You Can Pick Your Friends, But You Can't Pick Your Monkeys: Origins of Attachment Theory

One of the greatest temptations in the field of psychology is the urge to leap from research on animal behavior to a conclusion about human beings. Unfortunately, unless research about human beings substantiates the conclusion, the landing may be a bumpy and unreliable one. This danger does not always stop leapers; Alan Schore’s “modern attachment theory” is based on a number of such leaps, and as I have pointed out elsewhere, Schore does not make much of an effort to insure that readers realize which animals were the actual subjects of the research he cites.

The history of attachment theory, right back to John Bowlby’s time, has been characterized by generalization from animal behavior to human beings’ child care and early development. Bowlby originally compared human emotional attachment to the “imprinting” of ducks on the first moving objects they saw, and their later following of the imprinted object (usually the mother) and eventual courtship and mating with another member of their own species. Imprinting had an enormous impact on the duck’s life, determining that it might spend its early life following a toy train, or in adulthood “fall in love” with a human caretaker and ignore available mates of its own species. Considering the facts of duck behavior, Bowlby at first thought that human attachment would have similar mechanisms and effects, including “monotropy” (an inability to make an attachment to more than one human being). But further observation showed that attachment did not occur in the first days of life as imprinting did, that human beings had the ability to develop more than one attachment, and that a child who lost the first attachment relationship was capable, under the right circumstances, of developing a strong emotional attachment to a new caregiver.

Bowlby realized that the leap had gone too far and had landed on the wrong spot. Although human attachment was in some ways analogous to imprinting, it was not the same thing, and it was not possible to draw safe conclusions about human development simply from observations of duck behavior.

Bowlby and his colleagues then moved on to consider another type of animal behavior-- this time, an animal much more like human beings than ducks are. As is well known, Bowlby was much interested in the work of the comparative psychologist Harry Harlow on rhesus monkeys. Harlow demonstrated that rhesus babies, when separated from their mothers, sought out soft fabric model “mothers” and clung to them even though those “mothers” offered no nourishment. They would leave the soft mother to drink from a wire-framed “mother” that contained a bottle of milk, then scurry back to the soft model. Both Bowlby and Harlow were taken with the fact that the rhesus babies did not seem “attached” to the models that supplied milk; this result was in contradiction to Freud’s belief that the experience of feeding created emotional attachment, and it supported Bowlby’s argument that there was something in the social experience with the caregiver that triggered the development of attachment. Bowlby and Harlow were also interested in the later difficulties of the rhesus babies as adults, when they were reluctant to mate and did a very poor job of caring for their own infants if they had them. This outcome seemed to suggest that attachment experiences determined a great deal about personality development, an idea that was later built into Bowlby’s attachment theory and that has informed much of the later research on attachment.

Here’s an important question, though: What if Harlow had chosen some other kind of monkey? This was an issue which in fact received much attention from psychologists and zoologists in the couple of decades following Harlow’s reports and Bowlby’s adoption of the Harlow studies as evidence for attachment theory. The discussion at the time-- largely forgotten now that everyone has seen films of sad-looking rhesus babies on wire “mothers”-- focused on the fact that monkeys exhibit species differences in maternal-infant behavior. A monkey is not “just a monkey”, but a particular kind of monkey. (Much less work on these differences is done today because of the great expense of field studies and current concerns about the ethical treatment of lab animals.)

Harlow worked with rhesus monkeys, Macaca mulatta, a monkey that has frequently been employed in various types of research and which gave its common name to the Rh factor well-known to influence human reproductive success. But other researchers pointed out that the results of behavioral work with rhesus monkeys might not be the same as similar work with other types of monkeys. In one review article (Seay & Gottfried [1975]. A phylogenetic perspective for social behavior in primates. Journal of General Psychology, 75, 5-17), the authors described typical maternal-infant behavior and responses to separation in several monkey species in addition to Macaca mulatta.

Seay and Gottfried noted that in spite of the developmental difficulties of the “surrogate”-reared rhesus infants, rhesus monkeys who had somewhat less deprivation all eventually did well, whether they were reared in small groups of infants, reared alone but had a play period with other infants daily, were reared by brutal or abusive mothers, or had normal rearing by their mothers. They concluded that only an extremely unfavorable environment would alter these animals’ play, aggression, or sexual behavior. In addition, they stated that “even the organism maturing in an environment inadequate to support species-typical behavior will not develop unique techniques for coping with that environment. Rather, his behavioral repertoire will consist of fragments of the behavior patterns which ensure individual and species survival for most of his species-mates” (p. 10).

Comparing the rhesus monkey to other species, these authors noted that their own work on a different monkey, Macaca fascicularis, showed results rather similar to that on Macaca mulatta. However, the African red monkey (patas) showed a different pattern of social behavior. If rhesus monkeys were housed in cages such that the infants could go out to a central playground, when one came out, one or more others would join him. When an infant patas monkey came out, though, other patas infants did not join him—or, if one did, the first baby went back to his mother. As patas monkeys got older, they played chasing games, but unlike rhesus monkeys did not contact each other much.

Rhesus mothers object to physical disturbance from their infants, and will bite or hit an annoying baby. However, they will allow “strange” babies to come into the cage, as long as they “behave”. Patas mothers allow their babies to explore or play-attack them, and either do not respond or respond playfully-- but they will not allow a strange baby to come in. When nursing, rhesus babies are belly-to-belly with their mothers; patas babies do not have much of the body surface touching the mother. All monkey babies are disturbed by separation from the mother, but patas babies recover more quickly than rhesus babies do.

Who are we humans like? Should we accept a theory of personality development based on rhesus monkeys, or are we more like patas monkeys? The best guess is that we are like ourselves. Like other species, we have our own patterns of social interaction and of response to environmental changes. We may resemble other species, and their behavior may seem familiar and appealing to us. But when we come down to it, the behavior and development of other species can only provide a hint about what human beings might be like. We need to be cautious about our leaps from animal evidence to theories about humans--- however, cute, sad, and sympathetic those baby monkeys look to us.