Fertility control in wildlife: humans as a model
by
Barfield JP, Nieschlag E, Cooper TG.
Institute of Reproductive Medicine, University of Münster, D-48129 Münster, Germany.
Contraception. 2006 Jan;73(1):6-22.
ABSTRACT
In a time of accelerated extinction rates and biodiversity loss, it may seem illogical to be concerned with methods limiting the reproduction of wild populations; however, there is an urgent need to inhibit the proliferation of a wide variety of species. The range of animals for which fertility control is desired makes the development of a single method impossible. The various reproductive strategies used by individual species, the desired outcome of contraceptive programs (reversible or irreversible; male or female directed) and our ignorance of the reproductive biology of many endangered species necessitate thorough species-specific investigations. As fertility control in humans is a reality and research into methods of fertility control is more advanced, humans serve as a model for developing contraceptive approaches for wild species. Population control by traditional methods (indirect or direct intervention by culling, poisoning, translocation, etc.) is increasingly unacceptable to the public, making human studies even more valuable for finding solutions to overabundant wild populations. This review compares and contrasts the range of contraceptive methods used in both wildlife and humans.
‘I’ll find an answer that’s good enough for them,’ he said to himself, as he slipped the letter into his post-box.{246} THE FERRY-BOAT. THE FERRY-BOAT. "Why, I thought it was on a hill, or something of the sort; I had no reason to think so, of course, but I had formed that picture of it." The Clockwork man shook his head. "We have houses, but they are not full of things like yours are, and we don't live in them. They are simply places where we go when we take ourselves to pieces or overhaul ourselves. They are—" his mouth opened very wide, "the nearest approach to fixed objects that we have, and we regard them as jumping-off places for successive excursions into various dimensions. Streets are of course unnecessary, since the only object of a street is to lead from one place to another, and we do that sort of thing in other ways. Again, our houses are[Pg 146] not placed together in the absurd fashion of yours. They are anywhere and everywhere, and nowhere and nowhen. For instance, I live in the day before yesterday and my friend in the day after to-morrow." This principle is somewhat obscure, and the nature of percussive forces not generally considered—a matter which may be illustrated by considering the action of a simple hand-hammer. Few [103] people, in witnessing the use of a hammer, or in using one themselves, ever think of it as an engine giving out tons of force, concentrating and applying power by functions which, if performed by other mechanism, would involve trains of gearing, levers, or screws; and that such mechanism, if employed instead of a hammer, must lack that important function of applying force in any direction as the will and hands may direct. A simple hand-hammer is in the abstract one of the most intricate of mechanical agents—that is, its action is more difficult to analyse than that of many complex machines involving trains of mechanism; yet our familiarity with hammers causes this fact to be overlooked, and the hammer has even been denied a place among those mechanical contrivances to which there has been applied the name of "mechanical powers." ‘When anyone prefers beauty to virtue, what is this but the real and utter dishonour of the soul? For such a preference implies that the body is more honourable than the soul; and this is false, for there is nothing of earthly birth which is more honourable than the heavenly, and he who thinks otherwise of the soul has no idea how greatly he undervalues this wonderful possession.’47 Monday, 3rd hour That is the truth. We left the caravan far behind. In the gorge with its rosy-pink soil the silence was exquisite, the air had the freshness of a mountain height, and quite inexplicably amid these barren rocks, where there was not a sign of vegetation, there was a scent of honey and almonds. Life went on very much the same at the post when there was only the infantry left in possession. As there was nothing to do at any time, there was nothing the less for that. On the principle that loneliness is greatest in a crowd, Stanton was more isolated now[Pg 183] than Grant had been in the days when there had been no railroad west of Kansas. The railroad was through the southwest now, but it was a hundred miles away. It was unsafe to ride outside the reservation, there was no one for hops, the only excitement was the daily addition to the list of slaughtered settlers. Felipa spent most of her time with the Ellton baby. Miss McLane had been married to Landor's second lieutenant for a year and a half, and they were very happy. But Felipa in the knowledge of the strength of her own love, which gained new might each time that she wrestled with it and threw it back upon the solid ground of duty, found their affection decidedly insipid. Like the majority of marital attachments, it had no especial dignity. It was neither the steadfast friendship she felt for her husband, nor the absolute devotion she would have given Cairness. Si strode over to the group, snatched the bat from Harry's hand, spanked him with it, and started for the others of the group. HoME日本1级:A片
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