Pangenesis was
Charles Darwin's hypothetical mechanism for
heredity. He presented this 'provisional hypothesis' in his
1868 work
The Variation of Animals and Plants Under Domestication and felt that it brought 'together a multitude of facts which are at present left disconnected by any efficient cause'. The etymology of the word comes from the
Greek words
pan (a prefix meaning "whole", "encompassing") and
genesis ("birth") or
genos ("origin").
The idea itself is now seen as deeply flawed and not supported by observation, yet it represents Darwin's attempt to explain such diverse phenomena as
Simply put, the theory holds that body cells shed
gemmules which collect in the reproductive organs prior to fertilization. Thus every cell in the body has a 'vote' in the constitution of the offspring. Atavisms arise due to the awaking of long-dormant gemmules while limbs regenerate due to the activation of gemmules from the missing limb which circulate in the main part of the body.
Later Elaboration
In his later work,
The Descent of Man, Darwin elaborated further on the model. In a section on the "Laws of inheritance," Darwin specified that two elements in particular were most important: the
transmission and the
development of inherited characteristics. Darwin's insights were that characteristics could be transmitted which were not at the time of transmission actually being manifest in the parent organism, and that certain traits would manifest themselves at the same point of development (say, old age) in both the parent and child organisms. In order to make sense of his theory of
sexual selection, he also stipulated that certain traits could be passed through organisms but would only develop depending on the sex of the organism in question.
Galton's experiments on rabbits
Darwin's half-cousin
Francis Galton conducted wide-ranging inquiries into heredity which led him to refute Charles Darwin's hypothetical theory of pangenesis. In consultation with Darwin, he set out to see if
gemmules were transported in the blood. In a long series of experiments in 1869 to 1871, he transfused the blood between dissimilar breeds of rabbits, and examined the features of their offspring
[1]. He found no evidence of characters transmitted in the transfused blood . Darwin challenged the validity of Galtons experiment, givng his reasons in an article published in 'Nature'
[2] where he wrote: "Now, in the chapter on Pangenesis in my "Variation of Animals and Plants under Domestication," I have not said one word about the blood, or about any fluid proper to any circulating system. It is, indeed, obvious that the presence of gemmules in the blood can form no necessary part of my hypothesis; for I refer in illustration of it to the lowest animals, such as the Protozoa, which do not possess blood or any vessels; and I refer to plants in which the fluid, when present in the vessels, cannot be considered as true blood." He goes on to admit: "Nevertheless, when I first heard of Mr. Galton's experiments, I did not sufficiently reflect on the subject, and saw not the difficulty of believing in the presence of gemmules in the blood."
Historical precedents
In pangenesis one finds a remarkable similarity to the work of
Pierre Louis Moreau de Maupertuis and Georges-Louis Leclerc%2C Comte de Buffon, specifically their use of the concept of "chemical affinity". A wider historical view finds us analyzing the tension that Newton's concept, the "force of gravity", created between himself and the contintental materialists. The latter felt that this mysterious, invisible force was akin to an invocation of mysticism. Likewise, the argument for a "vis essentialis" in biology has a similar quasi-scientific sound and might serve to remind us of the rudimentary state, and fertile philosophical ground, of theoretical speculations during that earlier period in time.
It is also a remarkable exercise, for the curious student, to juxtapose the theory of pangenesis with modern concepts in developmental biology and genetics, specifically, the origin, migration, and function of the primordial germ cells and the "chemical affinities" regarded in the study of DNA..
External links
See also
Charles Robert Darwin
At the age of 51, Charles Darwin had just published On the Origin of Species.
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Heredity (the adjective is hereditary
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atavism is a real or supposed evolutionary throwback, such as traits reappearing which had disappeared generations ago.[1] Atavisms occur because genes for previously existing phenotypical features are often preserved in DNA, even though the genes are not expressed in
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hybrid has two meanings.[1]
The first meaning is the result of interbreeding between two animals or plants of different taxa. Hybrids between different species within the same genus are sometimes known as interspecific hybrids or crosses.
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Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck (August 1, 1744 – December 18, 1829) was a French soldier, naturalist, academic and an early proponent of the idea that evolution occurred and proceeded in accordance with natural laws.
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In biology, regeneration is an organism's ability to replace body parts. Aside from being used to generally describe any number of specific healing processes, regeneration also is a specific method of healing that is noted for its ability to regrow lost limbs, severed nerve
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Gemmules were imagined particles of inheritance proposed by Charles Darwin as part of his Pangenesis theory. This appeared in his book Variation of Plants and Animals Under Domestication, published in 1868, nine years after the publication of his famous book
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The Descent of Man, and Selection in Relation to Sex is a book on evolutionary theory by English naturalist Charles Darwin, first published in 1871. It was Darwin's second large book on evolutionary theory, following his 1859 work, The Origin of Species
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Sexual selection is the theory proposed by Charles Darwin that states that the frequency of traits can increase or decrease depending on the attractiveness of the bearer. Biologists today distinguish between "male to male combat" (it is usually males who fight), "mate choice"
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Francis Galton
Francis Galton
Born January 16 1822(1822--)
Birmingham, England
Died January 17 1911 (aged 90)
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Gemmules were imagined particles of inheritance proposed by Charles Darwin as part of his Pangenesis theory. This appeared in his book Variation of Plants and Animals Under Domestication, published in 1868, nine years after the publication of his famous book
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Pierre-Louis Moreau de Maupertuis (July 17, 1698 – July 27, 1759) was a French mathematician, philosopher and man of letters. He is often credited with having invented the principle of least action.
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Lamarckism or Lamarckian evolution refers to the once widely accepted idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring (also known as based on heritability of acquired characteristics or "soft inheritance").
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