Similarities Between 'Charles Darwin And Blending Inherita'

As a child, one is constantly taught that a fact is simply an idea that can be proven. Albeit, in the scientific world, a fact connotes some form of evidence is needed, it is frequently used to describe a widely accepted notion about how the world works. According to the NCSE, a scientific fact is, “An observation that has been repeatedly confirmed and for all practical purposes is accepted as “true”” (para 2). These facts must be an observable function of the world, however, truth is subjective. What one society holds to be true does not always coincide with the truths held by a different society. Even within one society, notions perceived as the truth may change with time. The NCSE concurs that a scientific fact is fluid, and, “what is accepted
as a fact today may be modified or even discarded tomorrow” (para 2). Truth is fundamentally a social construct; if enough people in a society believe something to be true, it will become a truth within that society. Once believes shift, ideas considered as true are altered as well. The 19th century is notorious for its misconception of genetic inheritance.
During this time, it was widely believed that during the process of fertilization, the alleles of the parents would combine and create a middle-ground zygote, who would become a physical manifestation of the fusion. This was known as “blending inheritance.” Peter Vorzimmer writes in his essay, “Charles Darwin and Blending Inheritance,” “By the time the study of hereditary phenomena became a scientific discipline…blending inheritance had become accepted as axiomatic…In fact, it was, to many nineteenth-century naturalists, the rule” (4). Blending inheritance was accepted as a truth by 19th century society, thus, making it a scientific fact of that time. Fortunately, as society learned more about the process of genetic inheritance, the farcicality of this theory was plain to
see. Gregor Mendel, the scientist best known for his pea plant experiment, was able to easily disprove this erroneous conception of genetic inheritance. During the initial round of his pea plant experiment, Mendel crossed two green plants, one tall and the other short. According to blending inheritance, the two height alleles in these parent plants would merge and create a medium-height offspring. Unsurprisingly, the results did not support this idea. The offspring turned out to be a tall, green plant. Mendel repeated the same procedure four times, and each time it resulted in a tall, green offspring. The reason for this outcome is that the ‘tall’ allele is a dominant allele, and it trumps over the recessive short allele. When the two plants (short and tall) were crossed, the alleles did not mix, but were put together to create a heterozygous trait in the zygote. Since the dominant allele is always expressed in a heterozygous trait, all the offsprings were phenotypically tall. Just through this simple experiment, blending inheritance was refuted. There not much backlash or resistance to the debunking of blending inheritance.
This is mainly due to the fact that during the time it was being invalidated, Charles Darwin published his theory of evolution. Darwin claimed that evolution was made possible through adaptation by natural selection. From there, he created his three Necessary and Sufficient conditions: there must be variation in a trait within a population, the variation must be heritable, and the variation must influence the fitness of the population. Darwin’s postulates were chiefly evident in the finches of the Galapagos Islands, which was where modern-day anthropologists, Peter and Rosemary Grant, extensively focused their study of Darwinian evolution. The results collected by the Grants were startling. During the year 1977, the Galapagos Islands suffered through a period of extreme drought. This caused the seeds to become large and hard. Due to the change in the type of food available, large-beaked finches were able to exploit these newly enlarged seeds, whereas small-beaked finches were unable to do so, and many died off. However, six years later, in 1983, the island was struck by El Nino. This extended down-pour caused the seeds to soften and shrink in size. In contrast to the effect of the drought, the small-beaked finches thrived on the smaller seeds, whereas the large-beaked finches were not adapted to acquiring such miniscule seeds, and died off. This drastic change in weather and food availability is
clear evidence of Darwin’s theory of evolution. The finches that were able to adapt to changes in the environment survived and reproduced, whereas, those unable to adapt gradually died off. Considering the validity of Darwin’s theory, blending inheritance is nonsensical. Blending inheritance would have made it impossible for natural selection to favor a trait due to the fact that every individual would be a mixture of different alleles, and if nature were to favor one particular trait, only one individual would have that trait. This would thereby cause the extinction of Homo sapiens. Luckily, blending inheritance is just a preposterous idea, otherwise, I would not be alive today to take this physics course.