependent on its parents for several years.  The time and energy it takes
for adults to protect and raise their babies is huge.  There must be a really strong reason why humans evolved to
be so helpless and vulnerable as young children.
      
Look no further than the human brain.  Between infancy and adulthood, the human brain is going to increase in
size fourfold.  We know that evolving bigger brains pushed our ancient ancestors forward in the struggle for
survival, but there was one very serious constraint: the size of the female pelvis.  There is a point at which the
head will no longer fit through the birth canal.  Even though the pelvis can stretch a bit during labor and the
baby's head can be safely compressed a little, if the head was much bigger than the birth canal the results would
be disastrous.  Either the baby couldn't be born at all, or serious brain damage inside the soft fetal skull would be
inevitable.
      
After birth, powerful instincts must step in and drive the newborn to persuade its parents to take care of it.  The
baby's cry is a crucial signal, a kind of SOS, which tells the mother to attend to the child.  Just on the off chance
the parents are wandering some distance from camp, perhaps to gather food, babies can wail at a volume which
is completely out of proportion to their body size.  And in return, there is something in a mother's instinct that
makes a baby's cry almost irresistible.
      
It is fair to say that in almost all cultures we know of, both past and present, the mother carries out the lion's share
of the work in bringing up a baby.  But fathers also play a role in keeping the baby warm, fed, and happy.  There
is little doubt that historically men have been important providers of food and security for the family group,
especially if the mother has a baby in tow and is therefore more vulnerable to attack or potential starvation.
      
In step pheromones: chemicals which aren't smelled consciously in the normal way but are transmitted directly to
the emotional centers of the brain through a special bundle of nerves in the nasal spectrum rather than via the
olfactory nerve, the way conscious smells are usually transmitted to the brain.  Baby pheromones have been
shown to have a calming effect, counteracting the traditional male role of hunter and fighter.  In fact, these
pheromones seem to be directed specifically at the baby's father.  Babies are very sensitive to violence and
physical danger.  We see the very first sign of the fight or flight response in very young babies.  It's called the
'Moro' reflex.  If the baby hears a loud noise, it will throw its arms forward, bringing them together in a protective
gesture and then relax.  A few weeks later this instinct develops into the 'startle' response: the mouth opens
(possibly to increase oxygen flow), the head lowers and the shoulders and arms sag, as though the baby is
expecting a body blow.
      
Very soon after birth, babies start to imitate the facial expressions of adults.  If an adult smiles, babies will start to
smile back.  There is no doubt that with this instinctive trick, babies can exert an enormous emotional pull on their
parents.  It is central to the bonding process- the growth of the deeply rooted, powerful emotional ties between
parent and child.  At the heart of this process is the baby's capacity to recognize a human face.  Newborns
appear much more interested in a face than in other random objects, and they lock in with increased interest to
the basic arrangement of two eyes, a nose, and a mouth.  But newborn babies almost certainly can't grasp the
significance or meaning of a face or an expression- that doesn't begin to develop until they are about six months
of age.  It is purely instinct which programs them to respond in the way that they do, and it is this reaction which
means the parents are suckered in to caring for and protecting the baby with far more love and attention than
they would otherwise offer.
      
Soon the process of attachment does allow the infant to begin to recognize its parents and discern between them
and strangers.  Babies do begin to respond with more interest to the adults who care for them, feed them, and
protect them.  The ability to recognize faces is a deep-seated, innate part of being human.  It seems that there is
a specialized region of the brain which has evolved to control this one function.  It is easy to overlook, but the
ability to distinguish between faces is central to being able to engage in any social interaction in everyday life.
      
We are also experts in interpreting expression, particularly infants' facial expression.  This is another adaptive
mechanism which means the infant will essentially be less vulnerable in the first year or two of its life.  Relatively
young babies can read our emotional expressions almost as well as we can read theirs, and if the mother appears
to be scared- owing to an unwelcome intruder, a dangerous predator or even an exposed cliffside- then babies
take notice.  They can even monitor the tone of an adult's voice for an indication that something is wrong.
      
There is also the issue of 'nature vs nurture'.  When babies open their eyes and begin to register the existence of
the outside world, there begins an intricate process of neural development.  Instincts get switched on one by one,
an array of survival tools that come prepackaged in a baby.  But the brain cannot develop unless it receives the
right stimuli.  The environment in which we are brought up is critical for the development of human instinct.  Our
cognitive mechanisms for dealing with the world- whether they are face recognition, language acquisition, or
emotional development- will not appear of their own accord.  Also, beyond a certain point, it may be too late to
'switch' them on.
      
You may not believe that the games children play have much to do with their everyday survival, but research has
shown that play is a very significant and deep-rooted instinct with an important purpose.  Interestingly, animals
with bigger brains (for a given body size) spend significantly more time playing.  The hard-wired instinct to 'try out'
life in the adult world is an important means of communication and practice.  It seems that because our bigger
brains need time and experiences to develop in those first few years of life, one of evolution's solutions is to mold
our emotions and understanding of life through play, so that we are as well prepared as possible for survival in
the complex adult world.
      
Toddlers are like sponges when it comes to learning.  The human mind is primed to acquire rapidly the skills we
need to move around in and manipulate the physical world, as well as to form relationships with other human
beings and begin to communicate with them.  All the cognitive talents that appear in infancy and childhood- face
recognition, spatial awareness, the ability to speak and understand language- depend to a greater or lesser
extent on the environment and the people with which the infant interacts.  Noam Chomsky, the famous language
theorist, believes we're all born with innate structures in the brain that allow us to learn language, or at least all of
us have the genetic programming that will create these structures as we grow from an embryo into an infant.  He
suggested that language in every culture has a 'Universal Grammar'- a similarity in the way in which sentences in
all languages are constructed- which reflects this in-born, psychological 'module'.  Babies do seem to like the
sound of voices.  Newborns display more of an interest in the sounds of spoken language than, say, the sound of
a bell ringing.  Infants also pay more attention to their mother's voice; it is believed that they 'tuned in' to its timbre
and tone while in the womb.  Astonishingly, studies have shown that babies are primed to learn to recognize the
sounds of new words even while they're asleep.
      
The basic shape of these tools, which are constructed during the developmental period as a fetus, and later as a
newborn, is the same for everyone.  They don't depend on cultural differences or the environment in which we
bring up our children.  There may be differences in timing- certain cognitive abilities may show themselves earlier
or later, depending on how much stimulation the baby receives from the people around it- the modules may not
even be switched on at all, but they are there, a direct result of our evolutionary history, the psychological
solutions natural selection has found to the problems of life of the savannah.
      
      
Tools
       
Making tools was a key stage in the development of early man.  This ability was the result of having a big brain,
but tool-making in all probability was also a stimulus for its further growth.  And tool making, rather like the
development of language later, is almost certainly part of man's instinct.
      
Homo habilis was able to make flakes by hitting a piece of flint hard on another rock.  The broken off flakes were
an extremely effective tool for butchery, with a blunt back edge to grip and one sharp edge perhaps used to skin
animals and cut meat from the bone.  About 1.9 million years ago came Homo erectus.  The fashionable tool for
them was the classic handaxe- the symmetrical teardrop- or almond-shaped blade, cut from flint or a similar
stone.  It takes a lot of craft to cut, or 'knap', one of these handaxes.  The process requires a fine appreciation for
how a piece of flint fractures under impact, the optimum angle at which to hold the striking edge of the rock, how
to use a softer tool like a piece of antler as a hammer, and how to trim the circumference to a tapered and neatly
curved cutting edge.  The surprising fact is that once our ancestors had finally mastered the teardrop handaxe, its
design remained almost identical for something close to an incredible 1.8 million years; from China to the Thames
Valley, no other tools appear to have been fashioned, although some have argued that perhaps other wooden
tools have not survived.  Regardless though, it must have had an extremely important functional use in every day
life, a use that was probably vital to the success and survival of Homo erectus.  Whatever its precise use, what the
handaxe does represent is the foundation of our uniquely human ability to make the environment work for us, to
mold and shape it until it is fashioned for our own survival.
      
      
Food
       
The main challenge when it comes to eating well involves getting the right nutrients in the right amount and
avoiding harmful toxins.  These are the main driving forces behind our culinary instincts.  Just as plants have
evolved toxins to protect themselves from being eaten, we've evolved methods of avoiding them.  Bad smells and
taste often indicate the presence of harmful compounds.  If we inadvertently eat something toxic, we have
secondary lines of defense: gagging, vomiting, or diarrhea.
      
This also explains morning sickness.  A fetus' major organs are developing between six and fourteen weeks after
conception.  At around the same time, the mother's immune system temporarily lets down its guard, giving the
fetus free reign to establish itself in her uterus.  As a result, pregnant women are particularly susceptible to
bacteria and viruses during those weeks.  Normally, our bodies destroy invading pathogens without a problem,
but in early pregnancy they can cause maternal infection or even a miscarriage.  Over thousands of generations
we have evolved a strategy for protecting the developing fetus against dangerous poisons.  Once the vulnerability
of the fetus is reduced after the first trimester, the nutritional value of the food outweighs the risk and the
condition usually disappears.  It may be pretty unpleasant for the mother, but this mechanism probably played a
large part in helping our ancestors have healthy children, so it got passed on to future generations.
      
For our savannah ancestors, the most calorific foods contained the highest levels of fat (in the case of meat) and
sugar (in the case of ripened fruit).  Meat and ripened fruit were not that easy to come by, so the more powerful
our craving for these foods, the more effort we would put into finding them.  Those who carried the genetic
programming for craving fat and sugar and managed to satisfy those cravings were as a result stronger, had
more stamina, more reserves in times of scarcity, and better fertility.  They appeared to be better evolutionary
bets all around.  This is not true today.  A staggering fifty-eight million adults in the USA are overweight- not far
short of half the entire adult population- and another quarter of Americans are clinically obese.  70 percent of
cardiovascular disease is directly related to being overweight or obese.  Cravings for food have been transformed
from being our survival instinct into a new, self-inflicted and very deadly predator.
      
As it turns out, wild game roaming around the savannah have a much lower fat content than the corpulent,
sedentary cattle we breed to eat (about 4% compared to 25-30%).  The fat of wild game was also about five times
higher in polyunsaturated fats; modern cattle are packed full of more dangerous saturated fats.  Our
domestication of cattle has also provided us with a cheap source of fat-rich dairy products like milk, cream and
cheese.  Alongside this, our craving for sugar is now satisfied mostly by refined sugar in the form of soft drinks,
chocolate, sweets, and all kinds of processed food, rather than the healthier fructose found in ripe fruit.
      
The human body was designed for times of scarcity.  Life on the savannah was marked by a high degree of
uncertainty in many respects, particularly in the availability of food.  In times of famine, the body had to defend its
weight fiercely- a fact reflected in people's experience of dieting today.  Around 95% of dieters either fail
completely to lose weight, or they lose weight and put back on the same amount.  If you start reducing the amount
of food you consume, your body recognizes this as an ancient savannah famine and immediately slows down your
metabolic rate.  Even minimal weight loss of a pound a week will trigger this response.  In other words, the less
you eat, the less you need to eat before you start putting on weight again.  
      
On the savannah, there were chores to do: collecting water, gathering roots, crafting hand axes and flakes,
looking after babies.  Scavenging would involve hours of walking, and running if they were hunting live prey.  The
optimum situation was to burn all of the calories ingested.  That is why raising your metabolic rate through
exercise is a far more effective way of losing weight than cutting down your food intake.
      
      
Altruism
       
Kin selection does not explain altruism towards those people who do not share our genes.  Our system of sharing
can get rather complex, especially where there is a time lag between the exchange of favors.  The pooling of
resources in this way is mutually beneficial, but it does require a certain level of sophistication in the social group;
namely, it requires trust, and the ability to remember the actions of different individuals.  There is no point of
giving favors if one cannot be sure of a favor in return from the same individual.  Even the most hierarchical
human society needs the co-operation of its members- co-operation which is not solely founded on the threat of
force.  In the uncertain world of the savannah, we needed to get along and the smaller the group the more reliant
any natural leader is on the goodwill and co-operation of others.
      
In modern nation-states, co-operation reaches far beyond the natural group size of around 150 that was
mentioned earlier.  Our lives are intertwined like never before, and social, professional and family life is often
extremely dependent on massive networks of people acting in concert.  The logistics and technicalities of the
modern world are often taken for granted.  Virtually every aspect of our lives depends wholly on co-operation and
trust, and on taking risks.  
      
Large scale co-operation is not always easy to achieve.  The easiest kind of co-operation is the convention, an
arbitrary rule or law that exists to make everyone’s lives easier.  A good example is having a designated side of
the road on which we all drive.  Also, language is a tremendous feat of co-operation; it only works if everyone
involved follows the same rules.
      
Other kinds of co-operation are, in a sense, more difficult.  Say we have a group of Co-operators, people who
consistently contribute to the common good.  Projects that will make everyone’s quality of life better and the
benefits will easily outweigh the initial costs in time and energy.  From a self-interested perspective, it is perfectly
rational to become a Slacker, assuming no one realizes what you are doing.  The same problem arises for health
service taxation, army conscription, mass immunization and any other public good that depends on the vast
majority of people taking part.  With a large number of people who contribute, the rational thing to do, assuming
there is a large enough benefit to doing so, is to become a Slacker.  In the long term this is not good.  If everyone
does the same we would have no public goods- no health service, no army, no public toilets.  Still, because we
have no control over other people’s contributions, the rational course of action is to be a Slacker.  Better a
Slacker than a subsidizer of other people.
      
Slackers, or free-riders, get something for nothing.  They get all the benefits of group life without any of the cost-
therefore they will, on average, be more successful than the Co-operators.  The genes that predispose them to
slacking will do well and spread throughout the group.  So, in the language of game theory, a group of Co-
operators is not an evolutionarily stable strategy; it can be invaded by a Slacker, and then Slackers can take over
the group.  Not only that, but without Co-operators the group falls apart.  All the benefits of group living are lost.  
Games that involve co-operation are nearly always zero-sum games; the final outcome will generally outweigh the
sum of the initial costs.  We complain about taxation, but most of us would agree that the benefits of schools,
roads, police forces and hospitals outweigh the costs of our own contribution.
      
Fortunately, we have developed a type of cheat detection ‘module’.  We are very good at spotting the Slackers in
a group.  A key aspect of human social interaction is the appraisal of the faces of the people we meet, and
whether we see in those faces signs of trustworthiness.  It turns out that the amygdala and its connections with
part of the temporal cortex are the active pats of the brain when we make these judgments.  Moreover, in studies,
it seemed that the amygdala’s response was automatic and instinctive, while the cortex was activated only when
the subjects were asked to make a judgment.  These mechanisms presumably have evolved because human
survival depended to some considerable extent on our ability to assess other people and then make accurate
social judgments.
      
There has to be some punishment of the Slacker if our cheat detection module is to be of value.  Everyday life
throws up many opportunities for punishing Slackers, whether they are individuals, companies or institutions.  It
may take the form of a letter to a newspaper, or taking part in a demonstration or political campaign.  It may simply
mean a shouting match with someone who jumps the queue.  Often the costs involved are greater than one’s own
personal rewards, but as a whole we all benefit greatly.  Why would we inflict damage on ourselves to punish a
Slacker?  Anger.  So, all in all, our instincts for trust and co-operation are safeguarded by the mechanisms of
cheat detection, social norms and punishment.
      
In a population of real human beings, for co-operation to be beneficial, there has to be a strong likelihood of the
two individuals meeting again.  For early humans, this was extremely likely given that they lived in smallish groups
of no more than several dozen others.  Killing an animal, for instance, may have depended on luck, with only a
portion of the group being successful on any given day.  If an antelope or deer was killed, it would provide more
meat than one person or even an entire family can eat before it goes rotten.  Sharing meat is a sensible strategy,
so the luck is spread around the group; no one goes hungry and no meat is wasted.  Co-operation means that if
you make the kill you portions will not be as large on that day as if you had the entire animal to yourself, but this
cost is outweighed by the benefit of eating when you have had no luck on the hunting grounds.
      
Each generation inherits a tendency to co-operate, to defect, or to pursue a mixed strategy.  They do not need to
make a rational decision whenever they meet this type of situation, they need only act on their instincts.  If the
strategy is successful, it will increase the individual’s evolutionary fitness and enable the strategy to be passed on
more successfully to the next generation.
      
We are born to live our lives in collaboration with others, and we are born with the ability to realize when others
are failing to play their allotted role.  Social life, both on the savannah and here in the modern world, is a non-zero-
sum game.  We all benefit if we co-operate, we all lose if we do not.  Yet we should be aware that co-operation
within a group is the flip side of aggression between groups.  The closeness of battle-hardened soldiers is a
testament to the non-zero-sumness of organized violence.  Look after your buddy, because there may come a
time when you need him to look after you.  As the stakes get higher, so does the intensity of teamwork and group
spirit.  The warlike traditions of present-day foraging culture foster an immense amount of group harmony and
selflessness, and no doubt if we could look back half a million years we would see this reflected in the lives of our
early human ancestors.  War creates unity far more easily than peace ever could.  Co-operation during wartime
may have a higher purpose, but individual survival is still at the heart of one’s motivation.      
      
      
Morality/Spirituality
       
In order to have a sense of morality we need to understand the state of mind of other people.  There is a key
moment in the development of children when they begin to grasp that other people have different desires,
intentions or beliefs than themselves.  From the age of twelve months normally developed babies instinctively
follow a person's gaze if it quickly changes direction.  Infants will often flick from the adult's eyes to the object that
the adult is looking at.  We have a finely tuned ability to detect whether someone is looking at us, and if not,
where in fact they are looking.
      
Humans, as well as some species of monkey, can learn to perform a task by watching another person (or ape)
perform the same task and copying them.  This is due to structures in the frontal lobe called 'mirror neurons'.  
When we watch someone gripping an object, for example, muscles in our own hands tense slightly as though we
are priming them to perform the same action.  Indeed, it is possible, to catch oneself twitching, involuntarily, in
sympathy with another person's movement.  We may make the movement to kick a non-existent ball when
watching a player with whom we closely identify attempt to score in a match.  Sometimes when watching a film, one
can catch themselves ducking when a villain throws a punch at the main character.
      
Vilayanur Rmachandran and colleagues at the University of California at San Diego have conducted an
experiment that involves the suppression of certain brainwaves.  There are a variety of electrical wave patterns in
the brain, of which one type, mu waves, are found in the motor cortex.  These are associated with movements or
the intention to move but are blocked when a person moves his or her hand.  The reason for this would appear to
be some kind of imitative function.  Other experiments have shown similar patterns of brain activity between
'doing' and 'watching'.  A relevant part of the brain in humans is Broca's Area, a structure that is used for the
production of speech.  It has been proposed that mirror neurons could be the connection between action and
communication.  Since these structures seem to allow us to interpret and recognize another person's actions, they
may be implicated in the development of communication and speech.  Involuntary twitching in sympathy might
have been the first step in terms of gestures and hand movements that finally led to vocalized speech.  
Rmachandran is confident that the discovery of mirror neurons in Broca's Area will yield abundant insights into the
evolution of the human mind.  He thinks that they may be partly responsible for the crucial movement in human
evolution called the 'Great Leap Forward'.  Somewhere between forty-five and seventy-five thousand years ago
there were the beginnings of symbolic art, followed by a significant jump in the complexity of tools and weapons
and the invention of rituals such as burying the dead and beads and flowers.  The only reason that these cultural
advances 'stuck' in the minds and memories of the population was because we had the capability to imitate and
understand the actions of others., in the same way that language can only become lodged in the minds of a
population if the bulk of the population has the ability to learn quickly and easily.
      
If we can replicate the simple movements of another person in our own mind, it follows that we can replicate a
sense of pain or pleasure too.  Most of us are aware of wincing when we someone stub his or her toe, or when we
watch someone having a tooth pulled.  Mirror neurons may well be the key to our ability to understand the
emotional state of mind of another person.  We have the ability to 'read' other people's minds, we can put
ourselves in someone else's place, and to an extent we can understand their experiences, whether pleasurable or
painful.  It is a talent that starts early in life.  After twelve months, babies will start to interpret their environment
through the eyes of another; if a parent has a look of fear or disgust when they look at a toy, the child will
generally avoid it.  Infants as young as three years old will comfort their mothers if they are crying.  These actions
are the very beginnings of human empathy.
      
In real life rationality does not ignore emotion; the two combine to create a complex and fiendishly unpredictable
behavior.  This, perhaps, is coming close to what it means to be human.  We have a sense of fairness with a flip-
side of which being a feeling of guilt.  Our instinct for co-operation brings with it an inclination towards fairness, as
well as feelings of anger or spite if someone does not display fairness towards us.  We are not automata who
maximize our gain no matter what the situation.  And in everyday life all kinds of 'fuzzy' variables come into play.  
These feelings of fairness or guilt act as extremely useful regulators of our capacity to reciprocate or forge
alliances.  
      
An element of heroic behavior, particularly male heroics, may come down to sex.  The biology of sexual selection
influences all kinds of risky behavior, and heroic behavior is no exception.  It is a perfect mechanism for
advertising one's high quality genes.  It is also good because it plays on other people’s instincts for empathy.  We
are attuned to other people’s pain and admire those who can put a stop to it.  The most self-interested drive in
human psychology, sex, may be heavily involved in the most selfless acts of heroism.  The key word here is
‘involved’.  Sexual selection does not run the show.  In the rich and unpredictable world of human behavior, no
one is a prisoner of his or her genes.  But their presence will always be felt.
      
Most of us harbor a hope that pure altruism, unaffected by selfish impulse, exists in human life.  Nevertheless, we
may feel that even the most devoted and humble of hospice volunteers, anonymous donors or committed rescue
workers perform good deeds partly because of some feelings of pride, guilt or shame, or perhaps they get a risk-
taking thrill.  But we should still admire them, because they fight on the front lines of altruism, and most of us do
not.  Even if we have altruistic intentions, we may lack the courage to see them through.  So when altruism exists,
it should be treasured.  It has its instinctual roots in an ability to understand the pain and pleasure experienced by
others; it will be nurtured by our upbringing and our moral environment.  Ultimately, though, it is our capacity to
combine instinct, emotion and reason that gives us the ability to perform these remarkable acts.
      
Virtually every religion or system of ethics invented in recordable history has tried to find a way to provide a good
reason for people not to be selfish.  Paul Ehrlic, the distinguished Stanford biologist, believes that every ethical
system originated in the human mind, a biological entity.  He concedes that the capacity to construct a moral
system is a product of evolution.  We can imagine the consequences of our actions, think about alternatives, and
imagine what others are feeling.  All these are valuable qualities, and with free will are preconditions for creating a
moral system.  But the content of that system, he believes, is not dependent on our genes.  It is an outcome of
human culture, and as such can take many different forms.
      
Our ethical attitude can only be as good as our understanding of the world around us.  Among the many appalling
threats to our society triggered by the events of 11 September 2001 was one that was almost intangible.  It was
the violent language that followed the massacre of innocent civilians.  Winston believes that one of the key
causes of 9/11 was the violent language of hatred that preceded these murders, language which had slowly
dripped corrosively on the minds of the perpetrators and their supporters.  To nearly all of us they were
murderers, but, paradoxically, to themselves and their followers they were martyrs.
      
Many people believe that religion is outdated in today’s society, but it seems that most people still have a certain
spirituality.  There is a sense of believing but not belonging.  People are now more individual in their religious
beliefs and find that belonging to an established Church is no longer entirely relevant to their needs.  But religious
thinking is still strong and shows little sign of decline.  Most people still profess to believe in God.  In a world a
relatively high education and rationality, why would such an irrational belief such as this exist?  One possible,
indeed likely, solution is that religiosity and hence religion has given Homo sapiens an evolutionary advantage.  
There is also some evidence that religiosity- the ability to feel spiritual- may be inherited.  Religions have enabled
people to achieve by collective action what they never could alone.
      
It is certainly true that each religion has a different moral code, but there are some basic human values, it seems,
which are close to being universal.  A central tenet of the moral code of Western society would seem to be the
idea of the sanctity of human life.  Our moral values stem from our conviction that life is uniquely sacred and the
framework of our religious and secular law emanates from that principle.
      
Perhaps, as Voltaire famously wrote in the eighteenth century, ‘If God did not exist, it would be necessary to
invent Him.’  Maybe, with the growth of our huge brain and with the nature of our consciousness, man could not
after all stand naked and defenseless on the savannah.  Possibly, later in time, with the development of language
and the use of symbols, man grew an instinct for spirituality which pushed him to recognize and bury his dead and
to believe in a force which shaped his life, and led him to appreciate the preciousness of life in other humans.
      
Winston believes that in spite of our powerful instincts- instincts that influence virtually every aspect of our
behavior- we have, above all, an understanding of good and bad.  Central to this belief is the notion of man’s free
will.  Man has the ability and the freedom to choose between what is moral and what is immoral.
      
If there truly is free will, the one most powerful explanation of God is that he does not interfere- cannot interfere.  
His interference would effectively negate the freedom humans enjoy to do both great good and great harm to
each other.  Having set our universe in motion, God must leave it to man to decide how to handle his existence.
      
So religion does have a purpose.  Most people would be far less responsible, far less moral, far less likely to seek
the right path were it not for the set of rules that religion supplies.  Often these rules seem illogical or tedious, but
they serve the purpose of discipline, which is necessary for all humans.  To be useful and good, religion must
conform to morality.  That morality is critical, because together with religion it gives us a framework to control
those emotions that have arisen from the primitive beginnings of life, feelings which are unlearned and inherited-
our instincts.
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