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Chapter 5
Hominid Mind
We now have an outline of some
of the major steps in the transitions from monkeys to apes and from apes to
hominids, as well as some information on how their minds are distinctly different
from ours. In this chapter we continue to trace the stages through which the
minds of early hominids developed, approaching ever nearer the appearance of
our own modern human variety. We will pick up the story at the stage of Homo
erectus, approximately 2 million years ago, and then follow one model of the
evolution of human intelligence up to the period before the invention of agriculture
and cities. Over this time, hominids were evolving psychological mechanisms
that are shared by all races of modern humans. Further, the advent of language
was making possible the transmission of the rules and ideas of cultures, allowing
adaptive behavioral changes to occur at a much faster rate than genetic evolution
would permit. This brings us to modern human brains and minds, which were fully
present by about 100,000 years ago. These modern brains and minds are the subject
of Parts II and III of this book. The more recent shaping of our minds by the
invention of writing and other complex social innovations is discussed in Part
IV.
The Mimetic Intelligence of Early
Hominids
At the time of the appearance of
H. erectus, major changes were under way. More complex facial musculature suggests
a richer range of emotional expression than the present-centered and nonreflective
episodic minds of monkeys and apes could generate. This emotional expression
was probably supported by increased complexity of both the phonetic (sounds
or calls) and the prosodical (volume, pitch, tone, and emphasis) components
of vocalization. Changes in the skull and jaw permitted the generation of more
varied sounds. H. erectus had a larger brain, made more elaborate tools, used
fire, had seasonal base camps, and spread out of Africa over Eurasia. Its culture
mediated the transition from ape to human.
Merlin Donald, the psychologist
whose ideas were mentioned in Chapter 4, uses the word "mimetic" to
describe the intelligence of hominids at this stage of evolution and suggests
that mimetic intelligence remains embedded in the modern human mind. He
believes this intelligence is similar to that seen in prelinguistic children,
illiterate deaf-mutes, and patients seen in a clinical setting who have lost
language but retained social skills and who communicate by mime. Mimetic intelligence
is the kind of cognition needed to learn music, crafts, and sports---largely
by imitation, without language. This stage of archaic hominid cognition would
resemble the extra-linguistic features of the modern mind.
The ability to produce conscious,
self-initiated, representational acts that are intentional but not linguistic
is different from mimicry or imitation, for intentional representational acts
are used to reenact, or present again, an event or relationship. This happens
in games such as charades and is the basis of arts such as pantomime, ritual
dance, and visual tableaux. A central feature is the modeling of social structure.
Chimps learn only how to react to each individual in the larger group. Human
children model the group structure, playing role-acting games. Group mimesis
is what we call ritual. A single mimetic performance might include manual signals,
postural attitudes, facial expressions, nonverbal vocalization, and gesture.
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DESIGN NOTE: SELF-EXPERIMENT
To have a feel for mimetic intelligence
in your own experience, pause for a moment and imagine that you have suddenly
lost the use of language---not only can you not hear and speak it, but you
also cannot construct internal narrative sentences. That is, try to restrict
your thinking to visual and mechanical images of the sort you might need, for
example, to build a wall from stones. Internal words and sentences are not
necessary, only images of the process and its goal. Now, feel the many ways
in which you would still be able to communicate the process and goal through
gesture and movement. In the same way try signaling that you are hungry, wish
to go outside, want to meet someone, and so on.
***************
Donald suggests that mime, play,
games, skilled rehearsal, nonlinguistic gesticulation, tool making, other instrumental
skills, and many other expressive devices used in social control are products
of the mimetic system as it continuously models the episodic world. This system
is an elaboration, or summary, of episodic experience dealing with skills,
social roles, and emotional events. It is a distinctive hominid invention,
a kind of cognition that is distinguishable from language even in modern humans.
A simple drawing can be used to illustrate the idea that mimetic mind orders
and encapsulates the outputs of episodic mind (see Figure 5-1).
Figure 5-1
This drawing illustrates the idea
that mimetic intelligence is built by collecting isolated chunks of episodic,
present-centered information, indicated by the lines on the left, into sequences
of meaningful activity such as a set of instructions on how to do something.
Thus each mimetic routine, indicated by the lines on the right, encapsulates
a series of isolated actions that have not previously been linked together.
The emphasis here is on mimetic
intelligence as antedating verbal linguistic abilities, but we cannot rule
out the possibility that the two underwent a slow and continuous evolution
alongside each other. Whichever interpretation is correct, there is abundant
evidence that sophisticated conscious concepts can exist without language.
Adult humans who have been without language can describe a rich mental life
after they have learned language. Most word learning is attaching words to
preexisting concepts, objects, actions, collections, and social institutions.
Deaf people who have been isolated and have not learned sign language exhibit
advanced spatial knowledge and skills, can handle money, and can pantomime
narratives. In patients with brain lesions that disrupt language, mimetic skill
usually survives, and doctor and patient can communicate by sign or body language.
Destruction of mimetic abilities always takes language with it, and such patients
are much more out of touch with human reality.
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DESIGN NOTE: IMPORTANT POINT
Sophisticated conscious concepts
can exist without language. Adult humans who have been without language seem
indistinguishable in many of their cognitive skills from adults with language.
***************
Kinesic Communication
The mimetic intelligence we have
been describing underlies our body language, the nonverbal communication that
is signaled by kinetic motions---the kinesic communication---of our faces or
limbs. This usually has emotional significance, as when we open up our faces
to communicate affection or contract them if we are rejecting someone. These
gestures, along with many others, recur across cultures. We
join company with other higher vertebrates in using nonverbal communication
to model and set social roles. Detailed time-lapse movies can be analyzed to
document the fact that this nonverbal communication proceeds in many parallel
channels. Our mimetic exchanges usually occur within a larger framework that
includes linguistic expression, but words don't necessarily alter the nonverbal
elements of the exchange. Language can carry on in parallel, without disturbing
the fabric of spontaneous mimetic communication (see the accompanying self-experiment).
Different parts of our bodies, different movement patterns, are essentially
organs of social behavior. Social status is regulated by confidence, age, size,
and sex. (Is your chest puffed up or collapsed? Is your pelvis thrust forward
or pulled back?) Posture signals social rank, sexual attractiveness, and emotional
support. The signaling of social status by body carriage reaches its most complex
development in our species. For humans, as well as other social vertebrates,
an individual's relations with other members of the population is a central
factor in determining that individual's survival and reproduction.
***************
DESIGN NOTE: SELF-EXPERIMENT
You are aware of parallel channels
of communication from your own experience, especially when verbal and nonverbal
messages conflict. As an exercise,
pretend that you are delivering the following mixed messages (parentheses indicate
the physical action that is occurring while the preceding words are spoken).
I'd like to know you better (drawing
back).
I don't want to intrude on your
space (moving forward).
I really am happy to be here (looking
apprehensive).
I don't understand why people never
approach me (frown).
People are always trying to take
advantage of me (with seductive look).
I don't want to tell you what to
do (with commanding voice).
***************
Social Cohesion and Body Language
An overriding controller of our
movement is our social self-image. It is decisive in determining the most intimate
details of how we move in public. Get up from reading this book for a moment
and move about as though you were a person of the opposite gender. If you are
a man, imagine yourself moving as a woman, and vice versa. How does it feel?
The point here is that you carry your body in only one of many different possible
configurations, which are all indicative of social status and role. We can
become conscious of these configurations and can deliberately change them,
but usually they are unconscious, regulated by nonverbal social cues. The postures
we assume are emergent properties of our social group---of a sort of "group
mind." The complex and varied personalities that we act out require distinctive
holding patterns of postural muscles, as well as characteristic individual
configurations of our neuroendocrine and autonomic nervous systems.
We are programmed by our kinesic
context. Are you aware, in yourself, of the moments when you are imitating
the expression on a face you are looking at? This is a universal human tendency.
Synchronization of mood is crucial to smooth interaction, and it involves the
linking and orchestration of physical movements. The next time you are listening
sympathetically to someone else, note what happens if you suddenly stop the
subtle motions of your body or face whose rhythm is matching the speaker's.
We all tend to seek feedback, and the company of others, that confirms either
our current mood or the mood we have a disposition to be in.
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DESIGN NOTE: IMPORTANT POINT
We nonverbally transmit moods as
though they were viruses, and some people are more likely to be senders, and
others receivers. Have you ever noticed yourself imitating the expression on
a face you are looking at?
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To be a member of a group you must
mimic its behaviors, whether you are a seagull or a human. Carried to an extreme
by humans, complementary body language helps to define and cement the members
of a group together. The stereotyped evolved behavior of laughter also reinforces
group cohesion. Bonding, affiliative, and maternal behaviors are under the
influence of hormonal and autonomic mechanisms just as hardwired as those that
control fighting or fleeing. In many vertebrates they are enhanced by the hormone
oxytocin and correlate with energy-restoring and energy-building activities
of the parasympathetic nervous system. What we are dealing with here is an
integrated ensemble of mind, body, and world.
Origins of Language
To continue our story of hominid
evolution, we must now add language to these complex systems of emotional and
kinesic communication. Think about the constant narrative within our heads.
We use this narrative to communicate with ourselves and by vocalizing part
of it, with others, but what is its origin? No one would claim at this point
to have the definitive answer. It is hard, however, to observe the alarm calls
of the vervet monkey---different calls for eagles, for snakes, or for leopards---or
the body language and calls of chimpanzees without imagining them as signals
that might come under voluntary cortical control and that are strung together
in sequences to describe more complex events.
Language excels at organizing categories
in our natural and social world, even if it is not very good at conveying the
types of information that faces, smells, and emotions are able to convey. Although
there is evidence that a sudden flowering of language occurred around 50,000
years ago, this may well have been preceded by a long, slow adaptive evolution
of brain mechanisms underlying speech generation and comprehension. Language
mechanisms in australopithecines and in H. erectus may have been much more
sophisticated than we suppose from their simple stone tools.
The postulated base we are building
on is the episodic intelligence of the monkeys and apes (see Chapter 4) and
the mimetic intelligence of early hominids. In the former, current aspects
of the environment appear to control what an animal does next; there is no
thinking about long-term projects. Decisions to fight, flee, feed, mate, or
just scan the environment appear to be based on a present-centered reality.
The later stage we call mimetic intelligence adds the more extended communication
of social procedure and rituals. Language may have originated from oral reinforcement
of symbolic gestures used in communication, such as the facial expressions
that signal anger, sadness, puzzlement, derision, and disapproval, as well
as the body gestures of shrugging shoulders, waving, clenching the fist, and
the like. Linguistic and mimetic
pathways could thus have developed in parallel, the linguistic pathway enriching
and reinforcing the mimetic, even though it is possible to dissociate them
(as in the foregoing self-experiment).
***************
DESIGN NOTE: IMPORTANT POINT
The cognitive changes underlying
language did not necessarily develop to support spoken language as we now experience
it, because there would have been no language acquisition support system. The
words and symbols of language probably originated outside of language, with
symbols initially invented for nonlinguistic purposes.
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Internal Narrative
How, then, might spoken language
have arisen from the sets of 20--50 vocal signals that we see in some social
primates? The philosopher Daniel Dennett speculated that an early step may
have occurred when vocalizations that were used to share information ("tiger
coming," "no food here,") began to be used for communication
by an individual with itself as well as for communication between individuals.
An example might be "Food here?"---a question that was originally
addressed to others but then began to be asked by the individual in isolation,
talking to itself. Perhaps a
system that evolved for communication with other individuals---your mouth speaks,
other ears listen, others speak, you listen---could change into communication
within the individual: speaking and listening to oneself (Figure 5-2). The
virtues of talking very quietly to oneself and then silently answering, would
be recognized. The loop of self-stimulation would be maintained, but the peripheral
vocalization and audition portions would be dropped because they weren't contributing
much. "Talking to oneself" aloud would be slow and laborious, compared
to the swift unconscious cognitive processes it was based on, because it had
to make use of large tracts of nervous system designed for other purposes---in
particular for the production and comprehension of audible speech. Furthermore,
it would be just as linear (limited to one topic at a time) as the social communication
it evolved from. The idea of inventing new paths of internal communication
is quite reasonable and is observed clinically in human patients with brain
damage. The damaged area is not repaired, but new ways of performing the necessary
tricks are discovered.
Figure 5-2
Dennett speculates that the activities
of speaking and hearing, which originated in one individual's to signaling
another (A), might have then proved useful to individuals in isolation, first
as they spoke aloud and listened to themselves (B), and then as they developed
internal brain pathways that could accomplish this without peripheral vocalization
and audition (C).
Language as an Adaptation
Perhaps the most influential hypothesis
is that language is an adaptation that developed because it supported the distinctions
that need to be made in increasingly complex social organizations. One
possibility is that early hominid alliances based on grooming became impractical
as the increasing amount of time spent on grooming in a complex society interfered
with other activities. Language then evolved as a grooming substitute. Kinship,
marriage, and lineage tracing certainly became much more complex in the transition
from primate to hominid cultures. Social institutions grew more formalized
and were given names. Rather than language being a difference that gave rise
to culture, the stages of its formation are more likely to have been an outgrowth
of culture.
Social structures are made up of
relationships based on learned information about other group members. Social
status plays an important role in the organization of kinship and marriage
in both nonhuman and human primates. Information about social relationships
can be communicated with far greater precision with language than without,
making it easier to distinguish among close kin, kin at some remove, and individuals
in other lineages. Naming individuals and relationships can make it possible
to articulate the rules of social interactions between clans.
Evolution of Brain Structures Supporting
Language
What happened, in terms of brain
circuitry, to support the appearance of a human competence so distinctively
different from the vocalizations of other vertebrates? No other species, including
apes, has mastered the process of language production, although some chimpanzees
raised in captivity have shown a capacity to learn the meaning of some human
words and the syntax of simple sentences. Animal communication systems fall
into three classes. They can be the sort of random variation on a theme observed
in birdsong, a continuous signal that indicates the magnitude of some variable
(as when the liveliness of a worker bee's dance indicates to its hivemates
the richness of a food source), or a set of calls in which each serves a discrete
purpose, such as warning of the presence of a predator. The distinctively different
feature of human language is that an infinite number of meanings are made possible
by the combinatorial system called grammar. Thanks to grammar, the number of
complex words or sentences in a language is unlimited. Discrete elements are
arranged into combinations whose meaning derives from the meanings of their
parts.
***************
DESIGN NOTE: LONG IMPORTANT POINT
Hominid language is a distinctive
feature of the cerebral cortex, whereas the vocal calls of primates and other
animals are controlled by older neural structures in the brain stem and limbic
system that generate emotional behaviors. These older structures also control
human vocalizations other than language, such as laughing, sobbing, and shouting
in surprise or pain.
***************
In modern monkey brains we observe
areas, presumably present in our common ancestor, that appear to be homologs
of the Broca's and Wernicke's areas in humans, which are involved in the generation
and comprehension of language, respectively. The
Broca's homolog is involved in movements of the face, mouth, tongue, and larynx;
the Wernicke's homolog deals with sound sequences and vocal calls. As we saw
in Chapter 4, cranial endocasts of Homo habilis fossil skulls indicate enlargement
of these regions, and some
investigators think that the neural preconditions for language are first met
in this species. The most plausible
idea is that these modules were slowly co-opted by other functions, or perhaps
they were duplicated, with some of the duplicates taking on new inputs and
outputs. In one of the several hominid species (H. habilis, H. erectus) that
existed from 3 to 1 million years ago, an expansion or rearrangement of these
brain areas would have permitted a transition from gestural and sound communication
(mimetic intelligence) to phonemic language, in which the same sounds can be
combined in different ways to make sound units (words) with different meanings.
It has also been suggested that increases in the size of the frontal and parietal
cortex, and the appearance of cerebellar structures unique to the human brain,
are correlated with the development of language. It
is a pity that we cannot document stages in these transitions. Our soft hominid
brains leave no fossil records of the sort we find for skulls.
Language and the Evolutionary Tree
One might be tempted to phrase
the question as "How did chimpanzee brains change into human brains with
language?" but that approach is inappropriate. Implicitly, we would be
assuming that evolution is like a ladder, with one species leading to the next.
Rather, evolution is like a bush or tree, and the hominid evolutionary tree
is a complex one with most of its branch points shrouded in mystery. Figure
5-3 depicts some of the origins, breaks, and branches in the hominid transitions
discussed both in Chapter 4 and below. In the roughly 5 million years since
our branch split from that of present-day chimpanzees, there have been 300,000--400,000
generations during which we could have evolved brain structures supporting
a universal grammar while the chimps did not do so. The issue of whether "language" in
chimps and that in humans have similarities is largely beside the point. Even
if some chimps were taught to produce real signs and to group and order them
consistently, this would not show that the human ability derived from the chimp's.
The central point is that in the evolutionary tree, traits such as eyes, hands,
and vocalizations have appeared several times on different branches, most of
which did not lead to humans. Some of these animal adaptations, such as the
Doppler radar used by bats and the celestial navigation capabilities of some
migratory birds, rival human language in their sophistication and complexity.
Figure 5-3
Hominid evolution depicted as a "pagoda
tree" in which each level diverges into regional branches. The clusters
of hominids at each level are poorly understood. Archaic moderns include groups
distinctive to Africa and Europe (they are sometimes referred to as Heidelbergs,
the group from which Neanderthals arose) and groups distinctive to Asia (Mapas).
Fully modern humans diverged from a Heidelberg population in eastern Africa.
Adapted from Kingdon, Self-Made Man.
The Emergence of Modern Humans
What were hominids doing during
the mimetic and linguistic transitions we have discussed? There is evidence
of several waves of migration from Africa to the Eurasian continent over the
past 1--2 million years. Archaic humans were firmly established in the Far
East between 1 and 2 million years ago and in Europe no later than 700,000
years ago. An H. erectus site in Java has been dated to 1.8 million years ago. The
rest of the globe was populated much more recently (Australia 50,000 years
ago, Siberia 20,000 years ago, the Americas 11,000 years ago, and the Pacific
Islands 30,000--1500 years ago).
A controversial question has been
whether H. erectus evolved into H. sapiens, or a separate line that became
H. sapiens displaced H. erectus worldwide as it did the Neanderthals in Europe.
Two main hypotheses have been proposed. One hypothesis argues for a multiregional
evolution of humans whereby H. erectus, H. neanderthalensis, and other populations
semi-independently became the modern races of H. sapiens, with some gene flow
between them. The other hypothesis
contends that all modern humans derive from a small group of common ancestors
that lived in Africa. These individuals evolved into the modern races of humans
during their emigrations from Africa and displaced all other hominid lines. The
genetic evidence in favor of this second scenario is now very strong.
***************
DESIGN NOTE: IMPORTANT POINT
Compelling genetic evidence suggests
that all modern humans derive from a small group of common ancestors that lived
in Africa between 100,000 and 300,000 years ago.
***************
Evidence for the out-of-Africa
Hypotheses
The first data to point toward
an African origin of all modern humans generated great excitement several years
ago. It consisted of information on the genes of mitochondria, which are passed
on to offspring almost exclusively by the mother. Such genes have higher mutation
rates than nuclear genes, and the genetic distances between different human
groups can be inferred from the number of mutations. Groups that have evolved
independently of each other for a longer period of time should have accumulated
greater numbers of different mutations. A computer algorithm was used to construct
the most parsimonious sequence of changes that could have led to the genetic
differences observed today. The first attempts at applying this algorithm suggested
that mitochondrial DNA has been evolving for the longest time in Africa, with
the ancestral lineage of all current DNAs traced to a single woman---the "mitochondrial
Eve." Many other women
presumably lived at the same time, but their mitochondrial lineages simply
went extinct; that is, at some point they no longer had any descendants in
an unbroken female line. (Subsequent analyses have shown that the same data
set is also consistent with multiple genealogies, so it really doesn't resolve
the issue.)
A second line of evidence, however,
has supported the idea that all modern humans derive from a common ancestor
who lived 100,000 to 300,000 years ago. A
portion of the male Y chromosome (passed from father to son) contains the only
genetic material besides mitochondrial DNA (passed from mother to daughter)
that is inherited from just one parent and so is not recombined in ways that
make it more difficult to reconstruct an evolutionary history. The fact that
it shows very little variability across different races of modern humans suggests
that modern H. sapiens could have descended from a small group of male ancestors
who lived about 270,000 years ago. Another group of studies has now tackled
nuclear DNA, focusing on a piece of chromosome 12, which has a great variety
of patterns in sub-Saharan Africa, loses many patterns in Northeast Africa,
and is dominated by just one type in the rest of the world. This evidence implies
a series of small populations continually "budding off" from larger
ones, losing variety as they go. These
data suggest an African origin, dating to approximately 100,000 years ago,
for all non-African human populations. Studies on one site on the Y chromosome
suggest also that it was carried back into Africa from Asia, such that migration
occurred not only out of, but also back into, Africa.
Genetic and linguistic differences
between modern humans have been used to construct family trees describing the
radiation and diversification of current races of humans from an original African
stock. One branch separates
African from all other populations; a second splits Europeans from the remainder
of the non-Africans, and the relationships among the Native Americans, East
Asians, Australians, and Melanesians are controversial. Because genetic, migrational,
and linguistic family trees are so controversial, any particular story seems
to unravel within a few years. Most linguists believe that after 10,000 years,
little trace of a language remains in its descendants, which would make it
very unlikely that traces of the most recent ancestor of all contemporary languages
could be found.
Co-evolution of Humans and Their
Tools
The advent of tools caused the
circumstances of hominids to be more and more "self-made," essentially
turning us into artifacts of our own artifacts. (H.
erectus was making sharp stone flakes for cutting meat about 2 million years
ago and bifacial stone tools about 1.4 million years ago.) The fundamental
mechanism, termed the "Baldwin effect" after its discoverer, is that
new procedures or behaviors that increase reproductive success are followed
more slowly by evolved forms that support them. It seems likely that we adapted
to new technology (fire and tools) both physically and psychologically. Thus
cooking and processing food removed the need for massive jaws and allowed us
to colonize colder parts of the world. Similarly,
boats made possible our migration to distant lands and islands.
***************
DESIGN NOTE: IMPORTANT POINT
Humans have become "tools
of their tools," as slow, adaptive changes in body and brain design have
supported new technologies and behaviors.
***************
More sophisticated technology was
presumably a major factor in Pleistocene population explosions that occurred
in separate parts of the world. Africa's population increased rapidly approximately
80,000 years ago, whereas Europe's exploded about 40,000 years ago---a much
later date. This coincides with a large leap in the sophistication of tools,
and with the appearance of decorated artifacts and cave art. One
unsolved puzzle asks why the stocky Neanderthals, about 30 percent larger than
modern humans, coexisted with
modern humans in Europe and the Middle East for over fifty thousand years and
then disappeared. (Recent analysis
of DNA from Neanderthal fossil bones shows in fact that modern humans and Neanderthals
evolved independently over a period of more than 500,000 years.) The supposition
is that the Neanderthals must have lost some kind of evolutionary competition,
perhaps as moderns developed more elaborate social systems or superior tools
and better food procurement. The main challenge to survival faced by groups
of humans during these periods was probably other groups of humans competing
for the same resources.
***new section of text***
It is a curious fact that while
different groups of humas had spread over virtually all of the globe by 10,000
years ago, their development from bands (containing dozens of individuals)
through tribes (containing hundreds) and chiefdoms (thousands) to states (many
thousands) was very different in different regions. The relatively more rapid
development of Eurasian, and particularly western Eurasian, societies over
the past several thousand years led to social structures and technologies that
permitted them to subjugate most of the rest of the world by the end of the
19th century. Some have invoked racial (i.e. genetic) differences to explain
by Europeans were conquering Africans in the 19th century, rather than vice
versa. However, a far more plausible explanation is that fundamental differences
in geography have made some regions of the world much more favorable for the
development of societies ultimately able to support large armies with weapons
based on metal working technology. Jared Diamond points out that the Eurasian
land mass has provided a much larger number of plant and animal species amenable
to domestication than other areas of the world. The
fact that much of this land mass is at the same latitude has permitted travel
and a rapid diffusion of new plant and animal technologies that was not possible
elsewhere. Food surpluses allowed the development of states with bureaucratic
and military castes, along with sufficient resources to also support development
of military technologies. Further, a consequence of the high population densities
of the large cities that rose with the formation of states was that diseases
spread much more easily, resulting in the rapid evolution of disease resistance
in urban societies. Thus when Europeans spread to other regions of the globe,
smallpox, measles, influenze, typhus, and other infectious diseases played
as decisive a role as guns in decimating local populations.
*****end new section of text*****
The Origins of Mythic Intelligence
The mind-tool of words permitted
the evolution of language, the formulation of ideas, and the birth of a new
kind of culture. Donald suggests
that just as mimetic cognition collected episodic event perception into more
extended and instructive patterns, the next transition to an intelligence (which
he terms mythic) collected the scattered repertoires of mimetic culture under
the governance of integrative myth---a story of how things are (see Figure
5-4).
Figure 5-4
This drawing expands Figure 5-1
to the next proposed stage of hominid intelligence, the collection of sets
of mimetic repertoires into the different continuous stories that are the foundation
of a mythic intelligence supported by language.
Here we are talking about the middle
Paleolithic, 200,000 to 40,000 years ago---the time of archaic H. sapiens.
This is when the second major increase in brain size occurred and the vocal
tract began to assume its modern form. The suggestion is that during this period,
humans were all enveloped by a mythic participatory reality, without the sense
of self and other that is characteristic of modern Western culture. We feel
only vestiges of this today, as when we are overcome by powerful public emotions,
such as patriotism or civic pride, during song or chanting.
Symbolic devices such as the vocabulary
of a language supported mythic invention and the integration of shared knowledge.
Thus the separate repertoires of mimetic culture were collected under the umbrella
of integrative myth. Constructing histories of the past and models of the human
universe required both symbolic invention and phonological adaptation. The
story line of a myth could specify the proper places of plants, animals, humans,
and tools in the natural order. A collective mind could be governed by myth,
and it still is today in the arena of social values.
What Caused the Transition to Upper
Paleolithic Culture?
Why does the archeological record
show a relatively sudden appearance of artifacts and inventions long after
the brain of H. sapiens had attained its present size? The really great leap
in human tools and art didn't occur until 40,000 or 50,000 years ago---with
spear throwers appearing before harpoons or bows and arrows, beads and pendants
before cave painting. During
this period, the appearance of ornaments and images seems to signal the emergence
of new forms of social organization. Some
suggest that this "big bang" of cultural activity and development
correlates with a final gelling of language capabilities, as the anatomical
basis for modern spoken language and complex vocabularies fell into place.
Although most work has emphasized a European center (southwestern France) for
this sudden flowering of human culture, more recent evidence from archeological
sites in Africa suggests that advanced stone tools and blades were appearing
in Africa as early as 240,000 years ago. This
evidence raises the possibility of a slower evolution, rather than a revolution,
in human culture, tools, and language.
Evolutionary Psychology---The Search
for a Universal Mind
The story we have told so far is
now being viewed from a new perspective---one that many believe may be affecting
our thinking about ourselves as profoundly as the Freudian revolution did toward
the beginning of this century. The newly emerging field of evolutionary psychology
claims to describe and explain human behavior in a fundamentally new way. Instead
of Freud's picture of the mind as a bunch of squabbling persons---conscious
versus unconscious, superego versus ego versus id---it postulates a complex
array of behavioral modules evolved as adaptations to our Paleolithic ancestral
environment, modules that all modern humans share. We will review some of the
background for this model, keeping in mind that it is highly controversial.
Information presented in several subsequent chapters of this book in fact argues
against it, so it is important to outline both sides of the debate.
***************
DESIGN NOTE: IMPORTANT POINT
Evolutionary psychologists picture
the brain not as a general-purpose problem-solving machine but as something
closer to a Swiss Army knife, a gadget that includes separate tools that evolved
for specialized purposes.
***************
A brief history of recent trends
leading up to evolutionary psychology might be useful at this point. A number
of books popular in the 1960s argued that we should look to sex, aggression,
territoriality, pair bonding, or other socially evolved behaviors as the real
mechanisms that determine the form of human society. The
authors of these books did not see the history of our ideas and institutions
as an explanation of our current society but rather viewed them as the outcome
of interactions between individuals determined by blind biological processes.
All of these arguments were flawed, because each selected one aspect of what
it assumed to be the behavior of primitive humans and made that single aspect
account for the whole of culture. And the "drives" that were postulated
were often at variance with the facts.
The 1970s saw the appearance of
sociobiology, defined by its proponent E.O. Wilson as "the systematic
study of the biological basis of all social behavior." Early
sociobiological arguments frequently took contemporary human motivational terms
such as "aggression," "sex," "dominance," and "caste" and
assumed they were natural categories instead of mere projections of our fertile
minds onto those of animals. Evolutionary psychologists, as the intellectual
heirs of sociobiology, have maintained that early attempts at sociobiology
tried to skip psychological mechanisms and assumed a link too direct between
genes and complicated behaviors. Thus sociobiologists missed crucial causal
links by ignoring how evolved psychological mechanisms, whether genetic or
non-genetic, might play out in individuals and groups.
Genetic Arguments for an Evolved
Psychology
Some core ideas in evolutionary
theory suggest reasons why social modules of mind would have been a plausible
evolutionary adaptation for humans. A
starting point was the realization that males and females face different situations
in trying to pass their genes on to their offspring. For many animals, including
humans, males can reproduce hundreds of times a year, females only once. Thus
for a woman there is little (genetic) point in mating with multiple partners,
but each new partner offers a man a chance to get more of his genes into the
next generation. Women must sacrifice much more for reproduction than men do.
Hence women's reproduction is best served by their being selective about sexual
partners, judging the male's fitness and commitment and his potential to contribute
to or invest in the offspring. Sexual selection thus works in two ways: Males
evolve to compete for scarce female eggs, and females evolve to compete for
scarce male investment. The idea is that in many species there is an evolutionary "arms
race," wherein natural selection favors male brains that are good at deceiving
females about their future devotion and female brains that are good at spotting
deception. (One might call this the "sweet-talking" theory of evolution.)
***************
DESIGN NOTE: IMPORTANT POINT
In many species, males and females
need to follow different strategies for getting their genes onto the next generation.
***************
Comparative anthropological studies
show a universal pattern of women being more selective about sex partners than
men are, and men desiring sex with many partners. It appears that in all known
cultures, women with unrestrained libidos are judged more harshly than comparable
men. Thirty-seven different cultures have been documented in which males focus
on younger mates (better able to produce babies), whereas women prefer older
mates (better able to provide resources). Most
evolutionary psychologists would argue that it is implausible for all peoples
to have arrived at these similar customs independently, without significant
genetic encouragement and that it is unlikely that these behaviors were present
for 200,000--500,000 years, before modern humans radiated out of Africa, and
were transmitted purely by cultural means, without being extinguished in a
single culture.
What other selection pressures
might have acted on men and women to generate sexual differences in brain and
behavior? One approach to understanding the factors that may have shaped human
evolution during the Paleolithic is to observe existing hunter-gatherer societies.
Men generally are responsible for foraging over long distances and for the
construction of weapons used in war. Women specialize in food gathering near
the camp, making clothing, caring for children, and preparing the food. In
men this division of labor might lead to selection for long-distance route-finding
ability and targeting skills. In women it might favor short-range navigation,
perhaps using landmarks, fine motor capabilities, and subtle perceptual discriminations.
Some of the behavioral adaptations
that were appropriate to conditions in the Paleolithic may be damaging to us
today. All humans show dietary preferences for salt, fat, and sugar. These
are important nutrients, and they are likely to have been very scarce in our
ancestral environments, so unrestrained tastes for them would have been a useful
adaptation. Now, however, they are so easy to obtain that many of us get sick
from eating too much of them. Also
of dubious value in modern times is the evolved behavior of male aggression,
reflecting pressures of sexual selection common to most vertebrate species.
Another vestige of our ancestral behavior in modern human society is the vertebrate
male trait of raising the odds that his genes will be passed on by having not
just a spouse or mate, but other partners as well. That these behaviors, both
dietary and sexual, are "natural" does not excuse them; being predisposed
to a certain behavior doesn't mean that the disposition should be indulged.
Knowing we have such a predisposition does help, however, if we want to change
our behavior.
***************
DESIGN NOTE: IMPORTANT POINT
The fact that natural selection
gave the human brain mechanisms appropriate for action in the Paleolithic world
is no guarantee that these mechanisms are still useful today.
***************
Evolution of Cooperation
In the foregoing description, we
have been following a gene-centered argument, which rationalizes evolutionary
changes in terms of strategies used by our "selfish genes" (a term
popularized by Richard Dawkins) to propagate themselves. A next step is to
realize that it is not essential to pass on the genes that happen to be in
one's own body, so long as copies of those genes are transmitted. They can
be carried by close relatives whose reproduction one helps to ensure. Thus
genes that enhanced cooperation between family members would be favored by
natural selection. This process, referred to as kin selection, is found throughout
the invertebrate and vertebrate phyla, and chemical cues are frequently used
in recognizing one's kin. Extended
families---several generations living together---occur in about 3 percent of
avian and mammalian species. Families that control high-quality resources are
more stable over time, and that goes for an extended family of birds controlling
a granary of seeds hidden in trees as well as for a human aristocracy with
its hereditary land holdings. Poorer families tend to disintegrate over time,
so their genes are more likely to be diluted.
For humans the kin selection mechanism
may have given rise to the sympathy, empathy, compassion, and love that bond
family members together. Further, this may have provided a platform for a further
development: reciprocal altruism, or cooperation between genetically unrelated
members of the same species. A series of careful mathematical arguments has
demonstrated that the genes of groups of cooperating individuals should be
passed on more successfully than those of groups whose members do not cooperate.
Thus the appearance of genes that promoted the development of cooperative behaviors
would be favored. Reciprocal altruism is fundamental to all human cultures
and also in animal societies---especially chimpanzees---where individuals and
their past deeds are recognized and recorded. Selection for behaviors that
support cooperation could be an evolutionary force underlying the appearance
of a sense of obligation, sensitivity to betrayal, friendship, enmity, sympathy,
dislike, and gratitude.
***************
DESIGN NOTE: IMPORTANT POINT
Does the suggested origin of our
more noble behaviors from our "selfish genes" mean that our selfless
behaviors are really selfish---that we are being hypocrites? Not at all, the
evolutionary origins of our motives must be distinguished from the motives
themselves.
***************
What evidence is there that any
of these behaviors are modules of a "social mind" common to all humans?
One line of support comes from brain lesion studies. Stroke or cancer in certain
parts of the brain, especially the frontal lobes, appears to compromise social
behaviors while leaving many other faculties intact. Some intriguing evidence
also comes from psychological experiments showing that people are good at solving
difficult logical puzzles when these are cast in the form of social exchange,
particularly when the object is to find out whether someone is cheating. Is
there a "cheater-detection" module among the mental organs that govern
reciprocal altruism? Does a "group-forming module" enhance the capacity
for identification with other people as parts of a unified hunting or working
group, so that individuals make sacrifices for the group as a whole? To carry
these ideas to their extreme, reciprocal altruism might be rephrased as the
Golden Rule: "Do unto others as you would have them do unto you." Thus
it may provide us with a predisposition toward moral behavior, just as each
of us has, in the presence of other humans, a predisposition to learn a language.
A further element in building up
a story line for evolved psychologies in humans rests on looking not at the
origins of cooperation but at the consequences of competition. A wide variety
of both vertebrates and invertebrates have dominance-subordination hierarchies.
These result from compromises made by individuals in their competition for
mates, food, and other resources. Status hierarchies achieve their ultimate
sophistication in primate and human societies. Rank is signaled by a complex
set of facial, vocal, gestural, and body language cues that function essentially
as organs of social behavior. A significant part of the human male ego may
result from the same forces that produced the stag's massive antlers: sexual
competition among males.
It is fascinating, then, that human
societies display two highly developed, and frequently conflicting, adaptations---competition
(status hierarchies) and cooperation (reciprocal altruism). Think how much
of your own conscious life is spent in these two arenas, considering what groups
you belong to, what your status is, and whether to cooperate or compete. The
fundamental argument here is that although different cultures show astonishing
variation in the surface behaviors associated with either cooperation or status
competition, the underlying modules of behavior are the consequence of a genetic
and developmental environment that all humans share.
*****************
DESIGN NOTE: SELF-EXPERIMENT
Think for a moment about the activities
you engage in during a typical day. How many of them are colored by your sense
of your relative status with respect to others and by the question of whether
you will cooperate or compete with them? All social vertebrates face such choices.
******************
Evidence from Cross-Cultural Studies
The preceding discussion has a
very specific context for modern humans. We are all descendants of the humans
who constituted the final successful radiation out of Africa that began approximately
200,000 years ago, replacing all other hominid groups. Our minds are adapted
to the way of life of hunter-gatherers, not to modern circumstances such as
the invention of agriculture, which occurred only within the last 10,000 years.
Psychological solutions to problems faced by hunter-gatherers were crafted
over the past 1--2 million years, not the past 10,000. A "bottom-up" approach
to evolutionary psychology asks what these problems were (finding nutritious
foods, finding a mate, avoiding predation, communicating with others, detecting
cheating) and considers options for solving them. In
contrast, a "top-down" approach can be very useful in asking whether
common motifs across cultures suggest universal mechanisms, and
it is to this approach that we turn next.
*****************
DESIGN NOTE: IMPORTANT POINT
Using the idea of reverse engineering,
one approach to understanding our brains is to find out what they were designed
to do. It is the mechanisms that serve these purposes, and not necessarily
expressed cultural behaviors, that we might expect to be universal.
******************
A significant problem has been
that anthropologists are generally rewarded when they find differences between
cultures, not similarities. Many accounts of unusual behaviors have proved
to be flawed, such as Margaret Mead's claims that Samoans had free sex. Also
incorrect are claims that the Native American Hopi have a different concept
of time, Trobriand islanders have a different notion of cause and effect, and
the Inuits' proximity to snow makes them better able to distinguish more varieties
of white than most of us, even though more words for varieties of "white" are
used. These misunderstandings
have all been taken as evidence that fundamental categories of reality are
not "in" the world but are imposed by culture. An
extreme is the view of many cultural anthropologists that science is just another
culture to be studied, a culture that attempts a form of cognitive colonialism. A
vigorous debate exists in the American Anthropological Association and in many
academic departments, between biological and cultural anthropologists. The
biologists search for evolutionary and physiological bases for social behavior,
while cultural investigators deconstruct cultural texts and tracts by applying
postmodern criteria.
Listing and Evaluating Human Universals
Many candidates for universal human
behaviors suggested by cultural studies are related to language: metaphor,
narrative, poetry, myth, rituals, and words for units of time, body parts,
plants and animals, kinship, logical relations (same, different, not, in, part/whole),
and so on. Others are oriented more toward social structures, including such
generalizations as "hierarchical social organization results in economic
inequality," "labor is divided by sex and age," "male and
female natures are different," and "men dominate the political sphere." We
do not necessarily look for genes that dictate these traits; they do not have
to be instincts or innate psychological tendencies. They are the result of
complex interactions between developing humans brains and their social environments
and are only abstractly related to a universal mind.
***************
DESIGN NOTE: IMPORTANT POINT
Comparative cultural studies have
generated lists of human behaviors that seem to occur in all societies, and
the evidence for a core set of behaviors is compelling.
***************
Here is a list, offered by the
psychologist Steven Pinker in his book The Language Instinct, of suggested
instinctual modules, aside from language and perception, that might eventually
pass the test of universality.
1. Intuitive mechanics: knowledge
of the motions, forces, and deformations that objects undergo.
2. Intuitive biology: understanding
of how plants and animals work.
3. Number.
4. Mental maps for large territories.
5. Habitat selection: seeking of
safe, information-rich, productive environments, generally savannah-like.
6. Danger, including the emotions
of fear and caution; phobias for stimuli such as heights, confinement, risky
social encounters, and so on.
7. Food: what is good to eat.
8. Contamination, including the
emotion of disgust, reactions to certain things that seem inherently disgusting,
and intuitions about contagion and disease.
9. Monitoring of current well-being,
including the emotions of happiness and sadness and the moods of contentment
and restlessness.
10. Intuitive psychology: predicting
other people's behavior from their beliefs and desires.
11. A mental Rolodex: a database
of individuals, with blanks for kinship, status, or rank; history of exchange
of favors; and inherent skills and strengths, plus criteria that rank the value
of each trait.
12. Self-concept: gathering and
organizing information about one's value to other people and packaging it for
others.
13. Justice: sense of right, obligations,
and deserts, including the emotions of anger and revenge.
14. Kinship, including nepotism
and allocation of parenting effort.
15. Mating, including feelings
of sexual attraction, love, and intentions of fidelity and desertion.
How do we begin to evaluate such
a list of proposed universals? Among the varieties of human behaviors, there
are some with clear genetic components (facial recognition and language generation)
and some that seem much less likely to be genetically determined (the writing
of language and the control of vehicles such as horses and airplanes). In between
lies a large grey area populated by more or less plausible ideas like the "social
function of intellect" hypothesis, which suggests that reasoning and thought
(as opposed to learning and memory) evolved to hold human societies together
(making their members more likely to survive), not for learning facts or skills.
Cognitive psychology has turned up a number of interesting deviations from
what would be ideal reasoning---deviations that would make sense if we had
an innate predisposition to finding quick and dirty solutions to problems posed
by the logic of social exchanges. Unfortunately,
plausibility is not enough, and we will have to wait some time for fundamental
tests of the existence of instinctual or genetically influenced modules of
social mind.
Some geneticists and developmental
biologists are very critical of efforts to explain so many of our common behaviors
as evolutionary adaptations, and they would quarrel with the amount of space
devoted to the topic in this book. One of their points is that we cannot exclude
the possibility that a given behavior arose not as an adaptation, but rather
by accident. Testing the hypothesis that each of the universal behavioral modules---the
naive early physics, biology, psychology, and so on---is a semi-independent
adaptive module almost like a body part faces a problem. To understand where
a body part (such as a heart, a kidney, or an opposable thumb) came from, we
need to see how it varies or is shared by groups who descend from a common
ancestor. The proposed "mind modules" of evolutionary psychology
leave no fossils, they appear in only one instance (all modern humans), and
there are no creatures that have more or fewer of these proposed modules of
mind to compare ourselves with. Thus we simply can't know how they arose; we
can only speculate.
*****************
DESIGN NOTE: IMPORTANT POINT
A nagging problem is that any description
of a modern behavior in terms of its presumed adaptive significance in the
Paleolithic may be the equivalent of making up a "just so" story,
for we have few means of proving the point.
******************
Cognitive and developmental neuroscientists
are still in the early stages of formulating and testing plausible theories
of cellular mechanisms by which genetic instructions could be translated into "deception
detectors" or other social modules. Perhaps the situation will be clearer
when we understand better the brain circuits that underlie these behaviors.
It does not seem unreasonable to suggest that genetically determined developmental
programs of our brains incline us to learning social strategies influenced
by the local social environment, just as the product of our language "instinct" is
determined by the language spoken by individuals around us. The results have
elements that are universal across known cultures. The fact that a behavior
is universal does not imply some sort of direct link between a gene or genes
and that behavior. All that is required of the genetic structures is that they
allow the development of modules of behavior that form as human brains evolve
in a social dialog with other humans as well as through interaction with the
physical environment. That the result may be a module of social behavior present
in all humans may attest to the uniformity of the developmental environment
of those humans and not to genes directly establishing that behavior. Just
as feral children raised by animals in the wild are unable to develop language,
so they also presumably fail to develop the array of social modules of behavior
suggested by the evolutionary psychologists. We will discuss of the roles of
genes and environments further in Parts II and III of this book.
The Evolution of Ideas and Customs
In thinking about either universal
minds or culturally specific minds, we need to consider the time scale over
which the relevant processes are occurring. Until now, we have mainly emphasized
genetic and evolutionary mechanisms that underlie both constancy and change
between generations over many millennia. Body language and verbal communication
introduce a vastly more rapid way of ensuring both constancy and change within
cultures and a means by which cultures distinguish themselves from each other.
Ideas and customs, in addition to our genes, can act as units of information
transfer that regulate behavior and are passed from one generation to the next.
Students of animal behavior use
the term "phenotypic cloning" to describe the process by which parents
can so firmly impress behaviors on their offspring that the behaviors (phenotypes)
seem to be inherited. (In spite of what we like to think, we all act remarkably
like our parents as we grow older.) A core point is the argument that differences
in behavioral styles between one family line and another provide a context
for natural selection. The behaviors that work best are passed on because of
differential reproductive success, and less adaptive behaviors are lost from
the "phenotypic pool" analogous to the gene pool of genetics. This
mechanism acts also at the level of cultures of humans and animals, and in
this context it is termed group selection. Over longer periods of time, genetic
changes in individuals that facilitate the adaptive behaviors adopted by a
group might then be selected for. This is the Baldwin effect mentioned in the
section "Co-evolution of Humans and Their Tools" and is a scenario
offered by some evolutionary psychologists.
*****************
DESIGN NOTE: IMPORTANT POINT
In humans and other animals, learned
behaviors can be passed on as reliably and reproducibly as though the information
were in the chromosomes.
******************
Human cultural groups are adaptive
responses, just as are birds' feathers and mammals' fur. They are vehicles
of selection and have the effect of reducing the importance of differences
in fitness between individuals within the group. Groups
of humans organize and defend themselves as though the groups were individual
organisms, with homeostatic mechanisms and defense strategies. They have a
sense of "I," with childish and adult components. A
fascinating array of adaptive and maladaptive behaviors have been cataloged
by social psychologists. For instance, self-deception on the part of individuals,
tribes, and nations is so pervasive that it is tempting to speculate that it
has a biological ultimate cause---as though trying to do (or avoid) things
that rationally shouldn't be done (or avoided) in some cases generates variation
that accrues to the benefit of the species.
The Concept of Memes
To describe the propagation of
cultural ideas, the biologist Richard Dawkins has used a genetic analogy and
coined the term meme (rhymes with "cream"). Dawkins gives the opening
four notes of Beethoven's Fifth symphony as one example of a meme. He also
notes, as an example of a meme in animals, that in 1920s Britain, birds learned
to open milk bottles on people's doorsteps. A
few titmice then learned that they could puncture the foil caps to drink, and
this information was passed on to several other species. The philosopher Daniel
Dennett points out that one of the first major steps a human brain takes in
postnatal self-design is to provide an environment for specific cultural memes.
It gets adjusted to the local conditions that matter the most---in a few years,
it becomes a Swahili- or Japanese- or English-speaking brain. Newborns can
form sounds characteristic of any language, but they begin to specialize in
the language they hear and lose the ability to form "foreign" sounds.
The idea is that once our brains have built the entrance and exit pathways
for the vehicles of language, they swiftly become host to entities---the memes---that
are mostly specific to different cultures and have evolved to thrive in just
such a niche.
***************
DESIGN NOTE: IMPORTANT POINT
The term "meme" refers
to a unit of cultural information that replicates itself reliably. The meme
is a replicator, the cultural equivalent of the gene.
***************
The evolution of memes such as
creation myths could not begin until animal evolution had created species such
as the advanced hominids, with brains that could provide for their shelter
and habits of communication that could provide for their transmission. The
access that individuals have to the ideas of their cultures (we don't have
to reinvent the wheel) probably swamps most individual genetic differences
in brain design, largely removing the advantage from those who are born slightly
more inventive.
Evolution of Memes
Darwinian mechanisms are at work:
There is variation (different ideas or concepts), replication (these ideas
or concepts pass between humans via language and imitation), and differential
fitness (passing on some ideas, like a warning signal, is more useful than
transmitting others). However, in the world of memes the best ideas do not
always win; accident, timing, and marketing may be more important. We persist,
for example, in using the present-day typewriter keyboard, even though other
designs are much more efficient. Memes, as replicators, propagate at blinding
speed compared with the pace of gene evolution. Another important distinction
is that memes do not have the clearly defined, independent nature of genes,
so we can't quantify and analyze their transmission in the same manner. Another
crucial distinction is that ideas are not passively replicated and transmitted.
Instead, each individual or group passing them on can "add value," or
creatively alter them, during transmission. The success of an idea is measured
by the spread of its influence in the face of competing ideas.
*****************
DESIGN NOTE: IMPORTANT POINT
The evolution of memes should be
visualized not with the tree metaphor that we have used for the diversification
of biological species, but rather as a joining, parting, and interconnecting
of lineages---like the streams of a river delta running apart, and then sometimes
back together, as they move toward the ocean.
******************
Summary
The origins of our distinctly Homo
sapiens intelligence, how it is that hominids came to develop the ability to
use symbols and language, will always remain shrouded in uncertainty. We will
never have a direct view of the brain anatomy and physiology of 2 million years
ago. Still, some very strong clues suggest the progression of intelligences
that is outlined in this chapter. The appearance of new facial muscles that
we now use to communicate meaning and emotion, much more complex than those
of chimpanzees, probably reflects the development of a new kind of mimetic
hominid intelligence. This intelligence supported social interactions through
more sophisticated emotional kinesic communication, incorporating complex facial
expressions and other body language. As hominids developed skills and social
structures that permitted them to migrate out of Africa over the rest of the
globe, the intellectual challenge of coping with ever more complex environments
and social interactions was met in part by the invention of symbol use and
spoken language.
We are the descendants of a small
group of modern humans that originated in Africa approximately 200,000 years
ago and then moved out of Africa to displace all other contemporary hominids,
including the Neanderthals in Europe and the Middle East and the remaining
H. erectus in Asia. This restricted origin of modern humans lends support to
the idea that an evolved "social mind" underlies a universal human
nature---that in spite of the amazing diversity of human cultures, we do not
start with a completely blank slate. Evolutionary psychology portrays us as
influenced by universal psychological mechanisms that are adaptations to our
ancestral environment---to our past as hunter-gatherers in Paleolithic Africa.
The engine that has driven the blinding speed of modern human evolution has
been the evolution of ideas and customs. Culture determines in part what our
brains become, how they specialize during their development to perform particular
skilled motor activities, devise languages, and engage in rituals. Our biology
and our culture shape each other through a never-ending feedback loop that
operates during individual development and is transmitted from generation to
generation by teaching. These developmental processes that shape our individual
and social selves are the subject of Part II of this book.
Questions for Thought
1. Hand axes that have two faces
crafted to make a sharp cutting edge have been found at H. erectus sites dating
back to about 1.5 million years ago. Try to list the different kinds of intelligence,
such as the ability to plan ahead, that would be required for such a task.
Can this list be described as a set of capabilities intermediate between those
of modern apes and humans?
2. What evidence might you look
for to develop further the idea that humans become tools of their own tools---that
technologies such as spoken language or making spears facilitate adaptive supporting
changes in brain and body structures?
3. Imagine that you have discovered
a hidden mountain valley in Java in which a population of H. erectus has lived
for the past million years, isolated from contact with all other hominids.
Individuals communicate with sounds and gestures that bear no obvious relationship
to modern language but are obviously much more complex than the communications
used by modern apes. How would you go about determining whether this group
had yet invented symbols, things that represent something else because of a
relationship, convention, or resemblance.
4. The mating habits of humans
that are observed across many cultures, such as the preference of younger women
for older, financially secure male partners and the designation of symmetrical
faces as "attractive," is taken by some as evidence for an evolved
universal psychology in humans, strongly influenced by genetics. Can you think
of other explanations? Devise experiments one could perform to evaluate the
relative importance of innate biases and cultural instructions (including possible
thought experiments that, for ethical reasons, you wouldn't actually carry
out with real humans).
Suggestions for Further General
Reading
The first three books deal with
the origins of language.
Deacon, T.W. 1997. The Symbolic
Species---The Co-Evolution of Language and the Brain. New York. Norton.
Donald, M.D. 1991. Origins of the
Modern Mind. Cambridge, MA: Harvard University Press. This book is the source
of the descriptions of mimetic and mythic intelligence presented in this chapter.
Pinker, S. 1994. The Language Instinct.
New York: William Morrow. A number of points in this chapter are taken from
this book, which is a sheer pleasure to read. Chapter 13 discusses human universals.
Dawkins,R. 1976. The Selfish Gene.
Oxford, England: Oxford University Press. An introduction to the gene-centered
view of evolution that provides a basis for some of the ideas in evolutionary
psychology; also an introduction to the idea of memes.
Kingdon, J. 1993. Self-Made Man---Human
Evolution from Eden to Extinction? New York: Wiley. This book provides a detailed
account of hominid evolution and is the source of the information in Figure
5-3.
Wright, R. 1994. The Moral Animal.
New York: Pantheon Books. The description of evolutionary psychology in this
chapter draws heavily on this stimulating introduction to the area.
Reading on More Advanced or Specialized
Topics
Barkow, J.H., Cosmides, L., & Tooby,
J. 1992. The Adapted Mind. New York: Oxford University Press. A series of essays
on evolutionary psychology.
Brown, D.E. 1991. Human Universals.
Philadelphia: Temple University Press. A more detailed presentation of potential
universals in human behavior.
Sober, E., Wilson, D.S. 1994. Re-introducing
group selection to the human behavioral sciences. Behavioral and. Brain Sciences.
17:585--608. This essay deals with groups of animals or humans as units of
selection, arguing that the gene-centered view presented by Dawkins is too
restricted.
Sperber, D. 1996. Explaining Culture:
A Naturalistic Approach. Oxford, England: Blackwell. A consideration of the
evolution and epidemiology of cultural ideas.
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