Genetic Conflicts of Interest in Female Reproductive Rights.

( – promoted by buhdydharma )

There are several related serious issues concerning female reproductive rights that are seldom discussed, which to my mind form inherent and sound biological reasons for reproductive rights to favor female choice.  These biological facts point to conflicts of interest for males that under any rational system would disqualify males from interfering decisively in female choice.

(This diary has been exhumed from this graveyard, where it was originally interred in 2006.  )

 

The first conflict of interest concerns biological economies that people, especially males, tend to underestimate.  Reproduction is inherently asymmetrical.  Females get pregnant.  Males do not.  Females cannot walk away from pregnancy.  Males can, and often do, with the slightest investment of DNA.  Once a female is impregnated, she bears the sole economic and energy burdens of pregnancy, which is biologically quite expensive.  The male can choose to help, but remains utterly incapable of assuming the full responsibilities and risks of the burden.  Only the female is capable of assuming these responsibilities and risks alone.  This tends to be true across sexually reproducing species. Just as evolution has sculpted special body plans and physiologies for male and female sex roles, it has differentially sculpted male and female psychologies.  Males know they cannot be impregnated, and assume no risk or responsibility, but have plenty to gain should the female decide to keep the baby.  On the basis of this conflict of interest, they cannot be trusted to interfere in female choice.  “Jezebel wasn’t born with a silver spoon in her mouth,” precisely because “Papa was a Rolling Stone.”

A related conflict of interest borders on the sinister, because it shows the depth of the conflicts of interest between males and females in the form of genomic battles that can have serious health consequences for the female, but not the male.  Although sexual congress between consenting adults might feel like some intense experience of social harmony, such temporary physico-emotional processes belie the fundamental purpose of sexual congress, which is to maximize one’s own reproductive success, even at the expense of your mate.

In an excellent article in Tuesday’s Science Times, Harvard evolutionary biologist David Haig poses the following problem:

Pregnancy is absolutely central to reproduction, and yet pregnancy doesn’t seem to work very well.  If you think about the heart or the kidney, they’re wonderful bits of engineering that work day in and day out for years and years.  But pregnancy is associated with all sorts of medical problems.  What’s the difference?

Simple, he says:  The heart and lung belong to one person.  The fetus belongs to two.

It appears that Robert Trivers, who originally proposed the idea of genetic conflict within families, is right once again.  Consider an example of such genetic conflict.  Two avian hatchlings in a nest share about 50% of their genes.  They each want to maximize the Xeroxing of only their own genes, including those they share with their sibling, but their remaining differences give rise to considerable genetic conflict with respect to, say, who gets the most worms.  

Similar genetic conflicts exist between parent and offspring, who also share about half of their genes.  Frequently, an offspring wants more than the parent wants to deliver.  One hatchling may want more food, but it may be in the female parent’s best reproductive interest to spread the wealth, or even favor some offspring over others. The more successful hatchling will tend to get more than the mother wants to give.  

It is not always pretty. In hyenas, a dominant sibling (often female due to unusually high testosterone) will frequently kill a littermate soon after birth to maximize its own nutritional opportunities.  The fact of genetic conflict leaves one to re-consider the bawling brat in a supermarket standoff with its parents over a candy bar.  This is war.  Genetic conflict does not exactly reflect storybook family values preached by moralists, but makes good sense in light of modern biology.

More severe genetic conflicts exist between unrelated males and females that mate.  In the growing fetus that contains genetic material from both the male and female, battles between male and female genes occur for the control over the expression of certain genetic material, in order to favor the expression of certain traits, such as rates of nutrition and growth, even if it is at the expense of the pregnant female.

From the article:

Copies of some genes get shut down, depending on which parent they come from…A fetus does not sit passively in its mother’s womb and wait to be fed.  Its placenta aggressively sprouts blood vessels that invade its mothers tissues to extract nutrients.

Sort of creepy parasitic alien, no?

Dr. Haig first predicted that many complications of pregnancy would turn out to be produced by this [genetic] conflict.  One of the most common complications is pre-eclampsia, in which women experience dangerously high blood pressure late in pregnancy…Dr. Haig proposed that pre-eclampsia was just an extreme form of a strategy used by all fetuses.  The fetuses somehow raised the blood pressure of the mothers so as to drive more blood into the relatively low-pressure placenta.  Dr. Haig suggested that pre-eclampsia would be associated with some substance that fetuses injected into their mother’s bloodstreams.  Pre-eclampsia happened when fetuses injected too much of the stuff, perhaps if they were having trouble getting enough nourishment…One of the strategies he proposed was for mothers to shut down some of the genes in their own children.

This strategy takes advantage of the fact that most of our genes come in pairs.  We inherit one copy from the mother and one from our father.  In most cases, these pairs of genes behave identically.  But in the past fifteen years, scientists have identified more than 70 pairs of genes in which the copy from one parent never makes a protein.  In some cases, a parent’s gene is silenced.

So, evidence is beginning to accummulate that parental genes are literally in conflict, as predicted by Trivers.  The father’s genes may want to promote a trait such as growth, for example, even at the expense of the mother’s health.  In one case, turning off a particular gene of the father resulted in offspring that were 40% below average weight.  If another gene is disabled in the mother, the offspring were 125% heavier.  Thus, mother and father have different interests with respect to aspects of pregnancy, such as growth.  

Specifically, it is clearly not in the mother’s interest to give all her energy resources to the growing fetus.  The mother can sometimes defend against these hypertrophic excesses selfishly desired by the fetus/father by turning off relevant genes, but not always.  Sometimes, the selfish bastards get their way, at the female’s expense.  Males may want a child with a super large brain, though the female may die giving birth, because her birth canal cannot accommodate the selfish fathead.  Oh, well.  Back to the drawing board for Dad!  Plenty of fish in the sea, eh wot?  The pregnant mother’s health is always at the center of these genetic conflicts of interest.  The father’s health is not.  Males have an inherent conflict of interest, and should be recused from decisions of pregnancy.  The only one truly looking out for Mom 100% is Mom.   Period.  End of story.

One last thing: Quality of life matters, for both you and any progeny you intend to leave behind.  It is ALWAYS in your best interest as a reproducing agent to optimize your fitness and the fitness of your progeny.  That is EXACTLY the type of decision for which natural selection has designed you.  That is why you are here:  Because your ancestors made the best reproductive choices for themselves.   The fact that you exist today means that you are the cream of the crop with respect to reproductive decision-making.  

There are times in life when having a baby is optimal.  There are times when it will permanently damage your ultimate reproductive success.  Biologists refer to females as the “choosy” sex, because for some of the reasons mentioned above, they are more highly selective than men with respect to mating opportunities and investments.  Sure, guys like “Doctor” Frist, Reverend Dobson, and even yours truly would tend optimize our own reproductive success by frequently impregnating females with impunity.  Take a poker analogy: The man antes up, then stops, but can still share the pot.  The female antes, and continues betting until the pot is huge.  Letting males make the female’s bets is an incredibly bad idea for females.

One final last thing: Natural selection has provided us all with an urge to reproduce and have our offspring do well.  One would predict that abortion must be a difficult and unpleasant decision, because it is antithetical to our most basic instincts.  No need to add guilt trips.

Through a rational, scientific lens, female choice is rather self-evident.  Wingers always base their arguments on their conflicts of interest, wrapped in moralizing, devoid of rationality.  That’s why they hate science.

6 comments

Skip to comment form

  1. here.

    I obviously don’t limit my support for female choice based solely on medical issues.  For me the argument is inherently a question of reproductive success and rights.

    Having males decide when females reproduce is like having Larry Summers and Tim Geithner decide how to spend your future.

  2. posting this interesting exposition at this important moment.

    • halef on June 2, 2009 at 12:04 pm

    Unlike many species, the human female gives no obvious indication she is in estrus; the male cannot tell whether the female is practicing birth control (that was true even back to antiquity, though it obviously did not work reliably); and the male in fact cannot prevent the female from terminating a pregnancy, for which historically there have always been more options than surgical abortion.

    It seems to me that most if not all religious wingnut males of whatever persuasion are total control freaks, and this sort of powerlessness must drive them mad.

    I believe this is evident in religiously-motivated repression of females in terms of civic rights, property rights and education down to the medieval witch-hunts (which started by targeting “wise women” who knew how to control pregnancies prophylactically and ex post facto, at a time after the Black Death when both the church and secular authorities wanted to rebuild population as quickly as possible).

Comments have been disabled.