A higher male-to-female birth ratio after wars would not compensate for male deaths during wars. If you want an equal number of males and females in the next generation, you should arrange this with an equal male-to-female birth ratio (or really, slightly higher males as Cecil notes, but no differently in the aftermath of a big war than otherwise).
I would speculate that the number of people in a given generation is closer to proportional to the number of women who survive to reproductive age in the previous generation, than to the overall number of people who survive to reproductive age in the previous generation. Thus if replenishment is needed, a higher ratio of females would be appropriate. However, replenishment is not needed, as the babies and the dead soldiers are of different generations.
I find it interesting that the male proportion is slightly higher than the female proportion. Cecil suggests this is do to males engaging in dangerous preoccupations. However, this does not take into account the historical risks females faced during childbirth (that have been mitigated but not eliminated by modern medical care). So it is still riskier to be a man?
It’s not that males are more likely to die as adults, as Cecil suggests. It’s that “Male infants have been consistently noted to have a higher infant mortality rate than female infants.” See this article from the Journal of Parinatology, which includes 5 cites for that statement.
Basically, 105 boys are born for every 100 girls, but the extra 5 boys die as infants, so it evens out (although the cited article is about a study showing that male excess is decreasing). Male infants are at higher risk for prematurity and certain related conditions.
One of the things a doctor told me when my daughter was born extremely prematurely (23 weeks 6 days from Last Menstrual Period) was that if she was a boy, they wouldn’t even have attempted to save her. They would simply have told me I was having a miscarriage, not a premature baby. While one boy (James Elgin Gill) born earlier than her did survive with no long term ill effects, it’s vastly more common for male micropreemies to die within weeks or days or suffer severe disabilities than female micropreemies.
The fact that the doctor thinks he has the right to make that decision would not only make me go to another doctor, but also encourage anyone who had had a miscarriage to investigate, since, as far as I’m concerned, the doctor just committed euthanasia, which is still murder.
A doctor works for the patient. He makes no decisions on his own, especially those that involve lying to the patient.
ETA: Guess why I feel this way. I’m male, and almost died (or actually died, for 45 minutes) as a baby. Your doctor would have murdered me. I’d include some invective involving both the vulgar and the religiously profane, but I’m afraid the strength of the invective might get me in trouble. (And I never use the religiously profane.)
An extra 5 boys dying as infants would not account for the 105:100 ratio from an evolutionary point of view. Sex ratio theory predicts that mothers will, on average, invest equal amounts in sons and daughters.
If who wants it? All a mother “wants” is more descendants.
Yes. But natural selection does not optimize this number. That’s why we don’t see, or expect, a highly female-biased sex ratio. If the ratio were female-biased, it would be advantageous to a mother (to here genes, that is) to produce more sons, even though this would reduce the overall size of the generation after that.
It’s not about replenishment, but rather the relative evolutionary value of sons and daughters. To the extent that the dead males would have competed for mates with newly born males, the value of males is increased, and an adaptive sex ratio would be favored.
Everyone seems to be taking this as a straight scientific/genetic/biological issue, but there seems a strong sociological element, especially if you’re talking about reactions to war. Biology isn’t the only thing that effects birth ratios.
Suppose a working class within a society is strongly dependent on (or, perceives itself to be strongly dependent on) males for inheritance and manual labor. A couple that has a boy for their first child might have only that child, as they think that they have the necessary child for the continuation of the family. A couple that has a girl for their first child, on the other hand, are likely to have more children until they have a boy.
It would seem to me that such a mentality (one that seems likely to exist in historically androcentric human societies) would lead to a higher male to female birth ratio in some situations.
No, decisions of this sort cannot affect the sex ratio. Selective abortion, of course, could, and infanticide could affect the apparent ratio at birth.
If one wanted to help William James do a little more tap dancing, one could point out that World Wars One and Two were “home wars,” as opposed to the Napoleonic Wars, which for the French happened far away (until the end), and had a much more pronounced effect on the civilians’ psyche. Like the (debunked, I know) assertion that the birth rate went up right after 9/11, the argument would be that the women (who, let’s face it, control these things) were affected by these horrible events going on around them, and had more sex and with less protection.
‘Less protection’ would lead to relatively more males, since sperm carrying male DNA are faster but less enduring.
Perfectly clear. Except for the Iran thing. Still working on that.
Based on the theory made popular by Shettles, I believe. I don’t know if it’s *his *theory or not, but that’s where most people are familiar with it: that Y chromosome carrying sperm are smaller, lighter and fleeter, because they don’t have the excess weight of the X chromosome. However, just as male infants are weaker than female, the Y carrying sperm tend to weaken and die before the X carrying sperm do.
The practical upshot of this, if true, is that “male” sperm will outswim “female” sperm in a sprint. If you want a boy, you should have sex quite close to ovulation, so the fast male sperm get there just as the egg is released. If you want a girl, you should time intercourse for several days before the predicted date of ovulation, so the fast male sperm race off, drag race through all the stop lights, refuse to ask for directions, go through one end of the fallopian tubes and right out the other to die a lonely death somewhere near the bladder many hours before there even *is *an ovum to fertilize. The female sperm, while slower, are also longer lived. They pack a nice lunch of carbohydrates from the fertile female’s cervical fluid, they pace themselves and they arrive at the perfect time to fertilize the ovum after it’s made its way down the fallopian tube for their reproductive rendezvous, unimpeded by those boorish Ys.
However, if you’re aiming for a female, you’ve got to *stop *having sex a few days before ovulation, or you mess up your chances by introducing new, fresher, younger male sperm to the party who will outrace those fine fat female sperm with a headstart, working their way to the target.
So frequent unprotected sex very close to the time of ovulation is particularly ideal for making boys. Theoretically.
I think there’s also an assertion (perhaps dubious) out there that pregnancies that happen when birth control (condoms/spermicide) is used, tend to be girls. If true, that would lend credence to the theory. However, I can’t figure out how to google for that assertion - my google fu is failing. Anyway, as long as I’m hand-waving justifications into place, I thought I’d mention it.