This book is concerned with two problems: how eusociality, in which one
individual forgoes reproduction to enhance the reproduction of a
nestmate, could evolve under natural selection, and why it is found only
in some insects-termites, ants and some bees and wasps. Although
eusociality is apparently confined to insects, it has evolved a number
of times in a single order of insects, the Hymenoptera. W. Hamilton's
hypothesis, that the unusual haplodiploid mechanism of sex determination
in the Hymenoptera singled this order out, still seems to have great
explanatory power in the study of social ants. We believe that the
direction, indeed confinement, of social altruism to close kin is the
mainspring of social life in an ant colony, and the alternative
explanatory schemes of, for example, parental manipu- lation, should
rightly be seen to operate within a system based on the selective
support of kin. To control the flow of resources within their colony all
its members resort to manipulations of their nestmates: parental
manipulation of offspring is only one facet of a complex web of manipul-
ation, exploitation and competition for resources within the colony. The
political intrigues extend outside the bounds of the colony, to insects
and plants which have mutualistic relations with ants. In eusociality
some individuals (sterile workers) do not pass their genes to a new
generation directly. Instead, they tend the offspring of a close
relation (in the simplest case their mother).