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The foraging behaviour of the yellow-bellied glider was observed for more than 3 years in south-eastern
New South Wales. The use of different substrates by foraging gliders followed an annual cycle which
was correlated with the phenological pattern in the forest. Flowering and bark shedding on eucalypts
were the characters of tree phenology most useful for predicting the behaviour of foraging animals.
Gliders concentrated their foraging efforts on ephemeral food resources, particularly those obtained
from under loose bark; this led to a seasonal pattern in the use of tree species and habitats in the study
area. The preferred habitat of P. australis is likely to be characterised by a mosaic of tree-species
associations, including those which flower in winter. Smooth-barked eucalypts are important because
of the diversity of foraging substrates, and hence food resources, which they provide. The patchy
distribution of these gliders may be explained by differences in floristic diversity and the complexity of
the habitat mosaic.

Writing as someone outside the field of political science, but very much involved in studies of behavior-physiology interactions, James Davies' article seems to me to be compelling in its argument for a reorientation of much of political science to include biology. As Davies points out, there is clear and convincing evidence that different physiological states are associated with different probabilities of aggression. Moreover, he cited only a part of the available evidence. At this time, data strongly support two of his points: multiple factors (e.g., genetic, developmental) contribute to the long-run probability of aggression; and different levels of neurotransmitters and hormones contribute to the short-run probability of aggression. All higher animal forms (and lower forms insofar as is known) are capable of aggression, however, within-animal frequency and type of aggression differ. Thus, what factors alter the probability of aggression under different circumstances becomes a question of great interest. It is this issue that Davies addresses. Yet, he may not have gone far enough in his effort to alert readers about the importance of understanding physiological processes as an essential requisite for understanding aggression in particular and behavior in general.

The mystical title of this commentary on Professor Davies' provocative and timely key article is intended to emphasize my belief that many of the problems of attempting to relate biology to 'aggression' stem from deliberate or inadvertent reification. 'Aggression' is clearly a 'concept' and not an 'entity' and, as such, it is difficult to perceive the very diverse activities receiving this label as having a common physiology. Concepts are adopted (or eventually rejected) on the basis of usefulness not correctness. This is not to deny that any useful reference to aggression must concern animals, i.e., creatures with physiologies. Most individuals in their dispassionate moments would not regard the sea or a volcano as being aggressive and would certainly fail to apply this attribute to dry-rot fungus.