Kansas School Naturalist

THE "HAMMER TEST"

Humans generally value other humans and "higher" animals more than "lower" animals, plants, and non-living objects. This can be demonstrated by having students conduct a mental exercise described as the "hammer test." Lining up the virus and living organisms in order from primitive to recently derived, you are asked to mentally consider taking a hammer and smashing the organism. At what point would you hesitate? At what point would you definitely stop? Why would you stop in that exact spot? A good biology class with an understanding of the small gradations between these organisms will see how difficult it is to draw a line for many properties. A teacher who poses this mental exercise must be ready to help students clarify their concepts of "hurt" and "pain" and "consciousness."

It is important to help students understand how they cannot avoid "harming" some organisms. Every time a student swallows, thousands of mouth bacteria perish in stomach acid. Every defecation abandons billions of bacteria to dehydrate or rupture. Perhaps 150,000,000 yeasts are killed when you bake a loaf of bread. A predator that doesn't eat prey dies. The amino acids that we require are not all readily available in plants, thus revealing our ancestry was not strictly vegetarian. The more students learn, the more they will realize that concepts of life and death and pain and awareness are not black-and-white distinctions, but fade into gray areas. The science teacher helps the student learn this by "holding the students against the real world."

Erwin Schroedinger, in an important 1945 book, What is Life?, described how the ability to perceive the world was a property of most organisms, if not of all life itself. Of course, for a Paramecium that bumps into a wall, this "perception" is little more than a simple predictable chemico-physical response, certainly not the mental imaging we develop when we collide with a wall. The "ends" for some factors are clear: the Paramecium is not conscious or self-aware; the Chimpanzee is. "We have no evidence that organisms lacking a central nervous system are capable of thinking about objects and events." (Griffin, 1984) But as we proceed to examine more recently derived animals, we observe greater abilities to sense changes in the broader environment, to organize and interpret these sensations, and to respond with a more complex repertoire of behaviors. Finally, we observe David Attenborough, in Life On Earth, crouching in the midst of a family of mountain gorillas and whispering to the camera: "There is more meaning and mutual understanding in exchanging a glance with a gorilla than with any other animal I know...." And we listen when Jane Goodall reports that Chimpanzees: "...are capable of reasoned thought, generalization, abstraction, and symbolic representation. They have some concept of self. They have excellent memories...show a capacity for intentional communication . . . show emotions that are undoubtedly similar, if not identical, to human emotions-joy, pleasure, contentment, anxiety, fear, and rage. They even have a sense of humor." (Goodall, 1987) See the OTA report for lists of animals used in education and their similarities and differences to human anatomy and physiology.

LIFE and DEATH are often seen as an absolute good and bad, respectively. Yet to save the life of a plague-infected animal or human requires that we promote the death of the bacteria. Students in developmental biology are surprised to learn that animal development depends as much on certain cell lines dying at the appropriate time as it does on cell proliferation. Normal human cells live in tissue culture only several dozen replications, whereas cancer cell lines appear to be immortal. In evolution, death is a major agent in natural selection, and essential to keeping the numbers of maladapted individuals low.

PAIN is likewise vital to the survival of humans and complex animals. Pain is required for both the human baby and the young kitten to define where their bodies end and where the environment begins. It stops you from twisting the pickle jar lid so hard you damage the tissues in your hand. Leprosy patients without pain wear away fingers and toes. Children born with a rare absence of pain perception laugh as they seriously cut themselves and others. Pain is therefore as vital to life as sight, and we know it must be inflicted at certain times for greater good, as in receiving a MMR inoculation.

EMPATHY is the ability you have to put yourself in another person's shoes: "I know what she means." "I know what he must feel." This is based on the commonsense observation that people are very much alike in the way they perceive the world. It is obviously a trait we value greatly, the base of the "golden rule" in many cultures, and a process that (combined with symbol communication) makes history and literature possible. While we value empathy with other people and encourage it in our students, we must be very careful to distinguish this from the sympathy we may give a dog or cat. From our understanding of their structural differences and experimental evidence, we can be sure they do not perceive the world as we do. As you rub your cat under the ear, assuming it "likes" the massage, the smell-oriented feline is more likely getting an itch scratched, an "itch" more closely related to scent-marking than to affection for an owner.

ANTHROPOMORPHISM is the error of reading human characteristics into animals that couldn't possibly possess them. It is promoted by giving animals human names, by children's picture books with animals that talk and behave as humans, and by referring to mommy and daddy animals where there is no evidence of parental investment. Biology teachers have contributed to this by using animals' organs as representative models for the human system and not pointing out the differences that exist as well.

IMAGINATION--Much more work remains to be done on varieties and degrees of higher animal thinking (see Griffin, 1985), but one distinction between humans and other animals that can be understood by many students is "imagination," as described by Jacob Bronowski:

"What goes on in the mind when we imagine? You will hear from me that one answer to this question is fairly specific: which is to say, that we can describe the working of the imagination. And when we describe it as I shall do, it becomes plain that imagination is a specifically human gift. To imagine is the characteristic act, not of the poet's mind, or the painter's, or the scientist's, but of the mind of man.

"My stress here on the word "human" implies that there is a clear difference in this between the actions of men and those of other animals. Let me then start with a classical experiment with animals and children which Walter Hunter thought out in Chicago about 1910. That was the time when scientists were agog with the success of Ivan Pavlov in forming and changing the reflex actions of dogs, which Pavlov had first announced in 1903. Pavlov had been given a Nobel prize the next year, in 1904, although in fairness I should say that the award did not cite his work on the conditioned reflex, but on the digestive glands.

"Hunter duly trained some dogs and other animals on Pavlov's lines. They were taught that when a light came on over one of three tunnels out of their cage, that tunnel would be open; they could escape down it, and were rewarded with food if they did. But once he had fixed that conditioned reflex, Hunter added to it a deeper idea: he gave the mechanical experiment a new dimension, literally--the dimension of time. Now he no longer let the dog go to the lighted tunnel at once; instead, he put out the light, and then kept the dog waiting a little while before he let him go. In this way Hunter timed how long an animal can remember where it has last seen the signal light to its escape route.

"The results were and are staggering. A dog or a rat forgets which one of three tunnels has been lit up within a matter of seconds--in Hunter's experiment, ten seconds at most. If you want such an animal to do much better than this, you must make the task much simpler: you must face it with only two tunnels to choose from. Even so, the best that Hunter could do was to have a dog remember for five minutes which one of two tunnels had been lit up.

"I am not quoting these times as if they were exact and universal; they surely are not. Hunter's experiment, more than fifty years old now, had many faults of detail. For example, there were too few animals, they were oddly picked, and they did not all behave consistently. It may be unfair to test a dog for what it saw, when it commonly follows its nose rather than its eyes. It may be unfair to test any animal in the unnatural setting of a laboratory cage. And there are higher animals, such as chimpanzees and other primates, which certainly have longer memories than the animals that Hunter tried.

"Yet when all these provisos have been made (and met, by more modern experiments), the facts are still startling and characteristic. An animal cannot recall a signal from the past for even a short fraction of the time that a man can--for even a short fraction of the time that a child can. Hunter made comparable tests with six-year-old children, and found, of course, that they were incomparably better than the best of his animals. There is a striking and basic difference between a man's ability to imagine something that he saw or experienced, and an animal's failure."