In Brief

Natural v. Judicial Selection. According to Justice Scalia’s opinion in Michael H. et al. v. Gerald D., the relationship between Michael and his out-of-wedlock daughter Victoria was not traditionally protected under the historic practices of American society.  To the contrary, he concluded, the marital family had traditionally been safeguarded against the kind of paternity claim asserted by Michael H.  By denying Michael H.’s claim to paternity and visitation rights, Scalia believed that he was reaffirming American family values.

Adultery in the animal kingdom is deeply rooted.  Among birds that have a long tradition of monogamous relationships, it was discovered that another male had fathered about 40% of the babies fed by an apparently monogamous male in his own nest.  Payne, R.B. and Payne, L.L., Animal Behavior, 38:457-467, 1989.  According to zoologists, there is a good reason for adultery.  The benefit of a monogamous relationship, from the female’s perspective, is that she gets assistance from the father in raising the offspring.   The male bird, by selecting an apparently monogamous female, is guaranteed that the offspring are his, not another’s, and that therefore his investment into their future is worth it.  Then why cheat? 

For the male, sperm are cheap to make, and the more females he impregnates, the greater chance of spreading his genes.  Since he is not burdened by having to invest energy into a big, nutrient rich, egg, or by being stuck with hungry offspring, he can readily venture outside the monogamy to increase his reproductive potential by copulating with other females.  Successful cheaters, like the polygamous male bird, produce many offspring who carry the cheater genes.  Like father, like son. 

The female is in a more difficult position.  Her reproductive cell – the egg – is more costly to produce because it is stocked with nutrients to sustain the development of the embryo into the early fetal stage.  Later on, if she is viviparous and bears live offspring, she literally must eat for two, expending valuable energy of her own to insure the viability of the baby inside her.  To make matters worse for her, since it is the female who gives birth to the baby, as a matter of course it becomes her job to feed it.  Otherwise, it might die and her investment would be gone.  What’s a mother to do? 

Her strategy is to find a male who is a willing provider, as well as being attractive to other females.  A vigilant husband ensures the mother that the children’s needs will be met, and that they will reach reproductive maturity.  Attractiveness in the mate serves another function.  An offspring who is desirable to members of the opposite sex is more likely to reproduce, and produce offspring, than one who is unattractive.  Reproduction by the mother’s offspring guarantees the continued dissemination of her genes.  Choosing an attractive mate is a strategy designed to increase the probability of desirable offspring, thereby increasing their chances of reproduction, facilitating genetic dispersion of her genes into the population.

If the female is lucky, she finds a mate who possesses both qualities at once.  But what happens when all the good males are gone?  If she settles for the leftovers, she may be stranded with a male whose genes are less desirable.  If so, she now has the incentive to copulate outside her apparently monogamous relationship.  Her goal is to secure a male who will help her raise the family, and find another male as a gamete donor to provide her children with good-looking genes.  Some biologists believe that this behavioral pattern is characteristic not only of birds, but also of humans. Read The Red Queen, by Matt Ridley, Penguin Books, 1993, Pages 173-244, Chapters 6 and 7, for a more complete discussion.

The rule laid down by the plurality in Michael H. et al. v. Gerald D is a reflection of evolutionary theory.  Carole D., like the unfaithful bird, chose the top executive in a French oil company as the caretaker and energy-provider for her children, but another man (presumably having superior genes for attractiveness) to provide the gametes.  She wants a man with money who is certain to be able to feed her children, and a man with attractive genes to ensure that her children have the highest reproductive potential.  If the same male happens to possess both qualities, so much the better.  But, if not, it makes perfect sense for Carole D. to have both, rather than give up one for the other.  Scalia’s rule simply codifies the evolutionary principle, encouraging cheating behavior.  This is a case where natural selection and judicial selection are perfectly consistent.

Why did William win, and Michael lose?  If William’s role, as the mom alleged in William TT, was simply to donate the sperm, why was her wish to limit William’s involvement with the child ignored, while Carole’s request in Michael H granted?

As pointed out in William TT, without a sperm-donor, the mother is unable to produce a child and disseminate her genes.  This puts her on the lookout for a man when she wants a child.  Usually, she marries him in order to get the financial resources and help from him in raising the product of their act.

The dad’s objective is more single-minded.  He simply wants to fertilize an egg with no strings attached.  Whereas the mother may need commitment, the father can usually get along without it.  This results in a conflict between the mother and father. To prevent the father from defecting once the child is born, an elaborate program of emotions have evolved that keeps the pair committed to each other.  This adaptive program masks the true nature of the relationship: for the father to inseminate an egg with his sperm, and for the mother to find both a high-quality sperm donor and provider to keep her child secure.  Emotions facilitate both deception and cooperation in the face of this reproductive truth.  The concept of love between the partners is a perfect solution since it creates a commitment between the partners, reducing the problem of defections.  When two parties “love” each other, they formalize their love by getting married, providing extra insurance that the father won’t defect after a successful pregnancy.  The result in Michael H supports this arrangement between married partners by ensuring that their expectations are met. 

The outcome of William TT gets at another aspect.  William should have been happy with the original agreement between him and the mother.  She did not request any financial support or assistance from him, giving him a baby without marriage or commitment.  He achieved his reproductive goal without giving up anything.  But there’s more at stake.  In most cases, the mother is going to need the father’s assistance, and therefore must deceive him into believing that he is not merely a one-time sperm-donor necessary for only a fleeting moment, but a necessary presence throughout the maturation of the child.  This is where the emotional adaptation – love and marriage – comes in.  The mother is William TT made a serious error – not by viewing William as a sperm donor, rather than father – but by expressing this outlook expressly to the court.  This risked undermining the basis of the cooperation between a father and mother in raising a child together.  The court sided with the dad this time to encourage long-term collaboration between the reproductive partners, and to suppress the nasty viewpoint that it was all about procreation.  In effect, they took the mother’s side of things, even though this particular mother lost out. 

Opposites Attract.  There is scientific truth to the old adage that opposites attract.  At least in mice, mate selection is driven by genetic differences.  In a striking series of experiments beginning in 1976, researchers discovered that, when given a choice, mice will pick mates who are dissimilar from themselves at the major histocompatibility complex (“MHC”).  Alberts and Ober, Yearbook of Phys. Anthro., 36:71-89, 1993; Bakker and Zbinden, Science, 414:262-263, 2001.  What is so attractive about MHC?

MHC is a cluster of genes that encode the cell surface proteins that modulate the immune response.  The MHC proteins play a crucial role in responding to pathogenic organisms and other foreign proteins (“antigens”).  There are a number of different MHC genes, and each gene has many different polymorphic alleles (alternative forms of the same gene which differ from each other in nucleotide and amino acid sequence).  In the general population, some alleles are rare, while others are more frequent, shared by many individuals.  The total number of different combinations of MHC genes and gene alleles is large, resulting in considerable heterogeneity in the population at the MHC locus.

The primary function of MHC proteins is to distinguish between self and foreign antigens.  They are expressed on the cell surface of specialized cells called “antigen presenting cells” (APC), and in that milieu, display foreign antigens to the immune cells (such as lymphocytes) who are directly responsible for initiating and carrying out an immune response.  The MHC proteins differ in the type of foreign antigen that they are capable of presenting to immune cells.  For this reason, diversity at the MHC locus is important.  Having many different MHC alleles allows an individual to respond to a greater array of pathogens and foreign antigens, affording important protection against disease.  Moreover, since pathogens try to escape immune surveillance by mutating, it is less likely that a pathogen has adapted to a rare MHC allele, giving individuals who express it an advantage.

Pairing with a mate who is genetically dissimilar at the MHC locus translates into offspring that have a different immune repertoire than either parent.  Greater diversity in MHC genes increases the range of foreign antigens that will be recognized by the immune system, reducing the likelihood that a pathogenic organism will avoid detection.  The result is healthier babies.  Hosts and their pathogens are in an ongoing conflict.  Each time a pathogen learns a way to evade the host’s defenses, the host counters, by adapting to the pathogen’s trick.  Creating a unique and different combination each turn of the reproductive rachet presents a new face to pathogens, providing a significant edge in the battle against foreign invaders. 

Another explanation for MHC preferences is to avoid inbreeding between relatives.  If mice were to find individuals with whom they were raised as unattractive, and even repulsive mating partners, it would discourage mating with relatives.  The downside of marrying close relatives is that it results in the expression of too many recessive genes, many which can code for deleterious genetic disease and traits.

Whether MHC preference is learned or a hard-wired and innate behavioural response is unresolved.  Several experiments have suggested that MHC choice is learned early in development by imprinting.  Mice raised with foster families chose mates based on the MHC genotype of their foster mother, rather than their own MHC genes, suggesting that MHC attraction is an acquired taste.  Penn and Potts, Proc. R. Soc. Lond. Ser. B, 265:1299-1306, 1998.

Disputes over family property. According evolutionary principles, an individual behaves in ways that maximize his reproductive success.  A sacrifice will be made only under circumstances where it accrues to the long-term benefit to the individual.  The main driving principle is that humans act in their own self-interest at the expense of others.  The simple reason generally offered for the emergence of selfishness is that in a game between cheaters and altruists, it’s the cheaters who come out ahead.  A cheater not only refuses to share resources with others, but also tricks the altruist into giving up his own valuable resources.  Cheaters end up with the biggest pot, defeating altruists in the evolutionary game.  Assuming that the propensity for cheating is genetically inherited, eventually the cheating phenotype replaces the less robust, altruistic form.

Even though cheating behavior is successful in many cases, there are circumstances where cooperation is favored.  A number of reasons have been offered to explain why individuals cooperate with one another, especially when it means loss of valuable resources, as well as missed opportunity to reproduce.  Cooperation between relatives has been explained by a principle called “kin selection.”  According to this theory, relatives cooperate with each other because they share the same genes.  Helping a relative at your own expense may be worthwhile because it facilitates the spread of copies of your own genes present in the helped relative.  Individuals are known to forego reproduction and resources presumably in order to further the interests of their relatives who share a significant number of genes between them.  Cooperation between non-relatives has been explained by reciprocity.  If you are nice to an unrelated individual in a particular circumstance, he may repay you by assisting you in the future.  Exchanging favors can be beneficial to both parties in the long-run.  Ridley, M. The Origins of Virtue, Penguin Book, 1996.

Inheritance law provides a rich source of material on the topic of kin selection.  Consider the following two disputes over the disposition of decedent’s property.

In the Matter of the Estate of Earl Sherry, 698 P.2d 94 (Wash.App. 1985).  Earl and Beverly Sherry were married in 1947.  Over the course of their 26 year marriage, they produced 6 children and acquired a several hundred thousand dollar interest in a large farm.  In 1956, Earl executed a will leaving all his estate to wife, or in the event she died first, to his named living, and any after-born, children.  When the couple’s marriage ended in divorce in 1974, they executed a property settlement agreement that left their interest in the farm to their six living children, by name, in equal shares.  Earl remarried Francis several years later, adopting Francis’s child Jamie, born in 1974.  Jamie was also Earl’s biological son.  In 1982, Earl died. (By this time, his marriage to Francis was in the process of dissolution.)  Earl’s children of his first marriage immediately filed claim to their shares in the farm based on the property settlement, asking the court to enforce the contract and divide it among them.  At the same time, Jamie claimed a share in the farm land based on Earl’s 1956 will.  The probate court, relying on a doctrine of “balancing of equities,” refused to enforce the contract for the first marriage children, instead doling out an equal share to the child of the second marriage.  On appeal, the court affirmed the probate court’s decision not to exclude the child of the second marriage because to hold otherwise, it said, would invade the rights of the innocent party to the action, Jamie Sherry.

Gonzalez v. Satrustegui, 870 P.2d 1188 (Ariz.App. Div. 1 1993).  Nona Satrustegui and Frank Satrustegui had lived together for 14 years before his sudden death in 1988.  They jointly operated a bar in Williams, Arizona, pooled their income, held joint bank accounts and property, and filed joint federal and state tax returns.  Although Nona and Frank held themselves out as husband and wife, and managed their affairs as such, they had never been legally married in any state.  In 1986, they executed joint wills, each leaving all of their estate to the other spouse, should one predecease the other.  All previous wills were revoked.  The wills stated that the couple was married.  A bank employee notarized the Satrustegui’s wills, but a second witness signature, as required by Arizona state law was not obtained. After Frank’s death, according to his wishes as stated in the 1986 will, all his estate was distributed to Nona.  A year later, Frank’s sister, Mary, filed a petition with the court, alleging that the Frank’s assets had been improperly conveyed to Nona.  Her claim was based on a 1971 will executed by Frank that left all his entire estate to Mary.  The 1986 will, she asserted, was defective because it did not have the two requisite witness signatures, and therefore the 1971 will must be followed. The court agreed with Mary that the 1986 will was an ineffective testamentary disposition, ordered Nona to give an accounting of estate assets and income, and scheduled a trial to determine damages.

In both cases, a decedent’s will unambiguously left property to an intended beneficiary, but only in one of these cases did the beneficiary receive it.  In Sherry, the will did not identify the party by his specific name, but it did refer to the class of legatees – afterborn children – to which the party Jamie Sherry belonged.  Nona Satrustegui in Gonzalez was specifically named in the decedent’s will as the beneficiary of all his estate.  When the disposition of the decedent’s property was challenged in court – in Sherry, by the decedent’s children from his first marriage, and in Gonzalez, by the decedent’s sister – the rule applied by the court was the law of consanguinity – kinship by blood, or, in the language of evolutionary biology, kin selection. 

In their divorce proceedings, Earl Sherry and his first wife Beverly had executed a property settlement agreement that left their joint property in the hands of their biological children by name.  Considering that Jamie was born before the property settlement was executed between Earl and Beverly, it is difficult not to believe his omission from it was intentional.  Since the land had been jointly owned and farmed by the couple, it is reasonable that Beverly would have wanted to give it to her children, not Earl’s from an affair that apparently took place while still married to her.  The property settlement agreed on by both parties presumably reflected this intent.  There was only one reason not to enforce it – kin selection.

Inheritance law is erected on the paradigm of kin selection.  When it comes to wills and other testimonial bequests, relatives are favored over non-relatives.  From the evolutionary perspective, this is sensible since putting a decedent’s resources in the hands of his relatives is in his best genetic interests.  Doing so confers economic benefits to the individuals who share his genes, favoring them in the Darwinian struggle to survive.  The rule also achieves consistency by making the heirs to his money the same as the heirs to his genes.  The preference for genes is observed in Gonzalez, where despite the testator’s clear intent to leave his property to his longtime companion, the court awarded it to his sister.  The principle of fairness relied on by the Sherry court to distribute money to Earl’s genetic heir Jamie was simply a statement of their genetic consanguinity.  What is fair, after all, is that which society considers morally correct, and moral correctness is simply a reflection of what is good for the genes.