It has been previously noted that in the course of evolution, morphogenesis has changed toward a reduction of the influence of external factors on the developmental process, making it more independent (Schmalhausen, 1949). In contrast with the proposed “target morphology” concept (Fields et al., 2020), organisms shapes form/result through an increasingly narrowing canalization of development. Organisms do not grow to a form (“target morphology”), but rather develop, resulting in it (“resulting morphology”). The difference between these growth modes is easily appreciated in their interaction with the environment: in the first strategy, the outcome is strictly set, while the second one allows intergenerational modifications to take place in accordance with changes taking place in the environment. Development, thus, —even if including target-directed cell movements— can be compared to a sort of extremely complex and highly regulated crystallization, which does not require some reference with which its advance should be compared (Levin, 2020). Living forms familiar to us, thus, result from the relatively stable environment they develop within (and, in many cases, from which influence they additionally isolate their ontogenesis). Morphological changes induced by changes in the environment (Schmalhausen, 1949; Tung and Levin, 2020) support this view on development, and is one of the sources of phenotypic variation in changing environments: the genotype in such conditions may still remain the same, but the phenotype expressed on its background can differ (Schmalhausen, 1982). Very similar to the case we presented for cells in the developing organism, observable living forms arise as “norms of reaction” in environments which typically have a limited and defined range of variability. The fitness of the emerged living form with the available environment determines whether it will survive (“be selected for”) or not (Schmalhausen, 1949, 1982). Interestingly, a similar regulation has been noticed at the tissular level: mechanisms controlling organ size regulate their overall size, and not the underlying proliferation of individual cells (Svetlov, 1978; Eder et al., 2017). Thus, development (and specification, as its particular case) can be considered to peak when no specialization/specification is further possible within the given environment. These are elements of the general theory of development we will not approach in the present work.
Видел в другой статье разбор "случаев новизны", возникновения нового в эволюции. Там вывод был примерно такой: большинство случаев связано с функциональным изменением генов, это не настоящая новизна, и лишь в одном случае - настоящая новизна, структурное изменение гена.
Как интересно складывается мышление. Нечто возникло как новое, но ему отказано в "новизне", поскольку некоторые сторонние соображения и критерии не выполнены. Новым предлаггается считать не просто новое генетически, но - определенным образом "генетически".