Mr. Spencer also holds that most mental phenomena, especially where
complex or social or moral, can only be explained as arising from
use-inheritance, which becomes more and more important as a factor of
evolution as we advance from the vegetable world and the lower grades of
animal life to the more complex activities, tastes, and habits of the
higher organizations (preface, and p. 74). But there happens to be a
tolerably clear proof that such changes as the evolution of complicated
structures and habits and social instincts _can_ take place
independently of use-inheritance. The wonderful instincts of the working
bees have apparently been evolved (at least in all their later social
complications and developments) without the aid of use-inheritance--nay,
in spite of its utmost opposition. Working bees, being infertile
"neuters," cannot as a rule transmit their own modifications and habits.
They are descended from countless generations of queen bees and drones,
whose habits have been widely different from those of the workers, and
whose structures are dissimilar in various respects. In many species of
ants there are two, and in the leaf-cutting ants of Brazil there are
_three_, kinds of neuters which differ from each other and from their
male and female ancestors "to an almost incredible degree."[11] The
soldier caste is distinguished from the workers by enormously large
heads, very powerful mandibles, and "extraordinarily different"
instincts. In the driver ant of West Africa one kind of neuter is three
times the size of the other, and has jaws nearly five times as long. In
another case "the workers of one caste alone carry a wonderful sort of
shield on their heads." One of the three neuter classes in the
leaf-cutting ants has a single eye in the midst of its forehead. In
certain Mexican and Australian ants some of the neuters have huge
spherical abdomens, which serve as living reservoirs of honey for the
use of the community. In the equally wonderful case of the termites, or
so-called "white ants" (which belong, however, to an entirely different
order of insect from the ants and bees) the neuters are blind and
wingless, and are divided into soldiers and workers, each class
possessing the requisite instincts and structures adapting it for its
tasks. Seeing that natural selection can form and maintain the various
structures and the exceedingly complicated instincts of ants and bees
and wasps and termites in direct defiance of the alleged tendency to
use-inheritance, surely we may believe that natural selection,
unopposed by use-inheritance, is equally competent for the work of
complex or social or mental evolution in the many cases where the strong
presumptive evidence cannot be rendered almost indisputable by the
exceptional exclusion of the modified animal from the work of
reproduction.
Ants and bees seem to be capable of altering their habits and methods of
action much as men do. Bees taken to Australia cease to store honey
after a few years' experience of the mild winters. Whole communities of
bees sometimes take to theft, and live by plundering hives, first
killing the queen to create dismay among the workers. Slave ants attend
devotedly to their captors, and fight against their own species. Forel
reared an artificial ant-colony made up of five different and more or
less hostile species. Why cannot a much more intelligent animal modify
his habits far more rapidly and comprehensively without the aid of a
factor which is clearly unnecessary in the case of the more intelligent
of the social insects?