rat mothers

Along the lines of infacticide, it is interesting that some birds of prey produce two offspring in a clutch every year, even though only one can survive. It was long assumed that the extra offspring was simply a sort of insurance policy in case anything happened to the first. But it actually serves a way of storing food for its earlier hatched sibling. Food is plentiful early in spring, but in short supply later in summer when the young birds are larger and have their greatest food demands. This is the time when the older chick kills and eats its younger sibling. The mother's fitness benefits from this strategy becuase without the second chick as food 'in the ice box', the first one would rarely survive.
So obligate fratricide, with mom as the 'enabler', is completely 'normal behavior' for these birds.

I like this part:

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Dr Catalano said: "These findings demonstrate yet again that we need not go to museums of natural history to find evidence of natural selection.

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"Indeed things as common and immediate as the gender and health of our children show its effects."

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...precisely what we are trying to convince the fossil-doubters on so many threads.

Asssuming you consider the nascent 'conception' (zygote) a complete person and accord it all the same rights. Oh, and don't some conceptions also happen by 'forceful means'. I ask you this: Who is most justified in deciding what pregancies to carry to term if not the one person with the biggest investment in the whole project - the mother. If not her, then to whom would you defer this decision ? Because by trying to deny her the right to a decision, you are 'de facto' making it for her.

I think your reasoning is air-tight here.
E.Z.

I think you have a good point Schraf.Rat seems to want to hold people to some specific level of responsibility for having sex that is difficult to justify in any comparative legal context.

No, it was just the feeling I got from the undercurrent in your posts. Forgive me if I'm wrong.As Schraf said:

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...just because something is legal doesn't mean that you get to blame society for your moral choice.

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If I divorced my wife for infidelity that would be my choice and I would bear all the responsibility for its consequences.
Just because I might have legal grounds for that decision would not in any way help me to justify it to myself. I would be far more likely to forgive her. (I can say that because I know she doesn't read this forum )And I happen to think that people who run up credit card debt are completely responsible for their own dilemma. It doesn't mean we deny them recourses toward resolving their dilemma.If an act of sex results in an accidental pregnancy, that couple should have a right to resolve their predicament as they see fit without society judging them for it. It's their responsibility (the preganancy and/or the abortion) and no one else's. That burden of responsibility need not be increased as a consequence of the moral judgements of others. That would be a truly criminal act, quite beyond any responsibility one could attach to consensual sex. You mean like buying cheap condoms that happen to break?This message has been edited by EZscience, 04-27-2006 09:27 AM

Strange. I got that impression also. I was honestly surprised when I finally clued in that old RR had actually been involved in such an un-godly act.

No personal attack, just personal commentary.
As far as logic, I don’t see any reason to repeat all the logic that has been leveled at you already that you have failed to negate. You continue to express moral opposition to the concept of abortion, and yet this did not stop you from resorting to one when you were personally in need of such a recourse. Hmmmm . OK. Logic. Let’s see.1. unborn baby = human
2. wrong to kill human
3. prenancy <> accident when sex is consensualI can see a tenuous link between the first two, but that third one that doesn’t seem very logically related to the other two.
I just don’t think you are ever going to be able to sell this “no pregancy from consensual sex can be an accident” angle.
Furthermore, what I (and others, likely) are reacting to is your implicit position that anyone engaging in sex should be forced to bear the full consequences of their actions, birth control or no, simply because . Easy for you to say now, Mr. Vasectomy.
Let me ask you this.
What if you wife had become pregnant after your vasectomy ? - possible if you didn’t wait quite long enough for the semen to clear.
Would you have considered it an ”accident’?Nice new avatar BTW. Is it meant to depict your approach to debating?

As opposed to mis-handling it in a correct manner?Come one rat, what if you didn't SEE the nail? Bacterial infection is therefore a deterministic consequence of your carelessness !?ABE: Are you aware of what you just wrote - how on earth can you or anyone else know what is "supposed to happen" ? The sex is not the accident. The accident is the f**ing egg getting fertilized!! Not all acts of sex result in fertilization, nor is all 'sex' purely reproductive in function. I think this has been mentioned earlier in the thread. I was intentionally walking down a wooden dock when I stepped on a rusty nail sticking out of it. I was bonking this hooker in Bankok and the damn rubber broke. The difference is ?This message has been edited by EZscience, 04-29-2006 09:13 PM

Returning to Schraf's OP, this article appeared in the NY Times today in the context of Mother's Day.

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One Thing They Aren't: Maternal

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As much as we may like to believe that mother animals are designed to nurture and protect their young, to fight to the death, if need be, to keep their offspring alive, in fact, nature abounds with mothers that defy the standard maternal script in a raft of macabre ways. There are mothers that zestily eat their young and mothers that drink their young's blood. Mothers that pit one young against the other in a fight to the death and mothers that raise one set of their babies on the flesh of their siblings.

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Reminded me of the original topic of this thread.Maternal manipulation of offspring survivorship can take many forms in nature, but its all about ensuring the survival of some at the expence of others.This message has been edited by EZscience, 05-09-2006 06:22 AM

Actually, the idea of animals ”assessing’ their population density and adjusting their reproduction accordingly was originally put forward by Wynne-Edwards in 1962 in his book Animal Dispersion in Relation to Social Behavior and his observations have been largely reinterpreted since. GC Williams was able to demonstrate convincingly in his book Adaptation and Natural Selection (1966) that most of the behaviors Wynne-Edwards was talking about were actually explainable by selection acting on the individual. The ”for the good of the species’ type argument, once common, is no longer considered an acceptable usage of the concept of group selection.Maternal infanticide is clearly explainable by indivdual selection. It is merely a strategy of the mother to (1) ensure the survival of one offspring at the expense of others, or (2) to tradeoff current reproductive effort (the outcome of which might be temporarily dismal) for the sake of increasing her future reproductive effort. All this makes sense when we realize that mothers are selected to maximize their own fitness function, not the fitness function of each of their progeny. The two are not the same, hence the manifestation of parent-offpsring conflicts as first outlined by Trivers in 1977.AbE. So to answer your question, fetal resorption, infanticide and abortion can all be viewed as mechanisms by which a female can manipulate the timing of her reproductive effort to ultimately maximize her own fitness, even the immediate result appears to be in conflict with that goal.EZThis message has been edited by EZscience, 05-09-2006 11:48 AM

...Or if she feeds one of the kids to the other two

Yes, I know it seems inefficient, give the loss of energy through double assimilation processes, but let's look at the ecological context in which this behavior usually occurs.When an eagle mother starts out with a brood of 2 chicks feeding both of them, food is abundant early in the season with no way to say how good the supply will be later when the chicks are larger. So the smaller, weaker one represents a store of food for the older one for later, in case its needed. (In some species the siblicide is facultative - only if needed - in others it is obligate). There is no other way for the mother to store food for later in the season except by temporarily turnign it into a chick. This is called the 'icebox hypothesis', orgiinally proposed by Alexander in 1974 (Ann. Rev. Ecol. System. 5:325-383 - if you're interested).Another example from insects. Most lady beetle mothers lay eggs in clusters so that some eggs serve as food for the first larvae to hatch. That way, their survival is improved when they have to go forth and seek out their first prey (aphids). If mom wanted to prevent this sibling cannibalism, all she would have to do is lay eggs singly - but she doesn't. In terms of theory, she is acting to maximize her minimum fitness (reducing her chance no offspring will survive), as opposed to shooting for maximum fitness (trying to get all eggs to survive).