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Dating Mating Sex and Reproduction, evolution, human nature, science

More on Sexual Selection

I’ve explained in a little detail how female selection can cause runaway growth, as in a peacock’s tail or, as it turns out, a human brain.  I’m just going to take a few minutes today to explore one more aspect of the math behind runaway selection.

In most sexually reproducing species, there is really no such thing as a “female gene” or a “male gene.”  That is, both females and males have the same genes, but they express differently depending on the sex of the individual.  To borrow an example from Richard Dawkins in The Blind Watchmaker, if you are female and your father has a very big penis, you are likely to have the genes for a very big penis, but since you are female, there will be no outward sign that you carry this gene.  It is dormant, or is busy doing something else that only applies to females.  (If there are any geneticists reading this, forgive me for simplifying it so much.)  However, if you have a son, there is a good chance that he will inherit from you the gene for a big penis.  We see this all the time, and in fact, when we are in polite company and are not speaking of genitalia, we often say that a boy resembles his maternal grandfather.  Intuitively, we all know this principle.

What isn’t so obvious is that this principle is one of the driving forces behind female sexual selection.  It also helps us to explain another human trait that we all recognize but perhaps have never considered as instinctive and evolutionary.  To put it simply, genes for traits and genes that make us prefer those traits are passed down in the same way.  In other words, if a particular generation of peahens mate with the peacocks with the biggest, brightest tails, this trend will only continue if the daughters also prefer to mate with the same kind of males.  Female preference must be just as genetic as the physical traits of the males.  To put it into human terms, if my father was short and stocky, then my mother probably has a genetic tendency to prefer short stocky men.  If I have a daughter, it is likely that I will pass on the genes for preferring short stocky men, even if I happen to be a tall and lanky man.  In a very real sense, when two people reproduce, they are passing on genes for preferring to reproduce with people just like them.  It’s well beyond the scope of this blog (and of my ability to communicate complex math)  to explain why this is mathematically necessary for runaway selection to work, but it is, and runaway selection works.  While some minor details may not be all worked out, it is certain that female preference must also be passed down through males. *

This should give us a moment’s pause.   It is no coincidence that women often compare their husbands to their fathers.  It is no coincidence that daughters of abusive fathers often marry abusive men.  I must temper this observation with a warning, though.  It would be wrong to suggest that these tendencies are “entirely genetic” just as it would be wrong to say they are “entirely environmental.”  In modern evolutionary science, the distinction between environment and genes is so blurred as to be almost unintelligible.  That is, genes express through their environment and the environment “expresses” through genes.  The “nature vs. nurture” debate, for all intents and purposes, is dead.  Neither side won because there was never a distinction to be made in the first place.  The harsh reality is that if you are attracted to abusive men, your daughter, regardless of the environment she grows up in, is likely to inherit the gene in you that gave you the tendency to respond to your environment in the way you did.   Furthermore, having a son will not stop the process.  His daughters are also quite likely to carry the same gene.**

Now, I must warn the reader that I am about to indulge in some self-congratulatory moral pronouncements.  They should be taken with a grain of salt, but I hope you will consider them nonetheless.  I feel that knowledge of the science of humanity comes with the price of moral obligation.  For instance, women who find themselves continually attracted to abusive men are responsible to their potential children, grandchildren, and great-grandchildren.  They must ask themselves whether or not it is justifiable to continue to pass on the genetic preference for such men.  I will not be taking the time in this particular blog to demonstrate just how clearly behavioral tendencies are linked to genes, but for any curious readers, I would recommend this book:

(Whoops!  Originally linked the wrong book.  Fixed now.)
The human mind is not a blank slate, and instinct is more powerful than we like to think.  I have asked in several of my recent posts whether or not we can change ourselves proactively, and whether we can decide to impose our own collective will upon natural selection.  I certainly don’t know if we can, but here is one potential avenue for exploration.  As we continue to learn more and more about exactly what particular genetic arrangements do in humans, can we voluntarily take it upon ourselves to move humanity in a direction that makes rational sense, even if it means overriding the very strong desire to reproduce?  I’m not talking about modifying genes in the laboratory.  I’m talking about using simple natural selection to our advantage for the good of everyone by examining not only our own physical traits, but our own preferences.
I realize this is dangerous talk.  I will almost certainly be accused of encouraging eugenics.  Someone will call me a Nazi.  It is likely that I will alienate many feminists.  In my defense, I would like to say that what I am thinking of is actually the polar opposite of these things.  I do not think it would be good to enforce a design on unwilling people.  I don’t presume to take away anyone’s right to reproduce if they want to.  Instead, I propose an intellectual realignment with regard to morality itself.  Instead of latching onto the idea of reproduction as the “goal” of being human, could we as a species promote the idea that reproduction is an option to be weighed with the highest of moral imperatives in mind?  Could we learn to view choosing to remain childless as an act of selfless altruism?  For that matter, could we examine all of our tendencies in the objective light of science, and could we use our discoveries as a moral compass for ourselves, mapping our future based on the likely fates of our potential descendants?  I don’t know.  Personally, I hope so.
* Curious readers should consult the works of Russel Lande and R.A. Fisher as starting points.
** We should note that abusive men are notoriously good at reproducing.  We may not like to admit it, but it’s a good evolutionary strategy.  Could this be the justification we need for defying our genes?


2 thoughts on “More on Sexual Selection

  1. Nazi
    I am trying to understand the long time-line involved in an example of a person being genetically predispositioned to be an abuser. Where does it begin? And perhaps I am taking your example the wrong way .. just push me in the right direction.

    Now, as for reproduction…My husband and I chose not to have children. I will share one reason behind our decision – My family has a history of addiction. When my husband and I sat down to discuss kids, all I felt was a fear that if I had kids the chances of raising that child and he/she having an addictive personality would increase because of my family history:

    Great-grandad was an alcoholic, so was grandpa and my dad. Both of my sisters have or are currently struggling with meth/alcohol/cocaine…

    what are your thoughts on this ?


    Posted by Renee Obsidianwords | January 28, 2009, 9:33 pm
  2. Well, for the sake of brevity, I didn’t go into painful detail on just how complicated genetic predispositions can be. All I really wanted to establish is that they do exist, and we can no longer avoid the reality that in a very real way, the parent is responsible for the child’s predispositions, even if they did their best to train them otherwise. We’ve seen a very interesting progression as psychology has moved from essentially guesswork (Freud) to evolutionary psychology. Before modern psychology, there was a tendency to blame mothers for all the faults of the children, which led to quite a bit of emotional distress and social embarrassment. Then, as a corollary to the rise of modern feminism, the doctrine became quite the opposite — everyone is responsible for themselves, and you can’t blame a mother for just “doing the natural thing” if she wants to.

    The truth, it appears, lies somewhere in the middle. Some things — mostly diseases — have been at the top of our list of things to figure out, and we’ve found genetic markers for them. In many cases, we can tell a potential parent that there is a relatively certain probability that they will pass on a particular genetic defect to their child, and this will manifest in a disease. What we haven’t spent a lot of time doing is analyzing personality traits. I think that there is enough sociological justification for this kind of research to be funded, and funded well. If nothing else, Robert Altmeyer’s work on the authoritarian personality demonstrates rather conclusively that some people really are born with certain personality traits, and these traits have a demonstrable and predictable effect on society.

    I dated a girl for several years whose family had a history of mental illness, suicide attempts, and dysfunction. She had decided that she did not want to reproduce, partly because there was so much of that in her immediate family that the odds seemed stacked against her potential children. I agreed with her wholeheartedly. (Two of her three brothers, her mother, and her maternal grandfather are mentally ill.)

    Sadly, we parted ways when she decided that the odds be damned, she wanted to have children. This, I feel, is a good example of what I’m talking about. We have, I believe, a moral responsibility to put such known quantities on the table and sometimes to make morally sound decisions that might be against our own instincts. I believe you were correct in your decision because addictive personalities do appear to run in the family. I’m not aware of any experiments attempting to isolate abusive marital behavior as a genetic trait, but it wouldn’t surprise me at all if such a finding were to be published.

    The broader point is that everything is genetic, whether it’s primarily environmentally triggered or whether it’s basically inevitable (as in the case of Down’s Syndrome). We must, in light of this fact, examine our own family history and look for trends such as the tendency towards substance addiction in yours, and face the reality that we may be passing on the same tendencies. We then owe it to ourselves to divorce ourselves from the notion that every potential human deserves a chance to be alive. I, for one, can look at some people who have had miserable lives because of genetics, and if I were given the choice between bringing another such person to life, or letting them go down in the ranks of “humans who never lived,” it would not be a difficult moral choice.

    Posted by hambydammit | January 28, 2009, 9:56 pm

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