Preformationism is the theory that all organisms were created at the same time, and that succeeding generations grow from homunculi, animalcules, or other fully-formed but miniature versions of themselves that have existed since the beginning of creation. The concept of a homunculus ( Latin for "little man" plural "homunculi" the diminutive of homo, "man" is often used to illustrate Animalcule ("little animal" from Latin animal + the diminutive suffix -culum) is an older term for a microscopic Animal or protozoan
In the case of humans, philosophers and theologians have conjectured that every individual existed as a homunculus in Adam's testicles (spermism) or Eve's ovaries (ovism). See also Adam and Eve Adam ( Hebrew: אָדָם was according to a literal interpretation of Genesis, the first man created by In Genesis, Eve is the first woman the wife of Adam. God created her from Adam's rib as his helpmate
Epigenesis, in contrast, is based on the idea that "each embryo or organism is gradually produced from an undifferentiated mass by a series of steps and stages during which new parts are added. " (Magner 2002, p. 154) [1]
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Philosophical development
Pythagoras was one of the first to elaborate a theory of generation, the biological production of offspring. "Pythagoras of Samos" redirects here For the Samian statuary of the same name see Pythagoras (sculptor. Generation (from the Greek γενεά) also known as procreation, is the act of producing Offspring. He advocated a patrocline theory whereas males contributed the essential characteristics of their offspring while females contributed only a material substrate. Pythagorus' theory heavily inspired Aristotle, who elaborated both upon preformation and epigenesis, two distinct theories of generation. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Subsequent theorists such as Galen, Realdo Colombo and Girolamo Fabrici built upon Aristotle's theories, which were prevalent well into the 17th century. Galen ( Greek: Γαληνός Galēnos; Latin: Claudius Galenus, Aelius Galenus, Claudius Aelius Galenus, or Matteo Realdo Colombo or Renaldus Columbus (c 1516 - 1559 was an Italian professor of Anatomy and a surgeon at the University of Padua Hieronymus Fabricius is the Latin name by which the Italian Anatomist Girolamo Fabrici ( May 20 1537 &ndash May 21 [1]
In 1651 William Harvey published On the Generation of Animals (De Generatione), a seminal work on embryology that contradicted many of Aristotle's fundamental ideas on the matter. William Harvey ( April 1, 1578 – June 3, 1657) was an English Physician who is credited with being the first in William Harvey ( April 1, 1578 – June 3, 1657) was an English Physician who is credited with being the first in Embryology (from Greek grc ἔμβρυον embryon, "unborn embryo" and grc -λογία -logia) is the study of the development However, Harvey couldn't support his ideas on epigenesis with evidence of a convincing mechanism of generation because animal gametes were too small to be seen without a microscope, and hormones were unknown. A gamete (from Ancient Greek γαμέτης; translated gamete = wife gametes = husband is a cell that fuses with another gamete A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body Although Harvey once postulated a "spiritous substance" that exerted its effect on the female body, he later rejected it as superfluous and thus unscientific. He guessed instead that fertilization occurred through a mysterious transference by contact, or contagion. [1]
Harvey's reformationist theories seemed to be compatible with natural philosophy at the time and to require less-radical hypotheses than epigenesis did. For the current in the 19th century German idealism see Naturphilosophie Natural philosophy or the philosophy of nature (from Epigenesis also suffered from perceived disharmony with dominant Christian theology because it suggested that unorganized matter could generate life without the need for God's intervention. Christian Theology is discourse concerning Christian faith Christian theologians use biblical Exegesis, rational analysis and argument
The groundbreaking scientific insights provided by Galileo and Newton, and Cartesianism provided a mechanistic framework that seemed to support preformationism. The period which many historians of science call the Scientific Revolution can be roughly dated as having begun in 1543 the year in which Nicolaus Copernicus published Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Cartesianism is the name given to the philosophical doctrine (or school of René Descartes. In Philosophy, mechanism is a Theory that all natural phenomena can be explained by physical causes Because of technological limitations, there was no available mechanical explanation for epigenesis. It was simpler and more convenient to postulate preformed miniature organisms that expanded in accordance with mechanical laws. Some naturalists claimed to actually see miniature preformed animals (animalcules) in eggs and miniature plants in seeds. Animalcule ("little animal" from Latin animal + the diminutive suffix -culum) is an older term for a microscopic Animal or protozoan [1]The term homunculus was used in the discussion of conception and birth. The concept of a homunculus ( Latin for "little man" plural "homunculi" the diminutive of homo, "man" is often used to illustrate
Elaboration of preformationism
After the discovery of spermatozoa in 1677 by Dutch microscopist Antonie van Leeuwenhoek, the epigenist theory proved more difficult to defend: how could complex organisms such as human beings develop from such simple organisms? Henceforth, Joseph de Aromatari, and then Marcello Malpighi and Jan Swammerdam made observations using microscopes in the late 17th century, and interpreted their findings to develop the preformationist theory. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known Antonie Philips van Leeuwenhoek (October 24 1632 &ndash August 30 1723 was a Dutch tradesman and Scientist from Delft, the Netherlands Marcello Malpighi ( March 10, 1628 - September 30, 1694) was an Italian doctor who gave his name to several physiological features Jan Swammerdam ( February 12, 1637, Amsterdam - February 17, 1680) was a Dutch biologist and microscopist During two centuries, until the invention of cell theory, preformationists would oppose epigenicists, and, inside the preformationist camp, spermists (who claimed the homonculus must come from the man) to ovists, who located the homonculus in the ova. Cell Theory refers to the idea that cells are the basic unit of structure in every living thing
Dutch microscopist Antonie van Leeuwenhoek was one of the first to observe spermatozoa. Antonie Philips van Leeuwenhoek (October 24 1632 &ndash August 30 1723 was a Dutch tradesman and Scientist from Delft, the Netherlands He described the spermatozoa of about 30 species, and thought he saw in semen, "all manner of great and small vessels, so various and so numerous that I do not doubt that they be nerves, arteries and veins. . . And when I saw them, I felt convinced that, in no full grown body, are there any vessels which may not be found likewise in semen. " (Friedman 76-7)[2]
Leeuwenhoek discovered that the origin of semen was the testicles and was a committed preformationist and spermist. He reasoned that the movement of spermatozoa was evidence of animal life, which presumed a complex structure and, for human sperm, a soul. (Friedman 79)[2]
In 1694, Nicolas Hartsoeker produce an image of tiny men inside the sperm, which he called "animalcule" or "homunculus. Nicolaas Hartsoeker ( 26 March 1656, Gouda - 10 December 1725, Utrecht) was a Dutch Mathematician The concept of a homunculus ( Latin for "little man" plural "homunculi" the diminutive of homo, "man" is often used to illustrate "
Philosopher Nicolas Malebranche was the first to advance the hypothesis that each embryo could contain even smaller embryos ad infinitum, like a Matryoshka doll. "Malebranche" redirects here For the fictional demons see Malebolge. Ad infinitum is a Latin phrase meaning " to Infinity." In context it usually means "continue forever without A matryoshka doll or a Russian nested doll, also called a stacking doll is a set of dolls of decreasing sizes placed one inside the other According to Malebranche, "an infinite series of plants and animals were contained within the seed or the egg, but only naturalists with sufficient skill and experience could detect their presence. " (Magner 158-9)[1] In fact, Malebranche only alleged this, observing that if microscopes enabled us to see very little animals and plants, maybe even smaller creatures could exist. He claimed that it was not unreasonable to believe that "they are infinite trees in only one seed," as he stated that we could already see chicken in eggs, tulips in bulbs, frogs in eggs. From this, he hypothethized that "all the bodies of humans and animals," already born and yet to be born, "were perhaps produced as soon as the creation of the world. " [3]
Ova were known in some non-mammalian species, and semen was thought to spur the development of the preformed organism contained therein. An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. Physiological aspects Internal and external fertilization Depending on the Species, spermatozoa can fertilize The theory that located the homonculus in the egg was called ovism. But when spermatozoa were discovered, a rival camp of spermists sprang up, claiming that the homunculus must come from the male. In fact, the term "spermatozoon," coined by Karl Ernst van Baer, means "seed animals. "[1]
With the discovery of sperm and the concept of spermism came a religious quandary. Why would so many little animals be wasted with each ejaculation of semen? Pierre Lyonet said the wastage proved that sperm couldn't be the seeds of life. Leibniz supported a theory called panspermism that the wasted sperm might actually be scattered (for example, by the wind) and generate life wherever they found a suitable host. Panspermia ( Gk. πάς/πάν (pas/pan all and σπέρμα ( sperma, seed is the Hypothesis that "seeds" of Life exist already
Leibniz also believed that “death is only a transformation enveloped through diminution,” meaning that not only have organisms always existed in their living form, but that they will always exist, body united to soul, even past apparent death. [4]
In the 18th century, some animalculists thought that an animal's sperm behaved like the adult animal, and recorded such observations. Some, but not all, preformationists at this time claimed to see miniature organisms inside the sex cells. But about this time, spermists began to use more abstract arguments to support their theories.
Jean Astruc, noting that parents of both sexes seemed to influence the characteristics of their offspring, suggested that the animalcule came from the sperm and was then shaped as it passed into the egg. Jean Astruc ( Sauves, Auvergne, March 19, 1684 - Paris, May 5, 1766) was a famous professor of medicine at Buffon and Pierre Louis Moreau also advocated theories to explain this phenomenon. Georges-Louis Leclerc fr Comte de Buffon ( September 7, 1707 April 16, 1788) was a French naturalist, mathematician biologist Pierre-Louis Moreau de Maupertuis ( July 17, 1698 &ndash July 27, 1759) was a French Mathematician, Philosopher [1]
Preformationism, especially ovism, was the dominant theory of generation during the 18th century. It competed with spontaneous generation and epigenesis, but those two theories were often rejected on the grounds that inert matter could not produce life without God's intervention. In the Natural sciences, Abiogenesis, or origin of life, is the study of how Life on Earth emerged from Inanimate Organic
Some animals' regeneration capabilities challenged preformationism, and Abraham Trembley's studies of the hydra convinced various authorities to reject their former views. Abraham Trembley ( 3 September 1710 &ndash 12 May 1784) was a Swiss naturalist. Hydra is a Genus of simple fresh-water animals possessing radial symmetry.
Lazaro Spallanzani experimented with regeneration and semen, but failed to discern the importance of spermatozoa, dismissing them as parasitic worms and concluding instead that it was the liquid portion of semen that caused the preformed organism in the ovum to develop. Lazzaro Spallanzani ( January 10, 1729 - February 12, 1799) was an Italian Biologist whose research of Biogenesis An ovum (plural ova) is a Haploid Female reproductive cell or Gamete.
Criticisms and cell theory
Caspar Friedrich Wolff, an epigenicist, was an 18th-century exception who argued for objectivity and freedom from religious influence on scientific questions. Caspar Friedrich Wolff ( January 18, 1733 &ndash February 22, 1794) was a German Physiologist and one of the founders of
Despite careful observation of developing embryos, epigenesis suffered from a lack of a theoretical mechanism of generation. Wolff proposed an "essential force" as the agent of change, and Immanuel Kant with Johann Friedrich Blumenbach proposed a "developing drive" or Bildungstrieb, a concept related to self-organization. Immanuel Kant (ɪmanuəl kant 22 April 1724 12 February 1804 was an 18th-century German Philosopher from the Prussian city of Königsberg Johann Friedrich Blumenbach ( May 11, 1752 – January 22, 1840) was a German doctor and Physiologist, Self-organization is a process of Attraction and repulsion in which the internal organization of a System, normally an open system, increases
Naturalists of the late 18th century and the 19th century embraced Wolff's philosophy, but primarily because they rejected the application of mechanistic development, as seen in the expansion of miniature organisms. It wasn't until the late 19th century that preformationism was discarded in the face of cell theory. Cell Theory refers to the idea that cells are the basic unit of structure in every living thing Now scientists "realized that they need not treat living organisms as machines, nor give up all hope of ever explaining the mechanisms that govern living beings. " (Magner 173)[1]
When John Dalton's atomic theory of matter superseded Descartes' philosophy of infinite divisibility at the beginning of the 19th century, preformationism was struck a further blow. John Dalton FRS (6 September 1766 &ndash 27 July 1844 was an English Chemist, Meteorologist and Physicist. This article focuses on the historical models of the atom For a history of the study of how atoms combine to form molecules see History of the molecule. Science is a body of empirical, theoretical, and practical knowledge about the natural world, produced by a global community of researchers The concept of infinite divisibility arises in different ways in Philosophy, Physics, Economics, Order theory (a branch of mathematics and There simply wasn't enough space at the bottom of the spectrum to accommodate infinitely stacked animalcules, without bumping into the constituent parts of matter. (Gee 43)[5]
References
- ^ a b c d e f g h Magner, Lois. A History of the Life Sciences. New York: Marcel Dekker, Inc, 2002
- ^ a b Friedman, David M. A Mind of Its Own: A Cultural History of the Penis. New York: The Free Press, 2001
- ^ Nicolas Malebranche, De la recherche de la vérité (The Search After Truth), book I, chapter VI, first section (1674-1675)
- ^ Smith, Justin Erik. "Malebranche" redirects here For the fictional demons see Malebolge. “Leibniz’s Preformationism: Between Metaphysics and Biology. ”Analecta Husserliana, the Yearbook of Phenomenological Research. Volume LXXVII. (2002) 161-192.
- ^ Gee, Henry. Jacob’s Ladder: The History of the Human Genome. New York: W. W. Norton & Company, Inc, 2004
- Clara Pinto Correia, The Ovary of Eve: Egg and Sperm Preformation, Chicago: University of Chicago Press, 1997. ISBN 0-226-66952-1