Todd E. Feinberg and Jon M. Mallat. The Ancient Origins of Consciousness: How the Brain Created Experience.
Cambridge, MA: MIT Press, 2016. ISBN: 9780262034333. Hardcover. $35U.S. 392
pages. Illustrated.
As I write this review, an old story has been circulating on
social media about a Frenchman who has 50-75% less than a normal size brain, an
IQ of 75, and who yet functions normally, has a family, and is employed. [1] That
is, he has all the requisite brain parts, but each one has been miniaturized.
How is it possible for someone with so little brain to function normally? To
some extent neurologist Todd E. Feinberg and biologist Jon M. Mallat address
this fascinating question in their book, The
Ancient Origins of Consciousness. Organisms do not need overly complex
brains to survive. In fact, sensory consciousness dates back to as long as 560
million years ago (mya) in tiny brains, according to these authors.
Of course the subject of Feinberg and Mallat’s book is not
so straightforward. Indeed, they tackle philosopher David Chalmers’ hard
problem of consciousness: How do the functions and mechanisms of the brain
result in phenomenal, subjective experience? How is being in function? Here
is a book by research scientists laden with data about, at base, philosophy of
mind. On the spectrum of 1 to 10, where at 1 sit those who claim consciousness
from material properties to 10 where we find the non-materialist
metaphysicians, these authors clearly lean to 1. They claim to have cracked
Chalmers’ hard problem, which won’t sit well with many near the 10 spectrum.
The Ancient Origins of
Consciousness is a copiously illustrated with figures and tables, fairly
easy to read for the non-specialist, well organized in ten chapters, and offers
a cogent argument for the early origin of primary consciousness. The book
includes a comprehensive index and boasts a robust bibliography. It is
important to emphasize that their angle is on sensory consciousness and the
authors are careful to state on a number of occasions that their mission is not
to find the origins of, for instance, theory of mind (or other high functions
of mind like reflection or intelligence). They do not claim that higher order
consciousness is 500 million years old. Instead, they chart a careful and
precise genealogy of primary consciousness using fossil evidence and research
data. There’s nothing to dislike about this book, and it is worth owning for
anyone interested in evolutionary or consciousness studies.
The authors rightly begin with Thomas Nagel, and his notion
of something it is like to be.
Phenomenal experience or qualia don’t depend on super intelligence or large
brains, they assert; and contrary to Chalmers, they set out to prove that they
can detail objectively neural pathways and so explain subjective, primary
consciousness. And they do. In terms of the evolution of sensory consciousness
Feinberg and Mallat go beyond qualia and explain referral or the projection of
neural states, mental unity via massive neuronal activity, and mental causation
or how neurons effect action. In essence, the authors are looking for both the
origin of affective consciousness and the hard problem itself – how the
emergent what it is to be like is reducible
to its components. The stages of consciousness run from the biological aspects
of all organisms, to reflexes in the nervous system, to attention, which is
more specialized and from which consciousness eventually arose.
Consciousness is embodied – it needs the physicality of a
particular brain to exist. Consciousness is a lively process of brain functions
– it is not a structure. They quote Evan Thompson: “‘A living being is not
sheer exteriority...but instead embodies a kind of interiority, that of its own
immanent purposiveness’” (19). While a reflex is not consciousness, in the
neural reactions we find the beginnings of the connections that will form
consciousness. Reflexes constitute different cell types where neurons differ in
types and functions, and the growing complexity, speed, and cellular diversity
in turn created hierarchies (27). An example of a hierarchy would be how the
function of the skin (touch) is represented in the brain or how the external
visual field is mapped (i.e., various sense stimuli are taken together) in the
brain. These mental sensations become part of what it is like to be.
The explosive proliferation of animal life in the Cambrian
Period is crucial to the argument presented by Feinberg and Mallat. However,
they are keen to point out that before the Cambrian a very small brain had
evolved in the predecessors to vertebrates. These non-vertebrate chordate ocean
feeders, such as amphioxus, were able to detect chemicals and had a touch
sense. While extraordinarily small, the brain of the amphioxus includes a
forebrain, neurons, and primitive brain regions that control different
functions. This brain is a precursor to that found in vertebrates. The neurons
in amphioxus are not connected in synapses with neurotransmitters but use chemicals
that modulate neurons, and this is the model for a simple, primitive
pre-vertebrate brain. Not until the evolution of sense perceivers in
vertebrates (eyes and ears) is there more complex sensory processing in the
brain. Nonetheless, we see in the pre-Cambrian the birth of the brain.
The Cambrian explosion runs from about 560-520mya and
introduces vertebrates which then evolve complex nervous systems. Predation
began in the period before the Cambrian, the precursor to the evolution of
senses for defense and elusiveness, and these in turn became more complex behaviors
and system in terrestrial vertebrates with the environment’s wealth of oxygen
and more opportunities for foraging better types of resources. The cost of
evolving such mental sensory maps was high in terms of energy needs, and only
the clades of arthropods (mostly predators) and vertebrates (in Cambrian early
fish) evolved sensory systems; it was less costly for others not to evolve
complex systems, and this explains why we still have, for instance, clams (64).
Even before the Cambrian, sensory consciousness was
possible, as with the amphioxus. It’s just that in vertebrates the brain parts
become not only larger but also more precise in segmentation and neural
hierarchies. As the vertebrate brain evolved, so did its cerebrum and cortex,
areas dealing with, among others, memory and decision making. Eyes went from
forming images to forming spatial images, and any complex mental images needed
to be processed and interpreted across several brain regions. Sensory
processing of images, smells, and sounds are recalled, referenced to, and
modified as necessary with new inputs. While the hippocampus brain region
(memory and selective attention) is not apparent until the vertebrates, the
genes to express it existed much earlier. Furthermore, the authors go as far as
saying that in the Cambrian vertebrate brain not only were predictions made but
simulations, that is, the manipulation of mental images.
Based on the foregoing, Feinberg and Mallat move to sentience
(and devote two chapters to the subject). Sentience is “when an organism
becomes consciously aware of its own internal bodily and affective feelings,”
like pleasure or pain (129). The affective limbic system, not in contact with
the environment, is involved in attraction (pleasure), aversion (displeasure)
and so employs valence; there is self, good/bad feelings, sadness and joy, and
fear; there are motives. Affective consciousness (compared to exteroceptive,
external mental images, and interoceptive, visceral pain), is found in subcortical
limbic areas going back 560mya. That is, they do not find affective
consciousness originating in cortical regions, which come later.
What are the behavioral criteria for affective
consciousness, they ask. Beyond any reflex response, the answer would include
any non-reflexive response of valence, a decision about cost/benefit,
frustration, and self-medication (as in awareness of acute pain so as to
alleviate it). They insist, however, that some goal-driven rewards could
reflect an unconscious behavior (153). Simple affective neuro-structures can be
found in lampreys (still present but of ancient origin) and other fish.
Must an organism have a backbone to experience simple
consciousness? What about insects, mollusks, flatworms, etc.? The authors set
out criteria for consciousness: 1. Complexity. Insect brains are too tiny. 2.
Multisensory neuronal hierarchies. We do find this in insects. 3. Isomorphic
(topographical/physical) sense pathways. Yes for insects. 4. Reciprocal neural
interactions. They say yes for insects but debatable for other organisms
without a backbone. 5. Separate sense pathways that merge in a brain for unity
of experience. This is highly debatable in insects. 6. Memory. Yes for insects.
7. Selective attention. Also yes for insects. In all, insect consciousness is
debatable. However, they claim the main criterion of sensory consciousness is
mental image formation, and this is evident in bumble bees and so therefore in
other arthropods. Clearly consciousness evolved to benefit vertebrates more
than other organisms.
The final chapter is a mega-conclusion that reiterates and
pulls together much of what came before. They offer and discuss in detail three
postulates. 1. Sensory consciousness is emergent with emphasis on the hierarchy
of sense modes across and in network with brain areas. 2. Consciousness arrives
through a continuum of species and adaptations. There is a diversity of
consciousness (i.e. no single emergent process) in the brain and interaction among:
exteroceptive consciousness (images/sensation, distance senses); interoceptive
consciousness (mental images/body senses); affective consciousness (inner
feelings). 3. Concerning the hard problem, consciousness and mental unity are
adaptive. Behavioral choices spring from unified mental maps that evolved over
time and selection pressures to benefit certain organisms. Others did not
evolve consciousness since it is costly, and they were able to survive without
it.
In terms of the hard problem, the authors are clear to
emphasize that no machine can explain (since it only observes) one’s subjective
what it is like experience. While an
adaptation, consciousness is a process
and “not a material thing” since it does not reside in one brain area (224).
But there is no hard problem, because the brain does create personal experience
and how the brain does so is explainable by virtue of scattered but
interlocking physical matter.
Notes
[1] See “Man with tiny brain shocks doctors.” New Scientist, 20 July 2007. Web. The
article reports on findings from the journal Lancet.
- GregoryF. Tague, Ph.D. is professor of English at St. Francis College, N.Y., and the author
of Evolution and Human Culture (Brill
2016) and Making Mind: Moral Sense and
Consciousness (Rodopi 2014). Copyright©Gregory F. Tague 2016. Reprinted
courtesy Consciousness, Literature and
the Arts journal, August 2016.
