Three Big Bangs Read online

  Although consciousness long preceded humans, there was an explosive state change when humans crossed a divide and gained their self-reflexive, ideational, linguistic, symbolic capacities. Humans are not simply conscious; they are self-conscious. The human brain is not just a scaled-up version of chimpanzee brain. Humans are remarkable in their capacities to process thoughts, ideas, symbolic abstractions figured into interpretive gestalts with which the world is understood and life is oriented. This higher consciousness is a constitutive dimension of humans absent in all other species. “I know that I know.”

  We do not know with precision when this took place; probably over millennia. The key threshold is the capacity to pass ideas from mind to mind. There is no clear evidence that chimpanzees attribute mental states to others. Chimps have little or no “theory of mind”; they do not know other minds are there with whom they might communicate, to learn what they know. Or, if you prefer to say that one chimp can know what another knows, chimps have a theory of immediate mind (one chimp sees that another chimp knows where those bananas are); humans have a theory of the ideational mind (one human teaches another the Pythagorean theorem). Humans have ideational uniqueness, further examined below.

  Animals are variously socialized, and become what they become interactively with their surroundings, which include the groups in which they live. But there is little or no evidence for any higher-order intentionality, even among primates that are highly social. Organisms with zero-order intentionality have no mental beliefs or desires at all. (We did find in the previous chapter that some geneticists can speak of genetic intention.) Animals clearly intend to change the behavior of other animals, first-order intentionality. Second-order intentionality would involve intent to change the mind, as distinguished from the behavior (though perhaps the behavior as well) of another animal. Third-order intentionality would involve one’s knowledge that another mind is intending to change one’s mind (Dennett 1987). Primates do not seem to realize that there are minds present to teach in others, although they often imitate each other’s behavior, as when adults are imitated by their offspring.

  In this higher-order sense of communication, conclude Dorothy L. Cheney and Robert M. Seyfarth, “signaler and recipient take into account each others’ states of mind. By this criterion, it is highly doubtful that any animal signals could ever be described as truly communicative.” They continue:

  It is far from clear whether any nonhuman primates ever communicate with the intent to inform in the sense that they recognize that they have information that others do not possess…. There is as yet little evidence of any higher-order intentionality among nonhuman species. (Cheney and Seyfarth 1990:142, 209)

  Although chimpanzees collaborate to hunt or get food, Michael Tomasello and his colleagues conclude, “it may be said with confidence that chimpanzees do not engage in collaborative learning…. They do not conceive of others as reflective agents—they do not mentally simulate the perspective of another person or chimpanzee simulating their perspective…. There is no known evidence that chimpanzees, whatever their background and training, are capable of thinking of other interactants reflectively” (Tomasello et al. 1993:504–505).

  Daniel Povinelli and his colleagues conclude of chimps: “There is considerable reason to suppose that they do not harbor representations of mental states in general…. Although humans, chimpanzees, and most other species may be said to possess mental states, humans alone may have evolved a cognitive specialization for reasoning about such states” (Povinelli, Bering, and Giambrone 2000:509; Povinelli and Vonk 2003). “Humans have a whole system that we call theory of mind that chimps don’t have” (Povinelli, quoted in Pennisi 1999:2076). Carl Zimmer concludes: “Of all the species on Earth, only humans possess what researchers call a ‘theory of mind’—the ability to infer what others are thinking…. After decades of studies, no one has found indisputable signs that chimps or other nonhuman primates have a theory of mind.” “Understanding what others are thinking is a human exclusive” (Zimmer 2003).

  Joaquín M. Fuster, a neuroscientist, finds that in human brains there is an “emergent property” that is “most difficult to define”:

  As networks fan outward and upward in associative neocortex, they become capable of generating novel representations that are not reducible to their inputs or to their individual neuronal components. Those representations are the product of complex, nonlinear, and near-chaotic interactions between innumerable elements of high-level networks far removed from sensory receptors or motor effectors. Then, top-down network building predominates. Imagination, creativity, and intuition are some of the cognitive attributes of those emergent high-level representations. (Fuster 2003:53)

  When one is imagining, daydreaming (or dreaming), the mental activity going on is remote from actual perception or bodily behaviors. Even if one is thinking about future behavior, there can be complex ideational structure remote from immediate experience. “Molybdenum steel has a higher tensile strength; maybe I should replace that failing crankshaft with better steel. I’ll ask Sam what he thinks.” Humans live in an ideational world, minds contemplating and contacting other minds. Christopher Frith shares his thoughts: “To get an idea from one brain into another, that’s a deeply mysterious thing that we do” (quoted in Zimmer 2003).

  Hyperimmense Brain: Neural Explosion

  Christian de Duve finds the rapid evolution of the human brain “dazzling”:

  Most impressive is the development of the brain, which took place at a staggering speed. After having taken some 600 million years to reach a volume on the order of 450 cm3 in our simian ancestors, the size of the hominoid brain went through an astonishingly rapid phase of expansion, virtually jumping to three times this value in a little more than two million years. On the evolutionary time scale, such a rate of change is no less than dazzling. (de Duve 2002:189)

  But now the information in DNA, however necessary, proves inadequate. Genes cannot wire up the mature human brain. Impressive though the amount of genetic information in humans is, this is far too little with which to build a functioning human brain. The number of neurons and their possible connections is far vaster than the number of genes coding for the neural system. So it is impossible for the genes to specify all the needed neural connections. The genes in fetus and womb seem to have learned how to generate by repeated algorithms a dynamic and open-ended neural network that, in due course, makes itself. Brain-forming genes do not specify some product with stereotyped function; rather, by splicing and resplicing, cutting and shuffling, the brain genes proliferate cascading neurons with almost endless possibilities of organization, depending on how they synaptically connect themselves up.

  Genes create the instruments, but the orchestration is cerebral. The secret of our advanced information lies somewhere else, resulting from genetic flexibility that opens up cerebral capacity. Barry J. Dickson concludes: “The ultimate challenge, after all, is to find out how a comparatively small number of guidance molecules generate such astonishingly complex patterns of neuronal wiring” (Dickson 2002:1963). “Changes in protein and gene expression have been particularly pronounced in the human brain. Striking differences exist in morphology and cognitive abilities between humans and their closest evolutionary relatives, the chimpanzees.” So conclude a team of molecular biologists and evolutionary anthropologists from the Max Planck Institutes in Germany (Enard et al. 2002).

  Geneticists decoded the human genome, confirming how little humans differ in their protein molecules from chimpanzees, yet simultaneously realizing that the startling successes of humans doing just this sequencing of their own genome as readily proves human distinctiveness. Humans have made an exodus from determination by genetics and natural selection and passed into a mental and social realm with new freedoms. In body structures generally, such as blood or liver, humans and chimpanzees are 95 to 98 percent identical in their genomic DNA sequences and the resulting proteins. But we have over three times their cranial cor
tex, over 300 percent difference in the head. This cognitive development has come to a striking expression point in the hominid lines leading to Homo sapiens, going from about 300 to 450 cubic centimeters of cranial capacity in chimpanzeelike ancestors to 1,400 to 1,500 cc. in humans. Nor is absolute brain size the only consideration; relative brain size is another. There too, relative to our body size, the human brain is proportionally bigger than that of any other animal. Some brains are more convoluted and complex than others of the same size. Neanderthal humans had somewhat larger brains than contemporary humans, though less convoluted.

  Animal brains are already impressive. In a cubic millimeter (about a pinhead) of mouse cortex there are 450 meters of dendrites and one to two kilometers of axons. Human brains multiply the cortex in mice 3,000 times. The connecting fibers in a human brain, extended, would wrap around the Earth 40 times.

  Geneticists have recently also sequenced the chimpanzee genome; comparing it with the human genome, they are still trying to figure out how so few genetic differences made such an enormous brainpower difference (Chimpanzee Sequencing and Analysis Consortium 2005). Quantitative genetic differences add into qualitative differences in capacity, an emerging cognitive possibility and practical performance that exceeds anything known in previous evolutionary achievements.

  Some transgenetic threshold seems to have been crossed. The human brain is of such complexity that descriptive numbers are astronomical and difficult to fathom. A typical estimate is 1012 neurons, each with several thousand synapses (possibly tens of thousands). Each neuron can “talk” to many others. The postsynaptic membrane contains more than a thousand different proteins in the signal-receiving surface. “The most molecularly complex structure known [in the human body] is the postsynaptic side of the synapse,” according to Seth Grant, a neuroscientist (quoted in Pennisi 2006). More than a hundred of these proteins were co-opted from previous, non-neural uses, but by far most of them evolved during brain evolution. “The postsynaptic complexes and the [signaling] systems have increased in complexity throughout evolution,” says Berit Kerner, geneticist at the University of California, Los Angeles (quoted in Pennisi 2006). This is nature’s nanotechnology.

  This nanophysiology is integrated into a dendritic network structured at multiple hierarchical levels. The nerve dynamics “don’t violate the equations of physics and chemistry, but they cannot be derived from them. They are new laws appropriate to the science of electro-physiology, which is removed by several hierarchical levels from atomic physics” and “independent of the equations of physics and chemistry” (Scott 1995:182). This network, formed and reformed, makes possible virtually endless mental activity. Much, even most of what goes on in our brains is below the level of conscious awareness, of course; but humans can bring novel cognitive capacities to critical focus.

  The result is a mental combinatorial explosion superimposed not just on the physics and chemistry, but further on the biological combinatorial explosion that we earlier met. The human brain is capable of forming something in the range of 1070,000,000,000 thoughts—a number that dwarfs the number of atoms in the visible universe (1080) (Flanagan 1992:37; Holderness 2001). On a cosmic scale, humans are minuscule atoms, but on a complexity scale, humans have “hyperimmense” possibilities in mental complexity (Scott 1995:81). In our 150 pounds of protoplasm, in our 3-pound brain is more operational organization than in the whole of the Andromeda galaxy.

  Genes make the kind of human brains possible that facilitate an open mind. But when that happens, these processes can also work the other way around. What began as a “bottom-up” process becomes a “top-down” process. In “top-down” causation an emergent phenomenon reshapes and controls its precedents, as contrasted with “bottom-up” causation, in which precedent, simpler causes are fully determinative of more complex outcomes. We encountered this before with organisms interacting with their chemistries. Now we encounter it again, at a higher level.

  Minds employ and reshape their brains to facilitate their chosen ideologies and lifestyles. We neuroimage brain blood flow to find that such thoughts can reshape the brains in which they arise. This in turn can affect bodily behavior. Michael Merzenich, a neuroscientist, reports his increasing appreciation of “what is the most remarkable quality of our brain: its capacity to develop and to specialize its own processing machinery, to shape its own abilities, and to enable, through hard brainwork, its own achievements” (Merzenich 2001:418).

  In the vocabulary of neuroscience, we have “mutable maps” in our cortical representations, formed and reformed by our deliberated changes in thinking and resulting behaviors. We do require dimensions of our brains that are specified by genetics, as in hearing and seeing. But our brains are also quite plastic, forging properties enabled by our genes but shaped by our experience, environmental and social (neuroplasticity). For example, with the decision to play a violin well, and resolute practice, string musicians alter the synaptic connections and thereby the structural configuration of their brains to facilitate fingering the strings with one arm and drawing the bow with the other (Elbert et al. 1995). Likewise, musicians enhance their hearing sensitivity to tones, enlarging the relevant auditory cortex by 25 percent compared with nonmusicians (Pantev et al. 1998).

  With the decision to become a taxi driver in London, and long experience driving in the city, drivers likewise alter their brain structures, devoting more space to navigation-related skills than non-taxi drivers have. “There is a capacity for local plastic change in the structure of the healthy adult human brain in response to environmental demands” (Maguire et al. 2000:4398). Similarly, researchers have found that “the structure of the human brain is altered by the experience of acquiring a second language” (Mechelli et al. 2004). Or by learning to juggle (Draganski et al. 2004).

  The human brain is as open as it is wired up. Our minds shape our brains. We form a synaptic self; synapses and experiential self are reciprocal processes. One can say that finding differing locations in the brain where differing kinds of mental activities take place is evidence for the physical basis of our mental activities. This is true. But another way to interpret the same evidence is that our mental decisions to become a violin player or taxi driver, or learn a second language, reallocate brain locations to new functions in support of these decisions. Violin players, taxi drivers, jugglers use highly localized areas of the brain. But other skills, such as gaining a higher education, are more pervasively distributed. The authors of a leading neuroscience text use the violin players as an icon for us all, and conclude: “It is likely that this is an exaggerated version of a continuous mapping process that goes on in everyone’s brain as their life experiences vary” (Bear, Connors, and Paradiso 2001:418). We have no apparatus to measure such more global synaptic changes, but every reason to think there are there (LeDoux 2002).

  Neuroscience went molecular (acetylcholine in synaptic junctions, voltage-gated potassium channels triggering synapsizing) to discover that what is really of interest is how these synaptic connections are configured by the information stored there, enabling function in the inhabited world. Our ideas and our practices configure and reconfigure our own sponsoring brain structures.

  Ideational Uniqueness: Cultural Explosion

  What is missing in the primates is precisely what makes a cumulative, transmissible human culture possible. The central idea is that acquired knowledge and behavior is learned and transmitted from person to person, by one generation teaching another. Ideas pass from mind to mind, in large part through the medium of language, with such knowledge and behavior resulting in a greatly rebuilt, or cultured, environment. Andrew Whiten finds:

  When we focus our comparative lens on culture, the evidence is all around us that a gulf separates humans from all other animals…. Ape culture may be particularly complex among non-human animals, yet it clearly falls short of human culture. An influential contemporary view is that the key difference lies in the human capacity for cumulative culture…. [In
chimps,] hints of cumulation exist, such as the refinement of using prop stones to stabilize stone anvils during nut cracking, but these remain primitive and fleeting by human standards. (Whiten 2005:52–53)

  Humans live under what Robert Boyd and Peter J. Richerson call “a dual inheritance system,” both genes and culture (Boyd and Richerson 1985). They find “that the existence of human culture is a deep evolutionary mystery on a par with the origins of life itself.” “Human societies are a spectacular anomaly in the animal world” (Richerson and Boyd 2005:126, 195). The human transition into culture is exponential, nonlinear, reaching extraordinary epistemic powers. To borrow a term from the geologists, humans have crossed an unconformity. To borrow from classical philosophers, we are looking for the unique differentia of our genus.

  What is quite surprising in humans is not so much that they have intelligence generically, for many other animals have specific forms of a generic intelligence. Nor is it that humans have intelligence with subjectivity, for there are precursors of this too in the primates. The surprise is that this intelligence becomes reflectively self-conscious and builds cumulative transmissible cultures. An information explosion gets pinpointed in humans.

  The variation on which selection acts does not arise in the genes but in the mind, ideational variation, not mutations in DNA. The selection, if it remains at times natural selection (more offspring in the next generation) passes over into ideational, cultural selection (Einstein over Newton, Jesus transforming Judaism). The evolved brain allows many sets of mind: one does not have to have Plato’s genes to be a Platonist, Darwin’s genes to be a Darwinian, or Jesus’ genes to be a Christian. The system of inheritance of ideas is independent of the system of inheritance of genes. Ideas can jump across genetic lines.

  The determinants of animal and plant behavior are never anthropological, political, economic, technological, scientific, philosophical, ethical, or religious. The intellectual and social heritage of past generations, lived out in the present, reformed and transmitted to the next generation, is regularly decisive in culture. “Culture,” by Margaret Mead’s account, is “the systematic body of learned behavior which is transmitted from parents to children” (1989:xi). Culture, according to Edward B. Tylor’s classic definition, is “that complex whole which includes knowledge, belief, art, morals, law, custom, and any other capabilities and habits acquired by man as a member of society” (1903:1).