Passage A
In evolutionary biology, the "adaptationist program" has long operated on the presumption that virtually all prominent traits in an organism have been shaped directly by natural selection to serve a specific utility. Critics like Stephen Jay Gould famously challenged this, introducing the concept of "spandrels"—byproducts of other evolutionary changes that are not themselves direct targets of selection. However, while acknowledging that not every trait originates as a direct adaptation, contemporary neo-Darwinians correctly maintain that once a byproduct arises, it immediately becomes subject to selective pressures. Over sufficient time, neutral byproducts that persist are almost inevitably co-opted for utility, meaning that distinguishing between a "primary adaptation" and an "exaptation" (a co-opted byproduct) is historically interesting but functionally irrelevant to analyzing an organism's current fitness landscape.
Passage B
The enduring influence of the adaptationist paradigm often leads biologists to construct "just-so stories"—plausible but untestable narratives about how a trait was sculpted by environmental pressures. The fundamental error in this approach is not merely historical inaccuracy, but the masking of structural constraints on evolution. When a trait is an architectural byproduct—a spandrel—its form is dictated by the organism's underlying developmental constraints, not by adaptation. Recognizing this distinction is not mere historical pedantry; it fundamentally changes how we model evolutionary trajectories. If we assume a trait was sculpted for its current use, we overestimate the power of natural selection and ignore the deep phylogenetic constraints that limit evolutionary possibilities. Therefore, distinguishing true adaptations from co-opted byproducts remains a necessary theoretical imperative for rigorous evolutionary analysis.
Based on the passages, evaluate the following statement:
The authors of Passage A and Passage B disagree over whether traits that originate as evolutionary byproducts can eventually serve a useful function for an organism.
Cevap: Cevap