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Four Billion Years of Genetically Modified Organisms

 “There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”

In this last sentence of his landmark 1859 publication The Origin of Species, Charles Darwin provided us the basis for his remarkable insights.

 

bbc_treeoflife

A stylized tree of life

His theory of evolution by natural selection is based on ‘randomly varying hereditary elements,’ as described by biologist Richard Dawkins. We now know that those hereditary elements are made up of units of DNA, and in the process of high fidelity copying required for life, imperfections or genetic modification occurs, which natural selection acts upon and results in the amazing biological diversity we see around us.

Advances in molecular biology and in DNA sequencing are enabling scientists to trace the genetic continuity and common ancestry of all species now living on earth (see Ayala, 2009). These advances, combined with morphological data, have produced many evolutionary trees describing the evolutionary history of animals, plants, and microbes; and a recent study provided the first attempt of a complete tree of life.

PNAS Tree of life

The first draft of the tree of life is comprised of about 2.3 million named species on the planet

Besides our DNA being the result of billions of years of modification of our ancestral lineage, we also have ‘foreign’ DNA that came from insertion through horizontal transfer.  We know that some eight percent of our DNA came from viral infections resulting in DNA from those viruses being integrated into our genome at various times throughout our evolution. This viral DNA has been linked to several attributes, including the development of the mammalian placenta. It is also reported that other microorganisms are an additional source of horizontally transferred DNA residing in our genome.

DNA derived from viruses has been also been reported in plants, and most intriguingly, the DNA from the soil bacterium Agrobacterium tumefaciens has been found in traditionally bred sweet potatoes. This is the same bacterium used as a vector by biotech seed companies to transfer desired genes into plants, and now it is found that transgenic DNA is a natural feature of the domesticated sweet potato gene pool. The authors note “Our finding, that sweet potato is naturally transgenic while being a widely and traditionally consumed food crop, could affect the current consumer distrust of the safety of transgenic food crops.”

As with many other advances derived from studying the world around us, we have learned a lot about DNA, genes and genomes, and have applied that knowledge for our benefit, especially in medicine and agriculture. Genetic modification, including horizontal gene transfer, is the foundation of biodiversity, and its adoption as a tool of plant breeding mimics in a more precise manner what nature has been doing on a large scale for some four billion years.

Animals and plants have evolved by vertical inheritance of genetic modifications and by horizontal gene transfer. In the case of humans, we appear to be a genetically modified, transgenic chimera. You might conclude that we have met the enemy and it is us, or (my preference) raise a toast – All hail GMOs!

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Darwin, C. 2003. The Origin of Species (1859) and The Voyage of the Beagle (1839). New York, NY: Everyman’s Library, Alfred A. Knopf.

Ayala, F.J. 2009. Molecular Evolution. In M. Ruse & J. Travis (Eds.), Evolution: the First Four Billion Years (pp.132-151). Cambridge, MA: Belknap Harvard.

Tree of Life Home Interactive Site

Dawkins, R. 2004. The Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution. Boston, MA: Houghton Mifflin.

2 comments on “Four Billion Years of Genetically Modified Organisms

  1. Splicing a fish gene into a tomato gene is not the same thing as what this article describes. Nor were any of these life forms patented for the profit of global corporations that use this “property right ” to sue farmers all over the world for saving seeds; which they have been doing for millennia.

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  2. I think you mean splicing a fish gene into a tomato plant or genome; but yes, it is a more precise technique that has been learned from figuring out how it occurs in nature. There are no animal genes in plant foods that are on the market (the last time I looked). However, if there were, how different would the result be from having a meal with a fish on one side of the plate and tomato salad on the other side? In both cases, their DNA will be sliced and diced to pieces upon swallowing and not survive digestion intact, and the same would be the case where a fish gene was present in the tomato genome.

    Patents on plants have been around in the the US since at least 1931, and many common fruits and ornamentals were patented prior to the arrival of transgenic crops. Patented GE crops have been overwhelmingly adopted by soy, corn, canola, cotton and sugar beet farmers because they see benefits in using them, and farmers who do not share that opinion and do not want to be bound by stewardship agreements simply buy other seed and can save them for the next crop. Even without such agreements, for many decades corn farmers have annually purchased hybrid seed because of the yield benefit, and they do not save these seed due to the declining benefit of hybrid vigor in each generation.

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