Lamarckian inheritance

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Lamarckian inheritance (or Lamarckism) was a theory developed by the French scientist Jean-Baptiste Lamarck in 1809[1] that stated the idea that the characteristics developed during an organisms lifetime could be passed onto their offspring by inheritance[2].

Lamarck created two laws to support his theory which were:

His “law of use and disuse” caused him debate the idea that organisms and life itself continued to grow and change continuously. Lamarck believed that as a habitat changed the organisms who lived there also adapted in order to survive in the new habitat. This theory supported the idea that if an organism began to use organs etc. that it usually never used then the organ would become larger and stronger over its lifetime. Similarly, if an organism stopped using organs etc. as much as it used to then they would weaken and decrease in size before disappearing in the end. He even believed that organisms could make new organs or change an organ’s role within its body[4][5][6].

Lamarck's law of acquired traits stated that organisms started off simply and due to them having to changed due to differences in their environment they eventually evolved into more varigated organisms.[7]

The example Lamarck used most often was giraffes' necks. He believed giraffes stretching their necks to reach leaves higher up on trees caused their necks to lengthen. This was then inherited by their offspring, who continued to stretch their necks to reach leaves, causing their necks to lengthen even more. This lengthening of a giraffe’s neck was, as before then carried on from generation to generation, with each extension of the giraffe’s neck being passed down to its offspring until you get the modern day giraffe with its long neck[8][9].

A study conducted in 2009 provides the experimental support for the Lamarckian theory of evolution was proposed by Larry A. Feig. In this research, scientists focused on Long-Term Potential in mice, the mechanism by which the connections between neuronal cells increases in strength and therefore improves the memory. During the experiment researchers intentionally produced genetically engineered mice with memory defect, this mice was raised up in an Enriched Environment that contained social interaction and different kind of exercises. Enriched Environment affected the mice development and improved its memory. The second part of the experiment involved the return of mice into ordinary conditions and mating it, to produce offspring. Results of the study showed that second generation of mice had improved memory, despite the fact that it had a defect[10].

References

  1. O'Neil D. Pre-Darwinian Theories. [Online]. Available from: http://anthro.palomar.edu/evolve/evolve_1.htm [Last accessed 29 November 2015]
  2. Mitteldorf J. Lamarckian Inheritance: Passing what you have learned to your children.[Online]. Available from: http://joshmitteldorf.scienceblog.com/2014/04/23/lamarckian-inheritance-passing-what-you-have-learned-to-your-children/ [Last accessed 29 November 2015]
  3. Understanding evolution. Early Concepts of Evolution: Jean Baptiste Lamarck. [Online]. Available from: http://evolution.berkeley.edu/evolibrary/article/history_09 [Last accessed 29 November 2015].
  4. O'Neil D. Pre-Darwinian Theories. [Online]. Available from: http://anthro.palomar.edu/evolve/evolve_1.htm [Last accessed 29 November 2015].
  5. Understanding evolution. Early Concepts of Evolution: Jean Baptiste Lamarck. [Online]. Available from: http://evolution.berkeley.edu/evolibrary/article/history_09 [Last accessed 29 November 2015].
  6. New World Encyclopedia contributors, 'Acquired characteristics', New World Encyclopedia [Online]. 9 August 2008, 01:32 UTC Available from: http://www.newworldencyclopedia.org/p/index.php?title=Acquired_characteristics&oldid=778309 [Updated 9th August 2008, Last accessed 29 November 2015]
  7. Understanding evolution. Early Concepts of Evolution: Jean Baptiste Lamarck. [Online]. Available from: http://evolution.berkeley.edu/evolibrary/article/history_09 [Last accessed 29 November 2015].
  8. O'Neil D. Pre-Darwinian Theories. [Online]. Available from: http://anthro.palomar.edu/evolve/evolve_1.htm [Last accessed 29 November 2015].
  9. New World Encyclopedia contributors, 'Acquired characteristics', New World Encyclopedia [Online]. 9 August 2008, 01:32 UTC Available from: http://www.newworldencyclopedia.org/p/index.php?title=Acquired_characteristics&oldid=778309 [Updated 9th August 2008, Last accessed 29 November 2015]
  10. 'Transgenerational rescue of a genetic defect in long-term potentiation and memory formation by juvenile enrichment' - Arai JA, Li S, Hartley DM, Feig LA. J Neurosci. 2009 Feb 4;29(5):1496-502. doi: 10.1523/JNEUROSCI.5057-08.2009. Available from: http://www.jneurosci.org/content/29/5/1496.short (accessed 02.12.2015)
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