It's adaptations all the way down

Abstract

Although antiadaptationist authors encourage us to consider alternatives to adaptationist positions, the alternatives offered do not necessarily relieve us of the burdens of adaptationist explanations. Even if something is an exaptation, it may be derived from an adaptation. If it is a byproduct, it is a byproduct of an adaptation. Even the ELM, the hypothetical exapted learning mechanism, is an evolved learning mechanism, though used outside its natural domain.