Human

Why do we act, think, and feel the way that we do? That's what Michael  Gazzaniga sets out to explain in "Human," using the latest research in cognitive neuroscience and evolutionary psychology. But it's one thing to look at the evolution of structures in our brains, or at antecedents of our behavior in ape behavior, or even at the activation of neurons during different aspects of our consciousness, but Gazzaniga wants to elucidate what it is that makes human beings unique and to do so without any reference to ego or soul or psyche or supernatural agency. And its kinda interesting that he kind of ends on a concept of "left brain interpreter" that sounds suspiciously like it could be any of those.

Gazzaniga comes with some major bona fides as the head of a cognitive science institute at the University of California at Santa Barbara, and he has done some major research on the cognition of people with split brains. The roster of people he has worked with is something of a who's who of neuroscience, people like Joseph LeDoux and Daniel Dennett. He cites the big guns in the field, so much of the important reseach going on in cognition and neuroscience and evolutionary psychology.

So why is it that I'm being talked down to with this book? It's like Gazzaniga decided to write a book on neuroscience for a popular audience and felt like he had to adopt a popular voice and make a number of cutesy asides in order to reach his audience. This was a book that I enjoyed a lot more in retrospect when I was able to look over my highlights and see past that voice. It does have a lot of good information that I was able to pull together better through reflection than on first reading.

Gazzaniga begins by looking at evolutionary antecedents for different stuctures in the brain, making a number of comparisons with ape brain and behavior. He presents evidence that the brain is continuing to evolve, with major growth spurts occurring as recently as 40,000 years ago coinciding with the development of speech and culture or even 6,000 years ago with the rise of urbanization and agriculture. (So where would that leave a climatolgical explanation of the domestication of emmer or eincorn wheat as advanced by someone like Jared Diamond?)  Perhaps as importantly as growth, however, has been a number of structural changes such as hemispheric differentiation, allowing more specialization and automation of certain brain functions, or the growth of particular areas of the pre-frontal cortex, especially those involved with memory, planning, abstract thinking, and cognitive flexibility.

Part of the "relentless progression of increasing relative brain size during the evolution of hominids," came about as "an adaptation to the complexities of social living." Groups became larger and more complex, and the cognitive demand for living in these groups "drove brain size expansion." I think that this gets at the heart of a lot of what Gazzaniga has to say: "what the human brain does best, what it seems built to do: think socially." Our ability to live in large, complex groups really depends on what seems to be a uniquely human characteristic, the "Theory of Mind," or our ability to accurately predict another person's moods, intentions, states of mind. Theory of Mind now seems pretty dependent on the existence of "mirror neurons" in our brain that are specifically attuned to others, especially allowing us to mimic them, perhaps the root of language and learning. 

Language facilitates social reciprocity with larger numbers of individuals (it's a whole lot easier and more efficient to talk with people than spend an inordinate amount of time picking lice from their fur), increasing the odds of survival, but also introducing the ability to lie and cheat. Protecting the validity of social reciprocity underlies what Gazzaniga and others (like Jonathan Haidt) call "universal moral modules," built on feelings of guilt or shame to prevent our own cheating, or on rage and anger to deter cheating in others. Patricia Churchland calls this "constraint satisfaction" in her new book, and it leads to a whole discussion about how much of our morality is biological and how much is rule-based, how much of our moral thinking is based on the kinship based hunter-gather groups that dominates so much of the human past, and how germane that past is to living in large multi-ethic urban environments.

For if we are left with biological constraint satisfaction for basing our morality, we also have to deal with the fact that we are hardwired for nonreflective beliefs and a bias toward negativity in our preconscious apprehension of new things and novel stimuli. First off, we have a "hot" emotional system that responds quickly and automatically to fear, anger, rage, and disgust. It operates directly through the amygdala, bypassing the "cooler," more reflective circuit operating primarily in the hippocampus and frontal lobes. But even then, most of the information that reaches consciousness has already been processed, classified, stored as a memory, and compared to other memories  prior to its emergence into our awareness. Most of our beliefs about the world have already been formed before we even know that they exist. "Nonreflective beliefs are the default mode of our thinking." Not only that, but they control most of our reflective thinking, since "the better  a reflective belief merges with a nonreflective belief, the more plausible it seems, the more intuitive and easier to learn or accept." We look for these plausible explanations, then, even if our information isn't all that accurate, making any approach to analytical, non-intuitive thinking extremely difficult, and in Gazzaniga's eyes, extremely rare. I guess that Nietzsche was right all along. We continually seek bad reasons for confirming what we already know.

If Gazzaniga seems to confirm Nietzsche on the one hand, he perhaps confirms Kant on the other. For what sounds kind of like "a priori" thinking to me comes from the idea that a major part of our nonreflective belief system is built on the concept of essentialism: we are hardwired to believe that things have inherent properties and characteristics, "a thing perceivable to the senses can have an embodied unobservable essence that is real," a quality that develops in our thinking by about the age of four or five. We also seem to attribute consciousness to animate objects investing them with "theory of mind" much like our own. We naturally assume that they have agency and purpose. Gazzaniga is saying that while we endow our pets with personalities, it just ain't necessarily so. We do the same with nature, a trait that Richard Dawkins calls  our HADD, Hyperactive Agent Detection Device: "we hyperactively detect agents where there are none, and this makes us suspect malice or benignity where, in fact, nature is only indifferent." (Dawkins, The God Delusion) We are Idealists and Cartesians before we are even aware of it.

One of the major essences that we buy into is the idea of ourselves, that which I feel makes me, me and you feel makes you, you (Spinoza called  it the conatus.) We each of us believe first of all in our own essences, which Gazzaniga says comes from specific processes in the brain. But then he gets a bit vague about these processes. When we take in information and store it as a memory, we first try to make sense of it. We fit it in with what we already know and use this knowledge to construct scenarios and give meaning to things and events. Gazzaniga says that we have a "left hemispheric interpreter" that forms hypotheses about all sensory inputs and processes going on, continually constructing meaning and narrative: "the left hemispheric interpreter constructs theories to assimilate perceived information into a comprehensible whole," even if the information turns out to be faulty and the theory demonstrably false. That's just  a part of who we are. And one of these theories is the sense of self: "I submit that it is the left-brain interpreter that is coming up with the theory, the narrative, and the self-image, taking the information from various inputs, from the “neuronal workspace,” and from the knowledge structures, and gluing it together, thus creating the self, the autobiography, out of the chaos of input."

But this left brain interpreter is a theoretical construct on Gazzaniga's part. There is no specific part of the brain, other than left hemisphere, where it might reside. It seems to be an "emergent property" that comes from "distributed processes throughout the brain." So, really, you could call it ego, or psyche, or soul, or whatever, and it would have as much validity as "left brain interpreter."

So, yes, Gazzaniga's book has a lot of good information, so much more than I've touched on here. But I guess I'm still left with a number of questions about its significance. Do I not have any say in the way that I think and the way that I feel? If I've already made up my mind before I make up my mind, then where does that leave the ideas of free will and responsibility? I feel like I've made a lot of important decisions, both good and bad, that have determined the directions my life has taken, and done so after a lot of careful thought and deliberation, at least sometimes. I guess that I need at least the illusion that I have some control over my life. It might be one of those demonstrably false theories developed by my left brain interpreter, but it does give me a reason to keep on keepin' on.

Author: Gazzaniga, Michael S.

Date Published: 2008

Length: 464 pp

electronic print