Evolutionarily speaking, all organisms' eco-adaptation is established in the history of biosphere evolution. The highest level adds "background design" to the next sublevel until the lowest level; during that process components differentiate under the eco-adaptation of the upper level and acquire specific behavior and meaning. The being's design history is a history of natural selection.
So we can deem that all studies about adaptation are essentially research on the deep structure, the issues of "ultimate cause" named by Mayr. In fact, the meaning of life primarily is a traditional issue of diversity biology, and it can be traced back to the early diversity comparison of traits or organs. This research arises from the human instinct to ask questions about nature. When a person sees a plant that is similar to another plant in leaves, shape, and branches, but not flower color, he may probably ask why it is so, and that is the beginning of comparative study. Afterward, the comparison develops further and further. Mayr sums up the life-meaning research as a quest for the ultimate cause of life structure and function, and puts it parallel with the investigation of the proximate cause of life structure and function.
But the systematics have discovered preliminary meaning relations by comparing species' phenotypic characters, and evolutionary biology discovered the meaning system by comparing evolutionary relationships between species.
However, they have not touched on the structure of meaning at the physiological level. So systematics can be seen as the early stage of meaning studies, and evolutionary biology can be seen as the medium stage. Since substantive evidence of life background vitastate has been found in intraspecific comparative research, meaning study is moving toward a deeper understanding, making a breakthrough in explaining adaptation physiologically. Then adaptational biology was born. And the deep-structure concept provides a theoretical tool for the interpretation of the meaning relationship.
In short, diversity research is essentially different from functional research. Its history shows that during its long developmental course, it has been looking for a hypothetical basic ideal that is long-lasting and remains unchanged. It believes that behind species' diversity is a deep-seated systemic order. This order goes beyond individual animals, at the same time infiltrating the internals of individuals and running through all the internal and external levels of individuals. It is not illusory and immaterial, and its true features can be revealed by comparison and classification. All the scholars engaged in classification may have this belief to some degree. This ideal is very different from the tradition of functional biology; although biology has undergone changes, the ideal remains the same and always in its independent line.
Functional biology seeks the effect-relation order among constitutional parts, inevitably pursuing the cause of processes, and this enables route tracking to become the essential approach. As the biotic routes have levels from the macrocosmic to microcosmic, this necessarily leads route tracking to go from macrocosmic to microcosmic; otherwise it could give rise to black-box and coarse-grain problems. Thus, seeking effect-relation order will lead to the reductionist research of the functional structural relation of the constitutional parts. Therefore, functional biology starts by experimenting on constitutional relationships, then proceeds to study the network system of functional relationships among constitutional parts, and finally takes shape by forming its core¡ªthe cause of the functions. These are the three main components of functional biology, with a core running throughout: function.
Diversity biology seeks the deep-seated systemic order, inevitably going on to pursue the cause of species diversity. The deep-seated systemic relationship among species of the existing biosphere, and in relation to species eliminated in the past, can only be found by delving into the historic origin and evolution of the species. Thus, the pursuit of a deep-seated systemic order may further develop to evolutionary research. As a result, we say that adaptational biology starts from systemic comparison and classification of species, and then goes to the basic level, studying the deep-seated systemic order of the biosphere, and finally finds the cause of evolution (that is the core of adaptational biology).These are the three main components of adaptational biology, with a central concept running throughout: adaptation.