Hierarchy of evolutionary analysis

The view that evolutionary analysis can be divided into several levels of hierarchy.

General evolutionary theory

General theory based on inclusive fitness forms the top level:

The first level of analysis is general evolutionary theory. In its modern form, general evolutionary theory is understood as inclusive fitness theory. Adaptations are selected and evolve as a consequence of the degree to which they promote inclusive fitness. … At this general level, even though we talk about evolutionary “theory”, it is widely acepted by biological scientists as fact. … There are observations that could falsify general evolutionary theory. …

General evolutionary theory is the guiding paradigm for the entire field of biology as well as for evolutionary psychology. So when an evolutionary psychologist tests an evolutionary hypothesis, he or she is not testing “general evolutionary theory,” which is assumed to be true in its general outlines. Becuase no compelling alternatives have been proposed over the past centry, and because there is overwhelming evidence supporting general evolutionary theory, these assumptions are reasonable. —p42-44, Evolutionary psychology

Middle-level evolutionary theory

Middle-level theories derived from inclusive fitness, such as parental investment:

Moving one level down, we find middle-level theories such as Robert Trivers’s theory of parental investment and sexual selection. These middle-level theories are still fairly broad, covering entire domains of functioning. …

You can see that Trivers’s middle-level theory is compatible with general evolutionary theory; he is not proposing something that could not come about by the evolutionary process. At the same time, however, parental investment theory is not logically derivable from general evolutionary theory. There is nothing in inclusive fitness theory itself that says anything about parental investment. Thus middle-level theories must be compatible with general evolutionary theory, but they must also stand or fall on their own merits —p44-45, Evolutionary psychology

Specific evolutionary hypotheses

Specific evolutionary hypotheses. The content that people usually criticize as “just so stories” mainly falls at this level or the one below it.

One hypothesis that has been advanced for humans, for example, is that women have evolved specific preferences for men who have a lot of resources to offer. The logic is as follows. First, because women invest heavily in children, they have evolved to be choosy when they pick mates(standard prediction from parental investment theory). Second, the content of women’s choices should reflect whatever has historically increased the survival and reproduction of their children. therefore, women are hypothesized to have evolved mate preferences for men who are both able and willing to contribute resources to them and their children. This is an evolutionary psychological hypothesis because it proceses the existence of a specific psychological mechanism - a desire - that is designed to solve a specific human adaptive problem - that of securing a man who appears highly capable of investing in children.

This specific evolutionary psychological hypothesis can be tested empirically. Scientists can study women across a wide variety of cultures and determine whether they in fact prefer men who are both able and willing to contribute resources to them and their children. To provide strong tests of the hypothesis, however, we must see what specific predictions it generates - specific predictions derived from hypotheses. —Evolutionary psychology

Specific predictions derived from hypotheses

Specific predictions that can be derived assuming the hypothesis is true:

On the basis of the hypothesis that women prefer men who have a lot of resources to offer, we could make the following predictions:

women will value in men specific qualities known to be linked with the acquisition of resources such as social status, intelligence, and somewhat older age;

in a singles bar, women’s attention, as measured by eye gaze, will be drawn more to men who appear to have resources than to men who do not; and

women whose husbands fail to provide economic resources will be more likely to divorce them than women whose husbands do contribute economic resources.

—p45, Evolutionary psychology

Falsifiability

Falsifiability in evolutionary analysis:

This hierarchy of levels of analysis is useful in answering questions such as: What evidence could falsify evolutionary formulations? A particular hypothesis about a psychological mechanism could be wrong, even if the theory one level up that led to the hypothesis is entirely correct. Robert Trivers’s middle-level theory of parental investment could be correct, for example, even if it turned out that women have not evolved specific mate preferences for men with resources. Perhaps the relevant mutations for women’s preferences did not arise, or perhaps women in ancestral conditions were constrained from making their own mating choices.

Similarly, even if the specific evolutionary psychology hypothesis is correct - in this case, that women have evolved specific mate preferences for men with resources - there is no guarantee that each and every prediction derived from it will be correct. It might be the case, for example, that women do desire qualities in men linked with resources but do not divorce men who fail to provide for them. … The key point is that the evaluation of evolutionary formulations rests with the cumulative weight of the evidence, and not necessarily with any single prediction. Evolutionary hypotheses, when formulated precisely, are highly testable and eminently capable of being falsified when the evidence fails to support predictions derived from them. —p46, Evolutionary psychology