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These are excerpts and elaborations from my book "The Nature of Consciousness"
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The Prehistory of Brain In the 1940s the British anthropologist Kenneth
Oakleyspeculated that there may be three levels of
consciousness, corresponding to the three evolutionary layers of the brain:
awareness, controlled by the older part of the brain and related only to
conditioning; consciousness, controlled by the cortex and the hippocampus, and
related to the internal representation of the world; and self-awareness, due to
the most recent layer of the brain and related to the internal representation
of one's internal representation. John Ecclesspeculated that consciousness arose with the
advent of the mammalian neocortex, about 200 million years ago, the biologist
Lynn The US paleo-neurologist Harry Jerisonlooked at the fossil record for clues on the
selection pressures that led to increases in the size of the primate brain. Mammals evolved about 200 million years ago as
the nocturnal reptiles. Unlike reptiles (such as dinosaurs), whose cognitive
life was based on stimulus-response, mammals were capable of using sound to
create a cognitive map of their environment. When the big reptiles disappeared
70 million years ago, vision too became a major source of information for the
mammal brain, which evolved accordingly. In particular, the size of the brain
increased dramatically. The brain of mammals was flooded with sensory inputs,
and had to develop the ability to recognize an object that could be defined by
many (virtually infinitely many) different sets of inputs. The solution was to
develop a way to represent the perceptual world and use that representation to
recognize objects. Thus the mammalian brain developed the ability to process
stimuli by means of a conscious perceptual world, as opposed to the reflexes
of the reptilian brain. The function of consciousness was therefore to
create the perception of the object, regardless of what sets of inputs
originated the recognition. The reptilian brain was simply reacting to
stimuli, without any awareness of what those stimuli meant. The mammalian
brain was capable of transforming the stimuli into an object existing in time
and space, and then act accordingly. Jerisonspeculates that the human brain
is, first and foremost, a marvel of integration. The brain is flooded with
sensory data. If the brain had to analyze them one by one in isolation, it
would be virtually impossible to cope with the number of sensory data. Jerison
believes that the nervous system constructs a model of the world, and then uses
that model to understand sensory data. The key to constructing the model of
the world is to integrate all the sensory data themselves. As the model gets
refined, it also gets easier to recognize sensory data for what they are. A
sensory datum is not recognized in isolation, but it is recognized as part of a
scene. That scene, in turn, represents the integration of all the data that
have been perceived. The implication is that we
are conscious of something that is not necessarily the real world, but is
simply the world that we created. The world that we perceive is nothing more
than the model that we have created. That model is not necessarily the world as
it is: it is a plausible model of the world, given what we have learned so far
about it. The Prehistory Of Mind The British archeologist
Steven Mithenfound evidence in ancient history that "cognitive
fluidity" caused the modern mind to arise. First came social
intelligence, the ability to deal with other humans; then came natural-history
intelligence, the ability to deal with the environment, and tool-using
intelligence; last, language. Once the ability to fully connect all these
faculties developed, the modern mind was born. Crucial for the development of
the human mind was language. In particular, metaphor and analogy are the
fundamental features that allowed the human mind to develop as it is. Homo Sapiens Sapiens
appeared 100,000 years ago and initially behaved like Neanderthals, showing
little intelligence. Two momentous transformations in human behavior occurred
with art and technology (60,000 years ago) and with farming (10,000 years ago).
In order to explain these
breakthroughs, Mithenresorts to Jerry Fodor's modular model of the mind. Initially, human minds were dominated by
a general-purpose form of intelligence. Then a module appeared that was
specialized for socializing. The social-intelligence module was shared with
other primates so it must have predated humans. Then other modules, each
specific to one domain, were born
around the main general-purpose module. The modules evolved separately.
Eventually, Mithen admits four types of intelligence (four modules in the
mind): social, technical (tool-making, house building), natural-history (e.g., animal behavior) and
linguistic. These modules were not connected, these intelligences were not
communicating. Mithencan thus explain why there is
no archeological evidence of social life when (judging from brain size) social intelligence
must have been already quite developed: a cognitive barrier between social and
technical intelligence made it impossible for humans to conceive of tools for
social interaction. Originally, humans were hunters and gatherers (the
transition to farming occurred in the Middle East only about 10,000 years ago).
The hunter-gatherers of our pre-history were experts in many domains, but those
different kinds of expertise did not mix, precisely because the minds of those
humans could not mix different types of intelligence. "Cognitive
fluidity" (mixing different kinds of intelligence) changed that and caused
the cultural explosion of art, technology, religion. Suddenly, humans acquired
minds in which modules had been connected. For example, tools started being
used to transform nature. Religion was a by-product of mixing these
intelligences, because mixing intelligences one can produce supernatural
beings. Farming was also a product
of cognitive fluidity and in turn caused a redefining of intelligences (emergence
of new intelligences, disappearance of old ones). The factor that contributed
or caused cognitive fluidity may have been the dawning of consciousness.
Self-awareness may have integrated intelligences that for thousands of years
had been kept separate. Mithen's evolutionary theory mirrors in many ways the theory of child
development advanced by British psychologist Annette Karmiloff-Smith. Back to the beginning of the chapter "A History of Consciousness" | Back to the index of all chapters |
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