In a landmark 1979 paper with an absurdly long title (look it up for a laugh), gould and lewontin laid out an argument against automatically considering that all organismal structures, fuctions, and traits are adaptive in nature. statement 1: this paper laid the gorundwork for researchers to recognize that bird/dinosaur feathers are ikely not adaptiations for flight. Statement 2: However, we also know that different types of feathers are adaptive for different aspects of flight. For instance, peregrine falcons have particularly elongated wing feathers that are considered an adaptation for extremely fast flight - peregrines are in fact the fastest living animals on the planet. How do we know that feathers in general are not an adaptation for flight (related to statement 1)?

Adaptation is a difficult concept for scientists to describe. While we have an idea of what adaptation means and how it has worked through history, it is still a slippery concept. Moreover, there are various ways in which adaptation can be understood. Some researchers believe that adaptive traits were built by natural selection for their current roles. Others believe that adaptations are derived relative to traits of antecedent taxa. Finally, other require evidence of functional design in the biological characteristics that underlie the trait. However, we know that adaptations (such as feathers) do not always respond to a particular need (such as flight). This is because there is no perfect correspondence between the needs of the organism and its characteristics. Instead, what we find is a spectrum or more or less effective species in a particular environment. Therefore, contingency appears to have played a large role in adaptation.

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