ELLIOTT M. BLASS Fifteen years have passed since the first volume on developmental psychobiology (Blass, 1986) appeared in this series and 13 since the publication of the second volume (Blass, 1988). These volumes documented the status of the broad domain of scientific inquiry called developmental psychobiology and were also written with an eye to the future. The future has been revolutionary in at least three ways. First, there was the demise of a descriptive ethology as we had known it, to be replaced first by sociobiology and later by its more sophisticated versions based on quantitative predictions of social interactions that reflected relatedness and inclu sive fitness. Second, there was the emergence of cognitive science, including cogni tive development, as an enormously strong and interactive multidisciplinary effort. Making the "functional" brain more accessible made this revolution all the more relevant to our discipline. In the laboratory, immunocytochemical detection of immediate / early genes, such as los, now allows us to trace neuronal circuits activated during complex behaviors. The "functional" brain of primates, especially humans, was also made very accessible through neuroimaging with which we can look at and into brains as they solve and attempt to solve particular tasks. Those of us who were trained in neurology as graduate students two or three decades ago recognize only the people in white coats and patients in beds or on gurneys when we visit neurologi cal units today. The rest is essentially new."

In our attempts to interrogate Nature about the development of the nervous system, we ask such questions as "How do the nerve cells originate and how do the correct types of cells differentiate at their correct positions; how do the neurons link together to form circuits whose functions are properly coordinated; and how are the functions of nerve cells related to behavior, to thought, and to conscious ness?" Those problems are intellectually challenging, not only because solving them would give us practical advantages but also because while they remain unsolved they stimulate the imagination and challenge the intelligence. It is precisely because they are difficult and controversial and have defied complete solution that such problems continue to attract subtle minds. The understanding that we now have of neural ontogeny seems to me to be farther from complete knowledge than from total ignorance. Nonetheless, it gives us a slightly elevated position from which to survey the vicissitudes of the past, to appraise our present understanding, and to consider ways in which our knowl edge might develop in the future. The history of this subject affords a particularly piquant illustration of Arthur Lovejoy's comment that the "adequate record of even the confusions of our forebears may help, not only to clarify those confu sions, but to engender a salutary doubt whether we are wholly immune from different but equally great confusions."

ELLIOTT M. BLASS Fifteen years have passed since the first volume on developmental psychobiology (Blass, 1986) appeared in this series and 13 since the publication of the second volume (Blass, 1988). These volumes documented the status of the broad domain of scientific inquiry called developmental psychobiology and were also written with an eye to the future. The future has been revolutionary in at least three ways. First, there was the demise of a descriptive ethology as we had known it, to be replaced first by sociobiology and later by its more sophisticated versions based on quantitative predictions of social interactions that reflected relatedness and inclu sive fitness. Second, there was the emergence of cognitive science, including cogni tive development, as an enormously strong and interactive multidisciplinary effort. Making the "functional" brain more accessible made this revolution all the more relevant to our discipline. In the laboratory, immunocytochemical detection of immediate / early genes, such as los, now allows us to trace neuronal circuits activated during complex behaviors. The "functional" brain of primates, especially humans, was also made very accessible through neuroimaging with which we can look at and into brains as they solve and attempt to solve particular tasks. Those of us who were trained in neurology as graduate students two or three decades ago recognize only the people in white coats and patients in beds or on gurneys when we visit neurologi cal units today. The rest is essentially new.

The previous volume in this series (Blass, 1986) focused on the interface between developmental psychobiology and developmental neurobiology. The volume emphasized that an understanding of central nervous system development and function can be obtained only with reference to the behaviors that it manages, and it emphasized how those behaviors, in tum, shape central development. The present volume explores another natural interface of developmental psy chobiology; behavioral ecology. It documents the progress made by developmental psychobiologists since the mid-1970s in identifying capacities of learning and con ditioning in birds and mammals during the very moments following birth-indeed, during the antenatal period. These breakthroughs in a field that had previously lain dormant reflect the need to "meet the infant where it is" in order for behavior to emerge. Accordingly, studies have been conducted at nest temperature; infants have been rewarded by opportunities to huddle, suckle, or obtain milk, behaviors that are normally engaged in the nest. In addition, there was rejection of the exces sive deprivation, extreme handling, and traumatic manipulation studies of the 1950s and 1960s that yielded information on how animals could respond to trauma but did not reveal mechanisms of normal development. In their place has arisen a series of analyses of how naturally occurring stimuli and situations gain control over behavior and how specifiable experiences impose limitations on subsequent development. Constraints were identified on the range of interactions that remained available to developing animals as a result of particular events."