Shufflebrain

Bitterman began by training various species to perform choice tasks. His animals had to discriminate, say, A from B. He trained goldfish, turtles, pigeons, rats and monkeys to associate A with a reward and B with receiving nothing.

Then Bitterman played a dirty trick. He switched the reward button. Chaos broke out in the laboratory. Even the monkey became confused. But as time went by, the monkey began to realize that now B got you the peanut, not A. Then the rat began to get the idea. And the pigeon too! Meanwhile over in the aquarium, the goldfish was still hopelessly hammering away at the old choice. Unlike the other members of the menagerie, the fish could not kick its old habit and learn a new one.

What about his turtle? It was the most interesting of all Bitterman's subjects. Confronted with a choice involving spatial discrimination, the turtle quickly and easily made the reversal. But when the task involved visual recognition, the turtle was as bad the goldfish; it couldn't make the switch. It was as though the turtle's behavior lay somewhere between that of the fish and the bird. Turtles, of course, are reptiles. During vertebrate evolution, reptiles appeared after fishes (and amphibians) but before birds and mammals.

Now an interesting thing takes place in the evolution of the vertebrate brain. In reptiles, the cerebrum begins to acquire a cortex on its external surface. Was the cerebral cortex at the basis of his results? Bitterman decided to find out by scaping the cortex off the rat's cerebrum. Believe it or not, these rats successfully reversed the habit when give a space problem. But they failed when the choice involved visual discrimination. Bitterman's rats acted like turtles!

***

Bitterman's experiments illustrate that with the evolution of the cerebral cortex something had emerged in the vertebrate character that had not existed before. Simple arithmetic won't take us from bacterium to human being.

As embryos, each of us re-enacts evolution, conspicuously in appearance but subtly in behavior, as well. At first we're more like a slime mold than an animal. Up to about the fourth interuterine month, we're quite salamander-like. We develop a primate cerebrum between the forth and sixth month. When the process fails, we see in a tragic way how essential the human cerebral cortex is to the "Human Condition," in the Barry N. Schwartz sense of of the term.

Mesencephalia is one of the several terms applied to an infant whose cerebrum fails to differentiate a cortex.[11] A mesencephalic infant sometimes lives for a few months. Any of us (with a twist of an umbilical cord, or if mom took too long a swig on a gin bottle) might have suffered the same fate. Like its luckier kin, the mesencephalic child will cry when jabbed with a diaper pin; will suckle a proffered breast; will sit up; and it can see, hear, yawn, smile and coo. It is a living organism. But human though its genes and chromosomes and legal rights may be, it never develops a human personality, no matter how long it lives. It remains in the evolutionary bedrock out of which the dimensions of the human mind emerge. It stands pat at the stage where the human embryo looked and acted like the creature who crawls from the pond.

Yet there's no particular moment in development when we can scientifically delineate human from nonhuman: no specific minute, hour or day through which we can draw a neat draftsman's line. Development is a continuous process. The embryo doesn't arrive at the reptilian stage, disassemble itself and construct a mammal, de novo. In embryonic development, what's new harmoniously integrates with what's already there to move up from one ontological step to the next.[12] The embryo's summations demand Riemann's nonlinear rule: curvature!

What is arithmetic, anyway. What do we mean by addition and subtraction? At the minimum, we need discrete sets. The sets must equal each other--or be reducible to equal sets be means of constants; and their relationships must be linear. The correct adjective for describing a consecutive array of linear set is contiguous (not continuous), meaning that the successive members touch without merging into and becoming a part of each other--just the opposite of Riemann's test of continuity. This may seem utterly ridiculous. But if the sets in 1 + 1 + 1 surrender parts of themselves during addition, their sum will be something less than 3. We literally perform addition and subtraction with our fingers, abacus beads, nursery blocks and digital computers-- any device that uses discrete, discontinuous magnitudes.