The psychology curriculum has changed since some of you left the classroom. Not only has the Internet displaced many classrooms with online courses, but some courses that were once moderately popular have disappeared altogether. Fifty years ago, courses in comparative and differential psychology were common, along with behaviorism and requirements to take a foreign language. It’s my impression that even twenty-five years ago, these courses had mostly disappeared.
Courses in evolutionary psychology have filled in the comparative-psych gap to some extent, though without prerequisite coursework in evolutionary biology that leaves them open to intrusions of pop psychology and the buoyant proselytizing that once typified behaviorism.
Yet the proper use of interspecies comparisons and of individual differences are valuable parts of an education in psychology. It is dangerous to leave such comparisons to folk psychology and pseudoscience. (In particular, the old* “March of Progress” illustration contains a hopeless fallacy. Probably several.)
Nevertheless, when you have the hiccups and wonder where they came from, are you satisfied with an explanation that they are a holdover from tadpoles or fish? The biopsychosocial model forces us to look at very small as well as very large influences on our behavior, from genes to crowds, extending well beyond anyone’s individual experience. The causes for our behavior that we turn up may not make sense to us intuitively.
We often explain our behavior by comparing ourselves to others. Tadpoles are a pretty long reach when a medical explanation is at hand, even though tadpoles may do a much better job of explaining everyone else’s hiccups.
What are the right comparisons to find in explaining our behavior? Or since that question would have a very long answer, what kinds of comparisons should we avoid? Since the “others” to whom we compare ourselves are other humans or other species, we might ask what the traps are that beset social and interspecies comparisons.
We have trouble understanding our neighbors sometimes, despite even sophisticated efforts. Though other animals have minds, we cannot inhabit them, and even considering our hominid and other primate ancestors, from whom we have inherited many cognitive traits, we have to cast a suspicious eye on intuitively obvious explanations for our behavior.
BIO: It makes little sense to compare ourselves to other animals outside of an evolutionary framework. In explaining the outward, or phenotypic, similarities and differences it is useful to know what genotypic similarities and differences explain them. Psychologists face the difficult reality that most of the phenotypic traits that we seek to explain can’t be seen, though they may be measured.
In making behavioral comparisons it’s also useful to acknowledge that the ocean is not the same for humans as for marine animals, or air for birds, or mountains for goats.
A microscopic environment may turn up surprises for our macroscopic world, too. From our experience washing dishes in a basin we might expect the neurons and glia of the brain to fall to the bottom of the skull, yet it doesn’t happen.
The cellular scale is a different world from the one we can perceive. The hard life of sperm cells illustrates this. Unlike neurons, sperm cells are motile. Like most cells, sperm cells contend with a viscous environment that we large creatures don’t appreciate. (As is always the case, one thing leads to another, like this weird correlation.)
Maybe it’s unreasonable to expect anyone to intuit life on cellular level, but even insects and small mammals are a challenge, though J. B. S. Haldane’s essay “On Being the Right Size” is helpful. Here’s an informative excerpt:
“To the mouse and any smaller animal it [gravity] presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes…An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble. It can go in for elegant and fantastic forms of support like that of the daddy-longlegs. But there is a force which is as formidable to an insect as gravitation to a mammal. This is surface tension. A man coming out of a bath carries with him a film of water about one-fiftieth of an inch in thickness. This weighs roughly a pound. A wet mouse has to carry about its own weight of water. A wet fly has to lift many times its own weight and, as everyone knows, a fly once wetted by water or any other liquid is in a very serious position indeed. An insect going for a drink is in a great danger as man leaning out over a precipice in search of food. If it once falls into the grip of the surface tension of the water -that is to say, gets wet – it is likely to remain so until it drowns.”
Behavioral differences are common within the macroscopic realm as well. I might have included the distinctive functions of the whale’s voice in my discussion of voices in another post, but echolocation was not on the agenda.
PSYCHO: We humans are all relatives and we are surprisingly similar to each other. Our most recent common ancestor seems hardly in her grave. (Not to mention statistical estimates that are even more startling.) As a result, we’re all much closer relatives than you might guess from the average TV reality show.
For one thing, the population bottlenecks that nearly wiped us off the earth several times limited our genetic variability as a species, Furthermore, Homo sapiens originated in Africa, and each group that emigrated from the mother continent carried only a portion of its human genes. Where humans are concerned, Africa remains the most genetically diverse continent.
There was probably a lot of inbreeding in the early out-of-Africa generations and maybe for a long time afterward, not that you’d notice it today. European-Americans and a lot of other folks can pick almost any major royal figure before the Middle Ages, like Charlemagne or Genghis Khan, and find a link to their family.
Your unique pattern of experiences and your conscious outlook on life are different from mine. But in most of what we all do, we’re sheep. Cultures may differ, but the folks within each culture mostly don’t. This implies a paradox: Group averages don’t explain individuals, though every group is reducible to individuals, like brains to neurons; yet uncertain choices of individual neurons or people can give rise to utterly predictable behavior in a group.
When a trait results from the combination of heredity and the environment, the interaction is not additive in a simple way. That is, the development of the trait is not guided by genes and environment in a sequence, like following traffic signs.
Rather, the trait resembles a baked cake, in which we can no longer separate the influences of the eggs (genes) and the flour (environment). Sometimes it’s not worth the trouble of pulling them apart.
Interactions can be intriguing, though students studying the analysis of variance in grad school find cruder adjectives. The interaction of genes with the environment begins at birth and continues through life.
The simple view that every acorn will grow into an oak instead of a pine accounts for a public fascination with ancestry. We all know we inherited half of each parent’s genes. Yet there is no one-to-one relationship between genes and behavior.
As a result, evolutionary psychologists offer hypotheses about groups rather than individuals. Evolution, too, acts on populations, not individuals. It simply can’t occur in one individual in single generation. It’s a change in the distribution of genes in a population.
I think I’ve mentioned before that each of us is unique. The sources of variation are many, from gene expression to our brains’ sensitivity to the environment. As a result, our brains’ structure and activity patterns are as distinctive as fingerprints. Our selves ought to be unique as well, but in major ways they seem not to be. Some individual differences are dictated by the culture we live in, even when it comes to pain such as wind disorders in Tibet, brujeria in central America, and perhaps premenstrual syndrome in north America.
Then, too, genes are not destiny. Experience can alter the influence of our genes and how they express themselves. Or when we read that the heritability of some trait like intelligence is high, we shouldn’t resign ourselves to the idea that our own IQ is an unalterable trait.
SOCIAL: So we are mostly the same, with some variations in genes and experience. However, we shouldn’t apply group generalizations to ourselves without a lot of thought. Some folks try to predict behavior from genetically-influenced traits and claim to do it fairly well: criminal profilers, for example; divorce researchers; even physicists who study mobility. Even if their claims hold up, we should avoid applying their conclusions to our own behavior because of the ecological fallacy, which is the belief that group statistics can predict individual behavior.
Mining group data for correlations to apply to individuals of the group is also a risky adventure in spurious or illusory correlations. The fallacies that can invade conclusions about gene-behavior correlations got a good airing in the case of the so-called “warrior” gene a decade ago. There is no gene that is “for” a behavior in any one of us; many genes are pleiotropic and many behavioral traits are multifactorial.
Yet we persist in believing that the genes that make one subspecies look different from others must surely make it behave differently. For example, can we predict a dog’s behavior from its breed?
It’s widely assumed that a dog’s breed reflects its parentage–its genes or its genotype. So we’re asking whether genotype predicts phenotype, or outward expression of the genes, such as height and color. Someone who paid for a purebred golden retriever, a sporting dog, might not be happy with an Italian mastiff, a working dog. and vice versa.
But if genes contribute to a dog’s breed, does breed control its individual personality? Dogs illustrate the puzzle of personality. If breed has such a limited influence on individual behavior, what does that tell us about the genetic origin of personality? We might suspect that genes influence only some trait dimensions strongly and others weakly. We would guess that a gene’s influence depends on external conditions like a dog’s age or social rôle.
The same considerations apply to humans as we consider the ecological fallacy, which has taken on new importance with the spread of SARS-CoV-2 and COVID-19. Group differences do a poor job of predicting individual performance. If the Chicago Symphony Orchestra performs better than the Cleveland Orchestra it does not mean that Chicago has better trumpeters. And the death of Ralph Kiner a few years ago brings to mind the history of the Pittsburgh Pirates while he played for them; they stank. No one looking for a great hitter would have given the Pirates a second glance after looking at team statistics.