진화적 부산물

Although adaptations are the primary products of evolution, they are certainly not the only products. The evolutionary process also produces by-products of adaptations. By-products are characteristics that do not solve adaptive problems and do not have functional design. They are “carried along” with characteristics that do have functional design because they happen to be coupled with those adaptations, just as the heat from a light bulb is a by-product of design for light. —p40