 |
|
| |
[ Pobierz całość w formacie PDF ]
she was more prone to bring forth at certain epochs than at
others; and subsequent researches have established the accuracy
of the forecast." He further stated his belief in a "primordial
seasonal aptitude for procreation, the impress of which still
remains, and, to some extent, governs the breeding-times of
humanity." (A. Wiltshire, "Lectures on the Comparative Physiology
of Menstruation," _British Medical Journal_, March, 1883, pp.
502, etc.)
Westermarck, in a chapter of his _History of Human Marriage_,
dealing with the question of "A Human Pairing Season in Primitive
Times," brings forward evidence showing that spring, or, rather,
early summer, is the time for increase of the sexual instinct,
and argues that this is a survival of an ancient pairing season;
spring, he points out, is a season of want, rather than
abundance, for a frugivorous species, but when men took to herbs,
roots, and animal food, spring became a time of abundance, and
suitable for the birth of children. He thus considers that in
man, as in lower animals, the times of conception are governed by
the times most suitable for birth.
Rosenstadt, as we shall see later, also believes that men to-day
have inherited a physiological custom of procreating at a certain
epoch, and he thus accounts for the seasonal changes in the
birthrate.
Heape, who also believes that "at one period of its existence the
human species had a special breeding season," follows Wiltshire
in suggesting that "there is some reason to believe that the
human female is not always in a condition to breed." (W. Heape,
"Menstruation and Ovulation of _Macacus rhesus_," _Philosophical
Transactions_, 1897; id. "The Sexual Season of Mammals,"
_Quarterly Journal Microscopical Science_, 1900.)
Except, however, in one important respect, with which we shall presently
have to deal, few attempts have been made to demonstrate any annual
organic sexual rhythm. The supposition of such annual cycle is usually
little more than a deduction from the existence of the well-marked
seasonal sexual rhythm in animals. Most of the higher animals breed only
once or twice a year, and at such a period that the young are born when
food is most plentiful. At other periods the female is incapable of
breeding, and without sexual desires, while the male is either in the same
condition or in a condition of latent sexuality. Under the influence of
domestication, animals tend to lose the strict periodicity of the wild
condition, and become apt for breeding at more frequent intervals. Thus
among dogs in the wild state the bitch only experiences heat once a year,
in the spring. Among domesticated dogs, there is not only the spring
period of heat, early in the year, but also an autumn period, about six
months later; the primitive period, however, remains the most important
one, and the best litters of pups are said to be produced in the spring.
The mare is in season in spring and summer; sheep take the ram in
autumn.[128] Many of the menstruating monkeys also, whether or not sexual
desire is present throughout the year, only conceive in spring and in
autumn. Almost any time of the year may be an animal's pairing season,
this season being apparently in part determined by the economic conditions
which will prevail at birth. While it is essential that animals should be
born during the season of greatest abundance, it is equally essential that
pairing, which involves great expenditure of energy, should also take
place at a season of maximum physical vigor.
As an example of the sexual history of an animal through the
year, I may quote the following description, by Dr. A.W.
Johnstone, of the habits of the American deer: "Our common
American deer, in winter-time, is half-starved for lack of
vegetation in the woods; the low temperature, snow, and ice, make
his conditions of life harder for lack of the proper amount of
food, whereby he becomes an easier prey to carnivorous animals.
He has difficulty even in preserving life. In spring he sheds his
winter coat, and is provided with a suit of lighter hair, and
while this is going on the male grows antlers for defence. The
female about this time is far along in pregnancy, and when the
antlers are fully grown she drops the fawn. When the fawns are
dropped vegetation is plentiful and lactation sets in. During
this time the male is kept fully employed in getting food and
guarding his more or less helpless family. As the season advances
the vegetation increases and the fawn begins to eat grass. When
the summer heat commences the little streams begin to dry up, and
the animal once more has difficulty in supporting life because of
the enervating heat, the effect of drought on the vegetation, and
the distance which has to be traveled to get water; therefore,
fully ten months in each year the deer has all he can do to live
without extra exertion incident to rutting. Soon after the autumn
rains commence vegetation becomes more luxurious, the antlers of
the male and new suits of hair for both are fully grown, heat of
the summer is gone, food and drink are plentiful everywhere, the
fawns are weaned, and both sexes are in the very finest
condition. Then, and then only, in the whole year, comes the rut,
which, to them as to most other animals, means an unwonted amount
of physical exercise besides the everyday runs for life from
their natural enemies, and an unusual amount of energy is used
up. If a doe dislikes the attention of a special buck, miles of
racing result. If jealous males meet, furious battles take place.
The strain on both sexes could not possibly be endured at any
other season of the year. With approach of cold weather, climatic
deprivations and winter dangers commence and rut closes. In all
wild animals, rut occurs only when the climatic and other
conditions favor the highest physical development. This law holds
good in all wild birds, for it is then only that they can stand
the strain incident to love-making. The common American crow is a
very good study. In the winter he travels around the ricefields
of the South, leading a tramp's existence in a country foreign to
him, and to which he goes only to escape the rigors of the
northern climate. For several weeks in the spring he goes about
the fields, gathering up the worms and grubs. After his long
flight from the South he experiences several weeks of an almost
ideal existence, his food is plentiful, he becomes strong and
hearty, and then he turns to thoughts of love. In the pairing
season he does more work than at any other time in the year:
fantastic dances, racing and chasing after the females, and
savage fights with rivals. He endures more than would be possible
in his ordinary physical state. Then come the care of the young
and the long flights for water and food during the drought of the
summer. After the molt, autumn finds him once more in flock, and
with the first frosts he is off again to the South. In the wild
[ Pobierz całość w formacie PDF ]
zanotowane.pldoc.pisz.plpdf.pisz.plcs-sysunia.htw.pl
|
| |
|
|
|
| Podobne |
| |
|
| |
|