Reply to Bonnie on Evolutionary Explanations

Bonnie’s recent comment involved more than the topic of the last post.  To provide the context for the rest of the comment, my friend Ron posted this:

The problem with all teleological explanations is that many natural phenomena pursue multiple purposes. Although the "purpose" of the human eye is to see... we all look at each other's eyes to form judgments about personality... especially reproductive judgments. The Roman Catholic Church is especially intent on assigning reproductive purpose to monogamous marriage while ignoring friendship as a goal. THUS the question of whether one purpose is more "ultimate" than another purpose is often contingent upon contextual considerations.

This was in response to my recent post explanation and teleology2. I replied as follows:

If by ultimate we have in mind the proximate/ultimate distinction, it seems easy to sort out in case of eyes. Their ultimate function is clearly vision. This is powerfully reinforced by the observation that eyes are temporally and genetically prior to human eyes. Our ancestors had eyes long before the human species emerged.

That we have large whites around our corneas may be an adaptation. It allows us to tell when we are looking into one another's eyes and so facilitates communication. Since chimpanzees don't have such eyes, it is very probably a recent adaptation as runaway selection for intelligence and cooperation shaped our species. At any rate, it seems quite easy to assign these various features to primary and secondary functions.

I won't speak for the Catholics, but Aristotle (who has some purchase with them) also recognized reproduction as the primary function of marriage. This seems to me to be obviously true. It doesn't obviate (in fact it may comprehend) the function of friendship.

Bonnie in turn as this:

On eyes the ultimate (why) final cause of eye as vision could include seeing material objects and forms in the world. If one has an affinity with the poetic understanding of eyes as windows to the soul there are other questions. The ultimate evolutionary purpose of the white of eyes as an adaptive mechanism is purely speculative theory unless tested by scientific method. The science that studies sight at the most refined level is neuroscience.

I reply that the final cause of eyes as vision devices obviously includes seeing material objects and forms in the world.  Cats are looking for prey and prey are looking about for cats.  To test this, I need merely observe the cats and rabbits in my back yard.  The cat moves very slowly, because sudden movement is more visible to rabbits.  The rabbit responds to the cat by freezing, because movement is more visible to cats.  I am sure that the eyes of cats and rabbits are windows to their souls.  Most of what their souls are about is eating and not being eaten. 

What happens in human beings is a lot more poetic, I suspect; but then I am not a rabbit.  When I look at a painting by Joseph Turner, I am not trying to survive or mate.  I am pursuing beauty, which my evolutionary heritage has allowed me to pursue because all the necessary things have been provided.  My agenda is not the same as the agenda of my genes.  Much the same thing is happening when I watch the rabbits play with one another.  They leap at each other and seem to dance.  This may have some adaptive function, but it looks like simple fun.  A cat toying with a mouse is another example.  Good training for hunting, most likely; but a lot more fun for the one than the other. 

Yes, it is speculative that the large whites of human eyes may function to facilitate communication.  It is much easier to tell if a human being is looking at me because I can see the direction of her gaze.  Evolutionary explanations can rarely be tested in the same way that water can be tested for bacteria.  Mostly we have to make do with reverse engineering.  Why the large whites of the eyes?  It might be an accident of eye evolution.  Even if it is, that doesn’t mean that it wasn’t adaptive for another purpose once it was in place.  It might be adaptive for another reason, but the same holds.  All we can say for sure is that it doesn’t look like a complete accident that a species that benefits from interpersonal cooperation has eyes that allow one individual to tell when another is paying attention to her. 

Finally, there is this comment:

If the Greek translation of Aristotle’s ultimate theory carries any weight one might leap to conclusions about the composition of genes. In this era of biotechnology that is a big deal. The courts have wrestled with the question AMP v. Myriad 2013 and have settled upon a kind of genes are like chemistry analogy. It serves Occam’s Razor to simplify its work in resolving disputes between corporate and others interests. According to this analogy the simplest explanation is that genetic information is linear and their coded information is deterministic. Research scientists whose motives exclude the allure of profit and fame as primary incentives, increasingly theorize that a better analogy for the behavior of genes is more quantum physics. Their actions are less predictable than the simplified linear understanding that applies to chemistry. If I am correct, this fits Ron’s remarks about contextual influences.

I have been aware of this for a long time.  Since the discovery of genes, it has been tempting to believe that genes are legible: each codes for one trait and the code can be deciphered.  Once we decipher it, we can edit the code to produce the traits we desire.  I don’t think that anyone in the relevant fields believes that there is a simple, deterministic relation between genes and traits.  A single gene may code for many traits in the body, from the brain to the brawn.  Moreover, many genes depend on environmental inputs for their operation. 

Our genes code for flexibility.  When a cat decides whether to chase a rabbit or a fisherman whether to cast his line, each is making choices.  As I have argued in these posts, evolution works through animals by allowing each to pursue its own agenda.  A bull elk in a rut is not trying to produce the next generation of elk.  He is trying to beat the snot out of other bulls.  When I make dinner for my wife, I am not trying to get my genes into the next generation.  I am trying to make her happy.  That is how the beautiful emerges from the merely necessary.  

Who Benefits from Polygymous Marriage?

Here are some questions and suggested answers about marriage and polygyny that occur to me as I am writing lectures. 

First: What is marriage? 

I answer that marriage is a reciprocal exchange between one or more males and one or more females in which the female(s) offer the male(s) the opportunity to mate in exchange for the promise of investment in her offspring. 

I note that this is not restricted to the human species.  The pied flycatcher, a frequently adulterous English bird, exemplifies the system rather perfectly.  Adultery, of course, is what happens when one of the parties is tempted to cheat.  Males cheat by accepting the mating opportunity and then refusing to invest.  Females cheat by encouraging the male to invest in offspring that are not his own.  I also note that this excludes harem species to the extent that the male invests little or nothing in his offspring. 

It also excludes same sex marriage among humans, but I suggest that this may have no political or moral implications.  If same sex marriage is not really marriage, it is an extension of marital institutions to cover a very new kind of association.  That has to be judged according to its merits and I am, for what it’s worth, in favor of legal same sex marriage.

Second: what kind of marriage systems are there?

Three are logically possible:

1.       Monogamy (one male, one female),

2.      Polygyny (one male, more than one female), and

3.      Polyandry (one female, more than one male).

Monogamy is the most common in every human society, I suspect.  Most men (and apparently all male pied flycatchers) can only afford one wife and family.  Polygyny is also very common wherever some males do bring home enough bacon to support additional wives and kids.  Polygyny is thus, obviously, dependent upon social stratification. 

Third: why is polyandry so rare? 

There seem to be only one or two cases.  The reason seems obvious: if some number of females successfully monopolizes more than one male, then an equivalent number of females will be without mates.  Since more mates for a female does not mean more offspring, polyandry will reduce the reproductive potential of a society that practices it.  That will necessarily make it a bad option for most human societies. 

Fourth: who benefits from polygyny?

I find this question to be very interesting in so far as it is susceptible to logical analysis.  I am confining myself here to the logic of Darwinian strategies, so no one should think that I am making a case for polygyny in modern societies.  I am also making the cost/benefit analysis against the case of a society where all the marriages are monogamous.  Here is my list of winners in order of benefit:

1.       High status males

2.      All females who marry high status males (relative to those who marry monogamously)

3.      Each additional wife (relative to previous wives of the same husband)

4.      Woman who marry monogamously

Here are the losers, in order of loss:

1.       Males who are denied mates

2.      Males who marry monogamously

3.      Each wife relative to the next wife with the same husband. 

It’s pretty clear why high status males are the big winners.  They get as many wives and offspring as their status, substance, and stamina can afford.  Some men can be very big winners from a Darwinian point of view. 

Females do not benefit to a similar degree; however, in a polyandrous system, all the females get to marry up.  Consider a system in which there are fifty males and fifty females, ranked from one to fifty according to how competitive they would be in a free marriage market.  If each male is allowed three wives, then females one, two, and three all get to marry Prince Charming.  Females four, five and six get Prince Charming’s slightly less charming brother.  In this scenario, all the females get to marry up and the benefits get bigger as you go down the list of marriageable ladies.  In a larger system, where some females must settle for one husband, they still benefit.  Since the higher status males are soaking up the supply of wives, the remaining women will have a surplus of males to choose from. 

Of course, if females and males are roughly equal in numbers in the marriage market, for every male who gets three wives there will be two guys who have to go without.  Those are the big losers in the polygynous market.  Males who marry monogamously will have to pick their wives from the supply of females who didn’t rank even as a third wife for some fortunate aristocrat. 

Finally, there is the intra-familial conflict between multiple wives.  Cinderella does not benefit from the system, as she has to share Prince Charming and his resources with wives two and three.  Wives down the line benefit from marrying up, but wives one pay a cost for wives two and three in each case.  Tales of polygynous marriages almost always present the conflict between the older wife and the new girl in the harem. 

From a Darwinian point of view, most women benefit from polygyny and most men do not.  That hardly makes a case for polygyny even for women in modern times.  Polygyny requires a large degree of social stratification, which is one reason that it has been largely abandoned in modern societies along with those Downton Abbey houses.  This does explain a lot of the drama that is based on polygynous marriages a lot better than Freud ever explained anything.  Just sayin’. 

The Evolution of Marriage

Larry Arnhart discusses the biological roots of marriage in a recent post.  I am sorry to report that I agree with Larry on the basic issues.  I am happy to report some skepticism regarding a secondary issue. 

Larry is responding to Sherif Girgis, Ryan Anderson, and Robert George, who argue that marriage should be restricted to a monogamous, heterosexual relationship.  He tells us that the authors make two points: one, that marriage is an institution rooted in human biology and two, that if homosexual marriage is legalized this will effectively destroy heterosexual marriage. 

Larry agrees with the first point but thinks that it is inconsistent with the second point.  If heterosexual marriage is indeed rooted in nature, then it should survive any changes in legal norms.  I am inclined to agree. 

Allow me to add some of my own reflections.  Marriage is rooted in a simple biological dimorphism: women know who their children are while men do not.  When an infant issues from her mother, the mother knows that the infant is hers.  The father must rely, let us say, on less direct evidence.  How confident can he be that he is the biological father?  This has Darwinian implications, in so far as his natural instincts move him to invest in his offspring. 

The problem is widely shared among animals and has had enormous consequences for their evolution.  Males of many species try to secure paternity by keeping other males away from their mates.  Some jealously guard their harems.  Canines have evolved a mechanism called a “copulatory lock”.  When the male enters the female, his organ expands and locks him in place.  He cannot engage until sometime after ejaculation, which makes it more likely that the female will be safely impregnated.  That is the tie that binds. 

Security for paternity encourages the male to invest his time and other resources in his offspring.  Of course there is a trade-off.  If the male is fooled, he will waste his resources on the offspring of some other male.  Likewise, he will be tempted to hedge his bets by siring offspring with other females, perhaps with false promises of support.  Such is the soap opera of mammalian biology.  If male parental investment is to be maintained against or supported by selection pressure, some means of securing paternity have to be available to the male. 

The human institution of marriage was built on these biological foundations.  Marriage offers the male some assurance of paternity in exchange for his promise of investment.  That contract is reinforced by the larger community, which recognizes his authority over his sons and daughters.  See Aristophanes Clouds.  It also puts a disproportionate weight on the fidelity of the wife. 

However, marriage is not a product of biology even if it rests on biological foundations.  It arises and is maintained because it is one of the conditions for human flourishing in social conditions.  The telos, or purpose of marriage, was not reproductive success in a Darwinian sense.  It was to promote societies that are more stable and satisfying, given our evolved inclinations.  Human institutions cannot for long act against natural selection; however, they exist to serve us and not our genes. 

Given that brief consideration of the biological foundations of marriage, what does it mean to extend the institution to include homosexual couples?  It means only that an institution that has been developed for one purpose has been employed for another.  This is a commonplace in both biological and cultural history.  In the ubiquitous beetles, a second set of wings evolved into a retractable coat of armor.  Clothing likely emerges as a remedy for discomfort in hostile climates; however, it comes to serve other purposes such as displaying wealth and status, inviting seduction, providing pockets, etc. 

While heterosexual marriage evolved to serve purposes connected with biological reproduction and familial stability, there is no reason to suppose that it cannot serve other purposes.  Some have argued that same sex marriage can promote monogamy among male homosexuals, which might well be a good thing.  Whether it can really do that remains to be seen.  I have my doubts.  

I am in favor of legal same sex marriage for a rather simple reason.  When two persons of the same sex form a stable relationship, analogous to heterosexual marriage, the two partners should enjoy the same privileges as a heterosexual couple who have chosen to marry.  When one goes to the hospital, the other should have the same medical access that I and my wife have.  This strikes me as the decent thing to do. 

I see no reason to suppose that this undermines the functions of heterosexual marriage any more than wearing cloths to make a fashion statement undermines the purpose of good winter gear in these Dakotas. 

That said, I am not at all certain that I agree with Larry Arnhart regarding the privatization of marriage.  Such a step would certainly render moot the political arguments over marriage, just as the privatization of religion dramatically reduced the tendencies toward armed conflicts between sects.  However, this step clearly weakened religion as a force in secularized societies.  As I noted above, marriage is an artificial institution and it can be stronger or weaker in its effects, depending on how it is managed. 

I think that marriage is one of the most important institutions in human history.  We want to encourage it and strengthen it, in so far as we can.  I suspect that privatizing it would weaken it by placing in the category of things that are not serious enough to have legal consequences.  Because I agree with Larry that marriage has deep foundations in human biology, I don’t expect that this would kill marriage.  I do think that it might weaken it further.  If I am right, that would be a step in the wrong direction.