Letter/Observer Forum

Rhesus Pieces

The article, “With Psychologist at Helm, Zoo Atlanta Gets Wild,” (Observer, April 2003) while quite interesting, did contain errors commonly made in regard to Harry Harlow’s work. In a discussion of some of Harlow’s work, in the accompanying photograph it read “The experiments by Harry F. Harlow with infant rhesus monkeys and chicken-wire or cloth and padding ‘mothers’ demonstrated the strong bond that is created between mother and infant through cuddling and affection.”

While not central to the article, the discussion of Harlow’s work is incorrect. Unfortunately, like much of Harlow’s research on mother-child bond, this study reports a result discredited by Harlow himself. The preference of the baby monkey for the cloth “cuddly” mother, rather than the surrogate wire mother who delivered milk, was primarily due to the fact that the wire mother was cold to the touch. Much of the caloric intake of baby monkeys goes toward thermal regulation and the result – the preference of cloth over wire with milk – is dramatically altered when the wires of the surrogate mother are warmed. In fact, the baby monkey prefers the warm wire, milk-delivering mother. These facts are available in the literature and have been available for many years, yet they continue to be perpetuated, arguing that even baby monkeys prefer cuddly cloth to wire, milk-giving surrogates.

Unfortunately, this is just one of the many errors attributed to the work of Harlow. Harlow himself, for example, was able to show that motherless monkeys, while making terrible mothers with their first-born babies significantly improve with experience, such that latter born monkeys of these motherless monkeys were treated in a most normal fashion. These errors of reporting are serious since they reflect a clear bias toward the current view of the importance of mother in the child’s life, as opposed to peers or other people in the child’s social network, and the bias toward believing that early experiences with mothers have lasting effects even into the next generation.

In my book, Altering Fate: Why the Past Does Not Predict the Future (Lewis, 1997), I have pointed out these two errors of reporting in the primate literature as examples of the bias we have toward the role of early mothering in the child’s development. It is important to note that Harlow himself corrected some of these initial reporting errors through the publication of other papers. However, and this is important to appreciate outright, the failure of the scientific community to take note of these contradictory findings, points not only to the bias in our theoretical approach, but even more to the bias we have in referencing.

Michael Lewis
Robert Wood Johnson Medical School

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