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Polygamy, Fidelity and Intra-Family
|by Gaurang Bhatt, MD|
The old adage says truth is stranger than fiction. The facts behind male-female and mother-child relationships, confirms that. Insect mating rituals can be tales of tragic heroism or murderous manipulation. Spiders are classified as Arachnids after an extremely talented weaver named Arachnida who successfully challenged Athena in a competition and was transformed by the angry losing goddess into a spider. A uniquely prevalent anomaly in many spiders is that the female is bigger than the male and ferociously carnivorous and cannibalistic. The hesitant male gingerly approaches her web hormonally driven to mate. He serenades her by rhythmically plucking the spoke of her web to soothe her savage breast and while she is in a trance mounts her. He has very little time to escape her fang once the short process is complete and often fails to do so. She kills him with the poison in her fang and sucks up his enzyme liquefied body contents. Under the circumstances he leaves her mating orifice plugged by his penis, thus preventing access to her by another male and provides nutrition by self-sacrifice to allow her to give birth to his progeny. Was there ever a more devoted father? There are variations to the theme of the Black WIDOW as the female is called.
In most animals in which fertilization of eggs takes place within the female's body as opposed to in water, sperms are plentiful in any given male and ova are few in any given female. This leads to the female being more selective and the male being recklessly promiscuous. The male invests little or nothing in rearing the babies. This is why males have ornate colors and perform ritual mating dance or behavior. Those species in which the males are markedly bigger keep a captive harem of females and have notoriously small testicles in comparison to body size. There goes the myth of big cohones and macho men. When both sexes are promiscuous, the males develop larger testes and greater volume and numbers per ejaculate to compete with the sperms of her prior mate. In the rare case of seahorses where only the female is promiscuous the male looks after the babies and develops a pouch.
In birds, where the successful raising of nestlings requires the effort and investment of both parents, pair bonding takes place. Recently developed DNA tests clearly show that discreet undetected adultery occurs in nearly 33%, even amongst birds. This explains why pair bonded male birds still continue their singing mating calls. Human statistics are higher depending on culture and opportunity. Ladies, beware of singing men. I can hear the spinning of wheels in the brain of feminists. Are their no faithful males? Damn their souls.
And that brings me to Oxytocin and voles. Oxytocin is a polypeptide hormone that promotes the excretion of salt by the kidney. It is responsible for initiating uterine contractions during labor and contracts the breast ducts to expel milk. When injected in male rat brains it makes them want to cuddle and causes penile erection. Injection in female rat brains encourages cuddling and makes them assume the mating posture. Oxytocin has a companion polypeptide hormone called Vasopressin, which conserves water excretion from the kidney. Voles are rat-like rodents. Montane voles mate indiscriminately and the male after his few moments of bliss, rides into the sunset and never calls next morning or ever after, leaving the female to raise the babies for a brief spell before abandoning them. Prairie voles, a related but different species form lasting adoring relationships, cuddle up, lick their babies and fawn on them. Their motto is 'Semper Fidelis' without being marines. Both species of moles secrete the two hormones, but the Montane voles lack a receptor for the hormones in a part of the brain called Ventral Pallidum. The receptor is expressed by the turning on of a gene in the female Montane vole after delivery, for a short period allowing her to care for the babies before abandoning them. The male Prairie vole has large number of receptors in the Ventral Pallidum of its brain and coos and cuddles with the one he has mated with and fiercely attacks any other males who come near her, while ignoring other females and keeping his fond gaze on his Juliet.
Before sentimental readers drown in their tears, there are lethal subterranean conflicts underneath the enchanting surface in butterflies, fruit flies and humans. XX develops into a female and XY into a female. During cell division X pairs with another X or Y. Because of different sizes and interests (male vs. female), the two have different and sometimes antagonistic evolutionary paths. The X chromosome could develop a gene producing a protein lethal to Y bearing sperms. The egg would allow fertilization only by a X sperm thus producing only female babies. In the butterfly Acrea encedon, such an occurrence produces 97% females and only 3% males. Male fruit fly seminal fluid contains a protein product of a gene. This protein enters the bloodstream and brain of the female fruit fly diminishing its urge to mate with another male. Pairing manipulating males with resistant females leads to more effective and larger concentration of the protein in the fly's seminal fluid. The mating of this super fly with a non-resistant female often kills the female. Occasionally a driving gene on the human X chromosome produces a protein that the crucial SRY protein, the product of a single gene on the Y chromosome that makes the fetus develop into a male. The sex ratio of babies is skewed towards female until a mutation on the SRY gene restores the balance. These peculiarities of the Y allowed tracing the Jewish heritage of African Lembas and the Levy Y. A baby gets half its genes from the mother and half from the father. There is a process of methylation, called imprinting that modifies expression of genes. There is competition by which selective imprinting occurs of maternal genes by paternal genes and vice-versa. Thus two sets compete with each other to shut off rivals.
Even the seemingly harmonious mother child relationship is not without hidden conflict. The conception of a second Rh +ve fetus by a Rh-ve mother leads to fetal death due to attack by mother's antibodies. The fetus needs glucose from the mother's blood, which she is willing to supply. The fetus unwilling to leave the supply of a vital substance to the whim of the mother's body secretes a hormone that raises the mother's blood sugar level to increase its passage to itself. The mother increases her secretion of insulin to combat this and an antagonistic tussle results in much higher maternal blood sugar levels and gestational diabetes if the mother's pancreas is incapable of matching the aggressive fetal attack. If the fetus lacks the gene for increasing maternal blood sugar the pregnancy passes in harmony without adverse consequences for both.
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