The recent removal of Darwinian evolutionary theory from NCERT textbooks isn’t quite surprising. In fact, even back in 1859 when Darwin published On the Origin of Species, tremors were felt across several sectors of society, from science to religion. Evolutionism as a world view, the belief that natural and social systems were in a constant state of change, was a general and transformative principle, of which organic evolution, as proposed by Darwin, was a key advancement. Notably, Darwinian evolution was a late addition to the worldview of evolutionism. Nonetheless, owing to its implications, the idea attracted a lot of attention. In a letter to Friedrich Engels in 1860, Karl Marx stated that Darwin’s book contains “the basis in natural history for our view.” In a separate letter to Ferdinand Lasalle, Marx wrote that “Darwin’s book is very important and serves me as a basis in natural science for the class struggle in history.” The excitement of Marx and Engels had a twofold basis. First, the Darwinian theory of natural selection was a materialist theory that rejected Platonic and metaphysical ideals and substituted for them concrete forces among concrete existing objects. Second, it was a theory of change as opposed to stasis, part of the contemporary commitment to change.
Darwin’s proposition of a direct material force, defined as fitness, by which “nature” can “select” among variations within a species, in combination with his concentration on individual variation as the concrete object of study, created a mechanism for evolution that overthrew the earlier and contemporary ideas of evolutionary thinkers such as Lamarck and Geoffroy Saint-Hilaire. Darwinian evolution had three propositions:
- Individuals within a species vary in physiology, morphology, and behaviour, which is known as the principle of variation.
- Offspring resemble their parents on average more than they resemble unrelated individuals, also known as the principle of heredity.
Different variants leave different numbers of offspring, the principle of natural selection.
Evidently, these three propositions not only could account for change but for adaptation as well. Neither Lamarck nor Geoffroy Saint-Hilaire provided ad hoc explanations and had no empirical basis, whereas Darwin carried out extensive empirical studies to construct the propositions. Moreover, adaptive evolution in Lamarck’s conception of evolution entailed a metaphysical notion of “inner urge”, rooted in idealism.
A comparison of Darwinism with Newtonian ideas sheds interesting light. Newtonian revolution of the 17th century conceptualized abstracted and idealized bodies moving in ideal paths from which real bodies departed more or less. Idealization played a central and essential role in this case. Notably, Leonardo Da Vinci put forward a very similar understanding of nature, when drew his “ideal horse” following the golden ratio. Darwinian revolution of the nineteenth century on the other hand was totally removed in spirit and method from these ideas; he moved away from metaphysical concepts and brought to the fore the actual variety among natural objects (in this case species). For Darwin, variation is not an aberration but the norm, the driving force behind evolution.
However, it is worthy to note that Darwin’s theory of natural selection had key limitations. First, it did not deal with the origin of variation within a species. If selection chooses the most fit individuals, then eventually the species population should uniformly be the most fit type among those available in the beginning, leading to a lack of variation within the surviving population. Such a reduction in variation would lead to a decrease in natural selection and would destroy the necessary condition for further evolution. Later in the 20th century, the discovery of gene and genetic mutations led to a satisfactory explanation of a mechanism that could generate a variation within a species through the course of million years of evolution. Second, Darwin did not have a mechanism for the inheritance of variation. In Variation of Animals and Plants under Domestication (1868), he developed the “Provisional Theory of Pangenesis,” which postulated large numbers of unobserved “gemmules”, which were products of various organs and assembled in the reproductive organs. Darwin believed in mixing inheritance, whereby the characters of the offspring were somewhere in the middle between those of its parents. But this scheme of inheritance will lead to a decline in variation within a population. In other words, there was no solution to this contradiction until the discovery of Gregor Mendel’s pathbreaking experiments in 1900. Third, the theory of selection among variations could explain the slow transformation of a single species in time, but just via the three propositions, as described above, couldn’t explain speciation, i.e., the splitting of a species into diverse ones. An explanation of diversification required statements about the geographical distribution of species. If some members of a species colonized a new and distinct habitat such as an island, where environmental conditions differ from those the species is used to, natural selection would produce a new variety there and, as a result of its new adaptations, the island variety may no longer be able to interbreed with the main population. Darwin considered this process of speciation by geographical isolation, presumed at present to be the chief process of diversification, as particularly important. Darwin also postulated the possibility of speciation in organisms spread over large areas with many diverse ecological situations, even without sharp geographical boundaries between local populations. However, modern evolutionary theory puts somewhat less emphasis on the process of speciation in such quasi-continuously distributed species.
Darwinian theory of evolution was a quintessential product of the contemporary intellectual revolution. Consequently, it smashed the existing moribund ideas associated with the origin of life and the co-existence of different species. Nevertheless, just as it happens in any scientific field, new ideas have emerged in the field of evolution through the last one hundred and fifty years of rigorous research work; certain limitations of Darwinism have also been exposed, while some initial issues have been resolved. However, some of the fundamentals of Darwinian ideas, in particular, the emphasis on change and materialism remain a fulcrum in the field of evolutionary biology. The recent move in India to remove Darwinian evolutionary ideas in high school is the latest in many such attempts across the globe. Only truly revolutionary politics can embrace revolutionary ideas whereby a dialectical view of nature that sees socio-political and natural processes from a historical and holistic perspective is essential for the progress of society.
