Phylogenesis corresponds to the phylogenetic development of a species of living things. Thus, it is concerned with the processual evolutionary history of humans and other species and with the characteristics that distinguish these species. Studies on phylogenesis correspond to an analysis of single or multiple traits and are often summarized in phylogenetic trees. Phylogenetic analyses can also be performed on individual diseases.
What is phylogenesis?
Phylogenesis corresponds to the phylogenetic development of a species of living organisms. The term phylogenesis is used in biology to describe the phylogenetic development of a body of living things and their related groups. Sometimes the term also includes the progressive development of individual characteristics in the course of developmental history and in this case includes above all connections of evolution. Phylogenesis must be distinguished from ontogenesis, which refers to the development of single individuals within a particular species. A phylogenetic reconstruction for a particular group always takes place through studies of its hereditary characteristics. This analysis of traits is done on the living species as well as on its fossil representatives. The reconstruction of a phylogenesis aims at the clarification of relationships of individual species and, with taxonomy, also enables the reconstruction of phylogenetically natural systems. Often phylogenetic relationships are made visible by means of a representation in the phylogenetic tree.
Function and task
Phylogenetic studies exist for a variety of holistic, as well as individual, human traits. For example, there are now phylogenetic accounts of language that specifically address the emergence of language during its course and include molecular genetic studies of language genes. The morphology of the speech and language organs has been compared in these phylogenetic studies. Based on this comparison, the researchers described the evolution of language starting with unicellular organisms and concluding with recent humans. The speech genes of humans were compared molecularly with those of other animals such as mice, songbirds and microorganisms. The aim of the phylogenetic studies was predominantly to improve our understanding of human language. In addition to the question of where language is needed and the limits of language performance, epistemological questions arose. Phylogenetics provides the answer to the latter, that a species knows only as much of the truth as is compatible with the survival of the species. In phylogenetic comparisons of the morphology of speech and language organs, human language in particular has been compared with that of the chimpanzee. Because the chimpanzee has a rather irregular set of teeth and a shallow pharynx in addition to a widely advanced jaw, it has difficulty articulating in the direction of human speech. Genetically, however, humans and chimpanzees possess almost identical genes for speech motor skills. The chimpanzee is also better suited for the cognitive tendencies of human speech than any other species. In addition to this and similar phylogenetic studies, contemporary embryology, for example, also involves phylogenetic questions. In this field, for example, the main question is whether the development of a single organism can be understood as a reflection of the phylogeny. In this context, structures such as the pharyngeal arches of the human embryo play a role, which, from a phylogenetic point of view, probably correspond to relicts of features of the phylogenetic ancestors and would thus be comparable, for example, to the gills of fish. Causal links between phylogenesis and ontogenesis are a relevant area of research in embryology. In this area of research, phylogenesis addresses, for example, whether genetic control and developmental genes or embryonic formation principles and mechanisms can be understood as central targets for mechanisms of evolution or species change.
Diseases and disorders
In principle, individuals usually suffer from disease during ontogeny with severe deviations from phylogeny.Phylogenetic studies sometimes take place with respect to specific diseases themselves, in which case they attempt to trace the history of a particular disease in a given species and the adaptations of the species that may have resulted. An example of a disease for which phylogenetic studies exist is the HIV virus. Phylogenetic analysis of the viral disease suggests that the HIV virus has passed from an animal, such as a monkey, to a human individual three or even more times entirely independently. Using molecular clock 2, a time frame between 1930 and 1940 can be determined for this, with Africa emerging as the original country. These conclusions could be reached by reconstructing the phylogenies of different variants of the HIV virus. Diseases, of any kind, are examined for their history in the human species by means of phylogenetic analysis. For example, if there is a longer history of certain diseases in a given strain, the host and germ become more and more adapted to each other. Phylogenetic considerations have become the focus of research not only on diseases, but also on human bodily processes such as coughing. In this case, phylogenetics proves that the vital functions of swallowing, vomiting and breathing had to be protected by reflexes in all vertebrates due to the gill gut, as the anatomical structures can easily mix them up. Fish spew sturgeon particles or inedibles from the gill basket through the mouth by means of a powerful contraction at the pharyngeal muscle. Terrestrial vertebrates have a separation of the functions of coughing and spitting. The lungs and pharynx of these creatures are cleared of particles by coughing. The esophagus and stomach, on the other hand, rely on spitting. Land creatures clean the nose by means of sneezing.
