In order to picture gene-culture coevolution more
clearly, imagine two alien civilizations on distant planets. Both
have about the same level of cultural sophistication as human
beings, and both transmit virtually all of their cultures by means
of learning.
In one of the alien species only a single version
of each category of learning can be transmitted: one language, one
love song, one marriage ceremony, one mode of warfare, and so
forth. In this extreme form, a "pure genetic transmission" of the
culture, the genes restrict the learning process-even though the
culture is taught in classrooms, recorded in books, and so
forth.
The biological model is the white-crowned
sparrows of California, which must hear the song of their own
species in order to learn it but are impervious to all other
songs.
The second alien species outwardly resembles the
first, but it possesses a totally blank-state mind. All cultural
possibilities are open to the inhabitants. They can be taught any
language, any song, any martial tactic with approximately equal
ease. In this "pure cultural transmission" scenario, the genes
direct the construction of the body and brain but not the
behaviour. The mind is entirely a product of the accidents of
history, including the place the aliens live in, the foods they
encounter, and the stray inventions of words and gestures.
Human beings are between these extremes. Our
social behaviour is based on gene-culture transmission: an immense
array of possibilities can be learned, innovation occurs
frequently, but biological properties in the sense organs and brain
make it more likely that certain choices will be preferred or at
least more easily learned than others.
In some categories, such as incest avoidance, the
choices are narrowly constrained. In others, such as the semantic
content of particular languages the choices are very broad and more
nearly equipotent
This conception of mental development brings us
to the question of variation in the choice of culturgens among
members of a given society and among entire societies.
The evolution of culture displays some striking
parallels with genetic evolution. Innovations appear in the
population in the manner of mutations, spread like genes, and are
favoured or abandoned by processes resembling natural selection and
random drift. The interaction of these biologically based entities
with the environment is as complex as that controlling conventional
genetic evolution. Among the variables that must eventually be
taken into account are the particular environment in which the
society lives, the degree of its contact with surrounding cultures,
the accidents of history, and the genetic variation among its
members.
An approach to understand the biological
underpinnings of mental life. reconstitutes cultural variation
along with central tendencies in a combined analytic-synthetic
fashion. This operates from the bottom up, using the facts of
biology and cognitive psychology to work into more complex social
phenomena.
It is logical to begin such an analysis with the
simple case of a human population that is genetically uniform with
reference to the processes of cognition. Charles Lumsden and R O
Wilson began with the simple observation that each individual comes
to favour certain marital customs, modes of dress, ethical
precepts, and so forth, from among those available. And every time
individuals modify their memories or face decisions in everyday
life, they enact intricate sequences of events in cognition that
obey the peculiar, constraining properties of semantic
memory.
Not all the culturgens being processed are
treated equally; cognition has not evolved as a wholly neutral
filter, and the mind incorporates and uses certain culturgens more
readily than others. Furthermore, the biases often shift with age,
creating patterns that change with the demographic properties of
societies.
Experience from sociological studies has shown
that such models can incorporate memory and social context to an
extent sufficient to fit choices made by individuals. Experience
and memory are combined to make the transition rates from one
alternative choice to another, using choices already made by
others, in other words the cultural context.
Few quantitative studies have been made of this
social influence, but enough is known to establish that it varies
substantially from one type of choice to another.
For example, sibling incest is avoided by
individuals throughout their lives regardless of the preferences of
others, whereas the direction of attention of individuals in street
crowds rises steadily in conformity with others as the percentage
looking in one direction increases.
With the aid of mathematical techniques, it is
possible to translate decision making and the effects of social
networks into patterns of cultural diversity. This defines the
relative frequencies of societies in which different percentages of
the members use or prefer to use each of the competing
culturgens.
A simple ethnographic distribution would be the
following:
- in 52
percent of the societies all members prefer outbreeding to
incest,
- in 46
percent of the societies 99 percent prefer outbreeding,
- and in 2
percent of the societies 98 percent prefer it.
A notable finding is that very substantial
cultural diversity can be expected even when all of the societies
are genetically biased to that particular category of cognition and
behaviour.
Even though all of humanity may be genetically
very likely to choose outbreeding over incest, substantial
variation will still arise among the societies in the percentages
of members choosing avoidance over acceptance.
Because the mind operates with an degree of
chance, what emerges is not a fixed percentage of individuals
making one choice across all societies but rather the pattern of
diversity, in other words, the form of the cultural
distribution.
A distinct curve will arise from each different
degree of bias toward one culturgen and each different degree of
sensitivity toward the choice already made by others in the
society.
For each category of cognition and behaviour,
human beings appear to have a distinctive degree of developmental
bias and sensitivity. As a result the amount and pattern of
cultural diversity can be expected to differ among these
categories.
It is often argued that the existence of cultural
diversity shows that there is no underlying genetic constraint.
That conclusion is incorrect: the mere occurrence of the diversity
says nothing one way or the other about constraints. On the other
hand, patterns of diversity can tell us a great deal.
Another common misconception is that the
existence of biological influence on diversity implies genetic
differences between the societies. But diversity arises in
distinctive patterns even in genetically uniform populations.
The models lead to another substantive result of
the gene-to-culture theory.
Quite small differences in bias and sensitivity
of the magnitude demonstrated among different categories of human
cognition and behaviour are enough to generate strong differences
among their patterns of cultural diversity.
Most strikingly, the distributions pass from a
single mode to multiple modes (a mode is a frequency higher than
surrounding frequencies) rather rapidly as sensitivity is altered.
These differences are great enough to be detected even with
relatively crude cultural data. They show how studies of cognitive
and social psychology can be fed directly into the data of
anthropology and sociology as part of a general quantitative theory
of culture.
The earliest and most primative primates probably
had most of their cognitive world "hard-wired." They had all the
specific knowledge they needed for survival. Primates really took
off from the rest of the mammals when we developed "general
intelligence," which could learn from trial and error, and which
could make generalizations based on experience. However, this
general intelligence was slow in acquiring new knowledge. To
accomplish that, specialized intelligences, or programmes, needed
to evolve.
The first of these was social intelligence, which
was the specialized ability to read and understand social
heirarchies. Early empathy and the ability to infer from your own
experience what other members of your species were thinking and
feeling was the greatest power this new intelligence conferred, and
became the origin of consciousness. The second specialized
intelligence was that of natural biology. This was very helpful in
expanding our observations of the world, and increased the food
sources which were available to primitive ancestors of homo
sapiens. The third specialized intelligence was technical
intelligence. This enabled early man to fashion tools and to use
them in ever more complex ways.
To these three intelligences -- psychology,
biology, and physics, so to speak -- was added linguistic
intelligence. This gave the conscious mind a voice. It also
enhanced the other three intelligences, especially social
intelligence. Prior to the evolution of linguistic intelligence,
peer communication was mostly visual and tactile. Speech was much
more efficient than grooming in building and maintaining social
bonds.
It was also linguistic intelligence that made
possible the next great leap to meta-intelligence. Linking the four
specialized intelligences, there evolved during the period leading
up to 40,000 years ago, a supraordinate intelligence which
permitted what we might now call multitasking, or integration among
the other specialized intelligences. We see the first evidence of
this in the bursting forth of art and religion at that time. None
of these appear to have been present prior to that time. Much like
a simple computer, the earliest primates had a set of basic
information. Then came a generalized processor. To this were added
specialized programmes for psychology, biology, physics, and
language. Finally, true homo sapiens developed a metaprogramme
linking the others and permitting genuine creativity to take
off.
Other indications of rapid changes during the
Middle- Upper Paleolithic transition (35,000 to 45,000 years ago)
in Europe include:
- a shift
in stone tool technology from predominantly "Rake" technologies to
"blade" technologies, achieved by means of more economic techniques
of core preparation.
- a
simultaneous increase in the variety and complexity of stone tools
involving more standardization of shape and a higher degree of
"imposed form" in the various stages of production.
- the
appearance of relatively complex and extensively shaped bone,
antler, and ivory artifacts.
- an
increase in the rate of technological change accompanied by
increased regional diversification of tool, forms.
- the
appearance of beads, pendants, and other personal ornaments made
from teeth, shell, bone, stone, and ivory blanks.
- the
appearance of sophisticated and highly complex forms of
representational or "naturalistic" art.
-
Associated changes in the socioeconomic organization of human
groups, marked by:
i a
more specialized pattern of animal exploitation, based on
systematic hunting
ii. a
sharp increase in the overall density of human
population
iii.
an increase in the maximum size of local residential
groups
iv.
the appearance of more highly "structured" sites, including more
evidence for hearths, pits, huts, tents, and other
habitations
Paralleling the biological evolution of early
humans was the development of cultural technologies that allowed
them to become increasingly successful at acquiring food and
surviving predators. The evidence for this evolution in culture can
be seen especially in four innovations:
- the
creation and use of tools
- new
subsistence patterns
- the
occupation of new environmental zones
-
architecture
- art
