rp6@jaguar.ucs.uofs.edu (PAWA RITU) (04/19/91)
Infanticide includes any form of lethal curtailment of parental investment in offspring brought about by conspecifics. Included in this definiton would be curtailment of parental investment through destruction of gametes or reabsorbtion of foetus (Charnov, ch.7). Why Infanticide occurs? Hrdy suggested four hypothesis: 1) Cannabilism 2) Competition for resources 3) sexual selection 4) parental manipulation Lot of evidence on sexula selection hypothesis. This hypothesis suggests that this form of infanticide appears to be most common among polygynous mating systems where breeding occurs throughout the year, and where male gets access to female for a short time(Hrdy, 1977 ; Chapman and hausfater, 1979). Ex. Langurs When the dominant male occupies the territory of another male, he kills the offsprings of that male. This happens for many reasons - Female becomes receptive to the new male faster and secondly the male has an increased chance of passing his own genes to the next generation. What mechanism prevent a male from harming his own offspring? Social cues, fetal and adult hormone, genetic differences , and neural timing systems are four known mechanism that change the male's behavior towards pups. ************************************************************************** I am doing my term-paper on "Infanticidal behavior." Does anyone have any information on this topic? Sub-topics * Fetal and adult hormone (testosterone) * Genetic differences (differences in strain) * Neural timing (light:day cycles) * social cues **************************************************************************
davidh@uhunix1.uhcc.Hawaii.Edu (David A. Helweg) (04/23/91)
In article <464@platypus.uofs.edu> rp6@jaguar.ucs.uofs.edu writes: > >Infanticide includes any form of lethal curtailment of parental investment >in offspring brought about by conspecifics. Included in this definiton >would be curtailment of parental investment through destruction of gametes >or reabsorbtion of foetus (Charnov, ch.7). Eisenberg (_Mammalian Radiations_) offers a definition of infanticide that does not include resorption. He suggests that one might differentiate between the seeming social phenomenon of infanticide and the curtailment of parental in- vestment. Specifically, he recommends that one look for evidence that the mother consumes the offspring (which, he suggests, indicates that the female is cutting her energetic losses and represents a risk aversive female strategy. Of course ungulates could not pursue this strategy well, being herbivores, but they could pursue it in the form of fetal resorption). It seems to me that a definition such as Charnov's could be extended reductio ad absurdum to include accidental loss of offspring. If Eisenberg has been held up as an alternative authority previously in this thread, well, a little redundancy goes a long way.
cl@lgc.com (Cameron Laird) (04/24/91)
In article <12606@uhccux.uhcc.Hawaii.Edu> davidh@uhunix1.uhcc.Hawaii.Edu (David A. Helweg) writes: . . . >It seems to me that a definition such as Charnov's could be extended reductio >ad absurdum to include accidental loss of offspring. . . . To some, that's not an approach ad absurdum. Accidents also have their reasons, and it's possible that they admit scientific investigation. An example: suppose the broods of first-time vireo mothers have many more accidents than those of more experienced birds. If there's enough other evidence, we might conclude that the species "practices" with its first nests, or that those offspring are relatively expendable, or perhaps something else. It might turn out that such mechanisms can be viewed as alternatives to narrow-sense infanticide. What's crucial here is that all these possibilities are susceptible to re- search; the answers might be either true, or false, and not just matters of definition. I've lost track of this thread; maybe your point was that it's possible to lump so much into a definition that it loses its usefulness. With that I certainly agree. -- Cameron Laird +1 713-579-4613 cl@lgc.com (cl%lgc.com@uunet.uu.net) +1 713-996-8546