From earliest times, man became aware of the importance of male and female in the generation of beings of the same species, and that characteristics such as height, skin color, etc., were transmitted from parents to descendants.
Thus, of course, a female dog when she crosses a dog will originate a puppy with characteristics of a dog and never a cat. But why?
Mendel, the initiator of genetics
Gregor Mendel was born in 1822 in Heinzendorf, Austria. He was the son of small farmers and, although a good student, had to overcome financial difficulties in order to study. In 1843, he entered as novice in the Augustinian monastery of the city of Brunn, today Brno, in the present Czech Republic.
After being ordained a monk in 1847, Mendel joined the University of Vienna, where he studied mathematics and science for two years. He wanted to be a natural science teacher, but failed the exams.
Back in Brunn, where he spent the rest of his life, Mendel remained interested in science. He did meteorological studies, studied the life of bees and grew plants, producing new varieties of apples and pears. Between 1856 and 1865, he conducted a series of experiments with peas to understand how hereditary traits were transmitted from parent to child.
On March 8, 1865, Mendel presented a paper to the Brunn Society of Natural History, in which he enunciated his laws of heredity, deduced from experiments with peas. Published in 1866, dated 1865, this work remained virtually unknown to the scientific world until the early twentieth century. As far as is known, few read the publication, and those who read failed to understand its enormous importance to biology. Mendel's laws were rediscovered only in 1900 by three independently working researchers.
Mendel died in Brunn in 1884. The last years of his life were bitter and full of disappointment. The monastery's administrative work prevented him from devoting himself exclusively to science, and the monk was frustrated that he had received no public recognition for his important discovery. Today Mendel is considered one of the most important figures in the scientific world, being considered the “Father” of genetics. In the monastery where he lived there is a monument in his honor, and the gardens where the famous pea experiments were carried out today are preserved.
The choice of plant
The pea is a legume herbaceous plant that belongs to the same group of beans and soybeans. In reproduction, pods containing seeds, peas, appear. His choice as a test material was not haphazard: an easy-to-cultivate plant with a short reproductive cycle that produces many seeds.
Since Mendel's time, there have been many varieties available, with features that are easy to compare. For example, the variety in which purple flowers could be compared with the variety that produced white flowers; the one that produced smooth seeds could be compared to the one that produced rough seeds, and so on.
Another advantage of these plants is that stamen and pistil, the components involved in the sexual reproduction of the plant, are enclosed within the same flower, protected by the petals. This favors self-pollination and, by extension, self-fertilization, forming offspring with the same characteristics as parent plants.
From self-pollination, Mendel produced and separated several pure pea strains for the traits he intended to study. For example, for flower color purple flowering plants always produced purple flowering plants as descendants, as did the crossing of plants whose flowers were white. Mendel studied seven traits in pea plants: flower color, stem flower position, seed color, external seed appearance, pod shape, pod color, and plant height.