Sunday, August 02, 2009

Baby boys more likely than girls to die in infancy

Sifting through the pages of the CIA factbook, I noticed the virtual universality of higher infant mortality rates at the international level for boys than for girls. There are two marginal exceptions, Nepal and the Northern Mariana Islands, the latter also having the most unbalanced gender ratio favoring women in the world (numerically anyway--the red-blooded men of the islands might argue it actually favors them). For the other 221 countries or territorities for which there are data, boys are more likely than girls to die in the first year of life.

I wonder how various feminist theories explain this. Boys are expected to be tougher and consequently receive rougher treatment from their parents even before they begin crawling? They are encouraged to be more aggressive, and adopting a martial outlook leads them to engage in more risky behavior? How about blank slatist belief systems that hold environment up as the determinative factor in everything? Similar stories, I suppose.

One reason for this disparity is that boys tend to be larger than girls are and consequently are relatively more difficult to deliver without complication. Male babies are apparently also more susceptible to premature birth and respiratory problems than girls are. Further, though I am only speculating here, it seems plausible that as males tend to show more diversity than females do in several attributes like intelligence, they are more likely to suffer from too many bad draws that, in totality, lead to poor health outcomes.


Razib said...

more sex-linked problems. even if it isn't lethal or obvious it might be a fitness drag. also, testosterone has tendency to depress the immune system. don't know how important that might be before puberty. there's a relatively large literature on males being the 'weaker sex' re: disease and such because of the irony i guess.

TGGP said...

Did you find that pic via the same Overcoming Bias comment I read? Juggaloes have such classy funerals.

Stopped Clock said...

I think it basically comes down to the fact that boys have only one X chromosome and so are more likely to be born with all sorts of weird diseases that cause them to die soon after birth.

According to Wikipedia the population of the Marianas consists largely of immigrant sweatshop laborers who are exempt from US minimum wage law and are mostly female. How that plays into the increased rate of female infant mortality I don't know. As for Nepal, I guess its just the ubiquitous custom of valuing boys over girls and thus being more likely to let the girls die and hide behind malnutrition or disease as an alibi.

ironrailsironweights said...

Male I.Q. scores have a slightly higher standard deviation than do female scores. Most of the discussion of this fact involves its effects at the right tail of the bell curve, with a disproportionate percentage of males among people with genius-level scores. The thing is, there's also a disproportionate percentage of males at the left tail, in other words among the severely retarded. If I'm not mistaken, severe retardation is associated with high infant and early childhood mortality.


David said...

Interesting - I would have never though about something like this. What Stopped Clock said made a lot of sense.

bgc said...

Another explanation - which I think I got from Matt Ridley's The Red Queen - is that the default sex is female, and a female fetus is made into a male by hormones.

Thus being male is an unnatural state of intrinsic tension...

popularsymbolism said...

Audacious Epigone, while we're on this subject, what did you make of that CBC documentary, 'The Disappearing Male'? Would be interested in hearing your thoughts on the matter.

FeministX said...

Females also have longer life expectancy in most animal species.

The higher male birth rate is probably because of the single X and Y chromosomes- mutations on one chromosome are more likely to be expressed. There is also the issue of male fetuses being weaker in the uterus- I think male fetuses are also more likely to be miscarried, possibly because the maternal body is more foreign to them and sometimes even prone to immune attacks on them.

Why would this be a feminist issue?

silly girl said...

Razib cited a study a while back that showed that a very high percentage of all embryos were faulty and didn't grow. The question that comes to my mind is why males have more mutations that take so long to be fatal.


You kill me! I had to enlarge the pic to see your point.

agnostic said...

That picture is 1000 times better than "I love my dead gay son."

rob said...

FemX, it is a feminist issue because:

1) The sex difference is opposite of what feminism would predict a priori. It is something you have to explain away.

b. Feminists claim that disparities by sex result from discrimination and societal bias. Typically, they also claim that these things should be remediated. I'm lying of course. Discrimination and privelege only explain unequal outcomes favor boys and men. But that position does violate Blank Slate feminism.

iii) To stereotype, having their children die makes women sad. Fewer dead children would increase women's autonomy.

D Only the extremely rare, uh, biofeminist, evol-feminist? like you(Hell, you may be the only one) can make arguments from nature without violating core feminist principles. The rest have simply spent too long arguing against sociobiology and evolutionary psychology to start invoking it when it suits their purposes.

After all, a huge chunk of feminists argue that, say, rape is the result of patriarchy. They would never point out that forced sex occurs in countless animal species.

Lastly, as AP implied, sex ratios that 'favor' women do not. Women are most likely subjectively happier and objectively better-off with more men than women, because they have more men to choose from. Plus, more men means a buyers market for women. As a counterexample, black women in the US don't seem to appreciate that the sex ratio 'favors' them.

Oh yeah, you never answered answered my lesbian q. Do gay women prefer tall partners?

bbartlog said...

Variance in all dimensions of fitness should be higher in males since they benefit more from being in the top few percent.
This also implies more males with poor genetic draws, in the bottom few percent, who get culled.
The X chromosome in this case is more mechanism than cause. If lower variance in male fitness were desirable, there would be enough purifying selection on the X chomosome to achieve that state.

popularsymbolism said...

Related articles that might be related to infant mortality:

Male sex chromosome losing genes by rapid evolution, study reveals

Also read this snippet from Paul Ehrlich (rabid environmentalist/population control advocate)'s open memo to President Barack Obama:

A novel synthetic chemical added to the plastic in a sports bottle may increase its durability, but if it leaches into a baby bottle’s contents or into the environment and functions in
tiny doses as an endocrine-disrupting agent, is the risk worth the benefit?

That 'novel synthetic chemical' he is referring to is Bisphenol A, and in addition to being in plastics it's also in women cosmetics product. Although the cosmetics and chemical industry has claimed since 2007/2008 that they have stopped including it into their products, recent evidence points to the contrary:

ScienceNews: When BPA-free isn't

Also read:

Pancreatic Insulin Content Regulation by the Estrogen Receptor ERĪ±

This study tries to prove a correlation between Bisphenol A and infant mortality.

Conclusion: Chronic exposure to E2 and BPA might disrupt spermatogenesis in male pups.

Hence, I wager there is more to this than just sociological or fitness problems.

Audacious Epigone said...

Razib, SC, Peter, bbartlog,

Thanks for that.


Hah, no. Someone sent me a link to it through facebook a few weeks ago.


I don't have anything to add to Rob's response. To the extent that the gender disparity in infant mortality is societally/culturally influenced, it is probably due to things like bisphenal A, not differences in the way baby boys and girls are raised.

Popular Symbolism,

I remember the video tracing decreasing sperm counts in western men over the last several decades, attributed primarily to chemical processes, but I'm not in the know enough to really comment much on it now.

Thanks for the additional links. It's hard to show realistic concern for the state of things millions of years in the future, but out of curiosity, I wonder what differences from contemporary males would result from a new sex chromosome replacing Y.

TGGP said...

I have a post on the decaying Y chromosome here. It appears there are already some species were males only have one chromosome.

Anthony said...

It seems that it would make sense for men to have equal or greater diversity in pretty much any genetically-linked trait, because the Y-chromosome has fewer genes.