Earlier today I commented on the hypothetical "Green Beard Effect" that may lead organisms to behave favorably toward other organisms displaying the same trait or traits.
The "Hey, we’re the same" instinct–whether it specifically captures what Dawkins et al. have in mind with the Green Beard Effect–is definitely something present in higher species (and many lower ones as well).
But there’s also the contrary impulse–what we might call the "Vive la difference" instinct–which causes us to favorably regard others specifically because their traits are different than ours.
Perhaps the most obvious example of this is the fact that we find the opposite sex attractive. If we didn’t, mating and reproduction wouldn’t occur and the species would die out. We are therefore genetically programmed to find those with the opposite sexual characteristics to be sexually attractive.
This instinct manifests in other ways, too.
For example, all human societies have an incest taboo. The nature of the taboo (i.e., exactly who you can’t marry) varies from culture to culture, but there is always an incest taboo of some kind. It is a human universal and thus seems to be based in our genetics.
The reasons for the incest taboo are debated.
One of the most common explanations you hear for why the incest taboo exists is that, if it didn’t and if a lot of incest went on as a result, it would harm the population by causing children to have birth defects due to inbreeding.
Maybe.
If that’s the reason for the taboo then it isn’t a conscious one. The ancients, who didn’t have access to modern science, didn’t seem to justify the prohibition of incest on those grounds.
St. Thomas Aquinas, for example, says nothing about it in his discussion of why incest is wrong.
I did some research a number of years ago on the subject (as part of answering the regular question "Where did Cain get his wife?") and found individuals arguing that the birth defects resulting from incest are not as common as is commonly supposed and that, if really severe, survival-affecting ones appear in a population, they’ll die out (or cause the population as a whole to die out). Also, until very recently, many humans lived in small, fairly isolated communities and didn’t have a lot of opportunity for marrying outside their neighbors, with the result that there has been a lot more inbreeding (if not incest) in human history than is often supposed.
Then there are people who argue the opposite of all this.
I don’t know which side is correct, but I mention the former position just to call attention to its existence, for you seldom hear it articulated.
My own suspicion is that we have the incest taboo because it’s just in us genetically and we have historically and are presently trying to come up with intellectual justifications for why something that we instinctively feel to be wrong is actually wrong.
In other words, it’s just part of the law of God written on the hearts of men.
God’s laws are for our good, and so I’m sure that there is a benefit–or several benefits–that come to mankind as a result of the incest taboo. One of them may be that it helps to prevent birth defects, but I’m not sure that there aren’t other, greater reasons.
In general, the incest taboo has the effect of bringing new genes into a family line and thus increasing its genetic diversity. Genetic diversity will allow it to withstand hardships better since there is a greater likelihood that some in it will be able to better weather the latest plague, famine, forced migration, or what have you.
A prohibition on inbreeding also helps broaden social ties, which result in an individual having greater social resources to draw upon. Of all the arguments that St. Thomas makes against incest, the one that strikes me as having the most force is this:
[Incest] would hinder a man from having many friends: since through a man taking a stranger to wife, all his wife’s relations are united to him by a special kind of friendship, as though they were of the same blood as himself. Wherefore Augustine says (De Civ. Dei xv, 16): "The demands of charity are most perfectly satisfied by men uniting together in the bonds that the various ties of friendship require, so that they may live together in a useful and becoming amity; nor should one man have many relationships in one, but each should have one."
If people marry outside their own families then the social fabric is strengthened and the society does better as a result.
Whatever the benefits God intends us to have as a result of the incest taboo–whether it’s avoidance of birth defects, increase of genetic diversity, stronger social ties, or a combination of these or something else entirely–we do have an aversion to incest that appears in all societies and that is likely genetic.
It would thus seem to involve a preference (at least in terms of mating) for those who are different from us in that they aren’t too closely related.
But the preferential option of those who are different goes beyond a preference for the opposite sex and beyond a preference for those who aren’t too closely related to us. There is some, though weaker, evidence that there is at least something of a drive in us toward exogamy, or marriage outside our own group.
The fact that most people marry within their own group and have done so historically suggests that this is a weak desire, but there is still an attraction to the exotic. People from other cultures can seem mysterious and romantic or their accents may be perceived as sexy.
Or not.
Like I said, it’s a weak desire in humans or people would have gone further afield to find mates than they historically did most of the time.
Nevertheless, we’re attracted not only by similarities but also by differences.
” Also, until very recently, many humans lived in small, fairly isolated communities and didn’t have a lot of opportunity for marrying outside their neighbors…”
But if you study American Indian history, you will see that although they did live in small, isolated groups, they did however travel hundreds of miles every year, and there was extensive tribal intermarriage.
Of course, what society thinks constitutes incest has changed over the last couple of centuries. Until fairly recently, it was standard for people to mary their first cousin without comment, including all the progenitors of Israel, the house of David, and Jesus.
Isaac married his aunt, Rebekah. His son Jacob, named Israel, also married his cousins, Rachel and Leah, who were the daughters of Laban, i.e. his neices. Now that’s backwoods.
Lauhed outloud from the backwoodscomment!
Tom,
Are you saying Jesus was married? I’m not obsessed, it’s just that, IMHO, that was a poorly-worded part of your comment.
The fact that most people marry within their own group and have done so historically suggests that this is a weak desire, but there is still an attraction to the exotic. People from other cultures can seem mysterious and romantic or their accents may be perceived as sexy.
Reminds me of how in the Victorian era there was a bit of a fad for all things eastern, men liking the idea of “geisha girls”, and so on. And I remember one gentleman of that era, or perhaps it was an earlier period, who was only interested in black women. This goes against people’s commonly held ideas about people living at that time.
Hmm… in the last few days you have covered science fiction over an IPod, a science fiction convention, Pirates of the Caribbean II, British to American Spelling, Losing pounds while you sleep, Green Beards, and more Green Beards. I wonder where the jimmyakin.org site went that I enjoy.
Jimmy,
This was a well-written essay on incest, and a worthy subject for someone involved in apologetics and biblical history. The Church does delineate just how close is too close, or as Christopher West hs remarked, “If you have extra fingers, you’re too close.”
Even today, one man’s incest is another man’s normal society, depending upon the definition of the subject. There are places in the world that are just now coming out of relative isolation, where marriage to cousins has been common simply because there was nobody else to marry. And then there’s Utah.
By the way, has anyone answered the small boy’s question, “Did Adam and Eve have belly buttons?”
You forgot cooties. Brothers and sisters have cooties. And there’s no intrigue to them; their purpose is to annoy the crap out of you until you can move out on your own.
Without the incest taboo, there would never be anyone close to you who didn’t regard you as a potential sex partner.
I mean, obviously, there’s something to be said for regarding yourself as a man or a woman. But there’s also something to be said for knowing yourself, and having others know you, as simply a person. There should be someone who doesn’t care whether you’re sexually attractive or not.
I suspect this is also something of the power behind celibacy.
Leon Kass, in his book Genesis–The Beginning of Wisdom, adds another dimension on the incest topic. This forum is too short to elaborate his points but a key observation of his is his insight into what was Abram thinking when he passes off his wife, Sarai, to the Pharoh and Abimelech as his sister, and how Abram has to be taught what is upright and just. It’s only in the Genesis account with Abimelech that we indeed learn that Sarai was indeed Abram’s sister because their father was Terah. Sarai had a different mother than Abram tho. I found Kass’ book to be quite extraordinary. He even has insight into a hidden secret in the Genesis 5 geneology of the 10 generations from Adam to Noah. If you haven’t had a chance to read Kass’ book, here is an excerpt ~
http://www.press.uchicago.edu/Misc/Chicago/425673.html
Good call, Maureen. Makes a whole lot of sense to me.
Jimmy,
I’ve heard that there is an uncommon amount of incest between relatives who meet each other first as adults. I’ve also noticed that men and women frequently marry someone who could pass for their sister or brother; part of the like-me effect. How does this work into the conversation?
When I was a little girl I always wanted to marry my brother. He was so protective of me and defended me in my silly little battles. (he once beat up a boy who had pushed my head through narrow iron railings and had left me there while he went off home for his tea…ah, those were the ‘good’ ole days)
My brother loved me though I annoyed him and even gave me his snotty tissue to blow my nose on after he’d made me cry…what better qualities could a husband have? (lot’s methinks)
It made perfect sense to me in my childish way that since we shared our lives as children, we would do so as adults (and of course, we do, though not in the way I had imagined).
As I got older, I found my brother to be an annoying idiot. I remember thinking, “thank *** ‘I’ don’t have to marry the jerk”
And then I went and married another one. LOL!
So, Jimmy:
Who was Cain’s wife? You can’t leave us hanging like that! 😉