Das Strategic Pluralism Model

Eine interessante Betrachtung zum „Paarungsverhalten“ beim Menschen liefert das Strategic Pluralism Modell, dass stärker als die Sexual Strategies Theory (SST) darauf abstellt, dass verschiedene Situationen verschiedene Verhaltensweisen erforderlich machen:

During human evolutionary history, there were “trade-offs” between expending time and energy on child-rearing and mating, so both men and women evolved conditional mating strategies guided by cues signaling the circumstances. Many short-term matings might be successful for some men; others might try to find and keep a single mate, investing their effort in rearing her offspring. Recent evidence suggests that men with features signaling genetic benefits to offspring should be preferred by women as short-term mates, but there are trade-offs between a mate’s genetic fitness and his willingness to help in child-rearing. It is these circumstances and the cues that signal them that underlie the variation in short- and long-term mating strategies between and within the sexes.

Quelle: The evolution of human mating: Trade-offs and strategic pluralism

Dazu aus dem Artikel:

In the last two decades, evolutionary theorists have begun to acknowledge that selection pressures should not have produced a single “best” mating tactic (or mixture of tactics) for males and females in most species. Instead, selection should have fashioned considerable phenotypic diversity in mating (Gross 1996). Guided by concepts from game theory (Maynard Smith 1982 [see also Maynard Smith “Game Theory and the Evolution of Behaviour” BBS7(1) 1984]) and the theory of evolutionarily stable strategies (Dawkins 1980; Parker 1984), evolutionary biologists are now documenting how having alternative mating tactics gives individuals of each sex differential reproductive fitness in various species. Although relatively little theory and research have focused on the mating behavior of human beings, hundreds of studies have confirmed that males and females in a wide range of species display alternative mating tactics that reflect conditional strategies (Gross 1996). Burley’s (1986) finding that male zebra finches’ relative allocation of parental effort and extrapair mating effort is contingent on their attractiveness is a good illustration of a conditional strategy. Conditional strategies have five main properties (see Gross 1996):

(a) They involve different behavioral tactics that are consciously or unconsciously “chosen” by an individual;

(b) the choices between tactics are “made” in response to specific features or cues in the environment, often an individual’s status or attractiveness relative to other individuals;

(c) all individuals are genetically monomorphic (i.e., they are are genetically designed to enact the same tactics);

(d) during their evolution, the average adaptive values of different tactics were not equal except at a “switchpoint” on a continuum of environmental input (e.g., individuals’ relative status) where the costs and benefits of each tactic balanced out; and

(e) during their evolution, the chosen tactic tended to yield higher fitness for the individual than other tactics given current environmental conditions.

Thus, the environmental conditions moderate the fitness gains of pursuing different tactics (e.g., exerting parental effort, pursuing short-term matings), thereby affecting the optimal allocation of effort to different tactics. If males differ in the conditions under which they engage in different tactics, they are enacting alternate conditional strategies. Although alternate strategies can be noncontinuously distributed in a population (e.g., if certain males never invest in offspring and always seek short-term mates), they are usually distributed continuously. This should occur if males differ in how long they tolerate their mate’s absence before pursuing other mates, or if males differ in the degree to which they expect extra-pair mates to have certain desirable attributes (Dominey 1984). Alternate strategies can reflect genetic polymorphisms (see Gross 1996). Although such polymorphisms exist in nature and may underlie certain variations in human mating strategies (see Gangestad & Simpson 1990; Wilson 1994), we focus on conditional strategies in this article.

Und aus der Zusammenfassung:

Mating tactics are highly variable in both men and women and have evolved to be contingent on environmental factors. Complete theories of mating strategies must account for these individual differences and contextual effects. We have proposed that these phenomena cannot be fully understood without considering the nature of the trade-offs that underlie mating decisions in humans. We suggest that good gene sexual selection, in concert with good-parenting sexual selection, may have generated the variation and contextual effects associated with the short- and long-term mating tactics witnessed in both sexes. Given the demands of biparental care during evolutionary history, both men and women were selected to use long-term mating tactics and invest in offspring. However, they were also selected to use ecologically contingent, conditional mating strategies, dedicating some effort to shortterm and extra-pair mating under specific conditions.

Women may have evolved to trade off evidence of a man’s genetic fitness for evidence of his ability and willingness to invest in offspring. The specific mating tactics and preferences women adopted, however, depended on the nature and quality of their local environment. If the local environment was difficult and demanded biparental care, women placed more weight on the investment potential of prospective mates and less weight on indicators of their genetic fitness. As a result, a larger proportion of women adopted long-term mating tactics almost exclusively. If, on the other hand, the pathogens were prevalent in the local environment (or the environment signaled the importance of the genetic fitness of offspring), women placed more weight on indicators of the genetic fitness of prospective mates. In such environments, a larger proportion of women were willing to engage in short-term, extra-pair matings, allowing them to gain genetic benefits from men who provided less parental investment at the risk of losing parental investment from their primary mates. The mating tactics and preferences of women accordingly reflected the nature and quality of the environments in which they lived.

Whereas women “tracked” their environment, men tracked and adjusted their mating tactics and preferences to the behavior of women (Thiessen 1994). If most women expected heavy paternal investment, most men (especially those who displayed less fitness) offered more and perhaps exclusive parental investment, dedicating a greater portion of their effort to long-term mating tactics and parental investment. As a result, variance in men’s mating success was reduced. If women’s “demand” for genetic benefits increased, some men (especially those advertising such benefits) dedicated more effort to short-term, extra-pair mating tactics, thereby increasing variance in mating success among men. Only a small proportion of men (i.e., those who displayed the most fitness) were able to carry out short-term tactics successfully at all times, regardless of the environmental factors to which women were responding.

Hier zeigt sich auch gut das Zusammenspiel von biologischen Modellen mit der Umwelt. Je nach dieser können sich andere Verhaltensweisen lohnen. Auch wenn dadurch ganz andere Kulturen entstehen, kann das Modell, welches diesem Verhalten zugrundelegt, biologisch sein.