My fellow PT blogger Nigel Barber wrote a post on November 6, 2012 in which he questioned the notion that there may be universals in human behavior. As someone who does research on human behavioral universals (and has strong opinions about this), I would like to offer my own perspective on this issue.

First of all, what are human universals? They are traits that are shared by all members of our species, Homo sapiens. These traits can be genetic (all human beings have many of the same genes), anatomical (all human bodies share some basic characteristics), physiological (all human lungs, hearts, and digestive systems work the same way), or psychological and behavioral. No one really questions the existence of genetic, anatomical, or physiological human universals and no one really cares about them. Some controversy exists, however, as to whether human universals extend to our minds and our behavior. Do all human beings share some basic similarities in the way we think, experience emotions, and behave?

Nigel writes: “There are three serious problems with basing evolutionary psychology, or any science, on universals. First, the concept of universals is closer to Plato’s philosophy than it is to science. In short, it can be dismissed as more mysticism than science. After all, in the world of biology, all creatures are in continual flux as they adapt themselves to a perpetually changing environment.”

The concept of universals simply implies that there are groups of entities (living or non-living) in our universe that share some characteristics and that make them different from other groups of entities that don’t have these characteristics. All planets have something in common that distinguishes them from stars. Gases have common properties that are different from those of liquids or solids. All rocks are different from living organisms. Plants are different from animals. Insects are different from birds, and human beings are different from baboons. Scientists identify what properties are “universal” for the entities in a particular group and different from the properties of the entities in another group, whether these groups of entities are inanimate objects vs living organisms, or organisms of different species. There is nothing mystical about this. Plato’s philosophy, along with Aristotle’s, provided the conceptual foundations for modern science, including physics, chemistry, and the taxonomic classification of all living organisms. Sure, as Nigel says, “all creatures are in continual flux as they adapt themselves to a perpetually changing environment”, but this continual flux and adaptation do not result in rocks turning into plants, plants turning into animals, and baboons turning into people, or vice versa, on a daily basis. The boundaries between species, or between groups of organisms, or between living and nonliving entities remain fairly stable for LONG periods of time. As long as humans remain a single species, Homo sapiens, which can be clearly separated from other species on the basis of genetic, anatomical, or other criteria, it is perfectly legitimate, and scientific, to speak of human universals.

The fact that we can categorize living and non-living entities into different groups on the basis of their shared (universal) characteristics does not imply in any way that there is no variation within categories; indeed, no two rocks or two animals of the same species are perfectly identical to one another; in all animal species, there is a great deal of inter-individual variation in relation to age or gender or other factors, and genes and environment make important contributions to this variation.

Nigel’s second problem with human universals in behavior is empirical. He says “The constants are empirically testable and do not stand up very well. … The notion that women are universally less interested in casual sex might seem more robust. Yet, even this claim encounters problems. Indeed survey evidence indicates that women in some countries are far more interested in casual sex than men in others.” Nigel’s empirical problem is the typical objection raised by cultural social scientists whenever evolution-minded behavioral biologists make generalizations about human behavioral traits that appear to be universal: they find an exception by pointing to this or that small tribe on a remote island of the Pacific Ocean, in which the supposedly universal traits are absent, or people behave in exactly the opposite way to Westerners.

Let me give you a couple of examples of why finding exceptions to human universals does not constitute evidence that these universals do not exist. Dogs are born with one head so one may argue that one-headedness is a universal dog anatomical trait. Yet, every now and then a two-headed dog is born due to some genetic defect or alteration of early development. Human babies are born with two arms and two legs. Yet, every now and then a woman who ingested particular drugs during gestation gives birth to a baby with no arms or no legs. Do these exceptions constitute evidence against the existence of dog or human anatomical universals? No. The existence of anatomical or behavioral universals simply means that all individuals of a species have similar biological predispositions to be born with a particular anatomy or to exhibit particular behaviors. In some cases these predispositions are not expressed because there are genetic mutations or environmental effects. Biological influences are never rigidly deterministic. The environment can suppress or alter the expression of biological predispositions. This does not imply that the biological predispositions do not exist and that one cannot make generalizations about traits that are typical of a species.

Human psychological and behavioral universals (which may range from the way we experience and express emotions to the way we behave toward children, potential sex partners, or friends and enemies) exist and are well documented. There are of course exceptions to these universals, in the form of individuals or small groups who are different due to biological alterations or local environmental conditions including ecology, demography, history, and culture. More importantly, the human universals and their exceptions co-exist side by side with a great deal of inter-individual variation in traits that are not universal, for example, the type of language people speak or their particular religious beliefs.

Nigel has a third problem with human behavioral universals. He says: “Looking for them is a distraction from what I consider to be the much more interesting task of evolutionary analysis – accounting for variation. Instead of focusing on constants, it is time for evolutionary psychologists to take up the challenge of accounting for societal differences.”

For many human behavioral phenomena, there are both normative aspects (the universals) and inter-individual variation. Take, for example, infant attachment, namely the socio-emotional bond between an infant or child and her primary caregiver. There are aspects of attachment that are common to all infants and children across cultures (another human universal) and aspects of attachment that show inter-individual variation within and across cultures. Some psychologists are interested in the similarities in attachment across individuals and cultures, while others focus their research on the differences among individuals and cultures. Normative and variable aspects of attachment are not mutually exclusive. Who is to say what’s interesting and what’s not? What’s important work and what’s just a distraction?

A full understanding of human behavior requires the study of both universals and variation among individuals and groups. Evolutionary psychologists are interested in both the similarities and the differences in behavior between individuals. Some specialize in the study of universals, others in the study of variation. Evolutionary psychologists and cultural social scientists have a lot to learn from each other. Whether or not, as scientists, we find the work of our colleagues in other disciplines interesting or congenial, let’s not misrepresent it and let’s not dismiss it.

If you enjoyed this blog post and the previous ones, read my book Games Primates Play!

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