HEREDITY

Heredity Factor

Heredity is the transmission from one generation to the next of factors that determine the traits of offspring. The development of the understanding of how these factors are inherited is the focus of this article.

Early History.

The Greek philosopher Pythagoras postulated that all traits of an offspring are derived solely from its father’s semen. Aristotle thought that female also produce semen and that embryo is formed by a fusion of both types of semen. He further postulated that both male and female semen are produce by the body’s blood.

Until the 17th century, European medical school thought that hereditary factors in semen were derived from vapors emanating from each body organ. Antony Van Lewenhook, however, viewing human semen through his miscroscope, saw ‘animacules’ . It became generally accepted that sperm were the actual carries of hereditary factors from male to their offspring.

Other biologist studied the ovaries of animal, note the presence of swollen bodies-which they correctly assumed contained eggs –and hypothesized that these eggs were also units of transmission of hereditary factors.

Some biologist of the 17th and 18th centuries believed they saw miniature individuals in sperm or eggs, which led to the doctrine of preformation. According to this theory all parts of an adult are already formed at the beginning of embryonic life, but are formed during the developmental period. His doctrine of development, known as epigenesist, has been substantiated by countless observations and experiments.

It is important to note that the biologist who disproved preformation and advanced the idea of epigenesist 200 years ago still held beliefs similar to those of the ancient Greeks on the origin of the hereditary material. The 18th century scientist thought that the individual body organs produced tiny particles that had the potential parent. These biologist postulated that the articles that the particles from the various organs would be transferred to either sperm or egg, which, upon fusing, would have the potential of forming a total individual.