224
WILLIAM C. YOUNG
crested grebe, Podiceps cristatus, actively courts the male (258). Reversal of the roles is complete in the red-necked phalarope, Phahropus
lobatus. The females defend territories and display on the breeding
ground, the males incubate the eggs (264). There is a degree of bisexuality in the behavior of the black-crowned night heron, but in both
sexes the behavior characteristic of the sex is induced by androgens.
Estrogens alone did not stimulate any of the breeding behavior (241).
The significance of these deviant patterns is that all occur within a
hormonal framework that is essentially similar—the same steroid substances produced by tissues that are homologous with the tissues which
secrete these hormones in males and females in the other phyla. A survey
of the relationship between the hormones and behavior in birds reveals
additional evidence for the view that the locus of change as animals
have evolved resides more in the tissues on which the hormones act than
in the endocrine organs producing the hormones.
VIII. Mammals
The relationship between the hormones and reproductive behavior
has been studied more intensively in mammals than in the members of
any other vertebrate phylum. For this reason, conceptualization may be
more advanced, but we are still far from an understanding of the mechanisms by which hormones prepare the organism for the behavior it
displays. A number of reviews of descriptive and experimental investigations have appeared recently or should be cited because of their importance to workers in the field (2, 4-7, 317-326). Their substance will
not be repeated except when this is necessary to relate the situation in
mammals to that in the other vertebrate phyla.
Mating behavior including the increased activity encountered in
many species at the time of mating has received more attention than
other types of behavior known or suspected to be related to hormonal
action, i.e., aggressive behavior, nest building, and parental behavior.
Mating behavior can be divided rather arbitrarily into a preliminary or
courtship phase and a copulatory phase, although often and especially
under laboratory conditions or in controlled breeding situations, the
copulatory phase is entered into rather directly. This is explained perhaps by the circumstance that males of these species tend to be used
repeatedly. They are kept separate from females and are introduced into
their cages or enclosures at frequent intervals and only when the latter
are in heat. They know what is to come. During the courtship phase in
the laboratory rat, guinea pig, cattle, sheep, goat, swine, horse, and cat,
to select only a few examples, the males often sniff, lick, or bite the fur
on various parts of the female's body. They may explore and nose the
WILLIAM C. YOUNG
crested grebe, Podiceps cristatus, actively courts the male (258). Reversal of the roles is complete in the red-necked phalarope, Phahropus
lobatus. The females defend territories and display on the breeding
ground, the males incubate the eggs (264). There is a degree of bisexuality in the behavior of the black-crowned night heron, but in both
sexes the behavior characteristic of the sex is induced by androgens.
Estrogens alone did not stimulate any of the breeding behavior (241).
The significance of these deviant patterns is that all occur within a
hormonal framework that is essentially similar—the same steroid substances produced by tissues that are homologous with the tissues which
secrete these hormones in males and females in the other phyla. A survey
of the relationship between the hormones and behavior in birds reveals
additional evidence for the view that the locus of change as animals
have evolved resides more in the tissues on which the hormones act than
in the endocrine organs producing the hormones.
VIII. Mammals
The relationship between the hormones and reproductive behavior
has been studied more intensively in mammals than in the members of
any other vertebrate phylum. For this reason, conceptualization may be
more advanced, but we are still far from an understanding of the mechanisms by which hormones prepare the organism for the behavior it
displays. A number of reviews of descriptive and experimental investigations have appeared recently or should be cited because of their importance to workers in the field (2, 4-7, 317-326). Their substance will
not be repeated except when this is necessary to relate the situation in
mammals to that in the other vertebrate phyla.
Mating behavior including the increased activity encountered in
many species at the time of mating has received more attention than
other types of behavior known or suspected to be related to hormonal
action, i.e., aggressive behavior, nest building, and parental behavior.
Mating behavior can be divided rather arbitrarily into a preliminary or
courtship phase and a copulatory phase, although often and especially
under laboratory conditions or in controlled breeding situations, the
copulatory phase is entered into rather directly. This is explained perhaps by the circumstance that males of these species tend to be used
repeatedly. They are kept separate from females and are introduced into
their cages or enclosures at frequent intervals and only when the latter
are in heat. They know what is to come. During the courtship phase in
the laboratory rat, guinea pig, cattle, sheep, goat, swine, horse, and cat,
to select only a few examples, the males often sniff, lick, or bite the fur
on various parts of the female's body. They may explore and nose the