Sociobiological Factors Of Ultimate Causation

Evolutionary biologists distinguish between proximate and ultimate or evolutionary factors in understanding inherited traits at two levels of evolutionary causality. Proximate research deals extensively with immediate details of a mechanism (i.e., physical structure including the molecules involved, or on whole organism levels, specific circumstances that elicit behavior). Ultimate research addresses adaptive features deduced from intergenerational and genomic mechanisms. Both levels of causation are indispensable sides of a same coin, but, thus far, evolutionary psychology/psychiatry has largely taken up issues of ultimate causation.

The relatively new field of sociobiology (Wilson, 1975) concerns itself with biobe-havioral processes from ultimate causation to proximal expression. It is deeply rooted in the behavior genetics, developmental psychobiology, and sociobiology that preceded it (e.g., Bowlby, 1969; Scott and Fuller, 1965). The impact of Wilson's contributions was tempered by wide controversy including a rebuke from Gould and Lewontin (1979) that evolutionary "just so" stories were unsupported by research data and should be avoided. Segerstrale (2000) comprehensively reviewed the sociobiology field and concluded that by deploying scientific rules of evidence, sociobiological research has resulted in a solid body of data, earning it legitimacy as it moves beyond the rather political considerations of early critics.

Ethology is a related approach. Ethologists examine animal behavior via Tin-bergen's four perspectives: (1) mechanistic—neural, physiological, or psychological elements underlie expression and registration, (2) ontogenetic—development in an individual's life, (3) functional—how a given trait helps survival and reproduction, and (4) phylogenetic—how ancestral and contemporary features overlap or diverge. Ethology and sociobiology complement one another and are also compatible with psychiatry. They may assist the pathophysiological formulation of its conditions. The emergent field of evolutionary psychology has focused on selected features of this intellectual arena, reflecting how ultimate evolutionary theoretical framings and more proximal empirical analyses can cross fertilize each other.

Much work labeled as evolutionary psychology centers on altruistic behavior and inclusive fitness. Reciprocal altruism refers to exchange mechanisms ("I do for you and in return you will do for me") and does not represent altruism in the sense of losing or risking something for seemingly little gain (like losing one's life to rescue another person). Social insects present the outward paradox that nonreproducing members of the colony (e.g., helper ants, worker bees) work hard for the group, yet their individual genes do not directly descend to subsequent generations. Puzzled about how such insects evolved, evolutionary geneticist William Hamilton (1964) recognized that gene frequencies in relatives resemble each other proportionately more than do those of less related individuals (relatives share "the same genes") and, hence, indirect reproduction was possible via selection within an inclusive kinship.

Dawkins (1976, 1989) popularized Hamilton's ideas using the "selfish gene" met-aphor—an organism transiently embodies an immortal gene that never dies so long as the reproductive line perseveres or until mutation occurs. Hamilton's formula hinges on genetic relatedness and reads: C < Br [where C represents the costs to a giver, which must be less than the fitness benefits (B) obtained by helping an individual whose degree of relatedness is indicated by value r].

Hamilton's reasoning and formulas have been applied widely in evolutionary psychology to explain altruism in many species, including humans, and at various physiological levels ranging from germ cell to kin lineages. Daly and Wilson (1988) predicted that benefit and hostility to others would occur in proportion to kinship, and they documented that closer genetic relatives display greater benevolence and less deadly hostility toward each other with respect to familial violence. Spouses, in-laws, and step-children die more often in family violence by a factor of 10, compared to parents, siblings, and genetically related children. Moore et al. (2002) invoked similar Hamiltonian thinking for their findings on sperm behavior of European deer mice. Some sperm "paved the way" for others in the same ejaculate so that the latter gain more rapid access to the ovum. This "teamwork" allowed the first ejaculator to out-race sperm from other males mating near the same time. Since the helper sperm lost their capacity to bind to the zona pellucida and fertilize, they displayed altruistic behavior from an inclusive fitness perspective.

Darwin's (1871) proposals on sexual selection likewise remain central to evolutionary thinking with renewed interest in male-male competition on one hand and female selectivity on the other. Females possess greater investment from the greater time and body resources (e.g., ovulation, lactation) devoted to offspring, as well as a lower level of possible fecundity. This contrasts with males who sometimes invest only ejaculate with no ensuing parental concerns. Due to somatic constraints, fathers can never invest as much affiliation as mothers. This dichotomy of parental investment (Trivers, 1972) explains why females often demonstrate choosiness about prospective mates—estimating which candidate will produce better quality offspring, examining, for instance, fighting ability, cleverness, and health (lack of anemia may be assessed through red skin or appendages). The peahen illustrates another estimation of health, for example, when she evaluates the "ornament" of the peacock's tail. If fancy tails indicate male healthiness (he can afford such "luxury"), the better her offspring would be with his genes. It has been suggested that human estimations of "beauty" link to such fitness detection concerns (Miller, 2000).

Likewise, numerous authors (see Hrdy, 1999) note infanticide in many species practiced by a male newly consorting with the mother. He does this so that, in ultimate causation terms, his own genes sooner have access to the female's reproductive efforts and also to help assure that his own effort is not "cuckolded." In many species females quickly become fertile upon no longer nurturing the young of the previous father. Also, maternal infanticide can result from a mother's estimation of poor resources. For example, a woman early in life may kill her children, but later if married well, typically displays model maternal attachments. Some human cultures have sanctioned the culling of infants that may not thrive. Proximate mechanisms sometimes overcome ultimate gain. Hrdy (1999) points out that efficient proximate mechanisms sometimes eclipse the optimal relational, inclusive-fitness calculations of Hamilton, Trivers, and others. For instance, humans and other primates exhibit one such phenomenon prominently in the form of allomothering—infant care by other females ("aunties") or by adoptive parents.

Trivers (1974) suggested parents and offspring feel different values according to their roles, which explains many sibling and parent-child conflicts. For example, siblings commonly compete even though parents typically urge that they not; each sibling wishes to gather as many resources as possible, but the parents wish to apportion these equally, given that each child carries on an equal number of parental genes. Deriving from this tradition, Haig (1996) noted some genes even within a body might compete with others, as with eye color. Alleles with a gene from each parent express only one (dominant versus recessive). Examining imprinted genes conferred separately from mother and father, Haig investigated facets of pregnancy and fetal growth and concluded that certain of the father's genes seem to exploit the mother maximally for as many offspring as possible while hers work to conserve her resources to do a better job on fewer. Even body tissue may derive from one parent instead of the other; for instance, the elements of cerebral cortex may derive more from maternally imprinted genes, while development of subcortical areas (in mice) are influenced more by paternal ones (Keverne et al., 1996). Since subcortical areas facilitate emotional sociophysiology while cortical tissues foster more cognitive distinctions, it may be that paternal genes influence the more instinctual-emotional aspects of reproductive skills while maternal genes are more important for cognitive-economic decisions.

The scientific paradigm that "selfish motives" operate in organisms and their subparts (e.g., genes) via robustly neoDarwinian selection originally arose to counter earlier ideas that individuals perform altruistically for the "good of the group." This elicited powerful rebuttals reliant on precise application of Hamilton's kinship selection formulas. But in recent point-counterpoint contributions, commentators suggest models by which tightly bonded groups can indeed be considered "organisms" or adaptive units, wherein altruism operates at the level of group selection (as distinct from the direct consanguinity ratios that drive kinship selection); therefore self-sacrifice and altruism may merit more complex explanations (D.S. Wilson, 2002).

All humans are related to one other in the sense of sharing comparable genes, but this does not prevent formation of conspecific subgroups, alien and antagonistic to one another (Wrangham and Peterson, 1996). For example, human laughter facilitates in-and out-group operation: Bonding laughter cements in-group relations, but mocking laughter emphasizes the rejection of alien individuals (Eibl-Eibesfeldt, 1989). Obviously, scorn, shunning, and shame powerfully act in human emotional homeostasis and sociophysiological cascades that can promote mental distress.

LeCroy and Moller (2000) summarize evolutionary psychological perspectives from the human vantage point, whereas Wrangham and Peterson (1996) use a comparative primate perspective in a book provocatively titled Demonic Males. Chimpanzees and humans display similar male-bonding and warfare strategies, for instance, that dramatically contrast to bonobos, where females are far more influential perhaps in part as this allows them greater social time dedicated to sexual communication with less hostile aggression.

Psychiatric symptoms can sometimes represent proximate sociocommunicative mechanisms imprecisely deployed. Evolutionary psychiatrists have speculated that, if an individual's communicational mechanisms are stimulated at a time and place other than that which spawned its ultimate "design," then the person may develop a disorder. This relates closely to mismatch theory, which holds that mechanisms evolved for life in previous eras may not suit the present time (Bailey, 1989). In technical terms, this may reflect an aspect of genomic phenotypic elasticity. Along with Hamiltonian and selfish gene ideas, Glantz and Pearce (1989) utilized mismatch theory to formulate guidelines for an approach they called Evolutionary psychotherapy.

Darwinian game theory represents another powerful heuristic, particularly as population geneticist Maynard Smith (1982) specified evolutionary stable strategies (ESS) to analyze how individuals compete for heightened reproductive fitness in each generation. For example, a K -reproductive strategy entails much attention to the well-being of offspring, whereas another, r-reproductive strategy, entails fertilizing as many females as possible but investing little or nothing in those produced so that quantity gains emphasis over quality. Mealey (2000) elaborated how sex differences represent different developmental and evolutionary strategies. One of the most striking examples is male sociopathy with its characteristic selfishness and exploitation.

Over a century ago, Robertson (1890) suggested the symptoms of disease need to be traced to the functions of health, and that both need to be carried back to their origin in evolution. The next section deals with how this suggestion results in pathogenetic formulations for psychiatry. How has psychiatric disorder deviated from usual sociophysiological order?

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