The idea of preformism It is used in the field of biology to allude to the theory developed by the defenders of the preformation. The concept of preformation, meanwhile, arose in the 5th century BC stating that the structures of an adult organism are already present in the embryo of living beings, although miniature.
It can be said that preformism is a theory already discarded. According to the preformationists, the development of life takes shape from the growth of a homunculus found in the zygote.
Preformism is the opposite doctrine of epigenetism, which attributes the formation of the individual to a differentiation process that begins with a fairly homogeneous content. For preformism, there is no differentiation, but the organism is formed from the embryo.
Within preformism, a distinction was made between those who held the ovism (they believed that the being already formed was located in the Ovum unfertilized) and supporters of animalculism (which placed him in the semen).
The invention of microscope contributed to the rise of preformism. Many scientists, when detecting sperm, they believed that it was the homunculi or animáculos that were growing until the formation of the complete organism. The dutch Jan Swammerdam, the French Nicolas Malebranche, the Italian Marcello malpighi and german Gottfried Leibniz they were among the researchers promoting preformism.
When studying the history of preformism we can see different stages, and between them they span several centuries, even more than a millennium. Its origins go back to the Greece of the 5th century BC, at the hands of the philosophers Leucippus of Miletus and Democritus, who defended these ideas with great force.
However, it took several hundred years for this concept to gain more force and prevail in the scientific community of the time. From the second half of the seventeenth century, for various reasons preformism began to live what would be its boom. Its success was due in large part to the failure of Descartes to provide convincing evidence to support his theory of mechanistic epigenetism.
Another reason why preformism became so important at that time was the aforementioned invention of the microscope; We must not forget that until then the existence of the sperm, and their discovery was revealing for the scientific community, although at first they have not interpreted them in the most correct way.
The developing and the use of integral calculus (also called integration or integral) was another of the pillars of the success of preformism. This concept is defined as a way of generalizing the sum of infinite factors, of an infinitely small size; In other words, it is a continuous sum that is opposed to the operation known as derivative. In this context, he opened the doors to the assumption that matter could be divided infinitely, that is, that there were organic structures of an infinitely small size.
And so we come to the time of preformism known as neopreformism, where the mosaic development theory, according to which the nature of the parts of the body it is determined previously at the beginning of its development and independently of the rest.
We can also talk about genetic preformism, which is based on the following statement: the phenotype (according to biology and genetics, is the way in which genetic information is expressed according to the environment in which the organism is located) is absolutely encoded in the genotype (the genetic information present in organisms).
In the middle of century XVIII, preformism began to lose strength. On the contrary, at that time the postulates of epigenetism took on greater notoriety.